logger fixup

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

.github/workflows/job_coverage.yml

@@ -3,14 +3,16 @@ name: coverage
 on:
   push:
     branches: [ main, v3, v4 ]
+    paths-ignore:
+      - '.github/**'
+      - '.gitea/**'
   pull_request:
     branches: [ main, v3, v4 ]
-  # Allows you to run this workflow manually from the Actions tab
-  workflow_dispatch:
 
 jobs:
 
   build:
+    if: github.server_url != 'https://github.com'
     runs-on: ubuntu-latest
     steps:
     - name: checkout code
@@ -22,7 +24,7 @@ jobs:
       uses: actions/setup-go@v5
       with:
         cache-dependency-path: "**/*.sum"
-        go-version: 'stable' 
+        go-version: 'stable'
 
     - name: test coverage
       run: |
@@ -39,8 +41,8 @@ jobs:
       name: autocommit
       with:
         commit_message: Apply Code Coverage Badge
-        skip_fetch: true
+        skip_fetch: false
-        skip_checkout: true
+        skip_checkout: false
         file_pattern: ./README.md
 
     - name: push
@@ -48,4 +50,4 @@ jobs:
       uses: ad-m/github-push-action@master
       with:
         github_token: ${{ github.token }}
-        branch: ${{ github.ref }}
+        branch: ${{ github.ref }}

.github/workflows/job_lint.yml

@@ -3,10 +3,10 @@ name: lint
 on:
   pull_request:
     types: [opened, reopened, synchronize]
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
+    paths-ignore:
-    - v3
+      - '.github/**'
-    - v4
+      - '.gitea/**'
 
 jobs:
   lint:
@@ -20,10 +20,10 @@ jobs:
       uses: actions/setup-go@v5
       with:
         cache-dependency-path: "**/*.sum"
-        go-version: 'stable' 
+        go-version: 'stable'
     - name: setup deps
       run: go get -v ./...
     - name: run lint
-      uses: https://github.com/golangci/golangci-lint-action@v6
+      uses: golangci/golangci-lint-action@v6
       with:
         version: 'latest'

.github/workflows/job_test.yml

@@ -3,15 +3,12 @@ name: test
 on:
   pull_request:
     types: [opened, reopened, synchronize]
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
-    - v3
-    - v4
   push:
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
+    paths-ignore:
-    - v3
+      - '.github/**'
-    - v4
+      - '.gitea/**'
 
 jobs:
   test:

.github/workflows/job_tests.yml

@@ -3,15 +3,12 @@ name: test
 on:
   pull_request:
     types: [opened, reopened, synchronize]
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
-    - v3
-    - v4
   push:
-    branches:
+    branches: [ master, v3, v4 ]
-    - master
+    paths-ignore:
-    - v3
+      - '.github/**'
-    - v4
+      - '.gitea/**'
 
 jobs:
   test:
@@ -35,19 +32,19 @@ jobs:
         go-version: 'stable'
     - name: setup go work
       env:
-        GOWORK: /workspace/${{ github.repository_owner }}/go.work
+        GOWORK: ${{ github.workspace }}/go.work
       run: |
         go work init
         go work use .
         go work use micro-tests
     - name: setup deps
       env:
-        GOWORK: /workspace/${{ github.repository_owner }}/go.work
+        GOWORK: ${{ github.workspace }}/go.work
       run: go get -v ./...
     - name: run tests
       env:
         INTEGRATION_TESTS: yes
-        GOWORK: /workspace/${{ github.repository_owner }}/go.work
+        GOWORK: ${{ github.workspace }}/go.work
       run: |
         cd micro-tests
         go test -mod readonly -v ./... || true

.golangci.yml

@@ -1,5 +1,5 @@
 run:
   concurrency: 8
-  deadline: 5m
+  timeout: 5m
   issues-exit-code: 1
   tests: true

README.md

@@ -1,28 +1,28 @@
 # Micro
-![Coverage](https://img.shields.io/badge/Coverage-43.9%25-yellow)
+![Coverage](https://img.shields.io/badge/Coverage-34.1%25-yellow)
 [![License](https://img.shields.io/:license-apache-blue.svg)](https://opensource.org/licenses/Apache-2.0)
-[![Doc](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/go.unistack.org/micro/v4?tab=overview)
+[![Doc](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/go.unistack.org/micro/v3?tab=overview)
-[![Status](https://git.unistack.org/unistack-org/micro/actions/workflows/job_tests.yml/badge.svg?branch=v4)](https://git.unistack.org/unistack-org/micro/actions?query=workflow%3Abuild+branch%3Av4+event%3Apush)
+[![Status](https://git.unistack.org/unistack-org/micro/actions/workflows/job_tests.yml/badge.svg?branch=v3)](https://git.unistack.org/unistack-org/micro/actions?query=workflow%3Abuild+branch%3Av3+event%3Apush)
-[![Lint](https://goreportcard.com/badge/go.unistack.org/micro/v4)](https://goreportcard.com/report/go.unistack.org/micro/v4)
+[![Lint](https://goreportcard.com/badge/go.unistack.org/micro/v3)](https://goreportcard.com/report/go.unistack.org/micro/v3)
 
 Micro is a standard library for microservices.
 
 ## Overview
 
-Micro provides the core requirements for distributed systems development including RPC and Event driven communication. 
+Micro provides the core requirements for distributed systems development including SYNC and ASYNC communication. 
 
 ## Features
 
-Micro abstracts away the details of distributed systems. Here are the main features.
+Micro abstracts away the details of distributed systems. Main features:
 
 - **Dynamic Config** - Load and hot reload dynamic config from anywhere. The config interface provides a way to load application 
-level config from any source such as env vars, cmdline, file, consul, vault... You can merge the sources and even define fallbacks.
+level config from any source such as env vars, cmdline, file, consul, vault, etc... You can merge the sources and even define fallbacks.
 
 - **Data Storage** - A simple data store interface to read, write and delete records. It includes support for memory, file and 
 s3. State and persistence becomes a core requirement beyond prototyping and Micro looks to build that into the framework.
 
 - **Service Discovery** - Automatic service registration and name resolution. Service discovery is at the core of micro service 
-development. When service A needs to speak to service B it needs the location of that service.
+development.
 
 - **Message Encoding** - Dynamic message encoding based on content-type. The client and server will use codecs along with content-type 
 to seamlessly encode and decode Go types for you. Any variety of messages could be encoded and sent from different clients. The client 

SECURITY.md

@@ -1,15 +0,0 @@
-# Security Policy
-
-## Supported Versions
-
-Use this section to tell people about which versions of your project are
-currently being supported with security updates.
-
-| Version | Supported          |
-| ------- | ------------------ |
-| 3.7.x   | :white_check_mark: |
-| < 3.7.0 | :x:                |
-
-## Reporting a Vulnerability
-
-If you find any issue, please create github issue in this repo

broker/broker.go

@@ -6,8 +6,8 @@ import (
 	"errors"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 // DefaultBroker default memory broker
@@ -18,10 +18,6 @@ var (
 	ErrNotConnected = errors.New("broker not connected")
 	// ErrDisconnected returns when broker disconnected
 	ErrDisconnected = errors.New("broker disconnected")
-	// ErrInvalidMessage returns when invalid Message passed
-	ErrInvalidMessage = errors.New("invalid message")
-	// ErrInvalidHandler returns when subscriber passed to Subscribe
-	ErrInvalidHandler = errors.New("invalid handler")
 	// DefaultGracefulTimeout
 	DefaultGracefulTimeout = 5 * time.Second
 )
@@ -40,12 +36,14 @@ type Broker interface {
 	Connect(ctx context.Context) error
 	// Disconnect disconnect from broker
 	Disconnect(ctx context.Context) error
-	// NewMessage create new broker message to publish.
-	NewMessage(ctx context.Context, hdr metadata.Metadata, body interface{}, opts ...PublishOption) (Message, error)
 	// Publish message to broker topic
-	Publish(ctx context.Context, topic string, messages ...Message) error
+	Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error
 	// Subscribe subscribes to topic message via handler
-	Subscribe(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error)
+	Subscribe(ctx context.Context, topic string, h Handler, opts ...SubscribeOption) (Subscriber, error)
+	// BatchPublish messages to broker with multiple topics
+	BatchPublish(ctx context.Context, msgs []*Message, opts ...PublishOption) error
+	// BatchSubscribe subscribes to topic messages via handler
+	BatchSubscribe(ctx context.Context, topic string, h BatchHandler, opts ...SubscribeOption) (Subscriber, error)
 	// String type of broker
 	String() string
 	// Live returns broker liveness
@@ -57,27 +55,72 @@ type Broker interface {
 }
 
 type (
-	FuncPublish   func(ctx context.Context, topic string, messages ...Message) error
+	FuncPublish        func(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error
-	HookPublish   func(next FuncPublish) FuncPublish
+	HookPublish        func(next FuncPublish) FuncPublish
-	FuncSubscribe func(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error)
+	FuncBatchPublish   func(ctx context.Context, msgs []*Message, opts ...PublishOption) error
-	HookSubscribe func(next FuncSubscribe) FuncSubscribe
+	HookBatchPublish   func(next FuncBatchPublish) FuncBatchPublish
+	FuncSubscribe      func(ctx context.Context, topic string, h Handler, opts ...SubscribeOption) (Subscriber, error)
+	HookSubscribe      func(next FuncSubscribe) FuncSubscribe
+	FuncBatchSubscribe func(ctx context.Context, topic string, h BatchHandler, opts ...SubscribeOption) (Subscriber, error)
+	HookBatchSubscribe func(next FuncBatchSubscribe) FuncBatchSubscribe
 )
 
-// Message is given to a subscription handler for processing
+// Handler is used to process messages via a subscription of a topic.
-type Message interface {
+type Handler func(Event) error
-	// Context for the message.
+
+// Events contains multiple events
+type Events []Event
+
+// Ack try to ack all events and return
+func (evs Events) Ack() error {
+	var err error
+	for _, ev := range evs {
+		if err = ev.Ack(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// SetError sets error on event
+func (evs Events) SetError(err error) {
+	for _, ev := range evs {
+		ev.SetError(err)
+	}
+}
+
+// BatchHandler is used to process messages in batches via a subscription of a topic.
+type BatchHandler func(Events) error
+
+// Event is given to a subscription handler for processing
+type Event interface {
+	// Context return context.Context for event
 	Context() context.Context
-	// Topic returns message destination topic.
+	// Topic returns event topic
 	Topic() string
-	// Header returns message headers.
+	// Message returns broker message
-	Header() metadata.Metadata
+	Message() *Message
-	// Body returns broker message []byte slice
+	// Ack acknowledge message
-	Body() []byte
-	// Unmarshal try to decode message body to dst.
-	// This is helper method that uses codec.Unmarshal.
-	Unmarshal(dst interface{}, opts ...codec.Option) error
-	// Ack acknowledge message if supported.
 	Ack() error
+	// Error returns message error (like decoding errors or some other)
+	Error() error
+	// SetError set event processing error
+	SetError(err error)
+}
+
+// Message is used to transfer data
+type Message struct {
+	// Header contains message metadata
+	Header metadata.Metadata
+	// Body contains message body
+	Body codec.RawMessage
+}
+
+// NewMessage create broker message with topic filled
+func NewMessage(topic string) *Message {
+	m := &Message{Header: metadata.New(2)}
+	m.Header.Set(metadata.HeaderTopic, topic)
+	return m
 }
 
 // Subscriber is a convenience return type for the Subscribe method

broker/context.go

@@ -51,3 +51,13 @@ func SetOption(k, v interface{}) Option {
 		o.Context = context.WithValue(o.Context, k, v)
 	}
 }
+
+// SetPublishOption returns a function to setup a context with given value
+func SetPublishOption(k, v interface{}) PublishOption {
+	return func(o *PublishOptions) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}

broker/context_test.go

@@ -49,6 +49,17 @@ func TestSetSubscribeOption(t *testing.T) {
 	}
 }
 
+func TestSetPublishOption(t *testing.T) {
+	type key struct{}
+	o := SetPublishOption(key{}, "test")
+	opts := &PublishOptions{}
+	o(opts)
+
+	if v, ok := opts.Context.Value(key{}).(string); !ok || v == "" {
+		t.Fatal("SetPublishOption not works")
+	}
+}
+
 func TestSetOption(t *testing.T) {
 	type key struct{}
 	o := SetOption(key{}, "test")

broker/memory/memory.go

@@ -2,104 +2,66 @@ package broker
 
 import (
 	"context"
-	"strings"
 	"sync"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/options"
+	maddr "go.unistack.org/micro/v3/util/addr"
-	maddr "go.unistack.org/micro/v4/util/addr"
+	"go.unistack.org/micro/v3/util/id"
-	"go.unistack.org/micro/v4/util/id"
+	mnet "go.unistack.org/micro/v3/util/net"
-	mnet "go.unistack.org/micro/v4/util/net"
+	"go.unistack.org/micro/v3/util/rand"
-	"go.unistack.org/micro/v4/util/rand"
 )
 
-type Broker struct {
+type memoryBroker struct {
-	funcPublish   broker.FuncPublish
+	funcPublish        broker.FuncPublish
-	funcSubscribe broker.FuncSubscribe
+	funcBatchPublish   broker.FuncBatchPublish
-	subscribers   map[string][]*Subscriber
+	funcSubscribe      broker.FuncSubscribe
-	addr          string
+	funcBatchSubscribe broker.FuncBatchSubscribe
-	opts          broker.Options
+	subscribers        map[string][]*memorySubscriber
+	addr               string
+	opts               broker.Options
 	sync.RWMutex
 	connected bool
 }
 
-type memoryMessage struct {
+type memoryEvent struct {
-	c     codec.Codec
+	err     error
-	topic string
+	message interface{}
-	ctx   context.Context
-	body  []byte
-	hdr   metadata.Metadata
-	opts  broker.PublishOptions
-}
-
-func (m *memoryMessage) Ack() error {
-	return nil
-}
-
-func (m *memoryMessage) Body() []byte {
-	return m.body
-}
-
-func (m *memoryMessage) Header() metadata.Metadata {
-	return m.hdr
-}
-
-func (m *memoryMessage) Context() context.Context {
-	return m.ctx
-}
-
-func (m *memoryMessage) Topic() string {
-	return ""
-}
-
-func (m *memoryMessage) Unmarshal(dst interface{}, opts ...codec.Option) error {
-	return m.c.Unmarshal(m.body, dst)
-}
-
-type Subscriber struct {
-	ctx     context.Context
-	exit    chan bool
-	handler interface{}
-	id      string
 	topic   string
-	opts    broker.SubscribeOptions
+	opts    broker.Options
 }
 
-func (b *Broker) newCodec(ct string) (codec.Codec, error) {
+type memorySubscriber struct {
-	if idx := strings.IndexRune(ct, ';'); idx >= 0 {
+	ctx          context.Context
-		ct = ct[:idx]
+	exit         chan bool
-	}
+	handler      broker.Handler
-	b.RLock()
+	batchhandler broker.BatchHandler
-	c, ok := b.opts.Codecs[ct]
+	id           string
-	b.RUnlock()
+	topic        string
-	if ok {
+	opts         broker.SubscribeOptions
-		return c, nil
-	}
-	return nil, codec.ErrUnknownContentType
 }
 
-func (b *Broker) Options() broker.Options {
+func (m *memoryBroker) Options() broker.Options {
-	return b.opts
+	return m.opts
 }
 
-func (b *Broker) Address() string {
+func (m *memoryBroker) Address() string {
-	return b.addr
+	return m.addr
 }
 
-func (b *Broker) Connect(ctx context.Context) error {
+func (m *memoryBroker) Connect(ctx context.Context) error {
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
 	default:
 	}
 
-	b.Lock()
+	m.Lock()
-	defer b.Unlock()
+	defer m.Unlock()
 
-	if b.connected {
+	if m.connected {
 		return nil
 	}
 
@@ -113,126 +75,154 @@ func (b *Broker) Connect(ctx context.Context) error {
 	// set addr with port
 	addr = mnet.HostPort(addr, 10000+i)
 
-	b.addr = addr
+	m.addr = addr
-	b.connected = true
+	m.connected = true
 
 	return nil
 }
 
-func (b *Broker) Disconnect(ctx context.Context) error {
+func (m *memoryBroker) Disconnect(ctx context.Context) error {
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
 	default:
 	}
 
-	b.Lock()
+	m.Lock()
-	defer b.Unlock()
+	defer m.Unlock()
 
-	if !b.connected {
+	if !m.connected {
 		return nil
 	}
 
-	b.connected = false
+	m.connected = false
 	return nil
 }
 
-func (b *Broker) Init(opts ...broker.Option) error {
+func (m *memoryBroker) Init(opts ...broker.Option) error {
 	for _, o := range opts {
-		o(&b.opts)
+		o(&m.opts)
 	}
 
-	b.funcPublish = b.fnPublish
+	m.funcPublish = m.fnPublish
-	b.funcSubscribe = b.fnSubscribe
+	m.funcBatchPublish = m.fnBatchPublish
+	m.funcSubscribe = m.fnSubscribe
+	m.funcBatchSubscribe = m.fnBatchSubscribe
 
-	b.opts.Hooks.EachPrev(func(hook options.Hook) {
+	m.opts.Hooks.EachPrev(func(hook options.Hook) {
 		switch h := hook.(type) {
 		case broker.HookPublish:
-			b.funcPublish = h(b.funcPublish)
+			m.funcPublish = h(m.funcPublish)
+		case broker.HookBatchPublish:
+			m.funcBatchPublish = h(m.funcBatchPublish)
 		case broker.HookSubscribe:
-			b.funcSubscribe = h(b.funcSubscribe)
+			m.funcSubscribe = h(m.funcSubscribe)
+		case broker.HookBatchSubscribe:
+			m.funcBatchSubscribe = h(m.funcBatchSubscribe)
 		}
 	})
 
 	return nil
 }
 
-func (b *Broker) NewMessage(ctx context.Context, hdr metadata.Metadata, body interface{}, opts ...broker.PublishOption) (broker.Message, error) {
+func (m *memoryBroker) Publish(ctx context.Context, topic string, msg *broker.Message, opts ...broker.PublishOption) error {
-	options := broker.NewPublishOptions(opts...)
+	return m.funcPublish(ctx, topic, msg, opts...)
-	m := &memoryMessage{ctx: ctx, hdr: hdr, opts: options}
-	c, err := b.newCodec(m.opts.ContentType)
-	if err == nil {
-		m.body, err = c.Marshal(body)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	return m, nil
 }
 
-func (b *Broker) Publish(ctx context.Context, topic string, messages ...broker.Message) error {
+func (m *memoryBroker) fnPublish(ctx context.Context, topic string, msg *broker.Message, opts ...broker.PublishOption) error {
-	return b.funcPublish(ctx, topic, messages...)
+	msg.Header.Set(metadata.HeaderTopic, topic)
+	return m.publish(ctx, []*broker.Message{msg}, opts...)
 }
 
-func (b *Broker) fnPublish(ctx context.Context, topic string, messages ...broker.Message) error {
+func (m *memoryBroker) BatchPublish(ctx context.Context, msgs []*broker.Message, opts ...broker.PublishOption) error {
-	return b.publish(ctx, topic, messages...)
+	return m.funcBatchPublish(ctx, msgs, opts...)
 }
 
-func (b *Broker) publish(ctx context.Context, topic string, messages ...broker.Message) error {
+func (m *memoryBroker) fnBatchPublish(ctx context.Context, msgs []*broker.Message, opts ...broker.PublishOption) error {
-	b.RLock()
+	return m.publish(ctx, msgs, opts...)
-	if !b.connected {
+}
-		b.RUnlock()
+
+func (m *memoryBroker) publish(ctx context.Context, msgs []*broker.Message, opts ...broker.PublishOption) error {
+	m.RLock()
+	if !m.connected {
+		m.RUnlock()
 		return broker.ErrNotConnected
 	}
-	b.RUnlock()
+	m.RUnlock()
+
+	var err error
 
 	select {
 	case <-ctx.Done():
 		return ctx.Err()
 	default:
-	}
+		options := broker.NewPublishOptions(opts...)
 
-	b.RLock()
+		msgTopicMap := make(map[string]broker.Events)
-	subs, ok := b.subscribers[topic]
+		for _, v := range msgs {
-	b.RUnlock()
+			p := &memoryEvent{opts: m.opts}
-	if !ok {
-		return nil
-	}
 
-	var err error
+			if m.opts.Codec == nil || options.BodyOnly {
-
+				p.topic, _ = v.Header.Get(metadata.HeaderTopic)
-	for _, sub := range subs {
+				p.message = v.Body
-		switch s := sub.handler.(type) {
+			} else {
-		default:
+				p.topic, _ = v.Header.Get(metadata.HeaderTopic)
-			if b.opts.Logger.V(logger.ErrorLevel) {
+				p.message, err = m.opts.Codec.Marshal(v)
-				b.opts.Logger.Error(ctx, "broker  handler error", broker.ErrInvalidHandler)
-			}
-		case func(broker.Message) error:
-			for _, message := range messages {
-				msg, ok := message.(*memoryMessage)
-				if !ok {
-					if b.opts.Logger.V(logger.ErrorLevel) {
-						b.opts.Logger.Error(ctx, "broker handler error", broker.ErrInvalidMessage)
-					}
-				}
-				msg.topic = topic
-				if err = s(msg); err == nil && sub.opts.AutoAck {
-					err = msg.Ack()
-				}
 				if err != nil {
-					if b.opts.Logger.V(logger.ErrorLevel) {
+					return err
-						b.opts.Logger.Error(ctx, "broker handler error", err)
-					}
 				}
 			}
-		case func([]broker.Message) error:
+			msgTopicMap[p.topic] = append(msgTopicMap[p.topic], p)
-			if err = s(messages); err == nil && sub.opts.AutoAck {
+		}
-				for _, message := range messages {
+
-					err = message.Ack()
+		beh := m.opts.BatchErrorHandler
-					if err != nil {
+		eh := m.opts.ErrorHandler
-						if b.opts.Logger.V(logger.ErrorLevel) {
+
-							b.opts.Logger.Error(ctx, "broker handler error", err)
+		for t, ms := range msgTopicMap {
+			m.RLock()
+			subs, ok := m.subscribers[t]
+			m.RUnlock()
+			if !ok {
+				continue
+			}
+
+			for _, sub := range subs {
+				if sub.opts.BatchErrorHandler != nil {
+					beh = sub.opts.BatchErrorHandler
+				}
+				if sub.opts.ErrorHandler != nil {
+					eh = sub.opts.ErrorHandler
+				}
+
+				switch {
+				// batch processing
+				case sub.batchhandler != nil:
+					if err = sub.batchhandler(ms); err != nil {
+						ms.SetError(err)
+						if beh != nil {
+							_ = beh(ms)
+						} else if m.opts.Logger.V(logger.ErrorLevel) {
+							m.opts.Logger.Error(m.opts.Context, err.Error())
+						}
+					} else if sub.opts.AutoAck {
+						if err = ms.Ack(); err != nil {
+							m.opts.Logger.Error(m.opts.Context, "broker ack error", err)
+						}
+					}
+					// single processing
+				case sub.handler != nil:
+					for _, p := range ms {
+						if err = sub.handler(p); err != nil {
+							p.SetError(err)
+							if eh != nil {
+								_ = eh(p)
+							} else if m.opts.Logger.V(logger.ErrorLevel) {
+								m.opts.Logger.Error(m.opts.Context, "broker handler error", err)
+							}
+						} else if sub.opts.AutoAck {
+							if err = p.Ack(); err != nil {
+								m.opts.Logger.Error(m.opts.Context, "broker ack error", err)
+							}
 						}
 					}
 				}
@@ -243,21 +233,17 @@ func (b *Broker) publish(ctx context.Context, topic string, messages ...broker.M
 	return nil
 }
 
-func (b *Broker) Subscribe(ctx context.Context, topic string, handler interface{}, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+func (m *memoryBroker) BatchSubscribe(ctx context.Context, topic string, handler broker.BatchHandler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
-	return b.funcSubscribe(ctx, topic, handler, opts...)
+	return m.funcBatchSubscribe(ctx, topic, handler, opts...)
 }
 
-func (b *Broker) fnSubscribe(ctx context.Context, topic string, handler interface{}, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+func (m *memoryBroker) fnBatchSubscribe(ctx context.Context, topic string, handler broker.BatchHandler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
-	if err := broker.IsValidHandler(handler); err != nil {
+	m.RLock()
-		return nil, err
+	if !m.connected {
-	}
+		m.RUnlock()
-
-	b.RLock()
-	if !b.connected {
-		b.RUnlock()
 		return nil, broker.ErrNotConnected
 	}
-	b.RUnlock()
+	m.RUnlock()
 
 	sid, err := id.New()
 	if err != nil {
@@ -266,7 +252,56 @@ func (b *Broker) fnSubscribe(ctx context.Context, topic string, handler interfac
 
 	options := broker.NewSubscribeOptions(opts...)
 
-	sub := &Subscriber{
+	sub := &memorySubscriber{
+		exit:         make(chan bool, 1),
+		id:           sid,
+		topic:        topic,
+		batchhandler: handler,
+		opts:         options,
+		ctx:          ctx,
+	}
+
+	m.Lock()
+	m.subscribers[topic] = append(m.subscribers[topic], sub)
+	m.Unlock()
+
+	go func() {
+		<-sub.exit
+		m.Lock()
+		newSubscribers := make([]*memorySubscriber, 0, len(m.subscribers)-1)
+		for _, sb := range m.subscribers[topic] {
+			if sb.id == sub.id {
+				continue
+			}
+			newSubscribers = append(newSubscribers, sb)
+		}
+		m.subscribers[topic] = newSubscribers
+		m.Unlock()
+	}()
+
+	return sub, nil
+}
+
+func (m *memoryBroker) Subscribe(ctx context.Context, topic string, handler broker.Handler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	return m.funcSubscribe(ctx, topic, handler, opts...)
+}
+
+func (m *memoryBroker) fnSubscribe(ctx context.Context, topic string, handler broker.Handler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	m.RLock()
+	if !m.connected {
+		m.RUnlock()
+		return nil, broker.ErrNotConnected
+	}
+	m.RUnlock()
+
+	sid, err := id.New()
+	if err != nil {
+		return nil, err
+	}
+
+	options := broker.NewSubscribeOptions(opts...)
+
+	sub := &memorySubscriber{
 		exit:    make(chan bool, 1),
 		id:      sid,
 		topic:   topic,
@@ -275,64 +310,102 @@ func (b *Broker) fnSubscribe(ctx context.Context, topic string, handler interfac
 		ctx:     ctx,
 	}
 
-	b.Lock()
+	m.Lock()
-	b.subscribers[topic] = append(b.subscribers[topic], sub)
+	m.subscribers[topic] = append(m.subscribers[topic], sub)
-	b.Unlock()
+	m.Unlock()
 
 	go func() {
 		<-sub.exit
-		b.Lock()
+		m.Lock()
-		newSubscribers := make([]*Subscriber, 0, len(b.subscribers)-1)
+		newSubscribers := make([]*memorySubscriber, 0, len(m.subscribers)-1)
-		for _, sb := range b.subscribers[topic] {
+		for _, sb := range m.subscribers[topic] {
 			if sb.id == sub.id {
 				continue
 			}
 			newSubscribers = append(newSubscribers, sb)
 		}
-		b.subscribers[topic] = newSubscribers
+		m.subscribers[topic] = newSubscribers
-		b.Unlock()
+		m.Unlock()
 	}()
 
 	return sub, nil
 }
 
-func (b *Broker) String() string {
+func (m *memoryBroker) String() string {
 	return "memory"
 }
 
-func (b *Broker) Name() string {
+func (m *memoryBroker) Name() string {
-	return b.opts.Name
+	return m.opts.Name
 }
 
-func (b *Broker) Live() bool {
+func (m *memoryBroker) Live() bool {
 	return true
 }
 
-func (b *Broker) Ready() bool {
+func (m *memoryBroker) Ready() bool {
 	return true
 }
 
-func (b *Broker) Health() bool {
+func (m *memoryBroker) Health() bool {
 	return true
 }
 
-func (m *Subscriber) Options() broker.SubscribeOptions {
+func (m *memoryEvent) Topic() string {
-	return m.opts
-}
-
-func (m *Subscriber) Topic() string {
 	return m.topic
 }
 
-func (m *Subscriber) Unsubscribe(ctx context.Context) error {
+func (m *memoryEvent) Message() *broker.Message {
+	switch v := m.message.(type) {
+	case *broker.Message:
+		return v
+	case []byte:
+		msg := &broker.Message{}
+		if err := m.opts.Codec.Unmarshal(v, msg); err != nil {
+			if m.opts.Logger.V(logger.ErrorLevel) {
+				m.opts.Logger.Error(m.opts.Context, "[memory]: failed to unmarshal: %v", err)
+			}
+			return nil
+		}
+		return msg
+	}
+
+	return nil
+}
+
+func (m *memoryEvent) Ack() error {
+	return nil
+}
+
+func (m *memoryEvent) Error() error {
+	return m.err
+}
+
+func (m *memoryEvent) SetError(err error) {
+	m.err = err
+}
+
+func (m *memoryEvent) Context() context.Context {
+	return m.opts.Context
+}
+
+func (m *memorySubscriber) Options() broker.SubscribeOptions {
+	return m.opts
+}
+
+func (m *memorySubscriber) Topic() string {
+	return m.topic
+}
+
+func (m *memorySubscriber) Unsubscribe(ctx context.Context) error {
 	m.exit <- true
 	return nil
 }
 
 // NewBroker return new memory broker
 func NewBroker(opts ...broker.Option) broker.Broker {
-	return &Broker{
+	return &memoryBroker{
 		opts:        broker.NewOptions(opts...),
-		subscribers: make(map[string][]*Subscriber),
+		subscribers: make(map[string][]*memorySubscriber),
 	}
 }

broker/memory/memory_test.go

@@ -5,23 +5,12 @@ import (
 	"fmt"
 	"testing"
 
-	"go.uber.org/atomic"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/codec"
-	"go.unistack.org/micro/v4/metadata"
 )
 
-type hldr struct {
+func TestMemoryBatchBroker(t *testing.T) {
-	c atomic.Int64
+	b := NewBroker()
-}
-
-func (h *hldr) Handler(m broker.Message) error {
-	h.c.Add(1)
-	return nil
-}
-
-func TestMemoryBroker(t *testing.T) {
-	b := NewBroker(broker.Codec("application/octet-stream", codec.NewCodec()))
 	ctx := context.Background()
 
 	if err := b.Init(); err != nil {
@@ -33,31 +22,32 @@ func TestMemoryBroker(t *testing.T) {
 	}
 
 	topic := "test"
-	count := int64(10)
+	count := 10
 
-	h := &hldr{}
+	fn := func(evts broker.Events) error {
+		return evts.Ack()
+	}
 
-	sub, err := b.Subscribe(ctx, topic, h.Handler)
+	sub, err := b.BatchSubscribe(ctx, topic, fn)
 	if err != nil {
 		t.Fatalf("Unexpected error subscribing %v", err)
 	}
 
-	for i := int64(0); i < count; i++ {
+	msgs := make([]*broker.Message, 0, count)
-		message, err := b.NewMessage(ctx,
+	for i := 0; i < count; i++ {
-			metadata.Pairs(
+		message := &broker.Message{
-				"foo", "bar",
+			Header: map[string]string{
-				"id", fmt.Sprintf("%d", i),
+				metadata.HeaderTopic: topic,
-			),
+				"foo":                "bar",
-			[]byte(`"hello world"`),
+				"id":                 fmt.Sprintf("%d", i),
-			broker.PublishContentType("application/octet-stream"),
+			},
-		)
+			Body: []byte(`"hello world"`),
-		if err != nil {
-			t.Fatal(err)
 		}
+		msgs = append(msgs, message)
+	}
 
-		if err := b.Publish(ctx, topic, message); err != nil {
+	if err := b.BatchPublish(ctx, msgs); err != nil {
-			t.Fatalf("Unexpected error publishing %d err: %v", i, err)
+		t.Fatalf("Unexpected error publishing %v", err)
-		}
 	}
 
 	if err := sub.Unsubscribe(ctx); err != nil {
@@ -67,8 +57,58 @@ func TestMemoryBroker(t *testing.T) {
 	if err := b.Disconnect(ctx); err != nil {
 		t.Fatalf("Unexpected connect error %v", err)
 	}
+}
 
-	if h.c.Load() != count {
+func TestMemoryBroker(t *testing.T) {
-		t.Fatal("invalid messages count received")
+	b := NewBroker()
+	ctx := context.Background()
+
+	if err := b.Init(); err != nil {
+		t.Fatalf("Unexpected init error %v", err)
+	}
+
+	if err := b.Connect(ctx); err != nil {
+		t.Fatalf("Unexpected connect error %v", err)
+	}
+
+	topic := "test"
+	count := 10
+
+	fn := func(_ broker.Event) error {
+		return nil
+	}
+
+	sub, err := b.Subscribe(ctx, topic, fn)
+	if err != nil {
+		t.Fatalf("Unexpected error subscribing %v", err)
+	}
+
+	msgs := make([]*broker.Message, 0, count)
+	for i := 0; i < count; i++ {
+		message := &broker.Message{
+			Header: map[string]string{
+				metadata.HeaderTopic: topic,
+				"foo":                "bar",
+				"id":                 fmt.Sprintf("%d", i),
+			},
+			Body: []byte(`"hello world"`),
+		}
+		msgs = append(msgs, message)
+
+		if err := b.Publish(ctx, topic, message); err != nil {
+			t.Fatalf("Unexpected error publishing %d err: %v", i, err)
+		}
+	}
+
+	if err := b.BatchPublish(ctx, msgs); err != nil {
+		t.Fatalf("Unexpected error publishing %v", err)
+	}
+
+	if err := sub.Unsubscribe(ctx); err != nil {
+		t.Fatalf("Unexpected error unsubscribing from %s: %v", topic, err)
+	}
+
+	if err := b.Disconnect(ctx); err != nil {
+		t.Fatalf("Unexpected connect error %v", err)
 	}
 }

broker/noop.go

@@ -3,37 +3,24 @@ package broker
 import (
 	"context"
 	"strings"
-	"sync"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/metadata"
-	"go.unistack.org/micro/v4/options"
 )
 
 type NoopBroker struct {
-	funcPublish   FuncPublish
+	funcPublish        FuncPublish
-	funcSubscribe FuncSubscribe
+	funcBatchPublish   FuncBatchPublish
-	opts          Options
+	funcSubscribe      FuncSubscribe
-	sync.RWMutex
+	funcBatchSubscribe FuncBatchSubscribe
-}
+	opts               Options
-
-func (b *NoopBroker) newCodec(ct string) (codec.Codec, error) {
-	if idx := strings.IndexRune(ct, ';'); idx >= 0 {
-		ct = ct[:idx]
-	}
-	b.RLock()
-	c, ok := b.opts.Codecs[ct]
-	b.RUnlock()
-	if ok {
-		return c, nil
-	}
-	return nil, codec.ErrUnknownContentType
 }
 
 func NewBroker(opts ...Option) *NoopBroker {
 	b := &NoopBroker{opts: NewOptions(opts...)}
 	b.funcPublish = b.fnPublish
+	b.funcBatchPublish = b.fnBatchPublish
 	b.funcSubscribe = b.fnSubscribe
+	b.funcBatchSubscribe = b.fnBatchSubscribe
 
 	return b
 }
@@ -68,14 +55,20 @@ func (b *NoopBroker) Init(opts ...Option) error {
 	}
 
 	b.funcPublish = b.fnPublish
+	b.funcBatchPublish = b.fnBatchPublish
 	b.funcSubscribe = b.fnSubscribe
+	b.funcBatchSubscribe = b.fnBatchSubscribe
 
 	b.opts.Hooks.EachPrev(func(hook options.Hook) {
 		switch h := hook.(type) {
 		case HookPublish:
 			b.funcPublish = h(b.funcPublish)
+		case HookBatchPublish:
+			b.funcBatchPublish = h(b.funcBatchPublish)
 		case HookSubscribe:
 			b.funcSubscribe = h(b.funcSubscribe)
+		case HookBatchSubscribe:
+			b.funcBatchSubscribe = h(b.funcBatchSubscribe)
 		}
 	})
 
@@ -94,72 +87,43 @@ func (b *NoopBroker) Address() string {
 	return strings.Join(b.opts.Addrs, ",")
 }
 
-type noopMessage struct {
+func (b *NoopBroker) fnBatchPublish(_ context.Context, _ []*Message, _ ...PublishOption) error {
-	c    codec.Codec
-	ctx  context.Context
-	body []byte
-	hdr  metadata.Metadata
-	opts PublishOptions
-}
-
-func (m *noopMessage) Ack() error {
 	return nil
 }
 
-func (m *noopMessage) Body() []byte {
+func (b *NoopBroker) BatchPublish(ctx context.Context, msgs []*Message, opts ...PublishOption) error {
-	return m.body
+	return b.funcBatchPublish(ctx, msgs, opts...)
 }
 
-func (m *noopMessage) Header() metadata.Metadata {
+func (b *NoopBroker) fnPublish(_ context.Context, _ string, _ *Message, _ ...PublishOption) error {
-	return m.hdr
-}
-
-func (m *noopMessage) Context() context.Context {
-	return m.ctx
-}
-
-func (m *noopMessage) Topic() string {
-	return ""
-}
-
-func (m *noopMessage) Unmarshal(dst interface{}, opts ...codec.Option) error {
-	return m.c.Unmarshal(m.body, dst)
-}
-
-func (b *NoopBroker) NewMessage(ctx context.Context, hdr metadata.Metadata, body interface{}, opts ...PublishOption) (Message, error) {
-	options := NewPublishOptions(opts...)
-	m := &noopMessage{ctx: ctx, hdr: hdr, opts: options}
-	c, err := b.newCodec(m.opts.ContentType)
-	if err == nil {
-		m.body, err = c.Marshal(body)
-	}
-	if err != nil {
-		return nil, err
-	}
-
-	return m, nil
-}
-
-func (b *NoopBroker) fnPublish(_ context.Context, _ string, _ ...Message) error {
 	return nil
 }
 
-func (b *NoopBroker) Publish(ctx context.Context, topic string, msg ...Message) error {
+func (b *NoopBroker) Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error {
-	return b.funcPublish(ctx, topic, msg...)
+	return b.funcPublish(ctx, topic, msg, opts...)
 }
 
 type NoopSubscriber struct {
-	ctx     context.Context
+	ctx          context.Context
-	topic   string
+	topic        string
-	handler interface{}
+	handler      Handler
-	opts    SubscribeOptions
+	batchHandler BatchHandler
+	opts         SubscribeOptions
 }
 
-func (b *NoopBroker) fnSubscribe(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error) {
+func (b *NoopBroker) fnBatchSubscribe(ctx context.Context, topic string, handler BatchHandler, opts ...SubscribeOption) (Subscriber, error) {
+	return &NoopSubscriber{ctx: ctx, topic: topic, opts: NewSubscribeOptions(opts...), batchHandler: handler}, nil
+}
+
+func (b *NoopBroker) BatchSubscribe(ctx context.Context, topic string, handler BatchHandler, opts ...SubscribeOption) (Subscriber, error) {
+	return b.funcBatchSubscribe(ctx, topic, handler, opts...)
+}
+
+func (b *NoopBroker) fnSubscribe(ctx context.Context, topic string, handler Handler, opts ...SubscribeOption) (Subscriber, error) {
 	return &NoopSubscriber{ctx: ctx, topic: topic, opts: NewSubscribeOptions(opts...), handler: handler}, nil
 }
 
-func (b *NoopBroker) Subscribe(ctx context.Context, topic string, handler interface{}, opts ...SubscribeOption) (Subscriber, error) {
+func (b *NoopBroker) Subscribe(ctx context.Context, topic string, handler Handler, opts ...SubscribeOption) (Subscriber, error) {
 	return b.funcSubscribe(ctx, topic, handler, opts...)
 }
 

broker/noop_test.go

@@ -10,9 +10,9 @@ type testHook struct {
 }
 
 func (t *testHook) Publish1(fn FuncPublish) FuncPublish {
-	return func(ctx context.Context, topic string, messages ...Message) error {
+	return func(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error {
 		t.f = true
-		return fn(ctx, topic, messages...)
+		return fn(ctx, topic, msg, opts...)
 	}
 }
 

broker/options.go

@@ -5,13 +5,13 @@ import (
 	"crypto/tls"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/sync"
+	"go.unistack.org/micro/v3/sync"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options struct
@@ -23,8 +23,8 @@ type Options struct {
 	Tracer tracer.Tracer
 	// Register can be used for clustering
 	Register register.Register
-	// Codecs holds the codecs for marshal/unmarshal based on content-type
+	// Codec holds the codec for marshal/unmarshal
-	Codecs map[string]codec.Codec
+	Codec codec.Codec
 	// Logger used for logging
 	Logger logger.Logger
 	// Meter used for metrics
@@ -37,6 +37,11 @@ type Options struct {
 	// TLSConfig holds tls.TLSConfig options
 	TLSConfig *tls.Config
 
+	// ErrorHandler used when broker can't unmarshal incoming message
+	ErrorHandler Handler
+	// BatchErrorHandler used when broker can't unmashal incoming messages
+	BatchErrorHandler BatchHandler
+
 	// Addrs holds the broker address
 	Addrs []string
 	// Hooks can be run before broker Publish/BatchPublish and
@@ -54,11 +59,10 @@ func NewOptions(opts ...Option) Options {
 		Logger:          logger.DefaultLogger,
 		Context:         context.Background(),
 		Meter:           meter.DefaultMeter,
-		Codecs:          make(map[string]codec.Codec),
+		Codec:           codec.DefaultCodec,
 		Tracer:          tracer.DefaultTracer,
 		GracefulTimeout: DefaultGracefulTimeout,
 	}
-
 	for _, o := range opts {
 		o(&options)
 	}
@@ -74,16 +78,17 @@ func Context(ctx context.Context) Option {
 
 // PublishOptions struct
 type PublishOptions struct {
-	// ContentType for message body
+	// Context holds external options
-	ContentType string
+	Context context.Context
-	// BodyOnly flag says the message contains raw body bytes and don't need
+	// BodyOnly flag says the message contains raw body bytes
-	// codec Marshal method
 	BodyOnly bool
 }
 
 // NewPublishOptions creates PublishOptions struct
 func NewPublishOptions(opts ...PublishOption) PublishOptions {
-	options := PublishOptions{}
+	options := PublishOptions{
+		Context: context.Background(),
+	}
 	for _, o := range opts {
 		o(&options)
 	}
@@ -94,6 +99,10 @@ func NewPublishOptions(opts ...PublishOption) PublishOptions {
 type SubscribeOptions struct {
 	// Context holds external options
 	Context context.Context
+	// ErrorHandler used when broker can't unmarshal incoming message
+	ErrorHandler Handler
+	// BatchErrorHandler used when broker can't unmashal incoming messages
+	BatchErrorHandler BatchHandler
 	// Group holds consumer group
 	Group string
 	// AutoAck flag specifies auto ack of incoming message when no error happens
@@ -112,13 +121,6 @@ type Option func(*Options)
 // PublishOption func
 type PublishOption func(*PublishOptions)
 
-// PublishContentType sets message content-type that used to Marshal
-func PublishContentType(ct string) PublishOption {
-	return func(o *PublishOptions) {
-		o.ContentType = ct
-	}
-}
-
 // PublishBodyOnly publish only body of the message
 func PublishBodyOnly(b bool) PublishOption {
 	return func(o *PublishOptions) {
@@ -126,6 +128,13 @@ func PublishBodyOnly(b bool) PublishOption {
 	}
 }
 
+// PublishContext sets the context
+func PublishContext(ctx context.Context) PublishOption {
+	return func(o *PublishOptions) {
+		o.Context = ctx
+	}
+}
+
 // Addrs sets the host addresses to be used by the broker
 func Addrs(addrs ...string) Option {
 	return func(o *Options) {
@@ -133,10 +142,51 @@ func Addrs(addrs ...string) Option {
 	}
 }
 
-// Codec sets the codec used for encoding/decoding messages
+// Codec sets the codec used for encoding/decoding used where
-func Codec(ct string, c codec.Codec) Option {
+// a broker does not support headers
+func Codec(c codec.Codec) Option {
 	return func(o *Options) {
-		o.Codecs[ct] = c
+		o.Codec = c
+	}
+}
+
+// ErrorHandler will catch all broker errors that cant be handled
+// in normal way, for example Codec errors
+func ErrorHandler(h Handler) Option {
+	return func(o *Options) {
+		o.ErrorHandler = h
+	}
+}
+
+// BatchErrorHandler will catch all broker errors that cant be handled
+// in normal way, for example Codec errors
+func BatchErrorHandler(h BatchHandler) Option {
+	return func(o *Options) {
+		o.BatchErrorHandler = h
+	}
+}
+
+// SubscribeErrorHandler will catch all broker errors that cant be handled
+// in normal way, for example Codec errors
+func SubscribeErrorHandler(h Handler) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.ErrorHandler = h
+	}
+}
+
+// SubscribeBatchErrorHandler will catch all broker errors that cant be handled
+// in normal way, for example Codec errors
+func SubscribeBatchErrorHandler(h BatchHandler) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.BatchErrorHandler = h
+	}
+}
+
+// Queue sets the subscribers queue
+// Deprecated
+func Queue(name string) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.Group = name
 	}
 }
 
@@ -203,6 +253,14 @@ func SubscribeContext(ctx context.Context) SubscribeOption {
 	}
 }
 
+// DisableAutoAck disables auto ack
+// Deprecated
+func DisableAutoAck() SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.AutoAck = false
+	}
+}
+
 // SubscribeAutoAck contol auto acking of messages
 // after they have been handled.
 func SubscribeAutoAck(b bool) SubscribeOption {

client/backoff.go

@@ -5,7 +5,7 @@ import (
 	"math"
 	"time"
 
-	"go.unistack.org/micro/v4/util/backoff"
+	"go.unistack.org/micro/v3/util/backoff"
 )
 
 // BackoffFunc is the backoff call func

client/client.go

@@ -5,8 +5,8 @@ import (
 	"context"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 var (
@@ -29,24 +29,40 @@ var (
 )
 
 // Client is the interface used to make requests to services.
+// It supports Request/Response via Transport and Publishing via the Broker.
 // It also supports bidirectional streaming of requests.
 type Client interface {
 	Name() string
 	Init(opts ...Option) error
 	Options() Options
+	NewMessage(topic string, msg interface{}, opts ...MessageOption) Message
 	NewRequest(service string, endpoint string, req interface{}, opts ...RequestOption) Request
 	Call(ctx context.Context, req Request, rsp interface{}, opts ...CallOption) error
 	Stream(ctx context.Context, req Request, opts ...CallOption) (Stream, error)
+	Publish(ctx context.Context, msg Message, opts ...PublishOption) error
+	BatchPublish(ctx context.Context, msg []Message, opts ...PublishOption) error
 	String() string
 }
 
 type (
-	FuncCall   func(ctx context.Context, req Request, rsp interface{}, opts ...CallOption) error
+	FuncCall         func(ctx context.Context, req Request, rsp interface{}, opts ...CallOption) error
-	HookCall   func(next FuncCall) FuncCall
+	HookCall         func(next FuncCall) FuncCall
-	FuncStream func(ctx context.Context, req Request, opts ...CallOption) (Stream, error)
+	FuncStream       func(ctx context.Context, req Request, opts ...CallOption) (Stream, error)
-	HookStream func(next FuncStream) FuncStream
+	HookStream       func(next FuncStream) FuncStream
+	FuncPublish      func(ctx context.Context, msg Message, opts ...PublishOption) error
+	HookPublish      func(next FuncPublish) FuncPublish
+	FuncBatchPublish func(ctx context.Context, msg []Message, opts ...PublishOption) error
+	HookBatchPublish func(next FuncBatchPublish) FuncBatchPublish
 )
 
+// Message is the interface for publishing asynchronously
+type Message interface {
+	Topic() string
+	Payload() interface{}
+	ContentType() string
+	Metadata() metadata.Metadata
+}
+
 // Request is the interface for a synchronous request used by Call or Stream
 type Request interface {
 	// The service to call
@@ -105,5 +121,11 @@ type Option func(*Options)
 // CallOption used by Call or Stream
 type CallOption func(*CallOptions)
 
+// PublishOption used by Publish
+type PublishOption func(*PublishOptions)
+
+// MessageOption used by NewMessage
+type MessageOption func(*MessageOptions)
+
 // RequestOption used by NewRequest
 type RequestOption func(*RequestOptions)

client/context.go

@@ -32,6 +32,16 @@ func NewContext(ctx context.Context, c Client) context.Context {
 	return context.WithValue(ctx, clientKey{}, c)
 }
 
+// SetPublishOption returns a function to setup a context with given value
+func SetPublishOption(k, v interface{}) PublishOption {
+	return func(o *PublishOptions) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}
+
 // SetCallOption returns a function to setup a context with given value
 func SetCallOption(k, v interface{}) CallOption {
 	return func(o *CallOptions) {

client/context_test.go

@@ -39,6 +39,17 @@ func TestNewNilContext(t *testing.T) {
 	}
 }
 
+func TestSetPublishOption(t *testing.T) {
+	type key struct{}
+	o := SetPublishOption(key{}, "test")
+	opts := &PublishOptions{}
+	o(opts)
+
+	if v, ok := opts.Context.Value(key{}).(string); !ok || v == "" {
+		t.Fatal("SetPublishOption not works")
+	}
+}
+
 func TestSetCallOption(t *testing.T) {
 	type key struct{}
 	o := SetCallOption(key{}, "test")

client/lookup.go

@@ -4,8 +4,8 @@ import (
 	"context"
 	"sort"
 
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/errors"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
 )
 
 // LookupFunc is used to lookup routes for a service

client/noop.go

@@ -3,27 +3,32 @@ package client
 import (
 	"context"
 	"fmt"
+	"os"
 	"strconv"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/errors"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/semconv"
+	"go.unistack.org/micro/v3/selector"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/semconv"
+	"go.unistack.org/micro/v3/tracer"
 )
 
-// DefaultCodecs will be used to encode/decode data
+type noopClient struct {
-var DefaultCodecs = map[string]codec.Codec{
+	funcPublish      FuncPublish
-	"application/octet-stream": codec.NewCodec(),
+	funcBatchPublish FuncBatchPublish
+	funcCall         FuncCall
+	funcStream       FuncStream
+	opts             Options
 }
 
-type noopClient struct {
+type noopMessage struct {
-	funcCall   FuncCall
+	topic   string
-	funcStream FuncStream
+	payload interface{}
-	opts       Options
+	opts    MessageOptions
 }
 
 type noopRequest struct {
@@ -42,6 +47,8 @@ func NewClient(opts ...Option) Client {
 
 	n.funcCall = n.fnCall
 	n.funcStream = n.fnStream
+	n.funcPublish = n.fnPublish
+	n.funcBatchPublish = n.fnBatchPublish
 
 	return n
 }
@@ -146,6 +153,29 @@ func (n *noopStream) CloseSend() error {
 	return n.err
 }
 
+func (n *noopMessage) Topic() string {
+	return n.topic
+}
+
+func (n *noopMessage) Payload() interface{} {
+	return n.payload
+}
+
+func (n *noopMessage) ContentType() string {
+	return n.opts.ContentType
+}
+
+func (n *noopMessage) Metadata() metadata.Metadata {
+	return n.opts.Metadata
+}
+
+func (n *noopClient) newCodec(contentType string) (codec.Codec, error) {
+	if cf, ok := n.opts.Codecs[contentType]; ok {
+		return cf, nil
+	}
+	return nil, codec.ErrUnknownContentType
+}
+
 func (n *noopClient) Init(opts ...Option) error {
 	for _, o := range opts {
 		o(&n.opts)
@@ -153,6 +183,8 @@ func (n *noopClient) Init(opts ...Option) error {
 
 	n.funcCall = n.fnCall
 	n.funcStream = n.fnStream
+	n.funcPublish = n.fnPublish
+	n.funcBatchPublish = n.fnBatchPublish
 
 	n.opts.Hooks.EachPrev(func(hook options.Hook) {
 		switch h := hook.(type) {
@@ -160,6 +192,10 @@ func (n *noopClient) Init(opts ...Option) error {
 			n.funcCall = h(n.funcCall)
 		case HookStream:
 			n.funcStream = h(n.funcStream)
+		case HookPublish:
+			n.funcPublish = h(n.funcPublish)
+		case HookBatchPublish:
+			n.funcBatchPublish = h(n.funcBatchPublish)
 		}
 	})
 
@@ -332,6 +368,11 @@ func (n *noopClient) NewRequest(service, endpoint string, _ interface{}, _ ...Re
 	return &noopRequest{service: service, endpoint: endpoint}
 }
 
+func (n *noopClient) NewMessage(topic string, msg interface{}, opts ...MessageOption) Message {
+	options := NewMessageOptions(append([]MessageOption{MessageContentType(n.opts.ContentType)}, opts...)...)
+	return &noopMessage{topic: topic, payload: msg, opts: options}
+}
+
 func (n *noopClient) Stream(ctx context.Context, req Request, opts ...CallOption) (Stream, error) {
 	ts := time.Now()
 	n.opts.Meter.Counter(semconv.ClientRequestInflight, "endpoint", req.Endpoint()).Inc()
@@ -500,3 +541,90 @@ func (n *noopClient) fnStream(ctx context.Context, req Request, opts ...CallOpti
 func (n *noopClient) stream(ctx context.Context, _ string, _ Request, _ CallOptions) (Stream, error) {
 	return &noopStream{ctx: ctx}, nil
 }
+
+func (n *noopClient) BatchPublish(ctx context.Context, ps []Message, opts ...PublishOption) error {
+	return n.funcBatchPublish(ctx, ps, opts...)
+}
+
+func (n *noopClient) fnBatchPublish(ctx context.Context, ps []Message, opts ...PublishOption) error {
+	return n.publish(ctx, ps, opts...)
+}
+
+func (n *noopClient) Publish(ctx context.Context, p Message, opts ...PublishOption) error {
+	return n.funcPublish(ctx, p, opts...)
+}
+
+func (n *noopClient) fnPublish(ctx context.Context, p Message, opts ...PublishOption) error {
+	return n.publish(ctx, []Message{p}, opts...)
+}
+
+func (n *noopClient) publish(ctx context.Context, ps []Message, opts ...PublishOption) error {
+	options := NewPublishOptions(opts...)
+
+	msgs := make([]*broker.Message, 0, len(ps))
+
+	// get proxy
+	exchange := ""
+	if v, ok := os.LookupEnv("MICRO_PROXY"); ok {
+		exchange = v
+	}
+	// get the exchange
+	if len(options.Exchange) > 0 {
+		exchange = options.Exchange
+	}
+
+	omd, ok := metadata.FromOutgoingContext(ctx)
+	if !ok {
+		omd = metadata.New(0)
+	}
+
+	for _, p := range ps {
+		md := metadata.Copy(omd)
+		topic := p.Topic()
+		if len(exchange) > 0 {
+			topic = exchange
+		}
+		md[metadata.HeaderTopic] = topic
+		iter := p.Metadata().Iterator()
+		var k, v string
+		for iter.Next(&k, &v) {
+			md.Set(k, v)
+		}
+
+		md[metadata.HeaderContentType] = p.ContentType()
+
+		var body []byte
+
+		// passed in raw data
+		if d, ok := p.Payload().(*codec.Frame); ok {
+			body = d.Data
+		} else {
+			// use codec for payload
+			cf, err := n.newCodec(p.ContentType())
+			if err != nil {
+				return errors.InternalServerError("go.micro.client", "%s", err)
+			}
+
+			// set the body
+			b, err := cf.Marshal(p.Payload())
+			if err != nil {
+				return errors.InternalServerError("go.micro.client", "%s", err)
+			}
+			body = b
+		}
+
+		msgs = append(msgs, &broker.Message{Header: md, Body: body})
+	}
+
+	if len(msgs) == 1 {
+		return n.opts.Broker.Publish(ctx, msgs[0].Header[metadata.HeaderTopic], msgs[0],
+			broker.PublishContext(options.Context),
+			broker.PublishBodyOnly(options.BodyOnly),
+		)
+	}
+
+	return n.opts.Broker.BatchPublish(ctx, msgs,
+		broker.PublishContext(options.Context),
+		broker.PublishBodyOnly(options.BodyOnly),
+	)
+}

client/noop_test.go

@@ -0,0 +1,37 @@
+package client
+
+import (
+	"context"
+	"testing"
+
+	"go.unistack.org/micro/v3/codec"
+)
+
+type testHook struct {
+	f bool
+}
+
+func (t *testHook) Publish(fn FuncPublish) FuncPublish {
+	return func(ctx context.Context, msg Message, opts ...PublishOption) error {
+		t.f = true
+		return fn(ctx, msg, opts...)
+	}
+}
+
+func TestNoopHook(t *testing.T) {
+	h := &testHook{}
+
+	c := NewClient(Codec("application/octet-stream", codec.NewCodec()), Hooks(HookPublish(h.Publish)))
+
+	if err := c.Init(); err != nil {
+		t.Fatal(err)
+	}
+
+	if err := c.Publish(context.TODO(), c.NewMessage("", nil, MessageContentType("application/octet-stream"))); err != nil {
+		t.Fatal(err)
+	}
+
+	if !h.f {
+		t.Fatal("hook not works")
+	}
+}

client/options.go

@@ -6,17 +6,17 @@ import (
 	"net"
 	"time"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/selector"
-	"go.unistack.org/micro/v4/selector/random"
+	"go.unistack.org/micro/v3/selector/random"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options holds client options
@@ -137,6 +137,43 @@ func Context(ctx context.Context) Option {
 	}
 }
 
+// NewPublishOptions create new PublishOptions struct from option
+func NewPublishOptions(opts ...PublishOption) PublishOptions {
+	options := PublishOptions{}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}
+
+// PublishOptions holds publish options
+type PublishOptions struct {
+	// Context used for external options
+	Context context.Context
+	// Exchange topic exchange name
+	Exchange string
+	// BodyOnly will publish only message body
+	BodyOnly bool
+}
+
+// NewMessageOptions creates message options struct
+func NewMessageOptions(opts ...MessageOption) MessageOptions {
+	options := MessageOptions{Metadata: metadata.New(1)}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}
+
+// MessageOptions holds client message options
+type MessageOptions struct {
+	// Metadata additional metadata
+	Metadata metadata.Metadata
+	// ContentType specify content-type of message
+	// deprecated
+	ContentType string
+}
+
 // NewRequestOptions creates new RequestOptions struct
 func NewRequestOptions(opts ...RequestOption) RequestOptions {
 	options := RequestOptions{}
@@ -161,7 +198,7 @@ func NewOptions(opts ...Option) Options {
 	options := Options{
 		Context:     context.Background(),
 		ContentType: DefaultContentType,
-		Codecs:      DefaultCodecs,
+		Codecs:      make(map[string]codec.Codec),
 		CallOptions: CallOptions{
 			Context:        context.Background(),
 			Backoff:        DefaultBackoff,
@@ -337,6 +374,43 @@ func DialTimeout(d time.Duration) Option {
 	}
 }
 
+// WithExchange sets the exchange to route a message through
+// Deprecated
+func WithExchange(e string) PublishOption {
+	return func(o *PublishOptions) {
+		o.Exchange = e
+	}
+}
+
+// PublishExchange sets the exchange to route a message through
+func PublishExchange(e string) PublishOption {
+	return func(o *PublishOptions) {
+		o.Exchange = e
+	}
+}
+
+// WithBodyOnly publish only message body
+// DERECATED
+func WithBodyOnly(b bool) PublishOption {
+	return func(o *PublishOptions) {
+		o.BodyOnly = b
+	}
+}
+
+// PublishBodyOnly publish only message body
+func PublishBodyOnly(b bool) PublishOption {
+	return func(o *PublishOptions) {
+		o.BodyOnly = b
+	}
+}
+
+// PublishContext sets the context in publish options
+func PublishContext(ctx context.Context) PublishOption {
+	return func(o *PublishOptions) {
+		o.Context = ctx
+	}
+}
+
 // WithContextDialer pass ContextDialer to client call
 func WithContextDialer(fn func(context.Context, string) (net.Conn, error)) CallOption {
 	return func(o *CallOptions) {
@@ -448,6 +522,30 @@ func WithSelectOptions(sops ...selector.SelectOption) CallOption {
 	}
 }
 
+// WithMessageContentType sets the message content type
+// Deprecated
+func WithMessageContentType(ct string) MessageOption {
+	return func(o *MessageOptions) {
+		o.Metadata.Set(metadata.HeaderContentType, ct)
+		o.ContentType = ct
+	}
+}
+
+// MessageContentType sets the message content type
+func MessageContentType(ct string) MessageOption {
+	return func(o *MessageOptions) {
+		o.Metadata.Set(metadata.HeaderContentType, ct)
+		o.ContentType = ct
+	}
+}
+
+// MessageMetadata sets the message metadata
+func MessageMetadata(k, v string) MessageOption {
+	return func(o *MessageOptions) {
+		o.Metadata.Set(k, v)
+	}
+}
+
 // StreamingRequest specifies that request is streaming
 func StreamingRequest(b bool) RequestOption {
 	return func(o *RequestOptions) {

client/retry.go

@@ -3,7 +3,7 @@ package client
 import (
 	"context"
 
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/errors"
 )
 
 // RetryFunc that returning either false or a non-nil error will result in the call not being retried

client/retry_test.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"testing"
 
-	"go.unistack.org/micro/v4/errors"
+	"go.unistack.org/micro/v3/errors"
 )
 
 func TestRetryAlways(t *testing.T) {

client/test_request.go

@@ -1,7 +1,7 @@
 package client
 
 import (
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
 )
 
 type testRequest struct {

cluster/cluster.go

@@ -3,7 +3,7 @@ package cluster
 import (
 	"context"
 
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 // Message sent to member in cluster

cluster/hasql/cluster.go

@@ -0,0 +1,235 @@
+package sql
+
+import (
+	"context"
+	"database/sql"
+	"reflect"
+	"unsafe"
+
+	"golang.yandex/hasql/v2"
+)
+
+func newSQLRowError() *sql.Row {
+	row := &sql.Row{}
+	t := reflect.TypeOf(row).Elem()
+	field, _ := t.FieldByName("err")
+	rowPtr := unsafe.Pointer(row)
+	errFieldPtr := unsafe.Pointer(uintptr(rowPtr) + field.Offset)
+	errPtr := (*error)(errFieldPtr)
+	*errPtr = ErrorNoAliveNodes
+	return row
+}
+
+type ClusterQuerier interface {
+	Querier
+	WaitForNodes(ctx context.Context, criterion ...hasql.NodeStateCriterion) error
+}
+
+type Cluster struct {
+	hasql   *hasql.Cluster[Querier]
+	options ClusterOptions
+}
+
+// NewCluster returns [Querier] that provides cluster of nodes
+func NewCluster[T Querier](opts ...ClusterOption) (ClusterQuerier, error) {
+	options := ClusterOptions{Context: context.Background()}
+	for _, opt := range opts {
+		opt(&options)
+	}
+	if options.NodeChecker == nil {
+		return nil, ErrClusterChecker
+	}
+	if options.NodeDiscoverer == nil {
+		return nil, ErrClusterDiscoverer
+	}
+	if options.NodePicker == nil {
+		return nil, ErrClusterPicker
+	}
+
+	if options.Retries < 1 {
+		options.Retries = 1
+	}
+
+	if options.NodeStateCriterion == 0 {
+		options.NodeStateCriterion = hasql.Primary
+	}
+
+	options.Options = append(options.Options, hasql.WithNodePicker(options.NodePicker))
+	if p, ok := options.NodePicker.(*CustomPicker[Querier]); ok {
+		p.opts.Priority = options.NodePriority
+	}
+
+	c, err := hasql.NewCluster(
+		options.NodeDiscoverer,
+		options.NodeChecker,
+		options.Options...,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Cluster{hasql: c, options: options}, nil
+}
+
+func (c *Cluster) BeginTx(ctx context.Context, opts *sql.TxOptions) (*sql.Tx, error) {
+	var tx *sql.Tx
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if tx, err = n.DB().BeginTx(ctx, opts); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if tx == nil && err == nil {
+		err = ErrorNoAliveNodes
+	}
+
+	return tx, err
+}
+
+func (c *Cluster) Close() error {
+	return c.hasql.Close()
+}
+
+func (c *Cluster) Conn(ctx context.Context) (*sql.Conn, error) {
+	var conn *sql.Conn
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if conn, err = n.DB().Conn(ctx); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if conn == nil && err == nil {
+		err = ErrorNoAliveNodes
+	}
+
+	return conn, err
+}
+
+func (c *Cluster) ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error) {
+	var res sql.Result
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if res, err = n.DB().ExecContext(ctx, query, args...); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if res == nil && err == nil {
+		err = ErrorNoAliveNodes
+	}
+
+	return res, err
+}
+
+func (c *Cluster) PrepareContext(ctx context.Context, query string) (*sql.Stmt, error) {
+	var res *sql.Stmt
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if res, err = n.DB().PrepareContext(ctx, query); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if res == nil && err == nil {
+		err = ErrorNoAliveNodes
+	}
+
+	return res, err
+}
+
+func (c *Cluster) QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error) {
+	var res *sql.Rows
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if res, err = n.DB().QueryContext(ctx, query); err != nil && err != sql.ErrNoRows && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if res == nil && err == nil {
+		err = ErrorNoAliveNodes
+	}
+
+	return res, err
+}
+
+func (c *Cluster) QueryRowContext(ctx context.Context, query string, args ...interface{}) *sql.Row {
+	var res *sql.Row
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			res = n.DB().QueryRowContext(ctx, query, args...)
+			if res.Err() == nil {
+				return false
+			} else if res.Err() != nil && retries >= c.options.Retries {
+				return false
+			}
+		}
+		return true
+	})
+
+	if res == nil {
+		res = newSQLRowError()
+	}
+
+	return res
+}
+
+func (c *Cluster) PingContext(ctx context.Context) error {
+	var err error
+	var ok bool
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		ok = true
+		for ; retries < c.options.Retries; retries++ {
+			if err = n.DB().PingContext(ctx); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if !ok {
+		err = ErrorNoAliveNodes
+	}
+
+	return err
+}
+
+func (c *Cluster) WaitForNodes(ctx context.Context, criterions ...hasql.NodeStateCriterion) error {
+	for _, criterion := range criterions {
+		if _, err := c.hasql.WaitForNode(ctx, criterion); err != nil {
+			return err
+		}
+	}
+	return nil
+}

cluster/hasql/cluster_test.go

@@ -0,0 +1,171 @@
+package sql
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"golang.yandex/hasql/v2"
+)
+
+func TestNewCluster(t *testing.T) {
+	dbMaster, dbMasterMock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbMaster.Close()
+	dbMasterMock.MatchExpectationsInOrder(false)
+
+	dbMasterMock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(1, 0)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("master-dc1"))
+
+	dbDRMaster, dbDRMasterMock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbDRMaster.Close()
+	dbDRMasterMock.MatchExpectationsInOrder(false)
+
+	dbDRMasterMock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 40)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbDRMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("drmaster1-dc2"))
+
+	dbDRMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("drmaster"))
+
+	dbSlaveDC1, dbSlaveDC1Mock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbSlaveDC1.Close()
+	dbSlaveDC1Mock.MatchExpectationsInOrder(false)
+
+	dbSlaveDC1Mock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 50)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbSlaveDC1Mock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("slave-dc1"))
+
+	dbSlaveDC2, dbSlaveDC2Mock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbSlaveDC2.Close()
+	dbSlaveDC1Mock.MatchExpectationsInOrder(false)
+
+	dbSlaveDC2Mock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 50)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbSlaveDC2Mock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("slave-dc1"))
+
+	tctx, cancel := context.WithTimeout(t.Context(), 10*time.Second)
+	defer cancel()
+
+	c, err := NewCluster[Querier](
+		WithClusterContext(tctx),
+		WithClusterNodeChecker(hasql.PostgreSQLChecker),
+		WithClusterNodePicker(NewCustomPicker[Querier](
+			CustomPickerMaxLag(100),
+		)),
+		WithClusterNodes(
+			ClusterNode{"slave-dc1", dbSlaveDC1, 1},
+			ClusterNode{"master-dc1", dbMaster, 1},
+			ClusterNode{"slave-dc2", dbSlaveDC2, 2},
+			ClusterNode{"drmaster1-dc2", dbDRMaster, 0},
+		),
+		WithClusterOptions(
+			hasql.WithUpdateInterval[Querier](2*time.Second),
+			hasql.WithUpdateTimeout[Querier](1*time.Second),
+		),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	if err = c.WaitForNodes(tctx, hasql.Primary, hasql.Standby); err != nil {
+		t.Fatal(err)
+	}
+
+	time.Sleep(500 * time.Millisecond)
+
+	node1Name := ""
+	fmt.Printf("check for Standby\n")
+	if row := c.QueryRowContext(NodeStateCriterion(tctx, hasql.Standby), "SELECT node_name as name"); row.Err() != nil {
+		t.Fatal(row.Err())
+	} else if err = row.Scan(&node1Name); err != nil {
+		t.Fatal(err)
+	} else if "slave-dc1" != node1Name {
+		t.Fatalf("invalid node name %s != %s", "slave-dc1", node1Name)
+	}
+
+	dbSlaveDC1Mock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("slave-dc1"))
+
+	node2Name := ""
+	fmt.Printf("check for PreferStandby\n")
+	if row := c.QueryRowContext(NodeStateCriterion(tctx, hasql.PreferStandby), "SELECT node_name as name"); row.Err() != nil {
+		t.Fatal(row.Err())
+	} else if err = row.Scan(&node2Name); err != nil {
+		t.Fatal(err)
+	} else if "slave-dc1" != node2Name {
+		t.Fatalf("invalid node name %s != %s", "slave-dc1", node2Name)
+	}
+
+	node3Name := ""
+	fmt.Printf("check for PreferPrimary\n")
+	if row := c.QueryRowContext(NodeStateCriterion(tctx, hasql.PreferPrimary), "SELECT node_name as name"); row.Err() != nil {
+		t.Fatal(row.Err())
+	} else if err = row.Scan(&node3Name); err != nil {
+		t.Fatal(err)
+	} else if "master-dc1" != node3Name {
+		t.Fatalf("invalid node name %s != %s", "master-dc1", node3Name)
+	}
+
+	dbSlaveDC1Mock.ExpectQuery(`.*`).WillReturnRows(sqlmock.NewRows([]string{"role"}).RowError(1, fmt.Errorf("row error")))
+
+	time.Sleep(2 * time.Second)
+
+	fmt.Printf("check for PreferStandby\n")
+	if row := c.QueryRowContext(NodeStateCriterion(tctx, hasql.PreferStandby), "SELECT node_name as name"); row.Err() == nil {
+		t.Fatal("must return error")
+	}
+
+	if dbMasterErr := dbMasterMock.ExpectationsWereMet(); dbMasterErr != nil {
+		t.Error(dbMasterErr)
+	}
+}

cluster/hasql/db.go

@@ -0,0 +1,25 @@
+package sql
+
+import (
+	"context"
+	"database/sql"
+)
+
+type Querier interface {
+	// Basic connection methods
+	PingContext(ctx context.Context) error
+	Close() error
+
+	// Query methods with context
+	ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error)
+	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
+	QueryRowContext(ctx context.Context, query string, args ...interface{}) *sql.Row
+
+	// Prepared statements with context
+	PrepareContext(ctx context.Context, query string) (*sql.Stmt, error)
+
+	// Transaction management with context
+	BeginTx(ctx context.Context, opts *sql.TxOptions) (*sql.Tx, error)
+
+	Conn(ctx context.Context) (*sql.Conn, error)
+}

cluster/hasql/driver.go

@@ -0,0 +1,295 @@
+package sql
+
+import (
+	"context"
+	"database/sql"
+	"database/sql/driver"
+	"io"
+	"sync"
+	"time"
+)
+
+// OpenDBWithCluster creates a [*sql.DB] that uses the [ClusterQuerier]
+func OpenDBWithCluster(db ClusterQuerier) (*sql.DB, error) {
+	driver := NewClusterDriver(db)
+	connector, err := driver.OpenConnector("")
+	if err != nil {
+		return nil, err
+	}
+	return sql.OpenDB(connector), nil
+}
+
+// ClusterDriver implements [driver.Driver] and driver.Connector for an existing [Querier]
+type ClusterDriver struct {
+	db ClusterQuerier
+}
+
+// NewClusterDriver creates a new [driver.Driver] that uses an existing [ClusterQuerier]
+func NewClusterDriver(db ClusterQuerier) *ClusterDriver {
+	return &ClusterDriver{db: db}
+}
+
+// Open implements [driver.Driver.Open]
+func (d *ClusterDriver) Open(name string) (driver.Conn, error) {
+	return d.Connect(context.Background())
+}
+
+// OpenConnector implements [driver.DriverContext.OpenConnector]
+func (d *ClusterDriver) OpenConnector(name string) (driver.Connector, error) {
+	return d, nil
+}
+
+// Connect implements [driver.Connector.Connect]
+func (d *ClusterDriver) Connect(ctx context.Context) (driver.Conn, error) {
+	conn, err := d.db.Conn(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return &dbConn{conn: conn}, nil
+}
+
+// Driver implements [driver.Connector.Driver]
+func (d *ClusterDriver) Driver() driver.Driver {
+	return d
+}
+
+// dbConn implements driver.Conn with both context and legacy methods
+type dbConn struct {
+	conn *sql.Conn
+	mu   sync.Mutex
+}
+
+// Prepare implements [driver.Conn.Prepare] (legacy method)
+func (c *dbConn) Prepare(query string) (driver.Stmt, error) {
+	return c.PrepareContext(context.Background(), query)
+}
+
+// PrepareContext implements [driver.ConnPrepareContext.PrepareContext]
+func (c *dbConn) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	stmt, err := c.conn.PrepareContext(ctx, query)
+	if err != nil {
+		return nil, err
+	}
+
+	return &dbStmt{stmt: stmt}, nil
+}
+
+// Exec implements [driver.Execer.Exec] (legacy method)
+func (c *dbConn) Exec(query string, args []driver.Value) (driver.Result, error) {
+	namedArgs := make([]driver.NamedValue, len(args))
+	for i, value := range args {
+		namedArgs[i] = driver.NamedValue{Value: value}
+	}
+	return c.ExecContext(context.Background(), query, namedArgs)
+}
+
+// ExecContext implements [driver.ExecerContext.ExecContext]
+func (c *dbConn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	// Convert driver.NamedValue to any
+	interfaceArgs := make([]any, len(args))
+	for i, arg := range args {
+		interfaceArgs[i] = arg.Value
+	}
+
+	return c.conn.ExecContext(ctx, query, interfaceArgs...)
+}
+
+// Query implements [driver.Queryer.Query] (legacy method)
+func (c *dbConn) Query(query string, args []driver.Value) (driver.Rows, error) {
+	namedArgs := make([]driver.NamedValue, len(args))
+	for i, value := range args {
+		namedArgs[i] = driver.NamedValue{Value: value}
+	}
+	return c.QueryContext(context.Background(), query, namedArgs)
+}
+
+// QueryContext implements [driver.QueryerContext.QueryContext]
+func (c *dbConn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	// Convert driver.NamedValue to any
+	interfaceArgs := make([]any, len(args))
+	for i, arg := range args {
+		interfaceArgs[i] = arg.Value
+	}
+
+	rows, err := c.conn.QueryContext(ctx, query, interfaceArgs...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &dbRows{rows: rows}, nil
+}
+
+// Begin implements [driver.Conn.Begin] (legacy method)
+func (c *dbConn) Begin() (driver.Tx, error) {
+	return c.BeginTx(context.Background(), driver.TxOptions{})
+}
+
+// BeginTx implements [driver.ConnBeginTx.BeginTx]
+func (c *dbConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	sqlOpts := &sql.TxOptions{
+		Isolation: sql.IsolationLevel(opts.Isolation),
+		ReadOnly:  opts.ReadOnly,
+	}
+
+	tx, err := c.conn.BeginTx(ctx, sqlOpts)
+	if err != nil {
+		return nil, err
+	}
+
+	return &dbTx{tx: tx}, nil
+}
+
+// Ping implements [driver.Pinger.Ping]
+func (c *dbConn) Ping(ctx context.Context) error {
+	return c.conn.PingContext(ctx)
+}
+
+// Close implements [driver.Conn.Close]
+func (c *dbConn) Close() error {
+	return c.conn.Close()
+}
+
+// IsValid implements [driver.Validator.IsValid]
+func (c *dbConn) IsValid() bool {
+	// Ping with a short timeout to check if the connection is still valid
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+
+	return c.conn.PingContext(ctx) == nil
+}
+
+// dbStmt implements [driver.Stmt] with both context and legacy methods
+type dbStmt struct {
+	stmt *sql.Stmt
+	mu   sync.Mutex
+}
+
+// Close implements [driver.Stmt.Close]
+func (s *dbStmt) Close() error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.stmt.Close()
+}
+
+// Close implements [driver.Stmt.NumInput]
+func (s *dbStmt) NumInput() int {
+	return -1 // Number of parameters is unknown
+}
+
+// Exec implements [driver.Stmt.Exec] (legacy method)
+func (s *dbStmt) Exec(args []driver.Value) (driver.Result, error) {
+	namedArgs := make([]driver.NamedValue, len(args))
+	for i, value := range args {
+		namedArgs[i] = driver.NamedValue{Value: value}
+	}
+	return s.ExecContext(context.Background(), namedArgs)
+}
+
+// ExecContext implements [driver.StmtExecContext.ExecContext]
+func (s *dbStmt) ExecContext(ctx context.Context, args []driver.NamedValue) (driver.Result, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	interfaceArgs := make([]any, len(args))
+	for i, arg := range args {
+		interfaceArgs[i] = arg.Value
+	}
+	return s.stmt.ExecContext(ctx, interfaceArgs...)
+}
+
+// Query implements [driver.Stmt.Query] (legacy method)
+func (s *dbStmt) Query(args []driver.Value) (driver.Rows, error) {
+	namedArgs := make([]driver.NamedValue, len(args))
+	for i, value := range args {
+		namedArgs[i] = driver.NamedValue{Value: value}
+	}
+	return s.QueryContext(context.Background(), namedArgs)
+}
+
+// QueryContext implements [driver.StmtQueryContext.QueryContext]
+func (s *dbStmt) QueryContext(ctx context.Context, args []driver.NamedValue) (driver.Rows, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	interfaceArgs := make([]any, len(args))
+	for i, arg := range args {
+		interfaceArgs[i] = arg.Value
+	}
+
+	rows, err := s.stmt.QueryContext(ctx, interfaceArgs...)
+	if err != nil {
+		return nil, err
+	}
+
+	return &dbRows{rows: rows}, nil
+}
+
+// dbRows implements [driver.Rows]
+type dbRows struct {
+	rows *sql.Rows
+}
+
+// Columns implements [driver.Rows.Columns]
+func (r *dbRows) Columns() []string {
+	cols, err := r.rows.Columns()
+	if err != nil {
+		// This shouldn't happen if the query was successful
+		return []string{}
+	}
+	return cols
+}
+
+// Close implements [driver.Rows.Close]
+func (r *dbRows) Close() error {
+	return r.rows.Close()
+}
+
+// Next implements [driver.Rows.Next]
+func (r *dbRows) Next(dest []driver.Value) error {
+	if !r.rows.Next() {
+		if err := r.rows.Err(); err != nil {
+			return err
+		}
+		return io.EOF
+	}
+
+	// Create a slice of interfaces to scan into
+	scanArgs := make([]any, len(dest))
+	for i := range scanArgs {
+		scanArgs[i] = &dest[i]
+	}
+
+	return r.rows.Scan(scanArgs...)
+}
+
+// dbTx implements [driver.Tx]
+type dbTx struct {
+	tx *sql.Tx
+	mu sync.Mutex
+}
+
+// Commit implements [driver.Tx.Commit]
+func (t *dbTx) Commit() error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.tx.Commit()
+}
+
+// Rollback implements [driver.Tx.Rollback]
+func (t *dbTx) Rollback() error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.tx.Rollback()
+}

cluster/hasql/driver_test.go

@@ -0,0 +1,141 @@
+package sql
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"golang.yandex/hasql/v2"
+)
+
+func TestDriver(t *testing.T) {
+	dbMaster, dbMasterMock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbMaster.Close()
+	dbMasterMock.MatchExpectationsInOrder(false)
+
+	dbMasterMock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(1, 0)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("master-dc1"))
+
+	dbDRMaster, dbDRMasterMock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbDRMaster.Close()
+	dbDRMasterMock.MatchExpectationsInOrder(false)
+
+	dbDRMasterMock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 40)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbDRMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("drmaster1-dc2"))
+
+	dbDRMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("drmaster"))
+
+	dbSlaveDC1, dbSlaveDC1Mock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbSlaveDC1.Close()
+	dbSlaveDC1Mock.MatchExpectationsInOrder(false)
+
+	dbSlaveDC1Mock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 50)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbSlaveDC1Mock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("slave-dc1"))
+
+	dbSlaveDC2, dbSlaveDC2Mock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbSlaveDC2.Close()
+	dbSlaveDC1Mock.MatchExpectationsInOrder(false)
+
+	dbSlaveDC2Mock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 50)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbSlaveDC2Mock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("slave-dc1"))
+
+	tctx, cancel := context.WithTimeout(t.Context(), 10*time.Second)
+	defer cancel()
+
+	c, err := NewCluster[Querier](
+		WithClusterContext(tctx),
+		WithClusterNodeChecker(hasql.PostgreSQLChecker),
+		WithClusterNodePicker(NewCustomPicker[Querier](
+			CustomPickerMaxLag(100),
+		)),
+		WithClusterNodes(
+			ClusterNode{"slave-dc1", dbSlaveDC1, 1},
+			ClusterNode{"master-dc1", dbMaster, 1},
+			ClusterNode{"slave-dc2", dbSlaveDC2, 2},
+			ClusterNode{"drmaster1-dc2", dbDRMaster, 0},
+		),
+		WithClusterOptions(
+			hasql.WithUpdateInterval[Querier](2*time.Second),
+			hasql.WithUpdateTimeout[Querier](1*time.Second),
+		),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	if err = c.WaitForNodes(tctx, hasql.Primary, hasql.Standby); err != nil {
+		t.Fatal(err)
+	}
+
+	db, err := OpenDBWithCluster(c)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Use context methods
+	row := db.QueryRowContext(NodeStateCriterion(t.Context(), hasql.Primary), "SELECT node_name as name")
+	if err = row.Err(); err != nil {
+		t.Fatal(err)
+	}
+
+	nodeName := ""
+	if err = row.Scan(&nodeName); err != nil {
+		t.Fatal(err)
+	}
+
+	if nodeName != "master-dc1" {
+		t.Fatalf("invalid node_name %s != %s", "master-dc1", nodeName)
+	}
+}

cluster/hasql/error.go

@@ -0,0 +1,10 @@
+package sql
+
+import "errors"
+
+var (
+	ErrClusterChecker    = errors.New("cluster node checker required")
+	ErrClusterDiscoverer = errors.New("cluster node discoverer required")
+	ErrClusterPicker     = errors.New("cluster node picker required")
+	ErrorNoAliveNodes    = errors.New("cluster no alive nodes")
+)

cluster/hasql/options.go

@@ -0,0 +1,110 @@
+package sql
+
+import (
+	"context"
+	"math"
+
+	"golang.yandex/hasql/v2"
+)
+
+// ClusterOptions contains cluster specific options
+type ClusterOptions struct {
+	NodeChecker        hasql.NodeChecker
+	NodePicker         hasql.NodePicker[Querier]
+	NodeDiscoverer     hasql.NodeDiscoverer[Querier]
+	Options            []hasql.ClusterOpt[Querier]
+	Context            context.Context
+	Retries            int
+	NodePriority       map[string]int32
+	NodeStateCriterion hasql.NodeStateCriterion
+}
+
+// ClusterOption apply cluster options to ClusterOptions
+type ClusterOption func(*ClusterOptions)
+
+// WithClusterNodeChecker pass hasql.NodeChecker to cluster options
+func WithClusterNodeChecker(c hasql.NodeChecker) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.NodeChecker = c
+	}
+}
+
+// WithClusterNodePicker pass hasql.NodePicker to cluster options
+func WithClusterNodePicker(p hasql.NodePicker[Querier]) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.NodePicker = p
+	}
+}
+
+// WithClusterNodeDiscoverer pass hasql.NodeDiscoverer to cluster options
+func WithClusterNodeDiscoverer(d hasql.NodeDiscoverer[Querier]) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.NodeDiscoverer = d
+	}
+}
+
+// WithRetries retry count on other nodes in case of error
+func WithRetries(n int) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.Retries = n
+	}
+}
+
+// WithClusterContext pass context.Context to cluster options and used for checks
+func WithClusterContext(ctx context.Context) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.Context = ctx
+	}
+}
+
+// WithClusterOptions pass hasql.ClusterOpt
+func WithClusterOptions(opts ...hasql.ClusterOpt[Querier]) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.Options = append(o.Options, opts...)
+	}
+}
+
+// WithClusterNodeStateCriterion pass default hasql.NodeStateCriterion
+func WithClusterNodeStateCriterion(c hasql.NodeStateCriterion) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.NodeStateCriterion = c
+	}
+}
+
+type ClusterNode struct {
+	Name     string
+	DB       Querier
+	Priority int32
+}
+
+// WithClusterNodes create cluster with static NodeDiscoverer
+func WithClusterNodes(cns ...ClusterNode) ClusterOption {
+	return func(o *ClusterOptions) {
+		nodes := make([]*hasql.Node[Querier], 0, len(cns))
+		if o.NodePriority == nil {
+			o.NodePriority = make(map[string]int32, len(cns))
+		}
+		for _, cn := range cns {
+			nodes = append(nodes, hasql.NewNode(cn.Name, cn.DB))
+			if cn.Priority == 0 {
+				cn.Priority = math.MaxInt32
+			}
+			o.NodePriority[cn.Name] = cn.Priority
+		}
+		o.NodeDiscoverer = hasql.NewStaticNodeDiscoverer(nodes...)
+	}
+}
+
+type nodeStateCriterionKey struct{}
+
+// NodeStateCriterion inject hasql.NodeStateCriterion to context
+func NodeStateCriterion(ctx context.Context, c hasql.NodeStateCriterion) context.Context {
+	return context.WithValue(ctx, nodeStateCriterionKey{}, c)
+}
+
+func (c *Cluster) getNodeStateCriterion(ctx context.Context) hasql.NodeStateCriterion {
+	if v, ok := ctx.Value(nodeStateCriterionKey{}).(hasql.NodeStateCriterion); ok {
+		return v
+	}
+	return c.options.NodeStateCriterion
+}

cluster/hasql/picker.go

@@ -0,0 +1,113 @@
+package sql
+
+import (
+	"fmt"
+	"math"
+	"time"
+
+	"golang.yandex/hasql/v2"
+)
+
+// compile time guard
+var _ hasql.NodePicker[Querier] = (*CustomPicker[Querier])(nil)
+
+// CustomPickerOptions holds options to pick nodes
+type CustomPickerOptions struct {
+	MaxLag   int
+	Priority map[string]int32
+	Retries  int
+}
+
+// CustomPickerOption func apply option to CustomPickerOptions
+type CustomPickerOption func(*CustomPickerOptions)
+
+// CustomPickerMaxLag specifies max lag for which node can be used
+func CustomPickerMaxLag(n int) CustomPickerOption {
+	return func(o *CustomPickerOptions) {
+		o.MaxLag = n
+	}
+}
+
+// NewCustomPicker creates new node picker
+func NewCustomPicker[T Querier](opts ...CustomPickerOption) *CustomPicker[Querier] {
+	options := CustomPickerOptions{}
+	for _, o := range opts {
+		o(&options)
+	}
+	return &CustomPicker[Querier]{opts: options}
+}
+
+// CustomPicker holds node picker options
+type CustomPicker[T Querier] struct {
+	opts CustomPickerOptions
+}
+
+// PickNode used to return specific node
+func (p *CustomPicker[T]) PickNode(cnodes []hasql.CheckedNode[T]) hasql.CheckedNode[T] {
+	for _, n := range cnodes {
+		fmt.Printf("node %s\n", n.Node.String())
+	}
+	return cnodes[0]
+}
+
+func (p *CustomPicker[T]) getPriority(nodeName string) int32 {
+	if prio, ok := p.opts.Priority[nodeName]; ok {
+		return prio
+	}
+	return math.MaxInt32 // Default to lowest priority
+}
+
+// CompareNodes used to sort nodes
+func (p *CustomPicker[T]) CompareNodes(a, b hasql.CheckedNode[T]) int {
+	// Get replication lag values
+	aLag := a.Info.(interface{ ReplicationLag() int }).ReplicationLag()
+	bLag := b.Info.(interface{ ReplicationLag() int }).ReplicationLag()
+
+	// First check that lag lower then MaxLag
+	if aLag > p.opts.MaxLag && bLag > p.opts.MaxLag {
+		return 0 // both are equal
+	}
+
+	// If one node exceeds MaxLag and the other doesn't, prefer the one that doesn't
+	if aLag > p.opts.MaxLag {
+		return 1 // b is better
+	}
+	if bLag > p.opts.MaxLag {
+		return -1 // a is better
+	}
+
+	// Get node priorities
+	aPrio := p.getPriority(a.Node.String())
+	bPrio := p.getPriority(b.Node.String())
+
+	// if both priority equals
+	if aPrio == bPrio {
+		// First compare by replication lag
+		if aLag < bLag {
+			return -1
+		}
+		if aLag > bLag {
+			return 1
+		}
+		// If replication lag is equal, compare by latency
+		aLatency := a.Info.(interface{ Latency() time.Duration }).Latency()
+		bLatency := b.Info.(interface{ Latency() time.Duration }).Latency()
+
+		if aLatency < bLatency {
+			return -1
+		}
+		if aLatency > bLatency {
+			return 1
+		}
+
+		// If lag and latency is equal
+		return 0
+	}
+
+	// If priorities are different, prefer the node with lower priority value
+	if aPrio < bPrio {
+		return -1
+	}
+
+	return 1
+}

cluster/sql/cluster.go

@@ -0,0 +1,531 @@
+package sql
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+	"math"
+	"reflect"
+	"time"
+	"unsafe"
+
+	"golang.yandex/hasql/v2"
+)
+
+var errNoAliveNodes = errors.New("no alive nodes")
+
+func newSQLRowError() *sql.Row {
+	row := &sql.Row{}
+	t := reflect.TypeOf(row).Elem()
+	field, _ := t.FieldByName("err")
+	rowPtr := unsafe.Pointer(row)
+	errFieldPtr := unsafe.Pointer(uintptr(rowPtr) + field.Offset)
+	errPtr := (*error)(errFieldPtr)
+	*errPtr = errNoAliveNodes
+	return row
+}
+
+type ClusterQuerier interface {
+	Querier
+	WaitForNodes(ctx context.Context, criterion ...hasql.NodeStateCriterion) error
+}
+
+type Querier interface {
+	// Basic connection methods
+	PingContext(ctx context.Context) error
+	Close() error
+
+	// Query methods with context
+	ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error)
+	QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error)
+	QueryRowContext(ctx context.Context, query string, args ...interface{}) *sql.Row
+
+	// Prepared statements with context
+	PrepareContext(ctx context.Context, query string) (*sql.Stmt, error)
+
+	// Transaction management with context
+	BeginTx(ctx context.Context, opts *sql.TxOptions) (*sql.Tx, error)
+
+	// Connection pool management
+	SetConnMaxLifetime(d time.Duration)
+	SetConnMaxIdleTime(d time.Duration)
+	SetMaxOpenConns(n int)
+	SetMaxIdleConns(n int)
+	Stats() sql.DBStats
+
+	Conn(ctx context.Context) (*sql.Conn, error)
+}
+
+var (
+	ErrClusterChecker    = errors.New("cluster node checker required")
+	ErrClusterDiscoverer = errors.New("cluster node discoverer required")
+	ErrClusterPicker     = errors.New("cluster node picker required")
+)
+
+type Cluster struct {
+	hasql   *hasql.Cluster[Querier]
+	options ClusterOptions
+}
+
+// NewCluster returns Querier that provides cluster of nodes
+func NewCluster[T Querier](opts ...ClusterOption) (ClusterQuerier, error) {
+	options := ClusterOptions{Context: context.Background()}
+	for _, opt := range opts {
+		opt(&options)
+	}
+	if options.NodeChecker == nil {
+		return nil, ErrClusterChecker
+	}
+	if options.NodeDiscoverer == nil {
+		return nil, ErrClusterDiscoverer
+	}
+	if options.NodePicker == nil {
+		return nil, ErrClusterPicker
+	}
+
+	if options.Retries < 1 {
+		options.Retries = 1
+	}
+
+	if options.NodeStateCriterion == 0 {
+		options.NodeStateCriterion = hasql.Primary
+	}
+
+	options.Options = append(options.Options, hasql.WithNodePicker(options.NodePicker))
+	if p, ok := options.NodePicker.(*CustomPicker[Querier]); ok {
+		p.opts.Priority = options.NodePriority
+	}
+
+	c, err := hasql.NewCluster(
+		options.NodeDiscoverer,
+		options.NodeChecker,
+		options.Options...,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Cluster{hasql: c, options: options}, nil
+}
+
+// compile time guard
+var _ hasql.NodePicker[Querier] = (*CustomPicker[Querier])(nil)
+
+type nodeStateCriterionKey struct{}
+
+// NodeStateCriterion inject hasql.NodeStateCriterion to context
+func NodeStateCriterion(ctx context.Context, c hasql.NodeStateCriterion) context.Context {
+	return context.WithValue(ctx, nodeStateCriterionKey{}, c)
+}
+
+// CustomPickerOptions holds options to pick nodes
+type CustomPickerOptions struct {
+	MaxLag   int
+	Priority map[string]int32
+	Retries  int
+}
+
+// CustomPickerOption func apply option to CustomPickerOptions
+type CustomPickerOption func(*CustomPickerOptions)
+
+// CustomPickerMaxLag specifies max lag for which node can be used
+func CustomPickerMaxLag(n int) CustomPickerOption {
+	return func(o *CustomPickerOptions) {
+		o.MaxLag = n
+	}
+}
+
+// NewCustomPicker creates new node picker
+func NewCustomPicker[T Querier](opts ...CustomPickerOption) *CustomPicker[Querier] {
+	options := CustomPickerOptions{}
+	for _, o := range opts {
+		o(&options)
+	}
+	return &CustomPicker[Querier]{opts: options}
+}
+
+// CustomPicker holds node picker options
+type CustomPicker[T Querier] struct {
+	opts CustomPickerOptions
+}
+
+// PickNode used to return specific node
+func (p *CustomPicker[T]) PickNode(cnodes []hasql.CheckedNode[T]) hasql.CheckedNode[T] {
+	for _, n := range cnodes {
+		fmt.Printf("node %s\n", n.Node.String())
+	}
+	return cnodes[0]
+}
+
+func (p *CustomPicker[T]) getPriority(nodeName string) int32 {
+	if prio, ok := p.opts.Priority[nodeName]; ok {
+		return prio
+	}
+	return math.MaxInt32 // Default to lowest priority
+}
+
+// CompareNodes used to sort nodes
+func (p *CustomPicker[T]) CompareNodes(a, b hasql.CheckedNode[T]) int {
+	fmt.Printf("CompareNodes %s %s\n", a.Node.String(), b.Node.String())
+	// Get replication lag values
+	aLag := a.Info.(interface{ ReplicationLag() int }).ReplicationLag()
+	bLag := b.Info.(interface{ ReplicationLag() int }).ReplicationLag()
+
+	// First check that lag lower then MaxLag
+	if aLag > p.opts.MaxLag && bLag > p.opts.MaxLag {
+		fmt.Printf("CompareNodes aLag > p.opts.MaxLag && bLag > p.opts.MaxLag\n")
+		return 0 // both are equal
+	}
+
+	// If one node exceeds MaxLag and the other doesn't, prefer the one that doesn't
+	if aLag > p.opts.MaxLag {
+		fmt.Printf("CompareNodes aLag > p.opts.MaxLag\n")
+		return 1 // b is better
+	}
+	if bLag > p.opts.MaxLag {
+		fmt.Printf("CompareNodes bLag > p.opts.MaxLag\n")
+		return -1 // a is better
+	}
+
+	// Get node priorities
+	aPrio := p.getPriority(a.Node.String())
+	bPrio := p.getPriority(b.Node.String())
+
+	// if both priority equals
+	if aPrio == bPrio {
+		fmt.Printf("CompareNodes aPrio == bPrio\n")
+		// First compare by replication lag
+		if aLag < bLag {
+			fmt.Printf("CompareNodes aLag < bLag\n")
+			return -1
+		}
+		if aLag > bLag {
+			fmt.Printf("CompareNodes aLag > bLag\n")
+			return 1
+		}
+		// If replication lag is equal, compare by latency
+		aLatency := a.Info.(interface{ Latency() time.Duration }).Latency()
+		bLatency := b.Info.(interface{ Latency() time.Duration }).Latency()
+
+		if aLatency < bLatency {
+			return -1
+		}
+		if aLatency > bLatency {
+			return 1
+		}
+
+		// If lag and latency is equal
+		return 0
+	}
+
+	// If priorities are different, prefer the node with lower priority value
+	if aPrio < bPrio {
+		return -1
+	}
+
+	return 1
+}
+
+// ClusterOptions contains cluster specific options
+type ClusterOptions struct {
+	NodeChecker        hasql.NodeChecker
+	NodePicker         hasql.NodePicker[Querier]
+	NodeDiscoverer     hasql.NodeDiscoverer[Querier]
+	Options            []hasql.ClusterOpt[Querier]
+	Context            context.Context
+	Retries            int
+	NodePriority       map[string]int32
+	NodeStateCriterion hasql.NodeStateCriterion
+}
+
+// ClusterOption apply cluster options to ClusterOptions
+type ClusterOption func(*ClusterOptions)
+
+// WithClusterNodeChecker pass hasql.NodeChecker to cluster options
+func WithClusterNodeChecker(c hasql.NodeChecker) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.NodeChecker = c
+	}
+}
+
+// WithClusterNodePicker pass hasql.NodePicker to cluster options
+func WithClusterNodePicker(p hasql.NodePicker[Querier]) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.NodePicker = p
+	}
+}
+
+// WithClusterNodeDiscoverer pass hasql.NodeDiscoverer to cluster options
+func WithClusterNodeDiscoverer(d hasql.NodeDiscoverer[Querier]) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.NodeDiscoverer = d
+	}
+}
+
+// WithRetries retry count on other nodes in case of error
+func WithRetries(n int) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.Retries = n
+	}
+}
+
+// WithClusterContext pass context.Context to cluster options and used for checks
+func WithClusterContext(ctx context.Context) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.Context = ctx
+	}
+}
+
+// WithClusterOptions pass hasql.ClusterOpt
+func WithClusterOptions(opts ...hasql.ClusterOpt[Querier]) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.Options = append(o.Options, opts...)
+	}
+}
+
+// WithClusterNodeStateCriterion pass default hasql.NodeStateCriterion
+func WithClusterNodeStateCriterion(c hasql.NodeStateCriterion) ClusterOption {
+	return func(o *ClusterOptions) {
+		o.NodeStateCriterion = c
+	}
+}
+
+type ClusterNode struct {
+	Name     string
+	DB       Querier
+	Priority int32
+}
+
+// WithClusterNodes create cluster with static NodeDiscoverer
+func WithClusterNodes(cns ...ClusterNode) ClusterOption {
+	return func(o *ClusterOptions) {
+		nodes := make([]*hasql.Node[Querier], 0, len(cns))
+		if o.NodePriority == nil {
+			o.NodePriority = make(map[string]int32, len(cns))
+		}
+		for _, cn := range cns {
+			nodes = append(nodes, hasql.NewNode(cn.Name, cn.DB))
+			if cn.Priority == 0 {
+				cn.Priority = math.MaxInt32
+			}
+			o.NodePriority[cn.Name] = cn.Priority
+		}
+		o.NodeDiscoverer = hasql.NewStaticNodeDiscoverer(nodes...)
+	}
+}
+
+func (c *Cluster) BeginTx(ctx context.Context, opts *sql.TxOptions) (*sql.Tx, error) {
+	var tx *sql.Tx
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if tx, err = n.DB().BeginTx(ctx, opts); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if tx == nil && err == nil {
+		err = errNoAliveNodes
+	}
+
+	return tx, err
+}
+
+func (c *Cluster) Close() error {
+	return c.hasql.Close()
+}
+
+func (c *Cluster) Conn(ctx context.Context) (*sql.Conn, error) {
+	var conn *sql.Conn
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if conn, err = n.DB().Conn(ctx); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if conn == nil && err == nil {
+		err = errNoAliveNodes
+	}
+
+	return conn, err
+}
+
+func (c *Cluster) ExecContext(ctx context.Context, query string, args ...interface{}) (sql.Result, error) {
+	var res sql.Result
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if res, err = n.DB().ExecContext(ctx, query, args...); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if res == nil && err == nil {
+		err = errNoAliveNodes
+	}
+
+	return res, err
+}
+
+func (c *Cluster) PrepareContext(ctx context.Context, query string) (*sql.Stmt, error) {
+	var res *sql.Stmt
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if res, err = n.DB().PrepareContext(ctx, query); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if res == nil && err == nil {
+		err = errNoAliveNodes
+	}
+
+	return res, err
+}
+
+func (c *Cluster) QueryContext(ctx context.Context, query string, args ...interface{}) (*sql.Rows, error) {
+	var res *sql.Rows
+	var err error
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			if res, err = n.DB().QueryContext(ctx, query); err != nil && err != sql.ErrNoRows && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if res == nil && err == nil {
+		err = errNoAliveNodes
+	}
+
+	return res, err
+}
+
+func (c *Cluster) QueryRowContext(ctx context.Context, query string, args ...interface{}) *sql.Row {
+	var res *sql.Row
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		for ; retries < c.options.Retries; retries++ {
+			res = n.DB().QueryRowContext(ctx, query, args...)
+			if res.Err() == nil {
+				return false
+			} else if res.Err() != nil && retries >= c.options.Retries {
+				return false
+			}
+		}
+		return true
+	})
+
+	if res == nil {
+		res = newSQLRowError()
+	}
+
+	return res
+}
+
+func (c *Cluster) PingContext(ctx context.Context) error {
+	var err error
+	var ok bool
+
+	retries := 0
+	c.hasql.NodesIter(c.getNodeStateCriterion(ctx))(func(n *hasql.Node[Querier]) bool {
+		ok = true
+		for ; retries < c.options.Retries; retries++ {
+			if err = n.DB().PingContext(ctx); err != nil && retries >= c.options.Retries {
+				return true
+			}
+		}
+		return false
+	})
+
+	if !ok {
+		err = errNoAliveNodes
+	}
+
+	return err
+}
+
+func (c *Cluster) WaitForNodes(ctx context.Context, criterions ...hasql.NodeStateCriterion) error {
+	for _, criterion := range criterions {
+		if _, err := c.hasql.WaitForNode(ctx, criterion); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (c *Cluster) SetConnMaxLifetime(td time.Duration) {
+	c.hasql.NodesIter(hasql.NodeStateCriterion(hasql.Alive))(func(n *hasql.Node[Querier]) bool {
+		n.DB().SetConnMaxIdleTime(td)
+		return false
+	})
+}
+
+func (c *Cluster) SetConnMaxIdleTime(td time.Duration) {
+	c.hasql.NodesIter(hasql.NodeStateCriterion(hasql.Alive))(func(n *hasql.Node[Querier]) bool {
+		n.DB().SetConnMaxIdleTime(td)
+		return false
+	})
+}
+
+func (c *Cluster) SetMaxOpenConns(nc int) {
+	c.hasql.NodesIter(hasql.NodeStateCriterion(hasql.Alive))(func(n *hasql.Node[Querier]) bool {
+		n.DB().SetMaxOpenConns(nc)
+		return false
+	})
+}
+
+func (c *Cluster) SetMaxIdleConns(nc int) {
+	c.hasql.NodesIter(hasql.NodeStateCriterion(hasql.Alive))(func(n *hasql.Node[Querier]) bool {
+		n.DB().SetMaxIdleConns(nc)
+		return false
+	})
+}
+
+func (c *Cluster) Stats() sql.DBStats {
+	s := sql.DBStats{}
+	c.hasql.NodesIter(hasql.NodeStateCriterion(hasql.Alive))(func(n *hasql.Node[Querier]) bool {
+		st := n.DB().Stats()
+		s.Idle += st.Idle
+		s.InUse += st.InUse
+		s.MaxIdleClosed += st.MaxIdleClosed
+		s.MaxIdleTimeClosed += st.MaxIdleTimeClosed
+		s.MaxOpenConnections += st.MaxOpenConnections
+		s.OpenConnections += st.OpenConnections
+		s.WaitCount += st.WaitCount
+		s.WaitDuration += st.WaitDuration
+		return false
+	})
+	return s
+}
+
+func (c *Cluster) getNodeStateCriterion(ctx context.Context) hasql.NodeStateCriterion {
+	if v, ok := ctx.Value(nodeStateCriterionKey{}).(hasql.NodeStateCriterion); ok {
+		return v
+	}
+	return c.options.NodeStateCriterion
+}

cluster/sql/cluster_test.go

@@ -0,0 +1,171 @@
+package sql
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"golang.yandex/hasql/v2"
+)
+
+func TestNewCluster(t *testing.T) {
+	dbMaster, dbMasterMock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbMaster.Close()
+	dbMasterMock.MatchExpectationsInOrder(false)
+
+	dbMasterMock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(1, 0)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("master-dc1"))
+
+	dbDRMaster, dbDRMasterMock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbDRMaster.Close()
+	dbDRMasterMock.MatchExpectationsInOrder(false)
+
+	dbDRMasterMock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 40)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbDRMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("drmaster1-dc2"))
+
+	dbDRMasterMock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("drmaster"))
+
+	dbSlaveDC1, dbSlaveDC1Mock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbSlaveDC1.Close()
+	dbSlaveDC1Mock.MatchExpectationsInOrder(false)
+
+	dbSlaveDC1Mock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 50)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbSlaveDC1Mock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("slave-dc1"))
+
+	dbSlaveDC2, dbSlaveDC2Mock, err := sqlmock.New(sqlmock.MonitorPingsOption(true))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dbSlaveDC2.Close()
+	dbSlaveDC1Mock.MatchExpectationsInOrder(false)
+
+	dbSlaveDC2Mock.ExpectQuery(`.*pg_is_in_recovery.*`).WillReturnRows(
+		sqlmock.NewRowsWithColumnDefinition(
+			sqlmock.NewColumn("role").OfType("int8", 0),
+			sqlmock.NewColumn("replication_lag").OfType("int8", 0)).
+			AddRow(2, 50)).
+		RowsWillBeClosed().
+		WithoutArgs()
+
+	dbSlaveDC2Mock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("slave-dc1"))
+
+	tctx, cancel := context.WithTimeout(t.Context(), 10*time.Second)
+	defer cancel()
+
+	c, err := NewCluster[Querier](
+		WithClusterContext(tctx),
+		WithClusterNodeChecker(hasql.PostgreSQLChecker),
+		WithClusterNodePicker(NewCustomPicker[Querier](
+			CustomPickerMaxLag(100),
+		)),
+		WithClusterNodes(
+			ClusterNode{"slave-dc1", dbSlaveDC1, 1},
+			ClusterNode{"master-dc1", dbMaster, 1},
+			ClusterNode{"slave-dc2", dbSlaveDC2, 2},
+			ClusterNode{"drmaster1-dc2", dbDRMaster, 0},
+		),
+		WithClusterOptions(
+			hasql.WithUpdateInterval[Querier](2*time.Second),
+			hasql.WithUpdateTimeout[Querier](1*time.Second),
+		),
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer c.Close()
+
+	if err = c.WaitForNodes(tctx, hasql.Primary, hasql.Standby); err != nil {
+		t.Fatal(err)
+	}
+
+	time.Sleep(500 * time.Millisecond)
+
+	node1Name := ""
+	fmt.Printf("check for Standby\n")
+	if row := c.QueryRowContext(NodeStateCriterion(tctx, hasql.Standby), "SELECT node_name as name"); row.Err() != nil {
+		t.Fatal(row.Err())
+	} else if err = row.Scan(&node1Name); err != nil {
+		t.Fatal(err)
+	} else if "slave-dc1" != node1Name {
+		t.Fatalf("invalid node name %s != %s", "slave-dc1", node1Name)
+	}
+
+	dbSlaveDC1Mock.ExpectQuery(`SELECT node_name as name`).WillReturnRows(
+		sqlmock.NewRows([]string{"name"}).
+			AddRow("slave-dc1"))
+
+	node2Name := ""
+	fmt.Printf("check for PreferStandby\n")
+	if row := c.QueryRowContext(NodeStateCriterion(tctx, hasql.PreferStandby), "SELECT node_name as name"); row.Err() != nil {
+		t.Fatal(row.Err())
+	} else if err = row.Scan(&node2Name); err != nil {
+		t.Fatal(err)
+	} else if "slave-dc1" != node2Name {
+		t.Fatalf("invalid node name %s != %s", "slave-dc1", node2Name)
+	}
+
+	node3Name := ""
+	fmt.Printf("check for PreferPrimary\n")
+	if row := c.QueryRowContext(NodeStateCriterion(tctx, hasql.PreferPrimary), "SELECT node_name as name"); row.Err() != nil {
+		t.Fatal(row.Err())
+	} else if err = row.Scan(&node3Name); err != nil {
+		t.Fatal(err)
+	} else if "master-dc1" != node3Name {
+		t.Fatalf("invalid node name %s != %s", "master-dc1", node3Name)
+	}
+
+	dbSlaveDC1Mock.ExpectQuery(`.*`).WillReturnRows(sqlmock.NewRows([]string{"role"}).RowError(1, fmt.Errorf("row error")))
+
+	time.Sleep(2 * time.Second)
+
+	fmt.Printf("check for PreferStandby\n")
+	if row := c.QueryRowContext(NodeStateCriterion(tctx, hasql.PreferStandby), "SELECT node_name as name"); row.Err() == nil {
+		t.Fatal("must return error")
+	}
+
+	if dbMasterErr := dbMasterMock.ExpectationsWereMet(); dbMasterErr != nil {
+		t.Error(dbMasterErr)
+	}
+}

codec/frame.proto

@@ -17,7 +17,7 @@ syntax = "proto3";
 package micro.codec;
 
 option cc_enable_arenas = true;
-option go_package = "go.unistack.org/micro/v4/codec;codec";
+option go_package = "go.unistack.org/micro/v3/codec;codec";
 option java_multiple_files = true;
 option java_outer_classname = "MicroCodec";
 option java_package = "micro.codec";

codec/noop.go

@@ -3,7 +3,7 @@ package codec
 import (
 	"encoding/json"
 
-	codecpb "go.unistack.org/micro-proto/v4/codec"
+	codecpb "go.unistack.org/micro-proto/v3/codec"
 )
 
 type noopCodec struct {

codec/options.go

@@ -3,9 +3,9 @@ package codec
 import (
 	"context"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Option func

config/default.go

@@ -9,10 +9,10 @@ import (
 
 	"dario.cat/mergo"
 	"github.com/google/uuid"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	mid "go.unistack.org/micro/v4/util/id"
+	mid "go.unistack.org/micro/v3/util/id"
-	rutil "go.unistack.org/micro/v4/util/reflect"
+	rutil "go.unistack.org/micro/v3/util/reflect"
-	mtime "go.unistack.org/micro/v4/util/time"
+	mtime "go.unistack.org/micro/v3/util/time"
 )
 
 type defaultConfig struct {
@@ -210,7 +210,7 @@ func fillValue(value reflect.Value, val string) error {
 				return err
 			}
 			value.Set(reflect.ValueOf(v))
-		case value.Type().String() == "time.Duration" && value.Type().PkgPath() == "go.unistack.org/micro/v4/util/time":
+		case value.Type().String() == "time.Duration" && value.Type().PkgPath() == "go.unistack.org/micro/v3/util/time":
 			v, err := mtime.ParseDuration(val)
 			if err != nil {
 				return err

config/default_test.go

@@ -7,8 +7,8 @@ import (
 	"testing"
 	"time"
 
-	"go.unistack.org/micro/v4/config"
+	"go.unistack.org/micro/v3/config"
-	mtime "go.unistack.org/micro/v4/util/time"
+	mtime "go.unistack.org/micro/v3/util/time"
 )
 
 type cfg struct {

config/options.go

@@ -4,11 +4,11 @@ import (
 	"context"
 	"time"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/options"
+	"go.unistack.org/micro/v3/options"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Options hold the config options

errors/errors.proto

@@ -17,7 +17,7 @@ syntax = "proto3";
 package micro.errors;
 
 option cc_enable_arenas = true;
-option go_package = "go.unistack.org/micro/v4/errors;errors";
+option go_package = "go.unistack.org/micro/v3/errors;errors";
 option java_multiple_files = true;
 option java_outer_classname = "MicroErrors";
 option java_package = "micro.errors";

event.go

@@ -0,0 +1,27 @@
+package micro
+
+import (
+	"context"
+
+	"go.unistack.org/micro/v3/client"
+)
+
+// Event is used to publish messages to a topic
+type Event interface {
+	// Publish publishes a message to the event topic
+	Publish(ctx context.Context, msg interface{}, opts ...client.PublishOption) error
+}
+
+type event struct {
+	c     client.Client
+	topic string
+}
+
+// NewEvent creates a new event publisher
+func NewEvent(topic string, c client.Client) Event {
+	return &event{c, topic}
+}
+
+func (e *event) Publish(ctx context.Context, msg interface{}, opts ...client.PublishOption) error {
+	return e.c.Publish(ctx, e.c.NewMessage(e.topic, msg), opts...)
+}

flow/context.go

@@ -15,6 +15,15 @@ func FromContext(ctx context.Context) (Flow, bool) {
 	return c, ok
 }
 
+// MustContext returns Flow from context
+func MustContext(ctx context.Context) Flow {
+	f, ok := FromContext(ctx)
+	if !ok {
+		panic("missing flow")
+	}
+	return f
+}
+
 // NewContext stores Flow to context
 func NewContext(ctx context.Context, f Flow) context.Context {
 	if ctx == nil {

flow/context_test.go

@@ -1,5 +1,3 @@
-//go:build ignore
-
 package flow
 
 import (

flow/default.go

@@ -1,19 +1,17 @@
-//go:build ignore
-
 package flow
 
 import (
 	"context"
 	"fmt"
-	"path/filepath"
 	"sync"
 
-	"github.com/heimdalr/dag"
+	"github.com/silas/dag"
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/util/id"
+	"go.unistack.org/micro/v3/store"
+	"go.unistack.org/micro/v3/util/id"
 )
 
 type microFlow struct {
@@ -22,7 +20,7 @@ type microFlow struct {
 
 type microWorkflow struct {
 	opts   Options
-	g      *dag.DAG
+	g      *dag.AcyclicGraph
 	steps  map[string]Step
 	id     string
 	status Status
@@ -34,20 +32,20 @@ func (w *microWorkflow) ID() string {
 	return w.id
 }
 
+func (w *microWorkflow) Steps() ([][]Step, error) {
+	return w.getSteps("", false)
+}
+
 func (w *microWorkflow) Status() Status {
 	return w.status
 }
 
 func (w *microWorkflow) AppendSteps(steps ...Step) error {
-	var err error
 	w.Lock()
-	defer w.Unlock()
 
 	for _, s := range steps {
 		w.steps[s.String()] = s
-		if _, err = w.g.AddVertex(s); err != nil {
+		w.g.Add(s)
-			return err
-		}
 	}
 
 	for _, dst := range steps {
@@ -56,13 +54,18 @@ func (w *microWorkflow) AppendSteps(steps ...Step) error {
 			if !ok {
 				return ErrStepNotExists
 			}
-			if err = w.g.AddEdge(src.String(), dst.String()); err != nil {
+			w.g.Connect(dag.BasicEdge(src, dst))
-				return err
-			}
 		}
 	}
 
-	w.g.ReduceTransitively()
+	if err := w.g.Validate(); err != nil {
+		w.Unlock()
+		return err
+	}
+
+	w.g.TransitiveReduction()
+
+	w.Unlock()
 
 	return nil
 }
@@ -71,11 +74,10 @@ func (w *microWorkflow) RemoveSteps(steps ...Step) error {
 	// TODO: handle case when some step requires or required by removed step
 
 	w.Lock()
-	defer w.Unlock()
 
 	for _, s := range steps {
 		delete(w.steps, s.String())
-		w.g.DeleteVertex(s.String())
+		w.g.Remove(s)
 	}
 
 	for _, dst := range steps {
@@ -84,34 +86,91 @@ func (w *microWorkflow) RemoveSteps(steps ...Step) error {
 			if !ok {
 				return ErrStepNotExists
 			}
-			w.g.AddEdge(src.String(), dst.String())
+			w.g.Connect(dag.BasicEdge(src, dst))
 		}
 	}
 
-	w.g.ReduceTransitively()
+	if err := w.g.Validate(); err != nil {
+		w.Unlock()
+		return err
+	}
+
+	w.g.TransitiveReduction()
+
+	w.Unlock()
 
 	return nil
 }
 
+func (w *microWorkflow) getSteps(start string, reverse bool) ([][]Step, error) {
+	var steps [][]Step
+	var root dag.Vertex
+	var err error
+
+	fn := func(n dag.Vertex, idx int) error {
+		if idx == 0 {
+			steps = make([][]Step, 1)
+			steps[0] = make([]Step, 0, 1)
+		} else if idx >= len(steps) {
+			tsteps := make([][]Step, idx+1)
+			copy(tsteps, steps)
+			steps = tsteps
+			steps[idx] = make([]Step, 0, 1)
+		}
+		steps[idx] = append(steps[idx], n.(Step))
+		return nil
+	}
+
+	if start != "" {
+		var ok bool
+		w.RLock()
+		root, ok = w.steps[start]
+		w.RUnlock()
+		if !ok {
+			return nil, ErrStepNotExists
+		}
+	} else {
+		root, err = w.g.Root()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if reverse {
+		err = w.g.SortedReverseDepthFirstWalk([]dag.Vertex{root}, fn)
+	} else {
+		err = w.g.SortedDepthFirstWalk([]dag.Vertex{root}, fn)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	return steps, nil
+}
+
 func (w *microWorkflow) Abort(ctx context.Context, id string) error {
-	workflowStore := store.NewNamespaceStore(w.opts.Store, filepath.Join("workflows", id))
+	workflowStore := store.NewNamespaceStore(w.opts.Store, "workflows"+w.opts.Store.Options().Separator+id)
 	return workflowStore.Write(ctx, "status", &codec.Frame{Data: []byte(StatusAborted.String())})
 }
 
 func (w *microWorkflow) Suspend(ctx context.Context, id string) error {
-	workflowStore := store.NewNamespaceStore(w.opts.Store, filepath.Join("workflows", id))
+	workflowStore := store.NewNamespaceStore(w.opts.Store, "workflows"+w.opts.Store.Options().Separator+id)
 	return workflowStore.Write(ctx, "status", &codec.Frame{Data: []byte(StatusSuspend.String())})
 }
 
 func (w *microWorkflow) Resume(ctx context.Context, id string) error {
-	workflowStore := store.NewNamespaceStore(w.opts.Store, filepath.Join("workflows", id))
+	workflowStore := store.NewNamespaceStore(w.opts.Store, "workflows"+w.opts.Store.Options().Separator+id)
 	return workflowStore.Write(ctx, "status", &codec.Frame{Data: []byte(StatusRunning.String())})
 }
 
 func (w *microWorkflow) Execute(ctx context.Context, req *Message, opts ...ExecuteOption) (string, error) {
 	w.Lock()
 	if !w.init {
-		w.g.ReduceTransitively()
+		if err := w.g.Validate(); err != nil {
+			w.Unlock()
+			return "", err
+		}
+		w.g.TransitiveReduction()
 		w.init = true
 	}
 	w.Unlock()
@@ -121,11 +180,26 @@ func (w *microWorkflow) Execute(ctx context.Context, req *Message, opts ...Execu
 		return "", err
 	}
 
-	//	stepStore := store.NewNamespaceStore(w.opts.Store, filepath.Join("steps", eid))
+	stepStore := store.NewNamespaceStore(w.opts.Store, "steps"+w.opts.Store.Options().Separator+eid)
-	workflowStore := store.NewNamespaceStore(w.opts.Store, filepath.Join("workflows", eid))
+	workflowStore := store.NewNamespaceStore(w.opts.Store, "workflows"+w.opts.Store.Options().Separator+eid)
 
 	options := NewExecuteOptions(opts...)
 
+	steps, err := w.getSteps(options.Start, options.Reverse)
+	if err != nil {
+		if werr := workflowStore.Write(w.opts.Context, "status", &codec.Frame{Data: []byte(StatusPending.String())}); werr != nil {
+			w.opts.Logger.Error(w.opts.Context, "store write error", werr)
+		}
+		return "", err
+	}
+
+	var wg sync.WaitGroup
+	cherr := make(chan error, 1)
+	chstatus := make(chan Status, 1)
+
+	nctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
 	nopts := make([]ExecuteOption, 0, len(opts)+5)
 
 	nopts = append(nopts,
@@ -135,274 +209,143 @@ func (w *microWorkflow) Execute(ctx context.Context, req *Message, opts ...Execu
 		ExecuteMeter(w.opts.Meter),
 	)
 	nopts = append(nopts, opts...)
+	done := make(chan struct{})
 
-	if werr := workflowStore.Write(ctx, "status", &codec.Frame{Data: []byte(StatusRunning.String())}); werr != nil {
+	if werr := workflowStore.Write(w.opts.Context, "status", &codec.Frame{Data: []byte(StatusRunning.String())}); werr != nil {
-		w.opts.Logger.Error(ctx, "store error: %v", werr)
+		w.opts.Logger.Error(w.opts.Context, "store write error", werr)
 		return eid, werr
 	}
-
+	for idx := range steps {
-	var startID string
+		for nidx := range steps[idx] {
-	if options.Start == "" {
+			cstep := steps[idx][nidx]
-		mp := w.g.GetRoots()
+			if werr := stepStore.Write(ctx, cstep.ID()+w.opts.Store.Options().Separator+"status", &codec.Frame{Data: []byte(StatusPending.String())}); werr != nil {
-		if len(mp) != 1 {
+				return eid, werr
-			return eid, ErrStepNotExists
-		}
-		for k := range mp {
-			startID = k
-		}
-	} else {
-		for k, v := range w.g.GetVertices() {
-			if v == options.Start {
-				startID = k
 			}
 		}
 	}
 
-	if startID == "" {
+	go func() {
-		return eid, ErrStepNotExists
+		for idx := range steps {
-	}
+			for nidx := range steps[idx] {
-
+				wStatus := &codec.Frame{}
-	if options.Async {
+				if werr := workflowStore.Read(w.opts.Context, "status", wStatus); werr != nil {
-		go w.handleWorkflow(startID, nopts...)
+					cherr <- werr
-		return eid, nil
+					return
-	}
-
-	return eid, w.handleWorkflow(startID, nopts...)
-}
-
-func (w *microWorkflow) handleWorkflow(startID string, opts ...ExecuteOption) error {
-	w.RLock()
-	defer w.RUnlock()
-
-	//	stepStore := store.NewNamespaceStore(w.opts.Store, filepath.Join("steps", eid))
-	// workflowStore := store.NewNamespaceStore(w.opts.Store, filepath.Join("workflows", eid))
-
-	// Get IDs of all descendant vertices.
-	flowIDs, errDes := w.g.GetDescendants(startID)
-	if errDes != nil {
-		return errDes
-	}
-
-	// inputChannels provides for input channels for each of the descendant vertices (+ the start-vertex).
-	inputChannels := make(map[string]chan FlowResult, len(flowIDs)+1)
-
-	// Iterate vertex IDs and create an input channel for each of them and a single
-	// output channel for leaves. Note, this "pre-flight" is needed to ensure we
-	// really have an input channel regardless of how we traverse the tree and spawn
-	// workers.
-	leafCount := 0
-
-	for id := range flowIDs {
-
-		// Get all parents of this vertex.
-		parents, errPar := w.g.GetParents(id)
-		if errPar != nil {
-			return errPar
-		}
-
-		// Create a buffered input channel that has capacity for all parent results.
-		inputChannels[id] = make(chan FlowResult, len(parents))
-
-		if ok, err := w.g.IsLeaf(id); ok && err == nil {
-			leafCount += 1
-		}
-	}
-
-	// outputChannel caries the results of leaf vertices.
-	outputChannel := make(chan FlowResult, leafCount)
-
-	// To also process the start vertex and to have its results being passed to its
-	// children, add it to the vertex IDs. Also add an input channel for the start
-	// vertex and feed the inputs to this channel.
-	flowIDs[startID] = struct{}{}
-	inputChannels[startID] = make(chan FlowResult, len(inputs))
-	for _, i := range inputs {
-		inputChannels[startID] <- i
-	}
-
-	wg := sync.WaitGroup{}
-
-	// Iterate all vertex IDs (now incl. start vertex) and handle each worker (incl.
-	// inputs and outputs) in a separate goroutine.
-	for id := range flowIDs {
-
-		// Get all children of this vertex that later need to be notified. Note, we
-		// collect all children before the goroutine to be able to release the read
-		// lock as early as possible.
-		children, errChildren := w.g.GetChildren(id)
-		if errChildren != nil {
-			return errChildren
-		}
-
-		// Remember to wait for this goroutine.
-		wg.Add(1)
-
-		go func(id string) {
-			// Get this vertex's input channel.
-			// Note, only concurrent read here, which is fine.
-			c := inputChannels[id]
-
-			// Await all parent inputs and stuff them into a slice.
-			parentCount := cap(c)
-			parentResults := make([]FlowResult, parentCount)
-			for i := 0; i < parentCount; i++ {
-				parentResults[i] = <-c
-			}
-
-			// Execute the worker.
-			errWorker := callback(w.g, id, parentResults)
-			if errWorker != nil {
-				return errWorker
-			}
-
-			// Send this worker's FlowResult onto all children's input channels or, if it is
-			// a leaf (i.e. no children), send the result onto the output channel.
-			if len(children) > 0 {
-				for child := range children {
-					inputChannels[child] <- flowResult
 				}
-			} else {
+				if status := StringStatus[string(wStatus.Data)]; status != StatusRunning {
-				outputChannel <- flowResult
+					chstatus <- status
-			}
+					return
-
+				}
-			// "Sign off".
+				if w.opts.Logger.V(logger.TraceLevel) {
-			wg.Done()
+					w.opts.Logger.Trace(nctx, fmt.Sprintf("will be executed %v", steps[idx][nidx]))
-		}(id)
+				}
-	}
+				cstep := steps[idx][nidx]
-
+				// nolint: nestif
-	// Wait for all go routines to finish.
+				if len(cstep.Requires()) == 0 {
-	wg.Wait()
+					wg.Add(1)
-
+					go func(step Step) {
-	// Await all leaf vertex results and stuff them into a slice.
+						defer wg.Done()
-	resultCount := cap(outputChannel)
+						if werr := stepStore.Write(ctx, step.ID()+w.opts.Store.Options().Separator+"req", req); werr != nil {
-	results := make([]FlowResult, resultCount)
-	for i := 0; i < resultCount; i++ {
-		results[i] = <-outputChannel
-	}
-
-	/*
-		go func() {
-			for idx := range steps {
-				for nidx := range steps[idx] {
-					wStatus := &codec.Frame{}
-					if werr := workflowStore.Read(w.opts.Context, "status", wStatus); werr != nil {
-						cherr <- werr
-						return
-					}
-					if status := StringStatus[string(wStatus.Data)]; status != StatusRunning {
-						chstatus <- status
-						return
-					}
-					if w.opts.Logger.V(logger.TraceLevel) {
-						w.opts.Logger.Tracef(nctx, "will be executed %v", steps[idx][nidx])
-					}
-					cstep := steps[idx][nidx]
-					// nolint: nestif
-					if len(cstep.Requires()) == 0 {
-						wg.Add(1)
-						go func(step Step) {
-							defer wg.Done()
-							if werr := stepStore.Write(ctx, filepath.Join(step.ID(), "req"), req); werr != nil {
-								cherr <- werr
-								return
-							}
-							if werr := stepStore.Write(ctx, filepath.Join(step.ID(), "status"), &codec.Frame{Data: []byte(StatusRunning.String())}); werr != nil {
-								cherr <- werr
-								return
-							}
-							rsp, serr := step.Execute(nctx, req, nopts...)
-							if serr != nil {
-								step.SetStatus(StatusFailure)
-								if werr := stepStore.Write(ctx, filepath.Join(step.ID(), "rsp"), serr); werr != nil && w.opts.Logger.V(logger.ErrorLevel) {
-									w.opts.Logger.Errorf(ctx, "store write error: %v", werr)
-								}
-								if werr := stepStore.Write(ctx, filepath.Join(step.ID(), "status"), &codec.Frame{Data: []byte(StatusFailure.String())}); werr != nil && w.opts.Logger.V(logger.ErrorLevel) {
-									w.opts.Logger.Errorf(ctx, "store write error: %v", werr)
-								}
-								cherr <- serr
-								return
-							}
-							if werr := stepStore.Write(ctx, filepath.Join(step.ID(), "rsp"), rsp); werr != nil {
-								w.opts.Logger.Errorf(ctx, "store write error: %v", werr)
-								cherr <- werr
-								return
-							}
-							if werr := stepStore.Write(ctx, filepath.Join(step.ID(), "status"), &codec.Frame{Data: []byte(StatusSuccess.String())}); werr != nil {
-								w.opts.Logger.Errorf(ctx, "store write error: %v", werr)
-								cherr <- werr
-								return
-							}
-						}(cstep)
-						wg.Wait()
-					} else {
-						if werr := stepStore.Write(ctx, filepath.Join(cstep.ID(), "req"), req); werr != nil {
 							cherr <- werr
 							return
 						}
-						if werr := stepStore.Write(ctx, filepath.Join(cstep.ID(), "status"), &codec.Frame{Data: []byte(StatusRunning.String())}); werr != nil {
+						if werr := stepStore.Write(ctx, step.ID()+w.opts.Store.Options().Separator+"status", &codec.Frame{Data: []byte(StatusRunning.String())}); werr != nil {
 							cherr <- werr
 							return
 						}
-						rsp, serr := cstep.Execute(nctx, req, nopts...)
+						rsp, serr := step.Execute(nctx, req, nopts...)
 						if serr != nil {
-							cstep.SetStatus(StatusFailure)
+							step.SetStatus(StatusFailure)
-							if werr := stepStore.Write(ctx, filepath.Join(cstep.ID(), "rsp"), serr); werr != nil && w.opts.Logger.V(logger.ErrorLevel) {
+							if werr := stepStore.Write(ctx, step.ID()+w.opts.Store.Options().Separator+"rsp", serr); werr != nil && w.opts.Logger.V(logger.ErrorLevel) {
-								w.opts.Logger.Errorf(ctx, "store write error: %v", werr)
+								w.opts.Logger.Error(ctx, "store write error", werr)
 							}
-							if werr := stepStore.Write(ctx, filepath.Join(cstep.ID(), "status"), &codec.Frame{Data: []byte(StatusFailure.String())}); werr != nil && w.opts.Logger.V(logger.ErrorLevel) {
+							if werr := stepStore.Write(ctx, step.ID()+w.opts.Store.Options().Separator+"status", &codec.Frame{Data: []byte(StatusFailure.String())}); werr != nil && w.opts.Logger.V(logger.ErrorLevel) {
-								w.opts.Logger.Errorf(ctx, "store write error: %v", werr)
+								w.opts.Logger.Error(ctx, "store write error", werr)
 							}
 							cherr <- serr
 							return
 						}
-						if werr := stepStore.Write(ctx, filepath.Join(cstep.ID(), "rsp"), rsp); werr != nil {
+						if werr := stepStore.Write(ctx, step.ID()+w.opts.Store.Options().Separator+"rsp", rsp); werr != nil {
-							w.opts.Logger.Errorf(ctx, "store write error: %v", werr)
+							w.opts.Logger.Error(ctx, "store write error", werr)
 							cherr <- werr
 							return
 						}
-						if werr := stepStore.Write(ctx, filepath.Join(cstep.ID(), "status"), &codec.Frame{Data: []byte(StatusSuccess.String())}); werr != nil {
+						if werr := stepStore.Write(ctx, step.ID()+w.opts.Store.Options().Separator+"status", &codec.Frame{Data: []byte(StatusSuccess.String())}); werr != nil {
+							w.opts.Logger.Error(ctx, "store write error", werr)
 							cherr <- werr
 							return
 						}
+					}(cstep)
+					wg.Wait()
+				} else {
+					if werr := stepStore.Write(ctx, cstep.ID()+w.opts.Store.Options().Separator+"req", req); werr != nil {
+						cherr <- werr
+						return
+					}
+					if werr := stepStore.Write(ctx, cstep.ID()+w.opts.Store.Options().Separator+"status", &codec.Frame{Data: []byte(StatusRunning.String())}); werr != nil {
+						cherr <- werr
+						return
+					}
+					rsp, serr := cstep.Execute(nctx, req, nopts...)
+					if serr != nil {
+						cstep.SetStatus(StatusFailure)
+						if werr := stepStore.Write(ctx, cstep.ID()+w.opts.Store.Options().Separator+"rsp", serr); werr != nil && w.opts.Logger.V(logger.ErrorLevel) {
+							w.opts.Logger.Error(ctx, "store write error", werr)
+						}
+						if werr := stepStore.Write(ctx, cstep.ID()+w.opts.Store.Options().Separator+"status", &codec.Frame{Data: []byte(StatusFailure.String())}); werr != nil && w.opts.Logger.V(logger.ErrorLevel) {
+							w.opts.Logger.Error(ctx, "store write error", werr)
+						}
+						cherr <- serr
+						return
+					}
+					if werr := stepStore.Write(ctx, cstep.ID()+w.opts.Store.Options().Separator+"rsp", rsp); werr != nil {
+						w.opts.Logger.Error(ctx, "store write error", werr)
+						cherr <- werr
+						return
+					}
+					if werr := stepStore.Write(ctx, cstep.ID()+w.opts.Store.Options().Separator+"status", &codec.Frame{Data: []byte(StatusSuccess.String())}); werr != nil {
+						cherr <- werr
+						return
 					}
 				}
 			}
-			close(done)
-		}()
-
-		if options.Async {
-			return eid, nil
 		}
+		close(done)
+	}()
 
-		logger.Tracef(ctx, "wait for finish or error")
+	if options.Async {
-		select {
+		return eid, nil
-		case <-nctx.Done():
+	}
-			err = nctx.Err()
-		case cerr := <-cherr:
-			err = cerr
-		case <-done:
-			close(cherr)
-		case <-chstatus:
-			close(chstatus)
-			return eid, nil
-		}
 
-		switch {
+	logger.DefaultLogger.Trace(ctx, "wait for finish or error")
-		case nctx.Err() != nil:
+	select {
-			if werr := workflowStore.Write(w.opts.Context, "status", &codec.Frame{Data: []byte(StatusAborted.String())}); werr != nil {
+	case <-nctx.Done():
-				w.opts.Logger.Errorf(w.opts.Context, "store error: %v", werr)
+		err = nctx.Err()
-			}
+	case cerr := <-cherr:
-		case err == nil:
+		err = cerr
-			if werr := workflowStore.Write(w.opts.Context, "status", &codec.Frame{Data: []byte(StatusSuccess.String())}); werr != nil {
+	case <-done:
-				w.opts.Logger.Errorf(w.opts.Context, "store error: %v", werr)
+		close(cherr)
-			}
+	case <-chstatus:
-		case err != nil:
+		close(chstatus)
-			if werr := workflowStore.Write(w.opts.Context, "status", &codec.Frame{Data: []byte(StatusFailure.String())}); werr != nil {
+		return eid, nil
-				w.opts.Logger.Errorf(w.opts.Context, "store error: %v", werr)
+	}
-			}
+
+	switch {
+	case nctx.Err() != nil:
+		if werr := workflowStore.Write(w.opts.Context, "status", &codec.Frame{Data: []byte(StatusAborted.String())}); werr != nil {
+			w.opts.Logger.Error(w.opts.Context, "store write error", werr)
 		}
-	*/
+	case err == nil:
-	return err
+		if werr := workflowStore.Write(w.opts.Context, "status", &codec.Frame{Data: []byte(StatusSuccess.String())}); werr != nil {
+			w.opts.Logger.Error(w.opts.Context, "store write error", werr)
+		}
+	case err != nil:
+		if werr := workflowStore.Write(w.opts.Context, "status", &codec.Frame{Data: []byte(StatusFailure.String())}); werr != nil {
+			w.opts.Logger.Error(w.opts.Context, "store write error", werr)
+		}
+	}
+
+	return eid, err
 }
 
 // NewFlow create new flow
@@ -442,11 +385,11 @@ func (f *microFlow) WorkflowList(ctx context.Context) ([]Workflow, error) {
 }
 
 func (f *microFlow) WorkflowCreate(ctx context.Context, id string, steps ...Step) (Workflow, error) {
-	w := &microWorkflow{opts: f.opts, id: id, g: &dag.DAG{}, steps: make(map[string]Step, len(steps))}
+	w := &microWorkflow{opts: f.opts, id: id, g: &dag.AcyclicGraph{}, steps: make(map[string]Step, len(steps))}
 
 	for _, s := range steps {
 		w.steps[s.String()] = s
-		w.g.AddVertex(s)
+		w.g.Add(s)
 	}
 
 	for _, dst := range steps {
@@ -455,11 +398,14 @@ func (f *microFlow) WorkflowCreate(ctx context.Context, id string, steps ...Step
 			if !ok {
 				return nil, ErrStepNotExists
 			}
-			w.g.AddEdge(src.String(), dst.String())
+			w.g.Connect(dag.BasicEdge(src, dst))
 		}
 	}
 
-	w.g.ReduceTransitively()
+	if err := w.g.Validate(); err != nil {
+		return nil, err
+	}
+	w.g.TransitiveReduction()
 
 	w.init = true
 

flow/flow.go

@@ -1,5 +1,5 @@
 // Package flow is an interface used for saga pattern microservice workflow
-package flow // import "go.unistack.org/micro/v4/flow"
+package flow
 
 import (
 	"context"
@@ -7,7 +7,7 @@ import (
 	"sync"
 	"sync/atomic"
 
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 var (
@@ -125,6 +125,8 @@ type Workflow interface {
 	AppendSteps(steps ...Step) error
 	// Status returns workflow status
 	Status() Status
+	// Steps returns steps slice where parallel steps returned on the same level
+	Steps() ([][]Step, error)
 	// Suspend suspends execution
 	Suspend(ctx context.Context, id string) error
 	// Resume resumes execution

flow/options.go

@@ -4,11 +4,11 @@ import (
 	"context"
 	"time"
 
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 // Option func
@@ -123,6 +123,8 @@ type ExecuteOptions struct {
 	Start string
 	// Timeout for execution
 	Timeout time.Duration
+	// Reverse execution
+	Reverse bool
 	// Async enables async execution
 	Async bool
 }
@@ -165,6 +167,13 @@ func ExecuteContext(ctx context.Context) ExecuteOption {
 	}
 }
 
+// ExecuteReverse says that dag must be run in reverse order
+func ExecuteReverse(b bool) ExecuteOption {
+	return func(o *ExecuteOptions) {
+		o.Reverse = b
+	}
+}
+
 // ExecuteTimeout pass timeout time.Duration for execution
 func ExecuteTimeout(td time.Duration) ExecuteOption {
 	return func(o *ExecuteOptions) {

fsm/fsm_test.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"testing"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
 )
 
 func TestFSMStart(t *testing.T) {

go.mod

@@ -1,34 +1,44 @@
-module go.unistack.org/micro/v4
+module go.unistack.org/micro/v3
 
-go 1.22.0
+go 1.24.0
 
 require (
 	dario.cat/mergo v1.0.1
 	github.com/DATA-DOG/go-sqlmock v1.5.2
-	github.com/KimMachineGun/automemlimit v0.7.0
+	github.com/KimMachineGun/automemlimit v0.6.1
 	github.com/ash3in/uuidv8 v1.2.0
 	github.com/google/uuid v1.6.0
 	github.com/matoous/go-nanoid v1.5.1
 	github.com/patrickmn/go-cache v2.1.0+incompatible
 	github.com/silas/dag v0.0.0-20220518035006-a7e85ada93c5
-	github.com/spf13/cast v1.7.1
+	github.com/stretchr/testify v1.10.0
-	go.uber.org/atomic v1.11.0
 	go.uber.org/automaxprocs v1.6.0
-	go.unistack.org/micro-proto/v4 v4.1.0
+	go.unistack.org/micro-proto/v3 v3.4.1
 	golang.org/x/sync v0.10.0
-	google.golang.org/grpc v1.69.4
+	golang.yandex/hasql/v2 v2.1.0
-	google.golang.org/protobuf v1.36.3
+	google.golang.org/grpc v1.69.2
+	google.golang.org/protobuf v1.36.1
 	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
+	github.com/cilium/ebpf v0.16.0 // indirect
+	github.com/containerd/cgroups/v3 v3.0.4 // indirect
+	github.com/containerd/log v0.1.0 // indirect
+	github.com/coreos/go-systemd/v22 v22.5.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
+	github.com/docker/go-units v0.5.0 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/moby/sys/userns v0.1.0 // indirect
+	github.com/opencontainers/runtime-spec v1.2.0 // indirect
 	github.com/pbnjay/memory v0.0.0-20210728143218-7b4eea64cf58 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/rogpeppe/go-internal v1.13.1 // indirect
-	github.com/stretchr/testify v1.10.0 // indirect
+	github.com/sirupsen/logrus v1.9.3 // indirect
-	golang.org/x/net v0.34.0 // indirect
+	go.uber.org/goleak v1.3.0 // indirect
-	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/exp v0.0.0-20241210194714-1829a127f884 // indirect
+	golang.org/x/net v0.33.0 // indirect
+	golang.org/x/sys v0.28.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20241216192217-9240e9c98484 // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
 )

go.sum

@@ -2,20 +2,39 @@ dario.cat/mergo v1.0.1 h1:Ra4+bf83h2ztPIQYNP99R6m+Y7KfnARDfID+a+vLl4s=
 dario.cat/mergo v1.0.1/go.mod h1:uNxQE+84aUszobStD9th8a29P2fMDhsBdgRYvZOxGmk=
 github.com/DATA-DOG/go-sqlmock v1.5.2 h1:OcvFkGmslmlZibjAjaHm3L//6LiuBgolP7OputlJIzU=
 github.com/DATA-DOG/go-sqlmock v1.5.2/go.mod h1:88MAG/4G7SMwSE3CeA0ZKzrT5CiOU3OJ+JlNzwDqpNU=
-github.com/KimMachineGun/automemlimit v0.7.0 h1:7G06p/dMSf7G8E6oq+f2uOPuVncFyIlDI/pBWK49u88=
+github.com/KimMachineGun/automemlimit v0.6.1 h1:ILa9j1onAAMadBsyyUJv5cack8Y1WT26yLj/V+ulKp8=
-github.com/KimMachineGun/automemlimit v0.7.0/go.mod h1:QZxpHaGOQoYvFhv/r4u3U0JTC2ZcOwbSr11UZF46UBM=
+github.com/KimMachineGun/automemlimit v0.6.1/go.mod h1:T7xYht7B8r6AG/AqFcUdc7fzd2bIdBKmepfP2S1svPY=
 github.com/ash3in/uuidv8 v1.2.0 h1:2oogGdtCPwaVtyvPPGin4TfZLtOGE5F+W++E880G6SI=
 github.com/ash3in/uuidv8 v1.2.0/go.mod h1:BnU0wJBxnzdEKmVg4xckBkD+VZuecTFTUP3M0dWgyY4=
+github.com/cilium/ebpf v0.16.0 h1:+BiEnHL6Z7lXnlGUsXQPPAE7+kenAd4ES8MQ5min0Ok=
+github.com/cilium/ebpf v0.16.0/go.mod h1:L7u2Blt2jMM/vLAVgjxluxtBKlz3/GWjB0dMOEngfwE=
+github.com/containerd/cgroups/v3 v3.0.4 h1:2fs7l3P0Qxb1nKWuJNFiwhp2CqiKzho71DQkDrHJIo4=
+github.com/containerd/cgroups/v3 v3.0.4/go.mod h1:SA5DLYnXO8pTGYiAHXz94qvLQTKfVM5GEVisn4jpins=
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 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1VwoXQT9A3Wy9MM3WgvqSxFWenqJduM=
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
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 github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
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 github.com/kisielk/sqlstruct v0.0.0-20201105191214-5f3e10d3ab46/go.mod h1:yyMNCyc/Ib3bDTKd379tNMpB/7/H5TjM2Y9QJ5THLbE=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
@@ -26,10 +45,19 @@ github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
 github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/matoous/go-nanoid v1.5.1 h1:aCjdvTyO9LLnTIi0fgdXhOPPvOHjpXN6Ik9DaNjIct4=
 github.com/matoous/go-nanoid v1.5.1/go.mod h1:zyD2a71IubI24efhpvkJz+ZwfwagzgSO6UNiFsZKN7U=
+github.com/mdlayher/netlink v1.7.2 h1:/UtM3ofJap7Vl4QWCPDGXY8d3GIY2UGSDbK+QWmY8/g=
+github.com/mdlayher/netlink v1.7.2/go.mod h1:xraEF7uJbxLhc5fpHL4cPe221LI2bdttWlU+ZGLfQSw=
+github.com/mdlayher/socket v0.4.1 h1:eM9y2/jlbs1M615oshPQOHZzj6R6wMT7bX5NPiQvn2U=
+github.com/mdlayher/socket v0.4.1/go.mod h1:cAqeGjoufqdxWkD7DkpyS+wcefOtmu5OQ8KuoJGIReA=
+github.com/moby/sys/userns v0.1.0 h1:tVLXkFOxVu9A64/yh59slHVv9ahO9UIev4JZusOLG/g=
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 github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
 github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/pbnjay/memory v0.0.0-20210728143218-7b4eea64cf58 h1:onHthvaw9LFnH4t2DcNVpwGmV9E1BkGknEliJkfwQj0=
 github.com/pbnjay/memory v0.0.0-20210728143218-7b4eea64cf58/go.mod h1:DXv8WO4yhMYhSNPKjeNKa5WY9YCIEBRbNzFFPJbWO6Y=
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 github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 h1:Jamvg5psRIccs7FGNTlIRMkT8wgtp5eCXdBlqhYGL6U=
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 github.com/prashantv/gostub v1.1.0 h1:BTyx3RfQjRHnUWaGF9oQos79AlQ5k8WNktv7VGvVH4g=
@@ -38,32 +66,40 @@ github.com/rogpeppe/go-internal v1.13.1 h1:KvO1DLK/DRN07sQ1LQKScxyZJuNnedQ5/wKSR
 github.com/rogpeppe/go-internal v1.13.1/go.mod h1:uMEvuHeurkdAXX61udpOXGD/AzZDWNMNyH2VO9fmH0o=
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 github.com/silas/dag v0.0.0-20220518035006-a7e85ada93c5/go.mod h1:7RTUFBdIRC9nZ7/3RyRNH1bdqIShrDejd1YbLwgPS+I=
-github.com/spf13/cast v1.7.1 h1:cuNEagBQEHWN1FnbGEjCXL2szYEXqfJPbP2HNUaca9Y=
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hooks/metadata/metadata.go

@@ -0,0 +1,76 @@
+package metadata
+
+import (
+	"context"
+
+	"go.unistack.org/micro/v3/client"
+	"go.unistack.org/micro/v3/metadata"
+	"go.unistack.org/micro/v3/server"
+)
+
+var DefaultMetadataKeys = []string{"x-request-id"}
+
+type hook struct {
+	keys []string
+}
+
+func NewHook(keys ...string) *hook {
+	return &hook{keys: keys}
+}
+
+func metadataCopy(ctx context.Context, keys []string) context.Context {
+	if keys == nil {
+		return ctx
+	}
+	if imd, iok := metadata.FromIncomingContext(ctx); iok && imd != nil {
+		omd, ook := metadata.FromOutgoingContext(ctx)
+		if !ook || omd == nil {
+			omd = metadata.New(len(keys))
+		}
+		for _, k := range keys {
+			if v, ok := imd.Get(k); ok && v != "" {
+				omd.Set(k, v)
+			}
+		}
+		if !ook {
+			ctx = metadata.NewOutgoingContext(ctx, omd)
+		}
+	}
+	return ctx
+}
+
+func (w *hook) ClientCall(next client.FuncCall) client.FuncCall {
+	return func(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
+		return next(metadataCopy(ctx, w.keys), req, rsp, opts...)
+	}
+}
+
+func (w *hook) ClientStream(next client.FuncStream) client.FuncStream {
+	return func(ctx context.Context, req client.Request, opts ...client.CallOption) (client.Stream, error) {
+		return next(metadataCopy(ctx, w.keys), req, opts...)
+	}
+}
+
+func (w *hook) ClientPublish(next client.FuncPublish) client.FuncPublish {
+	return func(ctx context.Context, msg client.Message, opts ...client.PublishOption) error {
+		return next(metadataCopy(ctx, w.keys), msg, opts...)
+	}
+}
+
+func (w *hook) ClientBatchPublish(next client.FuncBatchPublish) client.FuncBatchPublish {
+	return func(ctx context.Context, msgs []client.Message, opts ...client.PublishOption) error {
+		return next(metadataCopy(ctx, w.keys), msgs, opts...)
+	}
+}
+
+func (w *hook) ServerHandler(next server.FuncHandler) server.FuncHandler {
+	return func(ctx context.Context, req server.Request, rsp interface{}) error {
+		return next(metadataCopy(ctx, w.keys), req, rsp)
+	}
+}
+
+func (w *hook) ServerSubscriber(next server.FuncSubHandler) server.FuncSubHandler {
+	return func(ctx context.Context, msg server.Message) error {
+		return next(metadataCopy(ctx, w.keys), msg)
+	}
+}

hooks/recovery/recovery.go

@@ -0,0 +1,94 @@
+package recovery
+
+import (
+	"context"
+	"fmt"
+
+	"go.unistack.org/micro/v3/errors"
+	"go.unistack.org/micro/v3/server"
+)
+
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		ServerHandlerFn:    DefaultServerHandlerFn,
+		ServerSubscriberFn: DefaultServerSubscriberFn,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}
+
+type Options struct {
+	ServerHandlerFn    func(context.Context, server.Request, interface{}, error) error
+	ServerSubscriberFn func(context.Context, server.Message, error) error
+}
+
+type Option func(*Options)
+
+func ServerHandlerFunc(fn func(context.Context, server.Request, interface{}, error) error) Option {
+	return func(o *Options) {
+		o.ServerHandlerFn = fn
+	}
+}
+
+func ServerSubscriberFunc(fn func(context.Context, server.Message, error) error) Option {
+	return func(o *Options) {
+		o.ServerSubscriberFn = fn
+	}
+}
+
+var (
+	DefaultServerHandlerFn = func(ctx context.Context, req server.Request, rsp interface{}, err error) error {
+		return errors.BadRequest("", "%v", err)
+	}
+	DefaultServerSubscriberFn = func(ctx context.Context, req server.Message, err error) error {
+		return errors.BadRequest("", "%v", err)
+	}
+)
+
+var Hook = NewHook()
+
+type hook struct {
+	opts Options
+}
+
+func NewHook(opts ...Option) *hook {
+	return &hook{opts: NewOptions(opts...)}
+}
+
+func (w *hook) ServerHandler(next server.FuncHandler) server.FuncHandler {
+	return func(ctx context.Context, req server.Request, rsp interface{}) (err error) {
+		defer func() {
+			r := recover()
+			switch verr := r.(type) {
+			case nil:
+				return
+			case error:
+				err = w.opts.ServerHandlerFn(ctx, req, rsp, verr)
+			default:
+				err = w.opts.ServerHandlerFn(ctx, req, rsp, fmt.Errorf("%v", r))
+			}
+		}()
+		err = next(ctx, req, rsp)
+		return err
+	}
+}
+
+func (w *hook) ServerSubscriber(next server.FuncSubHandler) server.FuncSubHandler {
+	return func(ctx context.Context, msg server.Message) (err error) {
+		defer func() {
+			r := recover()
+			switch verr := r.(type) {
+			case nil:
+				return
+			case error:
+				err = w.opts.ServerSubscriberFn(ctx, msg, verr)
+			default:
+				err = w.opts.ServerSubscriberFn(ctx, msg, fmt.Errorf("%v", r))
+			}
+		}()
+		err = next(ctx, msg)
+		return err
+	}
+}

hooks/requestid/requestid.go

@@ -0,0 +1,139 @@
+package requestid
+
+import (
+	"context"
+	"net/textproto"
+	
+	"go.unistack.org/micro/v3/client"
+	"go.unistack.org/micro/v3/metadata"
+	"go.unistack.org/micro/v3/server"
+	"go.unistack.org/micro/v3/util/id"
+)
+
+type XRequestIDKey struct{}
+
+// DefaultMetadataKey contains metadata key
+var DefaultMetadataKey = textproto.CanonicalMIMEHeaderKey("x-request-id")
+
+// DefaultMetadataFunc wil be used if user not provide own func to fill metadata
+var DefaultMetadataFunc = func(ctx context.Context) (context.Context, error) {
+	var xid string
+
+	cid, cok := ctx.Value(XRequestIDKey{}).(string)
+	if cok && cid != "" {
+		xid = cid
+	}
+
+	imd, iok := metadata.FromIncomingContext(ctx)
+	if !iok || imd == nil {
+		imd = metadata.New(1)
+		ctx = metadata.NewIncomingContext(ctx, imd)
+	}
+
+	omd, ook := metadata.FromOutgoingContext(ctx)
+	if !ook || omd == nil {
+		omd = metadata.New(1)
+		ctx = metadata.NewOutgoingContext(ctx, omd)
+	}
+
+	if xid == "" {
+		var id string
+		if id, iok = imd.Get(DefaultMetadataKey); iok && id != "" {
+			xid = id
+		}
+		if id, ook = omd.Get(DefaultMetadataKey); ook && id != "" {
+			xid = id
+		}
+	}
+
+	if xid == "" {
+		var err error
+		xid, err = id.New()
+		if err != nil {
+			return ctx, err
+		}
+	}
+
+	if !cok {
+		ctx = context.WithValue(ctx, XRequestIDKey{}, xid)
+	}
+
+	if !iok {
+		imd.Set(DefaultMetadataKey, xid)
+	}
+
+	if !ook {
+		omd.Set(DefaultMetadataKey, xid)
+	}
+
+	return ctx, nil
+}
+
+type hook struct{}
+
+func NewHook() *hook {
+	return &hook{}
+}
+
+func (w *hook) ServerSubscriber(next server.FuncSubHandler) server.FuncSubHandler {
+	return func(ctx context.Context, msg server.Message) error {
+		var err error
+		if xid, ok := msg.Header()[DefaultMetadataKey]; ok {
+			ctx = context.WithValue(ctx, XRequestIDKey{}, xid)
+		}
+		if ctx, err = DefaultMetadataFunc(ctx); err != nil {
+			return err
+		}
+		return next(ctx, msg)
+	}
+}
+
+func (w *hook) ServerHandler(next server.FuncHandler) server.FuncHandler {
+	return func(ctx context.Context, req server.Request, rsp interface{}) error {
+		var err error
+		if ctx, err = DefaultMetadataFunc(ctx); err != nil {
+			return err
+		}
+		return next(ctx, req, rsp)
+	}
+}
+
+func (w *hook) ClientBatchPublish(next client.FuncBatchPublish) client.FuncBatchPublish {
+	return func(ctx context.Context, msgs []client.Message, opts ...client.PublishOption) error {
+		var err error
+		if ctx, err = DefaultMetadataFunc(ctx); err != nil {
+			return err
+		}
+		return next(ctx, msgs, opts...)
+	}
+}
+
+func (w *hook) ClientPublish(next client.FuncPublish) client.FuncPublish {
+	return func(ctx context.Context, msg client.Message, opts ...client.PublishOption) error {
+		var err error
+		if ctx, err = DefaultMetadataFunc(ctx); err != nil {
+			return err
+		}
+		return next(ctx, msg, opts...)
+	}
+}
+
+func (w *hook) ClientCall(next client.FuncCall) client.FuncCall {
+	return func(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
+		var err error
+		if ctx, err = DefaultMetadataFunc(ctx); err != nil {
+			return err
+		}
+		return next(ctx, req, rsp, opts...)
+	}
+}
+
+func (w *hook) ClientStream(next client.FuncStream) client.FuncStream {
+	return func(ctx context.Context, req client.Request, opts ...client.CallOption) (client.Stream, error) {
+		var err error
+		if ctx, err = DefaultMetadataFunc(ctx); err != nil {
+			return nil, err
+		}
+		return next(ctx, req, opts...)
+	}
+}

hooks/requestid/requestid_test.go

@@ -0,0 +1,33 @@
+package requestid
+
+import (
+	"context"
+	"testing"
+
+	"go.unistack.org/micro/v3/metadata"
+)
+
+func TestDefaultMetadataFunc(t *testing.T) {
+	ctx := context.TODO()
+
+	nctx, err := DefaultMetadataFunc(ctx)
+	if err != nil {
+		t.Fatalf("%v", err)
+	}
+
+	imd, ok := metadata.FromIncomingContext(nctx)
+	if !ok {
+		t.Fatalf("md missing in incoming context")
+	}
+	omd, ok := metadata.FromOutgoingContext(nctx)
+	if !ok {
+		t.Fatalf("md missing in outgoing context")
+	}
+
+	_, iok := imd.Get(DefaultMetadataKey)
+	_, ook := omd.Get(DefaultMetadataKey)
+
+	if !iok || !ook {
+		t.Fatalf("missing metadata key value")
+	}
+}

hooks/sql/common.go

@@ -0,0 +1,51 @@
+package sql
+
+import (
+	"database/sql/driver"
+	"errors"
+	"fmt"
+	"runtime"
+)
+
+//go:generate sh -c "go run gen.go > wrap_gen.go"
+
+// namedValueToValue converts driver arguments of NamedValue format to Value format. Implemented in the same way as in
+// database/sql ctxutil.go.
+func namedValueToValue(named []driver.NamedValue) ([]driver.Value, error) {
+	dargs := make([]driver.Value, len(named))
+	for n, param := range named {
+		if len(param.Name) > 0 {
+			return nil, errors.New("sql: driver does not support the use of Named Parameters")
+		}
+		dargs[n] = param.Value
+	}
+	return dargs, nil
+}
+
+// namedValueToLabels convert driver arguments to interface{} slice
+func namedValueToLabels(named []driver.NamedValue) []interface{} {
+	largs := make([]interface{}, 0, len(named)*2)
+	var name string
+	for _, param := range named {
+		if param.Name != "" {
+			name = param.Name
+		} else {
+			name = fmt.Sprintf("$%d", param.Ordinal)
+		}
+		largs = append(largs, fmt.Sprintf("%s=%v", name, param.Value))
+	}
+	return largs
+}
+
+// getCallerName get the name of the function A where A() -> B() -> GetFunctionCallerName()
+func getCallerName() string {
+	pc, _, _, ok := runtime.Caller(3)
+	details := runtime.FuncForPC(pc)
+	var callerName string
+	if ok && details != nil {
+		callerName = details.Name()
+	} else {
+		callerName = labelUnknown
+	}
+	return callerName
+}

hooks/sql/conn.go

@@ -0,0 +1,467 @@
+package sql
+
+import (
+	"context"
+	"database/sql/driver"
+	"fmt"
+	"time"
+
+	"go.unistack.org/micro/v3/hooks/requestid"
+	"go.unistack.org/micro/v3/tracer"
+)
+
+var (
+	_ driver.Conn               = (*wrapperConn)(nil)
+	_ driver.ConnBeginTx        = (*wrapperConn)(nil)
+	_ driver.ConnPrepareContext = (*wrapperConn)(nil)
+	_ driver.Pinger             = (*wrapperConn)(nil)
+	_ driver.Validator          = (*wrapperConn)(nil)
+	_ driver.Queryer            = (*wrapperConn)(nil) // nolint:staticcheck
+	_ driver.QueryerContext     = (*wrapperConn)(nil)
+	_ driver.Execer             = (*wrapperConn)(nil) // nolint:staticcheck
+	_ driver.ExecerContext      = (*wrapperConn)(nil)
+	//	_ driver.Connector
+	//	_ driver.Driver
+	//	_ driver.DriverContext
+)
+
+// wrapperConn defines a wrapper for driver.Conn
+type wrapperConn struct {
+	d     *wrapperDriver
+	dname string
+	conn  driver.Conn
+	opts  Options
+	ctx   context.Context
+	//span  tracer.Span
+}
+
+// Close implements driver.Conn Close
+func (w *wrapperConn) Close() error {
+	var ctx context.Context
+	if w.ctx != nil {
+		ctx = w.ctx
+	} else {
+		ctx = context.Background()
+	}
+	_ = ctx
+	labels := []string{labelMethod, "Close"}
+	ts := time.Now()
+	err := w.conn.Close()
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Close", getCallerName(), td, err)...)
+		}
+	*/
+	return err
+}
+
+// Begin implements driver.Conn Begin
+func (w *wrapperConn) Begin() (driver.Tx, error) {
+	var ctx context.Context
+	if w.ctx != nil {
+		ctx = w.ctx
+	} else {
+		ctx = context.Background()
+	}
+
+	labels := []string{labelMethod, "Begin"}
+	ts := time.Now()
+	tx, err := w.conn.Begin() // nolint:staticcheck
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+		w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Begin", getCallerName(), td, err)...)
+			}
+		*/
+		return nil, err
+	}
+	w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Begin", getCallerName(), td, err)...)
+		}
+	*/
+	return &wrapperTx{tx: tx, opts: w.opts, ctx: ctx}, nil
+}
+
+// BeginTx implements driver.ConnBeginTx BeginTx
+func (w *wrapperConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
+	name := getQueryName(ctx)
+	nctx, span := w.opts.Tracer.Start(ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	span.AddLabels("db.method", "BeginTx")
+	span.AddLabels("db.statement", name)
+	if id, ok := ctx.Value(requestid.XRequestIDKey{}).(string); ok {
+		span.AddLabels("x-request-id", id)
+	}
+	labels := []string{labelMethod, "BeginTx", labelQuery, name}
+
+	connBeginTx, ok := w.conn.(driver.ConnBeginTx)
+	if !ok {
+		return w.Begin()
+	}
+
+	ts := time.Now()
+	tx, err := connBeginTx.BeginTx(nctx, opts)
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+		w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+		span.SetStatus(tracer.SpanStatusError, err.Error())
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "BeginTx", getCallerName(), td, err)...)
+			}
+		*/
+		return nil, err
+	}
+	w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "BeginTx", getCallerName(), td, err)...)
+		}
+	*/
+	return &wrapperTx{tx: tx, opts: w.opts, ctx: ctx, span: span}, nil
+}
+
+// Prepare implements driver.Conn Prepare
+func (w *wrapperConn) Prepare(query string) (driver.Stmt, error) {
+	var ctx context.Context
+	if w.ctx != nil {
+		ctx = w.ctx
+	} else {
+		ctx = context.Background()
+	}
+	_ = ctx
+	labels := []string{labelMethod, "Prepare", labelQuery, getCallerName()}
+	ts := time.Now()
+	stmt, err := w.conn.Prepare(query)
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+		w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Prepare", getCallerName(), td, err)...)
+			}
+		*/
+		return nil, err
+	}
+	w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Prepare", getCallerName(), td, err)...)
+		}
+	*/
+	return wrapStmt(stmt, query, w.opts), nil
+}
+
+// PrepareContext implements driver.ConnPrepareContext PrepareContext
+func (w *wrapperConn) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
+	var nctx context.Context
+	var span tracer.Span
+
+	name := getQueryName(ctx)
+	if w.ctx != nil {
+		nctx, span = w.opts.Tracer.Start(w.ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	} else {
+		nctx, span = w.opts.Tracer.Start(ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	}
+	span.AddLabels("db.method", "PrepareContext")
+	span.AddLabels("db.statement", name)
+	if id, ok := ctx.Value(requestid.XRequestIDKey{}).(string); ok {
+		span.AddLabels("x-request-id", id)
+	}
+	labels := []string{labelMethod, "PrepareContext", labelQuery, name}
+	conn, ok := w.conn.(driver.ConnPrepareContext)
+	if !ok {
+		return w.Prepare(query)
+	}
+
+	ts := time.Now()
+	stmt, err := conn.PrepareContext(nctx, query)
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+		w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+		span.SetStatus(tracer.SpanStatusError, err.Error())
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "PrepareContext", getCallerName(), td, err)...)
+			}
+		*/
+		return nil, err
+	}
+	w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "PrepareContext", getCallerName(), td, err)...)
+		}
+	*/
+	return wrapStmt(stmt, query, w.opts), nil
+}
+
+// Exec implements driver.Execer Exec
+func (w *wrapperConn) Exec(query string, args []driver.Value) (driver.Result, error) {
+	var ctx context.Context
+	if w.ctx != nil {
+		ctx = w.ctx
+	} else {
+		ctx = context.Background()
+	}
+	_ = ctx
+	labels := []string{labelMethod, "Exec", labelQuery, getCallerName()}
+
+	// nolint:staticcheck
+	conn, ok := w.conn.(driver.Execer)
+	if !ok {
+		return nil, driver.ErrSkip
+	}
+
+	ts := time.Now()
+	res, err := conn.Exec(query, args)
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Exec", getCallerName(), td, err)...)
+		}
+	*/
+	return res, err
+}
+
+// Exec implements driver.StmtExecContext ExecContext
+func (w *wrapperConn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
+	var nctx context.Context
+	var span tracer.Span
+
+	name := getQueryName(ctx)
+	if w.ctx != nil {
+		nctx, span = w.opts.Tracer.Start(w.ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	} else {
+		nctx, span = w.opts.Tracer.Start(ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	}
+	span.AddLabels("db.method", "ExecContext")
+	span.AddLabels("db.statement", name)
+	if id, ok := ctx.Value(requestid.XRequestIDKey{}).(string); ok {
+		span.AddLabels("x-request-id", id)
+	}
+	defer span.Finish()
+	if len(args) > 0 {
+		span.AddLabels("db.args", fmt.Sprintf("%v", namedValueToLabels(args)))
+	}
+	labels := []string{labelMethod, "ExecContext", labelQuery, name}
+
+	conn, ok := w.conn.(driver.ExecerContext)
+	if !ok {
+		// nolint:staticcheck
+		return nil, driver.ErrSkip
+	}
+
+	ts := time.Now()
+	res, err := conn.ExecContext(nctx, query, args)
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		span.SetStatus(tracer.SpanStatusError, err.Error())
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "ExecContext", getCallerName(), td, err)...)
+		}
+	*/
+	return res, err
+}
+
+// Ping implements driver.Pinger Ping
+func (w *wrapperConn) Ping(ctx context.Context) error {
+	conn, ok := w.conn.(driver.Pinger)
+
+	if !ok {
+		// fallback path to check db alive
+		pc, err := w.d.Open(w.dname)
+		if err != nil {
+			return err
+		}
+		return pc.Close()
+	}
+
+	var nctx context.Context //nolint: gosimple
+	nctx = ctx
+	/*
+		var span tracer.Span
+		if w.ctx != nil {
+			nctx, span = w.opts.Tracer.Start(w.ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+		} else {
+			nctx, span = w.opts.Tracer.Start(ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+		}
+		span.AddLabels("db.method", "Ping")
+		defer span.Finish()
+	*/
+	labels := []string{labelMethod, "Ping"}
+	ts := time.Now()
+	err := conn.Ping(nctx)
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		// span.SetStatus(tracer.SpanStatusError, err.Error())
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Ping", getCallerName(), td, err)...)
+			}
+		*/
+		return err
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+
+	return nil
+}
+
+// Query implements driver.Queryer Query
+func (w *wrapperConn) Query(query string, args []driver.Value) (driver.Rows, error) {
+	var ctx context.Context
+	if w.ctx != nil {
+		ctx = w.ctx
+	} else {
+		ctx = context.Background()
+	}
+	_ = ctx
+	// nolint:staticcheck
+	conn, ok := w.conn.(driver.Queryer)
+	if !ok {
+		return nil, driver.ErrSkip
+	}
+
+	labels := []string{labelMethod, "Query", labelQuery, getCallerName()}
+	ts := time.Now()
+	rows, err := conn.Query(query, args)
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Query", getCallerName(), td, err)...)
+		}
+	*/
+	return rows, err
+}
+
+// QueryContext implements Driver.QueryerContext QueryContext
+func (w *wrapperConn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
+	var nctx context.Context
+	var span tracer.Span
+
+	name := getQueryName(ctx)
+	if w.ctx != nil {
+		nctx, span = w.opts.Tracer.Start(w.ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	} else {
+		nctx, span = w.opts.Tracer.Start(ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	}
+	span.AddLabels("db.method", "QueryContext")
+	span.AddLabels("db.statement", name)
+	if id, ok := ctx.Value(requestid.XRequestIDKey{}).(string); ok {
+		span.AddLabels("x-request-id", id)
+	}
+	defer span.Finish()
+	if len(args) > 0 {
+		span.AddLabels("db.args", fmt.Sprintf("%v", namedValueToLabels(args)))
+	}
+	labels := []string{labelMethod, "QueryContext", labelQuery, name}
+	conn, ok := w.conn.(driver.QueryerContext)
+	if !ok {
+		return nil, driver.ErrSkip
+	}
+
+	ts := time.Now()
+	rows, err := conn.QueryContext(nctx, query, args)
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		span.SetStatus(tracer.SpanStatusError, err.Error())
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "QueryContext", getCallerName(), td, err)...)
+		}
+	*/
+	return rows, err
+}
+
+// CheckNamedValue implements driver.NamedValueChecker
+func (w *wrapperConn) CheckNamedValue(v *driver.NamedValue) error {
+	s, ok := w.conn.(driver.NamedValueChecker)
+	if !ok {
+		return driver.ErrSkip
+	}
+	return s.CheckNamedValue(v)
+}
+
+// IsValid implements driver.Validator
+func (w *wrapperConn) IsValid() bool {
+	v, ok := w.conn.(driver.Validator)
+	if !ok {
+		return w.conn != nil
+	}
+	return v.IsValid()
+}
+
+func (w *wrapperConn) ResetSession(ctx context.Context) error {
+	s, ok := w.conn.(driver.SessionResetter)
+	if !ok {
+		return driver.ErrSkip
+	}
+	return s.ResetSession(ctx)
+}

hooks/sql/driver.go

@@ -0,0 +1,94 @@
+package sql
+
+import (
+	"context"
+	"database/sql/driver"
+	"time"
+)
+
+var (
+// _ driver.DriverContext = (*wrapperDriver)(nil)
+// _ driver.Connector     = (*wrapperDriver)(nil)
+)
+
+/*
+type conn interface {
+	driver.Pinger
+	driver.Execer
+	driver.ExecerContext
+	driver.Queryer
+	driver.QueryerContext
+	driver.Conn
+	driver.ConnPrepareContext
+	driver.ConnBeginTx
+}
+*/
+
+// wrapperDriver defines a wrapper for driver.Driver
+type wrapperDriver struct {
+	driver driver.Driver
+	opts   Options
+	ctx    context.Context
+}
+
+// NewWrapper creates and returns a new SQL driver with passed capabilities
+func NewWrapper(d driver.Driver, opts ...Option) driver.Driver {
+	return &wrapperDriver{driver: d, opts: NewOptions(opts...), ctx: context.Background()}
+}
+
+type wrappedConnector struct {
+	connector driver.Connector
+//	name      string
+	opts      Options
+	ctx       context.Context
+}
+
+func NewWrapperConnector(c driver.Connector, opts ...Option) driver.Connector {
+	return &wrappedConnector{connector: c, opts: NewOptions(opts...), ctx: context.Background()}
+}
+
+// Connect implements driver.Driver Connect
+func (w *wrappedConnector) Connect(ctx context.Context) (driver.Conn, error) {
+	return w.connector.Connect(ctx)
+}
+
+// Driver implements driver.Driver Driver
+func (w *wrappedConnector) Driver() driver.Driver {
+	return w.connector.Driver()
+}
+
+/*
+// Connect implements driver.Driver OpenConnector
+func (w *wrapperDriver) OpenConnector(name string) (driver.Conn, error) {
+	return &wrapperConnector{driver: w.driver, name: name, opts: w.opts}, nil
+}
+*/
+
+// Open implements driver.Driver Open
+func (w *wrapperDriver) Open(name string) (driver.Conn, error) {
+	// ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second) // Ensure eventual timeout
+	// defer cancel()
+
+	/*
+		connector, err := w.OpenConnector(name)
+		if err != nil {
+			return nil, err
+		}
+		return connector.Connect(ctx)
+	*/
+
+	ts := time.Now()
+	c, err := w.driver.Open(name)
+	td := time.Since(ts)
+	/*
+		if w.opts.LoggerEnabled {
+			w.opts.Logger.Log(w.ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(w.ctx, "Open", getCallerName(), td, err)...)
+		}
+	*/
+	_ = td
+	if err != nil {
+		return nil, err
+	}
+
+	return wrapConn(c, w.opts), nil
+}

hooks/sql/gen.go

@@ -0,0 +1,165 @@
+//go:build ignore
+
+package main
+
+import (
+	"bytes"
+	"crypto/md5"
+	"fmt"
+	"io"
+	"sort"
+	"strings"
+)
+
+var connIfaces = []string{
+	"driver.ConnBeginTx",
+	"driver.ConnPrepareContext",
+	"driver.Execer",
+	"driver.ExecerContext",
+	"driver.NamedValueChecker",
+	"driver.Pinger",
+	"driver.Queryer",
+	"driver.QueryerContext",
+	"driver.SessionResetter",
+	"driver.Validator",
+}
+
+var stmtIfaces = []string{
+	"driver.StmtExecContext",
+	"driver.StmtQueryContext",
+	"driver.ColumnConverter",
+	"driver.NamedValueChecker",
+}
+
+func getHash(s []string) string {
+	h := md5.New()
+	io.WriteString(h, strings.Join(s, "|"))
+	return fmt.Sprintf("%x", h.Sum(nil))
+}
+
+func main() {
+	comboConn := all(connIfaces)
+
+	sort.Slice(comboConn, func(i, j int) bool {
+		return len(comboConn[i]) < len(comboConn[j])
+	})
+
+	comboStmt := all(stmtIfaces)
+
+	sort.Slice(comboStmt, func(i, j int) bool {
+		return len(comboStmt[i]) < len(comboStmt[j])
+	})
+
+	b := bytes.NewBuffer(nil)
+	b.WriteString("// Code generated. DO NOT EDIT.\n\n")
+	b.WriteString("package sql\n\n")
+	b.WriteString(`import "database/sql/driver"`)
+	b.WriteString("\n\n")
+
+	b.WriteString("func wrapConn(dc driver.Conn, opts Options) driver.Conn {\n")
+	b.WriteString("\tc := &wrapperConn{conn: dc, opts: opts}\n")
+
+	for idx := len(comboConn) - 1; idx >= 0; idx-- {
+		ifaces := comboConn[idx]
+		n := len(ifaces)
+		if n == 0 {
+			continue
+		}
+		h := getHash(ifaces)
+		b.WriteString(fmt.Sprintf("\tif _, ok := dc.(wrapConn%04d_%s); ok {\n", n, h))
+		b.WriteString("\t\treturn struct {\n")
+		b.WriteString(strings.Join(append([]string{"\t\t\tdriver.Conn"}, ifaces...), "\n\t\t\t"))
+		b.WriteString("\n\t\t}{")
+		for idx := range ifaces {
+			if idx > 0 {
+				b.WriteString(", ")
+				b.WriteString("c")
+			} else if idx == 0 {
+				b.WriteString("c")
+			} else {
+				b.WriteString("c")
+			}
+		}
+		b.WriteString(", c}\n")
+		b.WriteString("\t}\n\n")
+	}
+	b.WriteString("\treturn c\n")
+	b.WriteString("}\n\n")
+
+	for idx := len(comboConn) - 1; idx >= 0; idx-- {
+		ifaces := comboConn[idx]
+		n := len(ifaces)
+		if n == 0 {
+			continue
+		}
+		h := getHash(ifaces)
+		b.WriteString(fmt.Sprintf("// %s\n", strings.Join(ifaces, "|")))
+		b.WriteString(fmt.Sprintf("type wrapConn%04d_%s interface {\n", n, h))
+		for _, iface := range ifaces {
+			b.WriteString(fmt.Sprintf("\t%s\n", iface))
+		}
+		b.WriteString("}\n\n")
+	}
+
+	b.WriteString("func wrapStmt(stmt driver.Stmt, query string, opts Options) driver.Stmt {\n")
+	b.WriteString("\tc := &wrapperStmt{stmt: stmt, query: query, opts: opts}\n")
+
+	for idx := len(comboStmt) - 1; idx >= 0; idx-- {
+		ifaces := comboStmt[idx]
+		n := len(ifaces)
+		if n == 0 {
+			continue
+		}
+		h := getHash(ifaces)
+		b.WriteString(fmt.Sprintf("\tif _, ok := stmt.(wrapStmt%04d_%s); ok {\n", n, h))
+		b.WriteString("\t\treturn struct {\n")
+		b.WriteString(strings.Join(append([]string{"\t\t\tdriver.Stmt"}, ifaces...), "\n\t\t\t"))
+		b.WriteString("\n\t\t}{")
+		for idx := range ifaces {
+			if idx > 0 {
+				b.WriteString(", ")
+				b.WriteString("c")
+			} else if idx == 0 {
+				b.WriteString("c")
+			} else {
+				b.WriteString("c")
+			}
+		}
+		b.WriteString(", c}\n")
+		b.WriteString("\t}\n\n")
+	}
+	b.WriteString("\treturn c\n")
+	b.WriteString("}\n")
+
+	for idx := len(comboStmt) - 1; idx >= 0; idx-- {
+		ifaces := comboStmt[idx]
+		n := len(ifaces)
+		if n == 0 {
+			continue
+		}
+		h := getHash(ifaces)
+		b.WriteString(fmt.Sprintf("\n// %s\n", strings.Join(ifaces, "|")))
+		b.WriteString(fmt.Sprintf("type wrapStmt%04d_%s interface {\n", n, h))
+		for _, iface := range ifaces {
+			b.WriteString(fmt.Sprintf("\t%s\n", iface))
+		}
+		b.WriteString("}\n")
+	}
+
+	fmt.Printf("%s", b.String())
+}
+
+// all returns all combinations for a given string array.
+func all[T any](set []T) (subsets [][]T) {
+	length := uint(len(set))
+	for subsetBits := 1; subsetBits < (1 << length); subsetBits++ {
+		var subset []T
+		for object := uint(0); object < length; object++ {
+			if (subsetBits>>object)&1 == 1 {
+				subset = append(subset, set[object])
+			}
+		}
+		subsets = append(subsets, subset)
+	}
+	return subsets
+}

hooks/sql/options.go

@@ -0,0 +1,172 @@
+package sql
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/tracer"
+)
+
+var (
+	// DefaultMeterStatsInterval holds default stats interval
+	DefaultMeterStatsInterval = 5 * time.Second
+	// DefaultLoggerObserver used to prepare labels for logger
+	DefaultLoggerObserver = func(ctx context.Context, method string, query string, td time.Duration, err error) []interface{} {
+		labels := []interface{}{"db.method", method, "took", fmt.Sprintf("%v", td)}
+		if err != nil {
+			labels = append(labels, "error", err.Error())
+		}
+		if query != labelUnknown {
+			labels = append(labels, "query", query)
+		}
+		return labels
+	}
+)
+
+var (
+	MaxOpenConnections = "micro_sql_max_open_conn"
+	OpenConnections    = "micro_sql_open_conn"
+	InuseConnections   = "micro_sql_inuse_conn"
+	IdleConnections    = "micro_sql_idle_conn"
+	WaitConnections    = "micro_sql_waited_conn"
+	BlockedSeconds     = "micro_sql_blocked_seconds"
+	MaxIdleClosed      = "micro_sql_max_idle_closed"
+	MaxIdletimeClosed  = "micro_sql_closed_max_idle"
+	MaxLifetimeClosed  = "micro_sql_closed_max_lifetime"
+
+	meterRequestTotal               = "micro_sql_request_total"
+	meterRequestLatencyMicroseconds = "micro_sql_latency_microseconds"
+	meterRequestDurationSeconds     = "micro_sql_request_duration_seconds"
+
+	labelUnknown  = "unknown"
+	labelQuery    = "db_statement"
+	labelMethod   = "db_method"
+	labelStatus   = "status"
+	labelSuccess  = "success"
+	labelFailure  = "failure"
+	labelHost     = "db_host"
+	labelDatabase = "db_name"
+)
+
+// Options struct holds wrapper options
+type Options struct {
+	Logger             logger.Logger
+	Meter              meter.Meter
+	Tracer             tracer.Tracer
+	DatabaseHost       string
+	DatabaseName       string
+	MeterStatsInterval time.Duration
+	LoggerLevel        logger.Level
+	LoggerEnabled      bool
+	LoggerObserver     func(ctx context.Context, method string, name string, td time.Duration, err error) []interface{}
+}
+
+// Option func signature
+type Option func(*Options)
+
+// NewOptions create new Options struct from provided option slice
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		Logger:             logger.DefaultLogger,
+		Meter:              meter.DefaultMeter,
+		Tracer:             tracer.DefaultTracer,
+		MeterStatsInterval: DefaultMeterStatsInterval,
+		LoggerLevel:        logger.ErrorLevel,
+		LoggerObserver:     DefaultLoggerObserver,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+
+	options.Meter = options.Meter.Clone(
+		meter.Labels(
+			labelHost, options.DatabaseHost,
+			labelDatabase, options.DatabaseName,
+		),
+	)
+
+	options.Logger = options.Logger.Clone(logger.WithAddCallerSkipCount(1))
+
+	return options
+}
+
+// MetricInterval specifies stats interval for *sql.DB
+func MetricInterval(td time.Duration) Option {
+	return func(o *Options) {
+		o.MeterStatsInterval = td
+	}
+}
+
+func DatabaseHost(host string) Option {
+	return func(o *Options) {
+		o.DatabaseHost = host
+	}
+}
+
+func DatabaseName(name string) Option {
+	return func(o *Options) {
+		o.DatabaseName = name
+	}
+}
+
+// Meter passes meter.Meter to wrapper
+func Meter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
+// Logger passes logger.Logger to wrapper
+func Logger(l logger.Logger) Option {
+	return func(o *Options) {
+		o.Logger = l
+	}
+}
+
+// LoggerEnabled enable sql logging
+func LoggerEnabled(b bool) Option {
+	return func(o *Options) {
+		o.LoggerEnabled = b
+	}
+}
+
+// LoggerLevel passes logger.Level option
+func LoggerLevel(lvl logger.Level) Option {
+	return func(o *Options) {
+		o.LoggerLevel = lvl
+	}
+}
+
+// LoggerObserver passes observer to fill logger fields
+func LoggerObserver(obs func(context.Context, string, string, time.Duration, error) []interface{}) Option {
+	return func(o *Options) {
+		o.LoggerObserver = obs
+	}
+}
+
+// Tracer passes tracer.Tracer to wrapper
+func Tracer(t tracer.Tracer) Option {
+	return func(o *Options) {
+		o.Tracer = t
+	}
+}
+
+type queryNameKey struct{}
+
+// QueryName passes query name to wrapper func
+func QueryName(ctx context.Context, name string) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, queryNameKey{}, name)
+}
+
+func getQueryName(ctx context.Context) string {
+	if v, ok := ctx.Value(queryNameKey{}).(string); ok && v != labelUnknown {
+		return v
+	}
+	return getCallerName()
+}

hooks/sql/stats.go

@@ -0,0 +1,41 @@
+package sql
+
+import (
+	"context"
+	"database/sql"
+	"time"
+)
+
+type Statser interface {
+	Stats() sql.DBStats
+}
+
+func NewStatsMeter(ctx context.Context, db Statser, opts ...Option) {
+	options := NewOptions(opts...)
+
+	go func() {
+		ticker := time.NewTicker(options.MeterStatsInterval)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-ctx.Done():
+				return
+			case <-ticker.C:
+				if db == nil {
+					return
+				}
+				stats := db.Stats()
+				options.Meter.Counter(MaxOpenConnections).Set(uint64(stats.MaxOpenConnections))
+				options.Meter.Counter(OpenConnections).Set(uint64(stats.OpenConnections))
+				options.Meter.Counter(InuseConnections).Set(uint64(stats.InUse))
+				options.Meter.Counter(IdleConnections).Set(uint64(stats.Idle))
+				options.Meter.Counter(WaitConnections).Set(uint64(stats.WaitCount))
+				options.Meter.FloatCounter(BlockedSeconds).Set(stats.WaitDuration.Seconds())
+				options.Meter.Counter(MaxIdleClosed).Set(uint64(stats.MaxIdleClosed))
+				options.Meter.Counter(MaxIdletimeClosed).Set(uint64(stats.MaxIdleTimeClosed))
+				options.Meter.Counter(MaxLifetimeClosed).Set(uint64(stats.MaxLifetimeClosed))
+			}
+		}
+	}()
+}

hooks/sql/stmt.go

@@ -0,0 +1,287 @@
+package sql
+
+import (
+	"context"
+	"database/sql/driver"
+	"fmt"
+	"time"
+
+	"go.unistack.org/micro/v3/hooks/requestid"
+	"go.unistack.org/micro/v3/tracer"
+)
+
+var (
+	_ driver.Stmt              = (*wrapperStmt)(nil)
+	_ driver.StmtQueryContext  = (*wrapperStmt)(nil)
+	_ driver.StmtExecContext   = (*wrapperStmt)(nil)
+	_ driver.NamedValueChecker = (*wrapperStmt)(nil)
+)
+
+// wrapperStmt defines a wrapper for driver.Stmt
+type wrapperStmt struct {
+	stmt  driver.Stmt
+	opts  Options
+	query string
+	ctx   context.Context
+}
+
+// Close implements driver.Stmt Close
+func (w *wrapperStmt) Close() error {
+	var ctx context.Context
+	if w.ctx != nil {
+		ctx = w.ctx
+	} else {
+		ctx = context.Background()
+	}
+	_ = ctx
+	labels := []string{labelMethod, "Close"}
+	ts := time.Now()
+	err := w.stmt.Close()
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Close", getCallerName(), td, err)...)
+		}
+	*/
+	return err
+}
+
+// NumInput implements driver.Stmt NumInput
+func (w *wrapperStmt) NumInput() int {
+	return w.stmt.NumInput()
+}
+
+// CheckNamedValue implements driver.NamedValueChecker
+func (w *wrapperStmt) CheckNamedValue(v *driver.NamedValue) error {
+	s, ok := w.stmt.(driver.NamedValueChecker)
+	if !ok {
+		return driver.ErrSkip
+	}
+	return s.CheckNamedValue(v)
+}
+
+// Exec implements driver.Stmt Exec
+func (w *wrapperStmt) Exec(args []driver.Value) (driver.Result, error) {
+	var ctx context.Context
+	if w.ctx != nil {
+		ctx = w.ctx
+	} else {
+		ctx = context.Background()
+	}
+	_ = ctx
+	labels := []string{labelMethod, "Exec"}
+	ts := time.Now()
+	res, err := w.stmt.Exec(args) // nolint:staticcheck
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Exec", getCallerName(), td, err)...)
+		}
+	*/
+	return res, err
+}
+
+// Query implements driver.Stmt Query
+func (w *wrapperStmt) Query(args []driver.Value) (driver.Rows, error) {
+	var ctx context.Context
+	if w.ctx != nil {
+		ctx = w.ctx
+	} else {
+		ctx = context.Background()
+	}
+	_ = ctx
+	labels := []string{labelMethod, "Query"}
+	ts := time.Now()
+	rows, err := w.stmt.Query(args) // nolint:staticcheck
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "Query", getCallerName(), td, err)...)
+		}
+	*/
+	return rows, err
+}
+
+// ColumnConverter implements driver.ColumnConverter
+func (w *wrapperStmt) ColumnConverter(idx int) driver.ValueConverter {
+	s, ok := w.stmt.(driver.ColumnConverter) // nolint:staticcheck
+	if !ok {
+		return nil
+	}
+	return s.ColumnConverter(idx)
+}
+
+// ExecContext implements driver.StmtExecContext ExecContext
+func (w *wrapperStmt) ExecContext(ctx context.Context, args []driver.NamedValue) (driver.Result, error) {
+	var nctx context.Context
+	var span tracer.Span
+
+	name := getQueryName(ctx)
+	if w.ctx != nil {
+		nctx, span = w.opts.Tracer.Start(w.ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	} else {
+		nctx, span = w.opts.Tracer.Start(ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	}
+	span.AddLabels("db.method", "ExecContext")
+	span.AddLabels("db.statement", name)
+	defer span.Finish()
+	if len(args) > 0 {
+		span.AddLabels("db.args", fmt.Sprintf("%v", namedValueToLabels(args)))
+	}
+	if id, ok := ctx.Value(requestid.XRequestIDKey{}).(string); ok {
+		span.AddLabels("x-request-id", id)
+	}
+	labels := []string{labelMethod, "ExecContext", labelQuery, name}
+
+	if conn, ok := w.stmt.(driver.StmtExecContext); ok {
+		ts := time.Now()
+		res, err := conn.ExecContext(nctx, args)
+		td := time.Since(ts)
+		te := td.Seconds()
+		if err != nil {
+			w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+			span.SetStatus(tracer.SpanStatusError, err.Error())
+		} else {
+			w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+		}
+		w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+		w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "ExecContext", name, td, err)...)
+			}
+		*/
+		return res, err
+	}
+
+	values, err := namedValueToValue(args)
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		span.SetStatus(tracer.SpanStatusError, err.Error())
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "ExecContext", name, 0, err)...)
+			}
+		*/
+		return nil, err
+	}
+	ts := time.Now()
+	res, err := w.Exec(values) // nolint:staticcheck
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		span.SetStatus(tracer.SpanStatusError, err.Error())
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "ExecContext", name, td, err)...)
+		}
+	*/
+	return res, err
+}
+
+// QueryContext implements driver.StmtQueryContext StmtQueryContext
+func (w *wrapperStmt) QueryContext(ctx context.Context, args []driver.NamedValue) (driver.Rows, error) {
+	var nctx context.Context
+	var span tracer.Span
+
+	name := getQueryName(ctx)
+	if w.ctx != nil {
+		nctx, span = w.opts.Tracer.Start(w.ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	} else {
+		nctx, span = w.opts.Tracer.Start(ctx, "sdk.database", tracer.WithSpanKind(tracer.SpanKindClient))
+	}
+	span.AddLabels("db.method", "QueryContext")
+	span.AddLabels("db.statement", name)
+	defer span.Finish()
+	if len(args) > 0 {
+		span.AddLabels("db.args", fmt.Sprintf("%v", namedValueToLabels(args)))
+	}
+	if id, ok := ctx.Value(requestid.XRequestIDKey{}).(string); ok {
+		span.AddLabels("x-request-id", id)
+	}
+	labels := []string{labelMethod, "QueryContext", labelQuery, name}
+	if conn, ok := w.stmt.(driver.StmtQueryContext); ok {
+		ts := time.Now()
+		rows, err := conn.QueryContext(nctx, args)
+		td := time.Since(ts)
+		te := td.Seconds()
+		if err != nil {
+			w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+			span.SetStatus(tracer.SpanStatusError, err.Error())
+		} else {
+			w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+		}
+
+		w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+		w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "QueryContext", name, td, err)...)
+			}
+		*/
+		return rows, err
+	}
+
+	values, err := namedValueToValue(args)
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+
+		span.SetStatus(tracer.SpanStatusError, err.Error())
+		/*
+			if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+				w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "QueryContext", name, 0, err)...)
+			}
+		*/
+		return nil, err
+	}
+	ts := time.Now()
+	rows, err := w.Query(values) // nolint:staticcheck
+	td := time.Since(ts)
+	te := td.Seconds()
+	if err != nil {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelFailure)...).Inc()
+		span.SetStatus(tracer.SpanStatusError, err.Error())
+	} else {
+		w.opts.Meter.Counter(meterRequestTotal, append(labels, labelStatus, labelSuccess)...).Inc()
+	}
+
+	w.opts.Meter.Summary(meterRequestLatencyMicroseconds, labels...).Update(te)
+	w.opts.Meter.Histogram(meterRequestDurationSeconds, labels...).Update(te)
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(ctx, "QueryContext", name, td, err)...)
+		}
+	*/
+	return rows, err
+}

hooks/sql/tx.go

@@ -0,0 +1,63 @@
+package sql
+
+import (
+	"context"
+	"database/sql/driver"
+	"time"
+
+	"go.unistack.org/micro/v3/tracer"
+)
+
+var _ driver.Tx = (*wrapperTx)(nil)
+
+// wrapperTx defines a wrapper for driver.Tx
+type wrapperTx struct {
+	tx   driver.Tx
+	span tracer.Span
+	opts Options
+	ctx  context.Context
+}
+
+// Commit implements driver.Tx Commit
+func (w *wrapperTx) Commit() error {
+	ts := time.Now()
+	err := w.tx.Commit()
+	td := time.Since(ts)
+	_ = td
+	if w.span != nil {
+		if err != nil {
+			w.span.SetStatus(tracer.SpanStatusError, err.Error())
+		}
+		w.span.Finish()
+	}
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(w.ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(w.ctx, "Commit", getCallerName(), td, err)...)
+		}
+	*/
+	w.ctx = nil
+
+	return err
+}
+
+// Rollback implements driver.Tx Rollback
+func (w *wrapperTx) Rollback() error {
+	ts := time.Now()
+	err := w.tx.Rollback()
+	td := time.Since(ts)
+	_ = td
+	if w.span != nil {
+		if err != nil {
+			w.span.SetStatus(tracer.SpanStatusError, err.Error())
+		}
+		w.span.Finish()
+	}
+	/*
+		if w.opts.LoggerEnabled && w.opts.Logger.V(w.opts.LoggerLevel) {
+			w.opts.Logger.Log(w.ctx, w.opts.LoggerLevel, w.opts.LoggerObserver(w.ctx, "Rollback", getCallerName(), td, err)...)
+		}
+	*/
+	w.ctx = nil
+
+	return err
+}

hooks/sql/wrap.go

@@ -0,0 +1,19 @@
+package sql
+
+import (
+	"database/sql/driver"
+)
+
+/*
+func wrapDriver(d driver.Driver, opts Options) driver.Driver {
+	if _, ok := d.(driver.DriverContext); ok {
+		return &wrapperDriver{driver: d, opts: opts}
+	}
+	return struct{ driver.Driver }{&wrapperDriver{driver: d, opts: opts}}
+}
+*/
+
+// WrapConn allows an existing driver.Conn to be wrapped.
+func WrapConn(c driver.Conn, opts ...Option) driver.Conn {
+	return wrapConn(c, NewOptions(opts...))
+}

hooks/validator/validator.go

@@ -0,0 +1,194 @@
+package validator
+
+import (
+	"context"
+
+	"go.unistack.org/micro/v3/client"
+	"go.unistack.org/micro/v3/errors"
+	"go.unistack.org/micro/v3/server"
+)
+
+var (
+	DefaultClientErrorFunc = func(req client.Request, rsp interface{}, err error) error {
+		if rsp != nil {
+			return errors.BadGateway(req.Service(), "%v", err)
+		}
+		return errors.BadRequest(req.Service(), "%v", err)
+	}
+
+	DefaultServerErrorFunc = func(req server.Request, rsp interface{}, err error) error {
+		if rsp != nil {
+			return errors.BadGateway(req.Service(), "%v", err)
+		}
+		return errors.BadRequest(req.Service(), "%v", err)
+	}
+
+	DefaultPublishErrorFunc = func(msg client.Message, err error) error {
+		return errors.BadRequest(msg.Topic(), "%v", err)
+	}
+
+	DefaultSubscribeErrorFunc = func(msg server.Message, err error) error {
+		return errors.BadRequest(msg.Topic(), "%v", err)
+	}
+)
+
+type (
+	ClientErrorFunc    func(client.Request, interface{}, error) error
+	ServerErrorFunc    func(server.Request, interface{}, error) error
+	PublishErrorFunc   func(client.Message, error) error
+	SubscribeErrorFunc func(server.Message, error) error
+)
+
+// Options struct holds wrapper options
+type Options struct {
+	ClientErrorFn          ClientErrorFunc
+	ServerErrorFn          ServerErrorFunc
+	PublishErrorFn         PublishErrorFunc
+	SubscribeErrorFn       SubscribeErrorFunc
+	ClientValidateResponse bool
+	ServerValidateResponse bool
+}
+
+// Option func signature
+type Option func(*Options)
+
+func ClientValidateResponse(b bool) Option {
+	return func(o *Options) {
+		o.ClientValidateResponse = b
+	}
+}
+
+func ServerValidateResponse(b bool) Option {
+	return func(o *Options) {
+		o.ClientValidateResponse = b
+	}
+}
+
+func ClientReqErrorFn(fn ClientErrorFunc) Option {
+	return func(o *Options) {
+		o.ClientErrorFn = fn
+	}
+}
+
+func ServerErrorFn(fn ServerErrorFunc) Option {
+	return func(o *Options) {
+		o.ServerErrorFn = fn
+	}
+}
+
+func PublishErrorFn(fn PublishErrorFunc) Option {
+	return func(o *Options) {
+		o.PublishErrorFn = fn
+	}
+}
+
+func SubscribeErrorFn(fn SubscribeErrorFunc) Option {
+	return func(o *Options) {
+		o.SubscribeErrorFn = fn
+	}
+}
+
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		ClientErrorFn:    DefaultClientErrorFunc,
+		ServerErrorFn:    DefaultServerErrorFunc,
+		PublishErrorFn:   DefaultPublishErrorFunc,
+		SubscribeErrorFn: DefaultSubscribeErrorFunc,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}
+
+func NewHook(opts ...Option) *hook {
+	return &hook{opts: NewOptions(opts...)}
+}
+
+type validator interface {
+	Validate() error
+}
+
+type hook struct {
+	opts Options
+}
+
+func (w *hook) ClientCall(next client.FuncCall) client.FuncCall {
+	return func(ctx context.Context, req client.Request, rsp interface{}, opts ...client.CallOption) error {
+		if v, ok := req.Body().(validator); ok {
+			if err := v.Validate(); err != nil {
+				return w.opts.ClientErrorFn(req, nil, err)
+			}
+		}
+		err := next(ctx, req, rsp, opts...)
+		if v, ok := rsp.(validator); ok && w.opts.ClientValidateResponse {
+			if verr := v.Validate(); verr != nil {
+				return w.opts.ClientErrorFn(req, rsp, verr)
+			}
+		}
+		return err
+	}
+}
+
+func (w *hook) ClientStream(next client.FuncStream) client.FuncStream {
+	return func(ctx context.Context, req client.Request, opts ...client.CallOption) (client.Stream, error) {
+		if v, ok := req.Body().(validator); ok {
+			if err := v.Validate(); err != nil {
+				return nil, w.opts.ClientErrorFn(req, nil, err)
+			}
+		}
+		return next(ctx, req, opts...)
+	}
+}
+
+func (w *hook) ClientPublish(next client.FuncPublish) client.FuncPublish {
+	return func(ctx context.Context, msg client.Message, opts ...client.PublishOption) error {
+		if v, ok := msg.Payload().(validator); ok {
+			if err := v.Validate(); err != nil {
+				return w.opts.PublishErrorFn(msg, err)
+			}
+		}
+		return next(ctx, msg, opts...)
+	}
+}
+
+func (w *hook) ClientBatchPublish(next client.FuncBatchPublish) client.FuncBatchPublish {
+	return func(ctx context.Context, msgs []client.Message, opts ...client.PublishOption) error {
+		for _, msg := range msgs {
+			if v, ok := msg.Payload().(validator); ok {
+				if err := v.Validate(); err != nil {
+					return w.opts.PublishErrorFn(msg, err)
+				}
+			}
+		}
+		return next(ctx, msgs, opts...)
+	}
+}
+
+func (w *hook) ServerHandler(next server.FuncHandler) server.FuncHandler {
+	return func(ctx context.Context, req server.Request, rsp interface{}) error {
+		if v, ok := req.Body().(validator); ok {
+			if err := v.Validate(); err != nil {
+				return w.opts.ServerErrorFn(req, nil, err)
+			}
+		}
+		err := next(ctx, req, rsp)
+		if v, ok := rsp.(validator); ok && w.opts.ServerValidateResponse {
+			if verr := v.Validate(); verr != nil {
+				return w.opts.ServerErrorFn(req, rsp, verr)
+			}
+		}
+		return err
+	}
+}
+
+func (w *hook) ServerSubscriber(next server.FuncSubHandler) server.FuncSubHandler {
+	return func(ctx context.Context, msg server.Message) error {
+		if v, ok := msg.Body().(validator); ok {
+			if err := v.Validate(); err != nil {
+				return w.opts.SubscribeErrorFn(msg, err)
+			}
+		}
+		return next(ctx, msg)
+	}
+}

logger/level.go

@@ -4,18 +4,20 @@ package logger
 type Level int8
 
 const (
-	// TraceLevel level usually used to find bugs, very verbose
+	// TraceLevel usually used to find bugs, very verbose
 	TraceLevel Level = iota - 2
-	// DebugLevel level used only when enabled debugging
+	// DebugLevel used only when enabled debugging
 	DebugLevel
-	// InfoLevel level used for general info about what's going on inside the application
+	// InfoLevel used for general info about what's going on inside the application
 	InfoLevel
-	// WarnLevel level used for non-critical entries
+	// WarnLevel used for non-critical entries
 	WarnLevel
-	// ErrorLevel level used for errors that should definitely be noted
+	// ErrorLevel used for errors that should definitely be noted
 	ErrorLevel
-	// FatalLevel level used for critical errors and then calls `os.Exit(1)`
+	// FatalLevel used for critical errors and then calls `os.Exit(1)`
 	FatalLevel
+	// NoneLevel used to disable logging
+	NoneLevel
 )
 
 // String returns logger level string representation
@@ -33,6 +35,8 @@ func (l Level) String() string {
 		return "error"
 	case FatalLevel:
 		return "fatal"
+	case NoneLevel:
+		return "none"
 	}
 	return "info"
 }
@@ -58,6 +62,8 @@ func ParseLevel(lvl string) Level {
 		return ErrorLevel
 	case FatalLevel.String():
 		return FatalLevel
+	case NoneLevel.String():
+		return NoneLevel
 	}
 	return InfoLevel
 }

logger/options.go

@@ -8,7 +8,7 @@ import (
 	"slices"
 	"time"
 
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
 )
 
 // Option func signature
@@ -52,6 +52,12 @@ type Options struct {
 	AddStacktrace bool
 	// DedupKeys deduplicate keys in log output
 	DedupKeys bool
+	// FatalFinalizers runs in order in [logger.Fatal] method
+	FatalFinalizers []func(context.Context)
+}
+
+var DefaultFatalFinalizer = func(ctx context.Context) {
+	os.Exit(1)
 }
 
 // NewOptions creates new options struct
@@ -65,6 +71,7 @@ func NewOptions(opts ...Option) Options {
 		AddSource:        true,
 		TimeFunc:         time.Now,
 		Meter:            meter.DefaultMeter,
+		FatalFinalizers:  []func(context.Context){DefaultFatalFinalizer},
 	}
 
 	WithMicroKeys()(&options)
@@ -76,6 +83,13 @@ func NewOptions(opts ...Option) Options {
 	return options
 }
 
+// WithFatalFinalizers set logger.Fatal finalizers
+func WithFatalFinalizers(fncs ...func(context.Context)) Option {
+	return func(o *Options) {
+		o.FatalFinalizers = fncs
+	}
+}
+
 // WithContextAttrFuncs appends default funcs for the context attrs filler
 func WithContextAttrFuncs(fncs ...ContextAttrFunc) Option {
 	return func(o *Options) {
@@ -99,6 +113,7 @@ func WithAddFields(fields ...interface{}) Option {
 					iv, iok := o.Fields[i].(string)
 					jv, jok := fields[j].(string)
 					if iok && jok && iv == jv {
+						o.Fields[i+1] = fields[j+1]
 						fields = slices.Delete(fields, j, j+2)
 					}
 				}

logger/slog/slog.go

@@ -4,18 +4,16 @@ import (
 	"context"
 	"io"
 	"log/slog"
-	"os"
 	"reflect"
 	"regexp"
 	"runtime"
 	"strconv"
 	"sync"
 	"sync/atomic"
-	"time"
 
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/semconv"
+	"go.unistack.org/micro/v3/semconv"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 const (
@@ -34,6 +32,7 @@ var (
 	warnValue  = slog.StringValue("warn")
 	errorValue = slog.StringValue("error")
 	fatalValue = slog.StringValue("fatal")
+	noneValue  = slog.StringValue("none")
 )
 
 type wrapper struct {
@@ -85,6 +84,8 @@ func (s *slogLogger) renameAttr(_ []string, a slog.Attr) slog.Attr {
 			a.Value = errorValue
 		case lvl >= logger.FatalLevel:
 			a.Value = fatalValue
+		case lvl >= logger.NoneLevel:
+			a.Value = noneValue
 		default:
 			a.Value = infoValue
 		}
@@ -228,11 +229,12 @@ func (s *slogLogger) Error(ctx context.Context, msg string, attrs ...interface{}
 
 func (s *slogLogger) Fatal(ctx context.Context, msg string, attrs ...interface{}) {
 	s.printLog(ctx, logger.FatalLevel, msg, attrs...)
+	for _, fn := range s.opts.FatalFinalizers {
+		fn(ctx)
+	}
 	if closer, ok := s.opts.Out.(io.Closer); ok {
 		closer.Close()
 	}
-	time.Sleep(1 * time.Second)
-	os.Exit(1)
 }
 
 func (s *slogLogger) Warn(ctx context.Context, msg string, attrs ...interface{}) {
@@ -316,6 +318,8 @@ func loggerToSlogLevel(level logger.Level) slog.Level {
 		return slog.LevelDebug - 1
 	case logger.FatalLevel:
 		return slog.LevelError + 1
+	case logger.NoneLevel:
+		return slog.LevelError + 2
 	default:
 		return slog.LevelInfo
 	}
@@ -333,6 +337,8 @@ func slogToLoggerLevel(level slog.Level) logger.Level {
 		return logger.TraceLevel
 	case slog.LevelError + 1:
 		return logger.FatalLevel
+	case slog.LevelError + 2:
+		return logger.NoneLevel
 	default:
 		return logger.InfoLevel
 	}

logger/slog/slog_test.go

@@ -12,9 +12,9 @@ import (
 	"time"
 
 	"github.com/google/uuid"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/metadata"
+	"go.unistack.org/micro/v3/metadata"
-	"go.unistack.org/micro/v4/util/buffer"
+	"go.unistack.org/micro/v3/util/buffer"
 )
 
 // always first to have proper check
@@ -36,6 +36,24 @@ func TestStacktrace(t *testing.T) {
 	}
 }
 
+func TestNoneLevel(t *testing.T) {
+	ctx := context.TODO()
+	buf := bytes.NewBuffer(nil)
+	l := NewLogger(logger.WithLevel(logger.NoneLevel), logger.WithOutput(buf),
+		WithHandlerFunc(slog.NewTextHandler),
+		logger.WithAddStacktrace(true),
+	)
+	if err := l.Init(logger.WithFields("key1", "val1")); err != nil {
+		t.Fatal(err)
+	}
+
+	l.Error(ctx, "msg1", errors.New("err"))
+
+	if buf.Len() != 0 {
+		t.Fatalf("logger none level not works, buf contains: %s", buf.Bytes())
+	}
+}
+
 func TestDelayedBuffer(t *testing.T) {
 	ctx := context.TODO()
 	buf := bytes.NewBuffer(nil)
@@ -62,7 +80,7 @@ func TestTime(t *testing.T) {
 		WithHandlerFunc(slog.NewTextHandler),
 		logger.WithAddStacktrace(true),
 		logger.WithTimeFunc(func() time.Time {
-			return time.Unix(0, 0)
+			return time.Unix(0, 0).UTC()
 		}),
 	)
 	if err := l.Init(logger.WithFields("key1", "val1")); err != nil {
@@ -71,8 +89,7 @@ func TestTime(t *testing.T) {
 
 	l.Error(ctx, "msg1", errors.New("err"))
 
-	if !bytes.Contains(buf.Bytes(), []byte(`timestamp=1970-01-01T03:00:00.000000000+03:00`)) &&
+	if !bytes.Contains(buf.Bytes(), []byte(`timestamp=1970-01-01T00:00:00.000000000Z`)) {
-		!bytes.Contains(buf.Bytes(), []byte(`timestamp=1970-01-01T00:00:00.000000000Z`)) {
 		t.Fatalf("logger error not works, buf contains: %s", buf.Bytes())
 	}
 }
@@ -124,7 +141,7 @@ func TestWithDedupKeysWithAddFields(t *testing.T) {
 
 	l.Info(ctx, "msg3")
 
-	if !bytes.Contains(buf.Bytes(), []byte(`msg=msg3 key1=val1 key2=val2`)) {
+	if !bytes.Contains(buf.Bytes(), []byte(`msg=msg3 key1=val4 key2=val3`)) {
 		t.Fatalf("logger error not works, buf contains: %s", buf.Bytes())
 	}
 }
@@ -406,7 +423,7 @@ func TestLogger(t *testing.T) {
 func Test_WithContextAttrFunc(t *testing.T) {
 	loggerContextAttrFuncs := []logger.ContextAttrFunc{
 		func(ctx context.Context) []interface{} {
-			md, ok := metadata.FromIncomingContext(ctx)
+			md, ok := metadata.FromOutgoingContext(ctx)
 			if !ok {
 				return nil
 			}
@@ -415,7 +432,7 @@ func Test_WithContextAttrFunc(t *testing.T) {
 				key := strings.ToLower(k)
 				switch key {
 				case "x-request-id", "phone", "external-Id", "source-service", "x-app-install-id", "client-id", "client-ip":
-					attrs = append(attrs, key, v[0])
+					attrs = append(attrs, key, v)
 				}
 			}
 			return attrs
@@ -425,7 +442,7 @@ func Test_WithContextAttrFunc(t *testing.T) {
 	logger.DefaultContextAttrFuncs = append(logger.DefaultContextAttrFuncs, loggerContextAttrFuncs...)
 
 	ctx := context.TODO()
-	ctx = metadata.AppendIncomingContext(ctx, "X-Request-Id", uuid.New().String(),
+	ctx = metadata.AppendOutgoingContext(ctx, "X-Request-Id", uuid.New().String(),
 		"Source-Service", "Test-System")
 
 	buf := bytes.NewBuffer(nil)
@@ -438,17 +455,39 @@ func Test_WithContextAttrFunc(t *testing.T) {
 	if !(bytes.Contains(buf.Bytes(), []byte(`"level":"info"`)) && bytes.Contains(buf.Bytes(), []byte(`"msg":"test message"`))) {
 		t.Fatalf("logger info, buf %s", buf.Bytes())
 	}
-	if !(bytes.Contains(buf.Bytes(), []byte(`"x-request-id":"`))) {
+	if !(bytes.Contains(buf.Bytes(), []byte(`"x-request-id":`))) {
 		t.Fatalf("logger info, buf %s", buf.Bytes())
 	}
 	if !(bytes.Contains(buf.Bytes(), []byte(`"source-service":"Test-System"`))) {
 		t.Fatalf("logger info, buf %s", buf.Bytes())
 	}
 	buf.Reset()
-	imd, _ := metadata.FromIncomingContext(ctx)
+	omd, _ := metadata.FromOutgoingContext(ctx)
 	l.Info(ctx, "test message1")
-	imd.Set("Source-Service", "Test-System2")
+	omd.Set("Source-Service", "Test-System2")
 	l.Info(ctx, "test message2")
 
 	// t.Logf("xxx %s", buf.Bytes())
 }
+
+func TestFatalFinalizers(t *testing.T) {
+	ctx := context.TODO()
+	buf := bytes.NewBuffer(nil)
+	l := NewLogger(
+		logger.WithLevel(logger.TraceLevel),
+		logger.WithOutput(buf),
+	)
+	if err := l.Init(
+		logger.WithFatalFinalizers(func(ctx context.Context) {
+			l.Info(ctx, "fatal finalizer")
+		})); err != nil {
+		t.Fatal(err)
+	}
+	l.Fatal(ctx, "info_msg1")
+	if !bytes.Contains(buf.Bytes(), []byte("fatal finalizer")) {
+		t.Fatalf("logger dont have fatal message, buf %s", buf.Bytes())
+	}
+	if !bytes.Contains(buf.Bytes(), []byte("info_msg1")) {
+		t.Fatalf("logger dont have info_msg1 message, buf %s", buf.Bytes())
+	}
+}

logger/unwrap/unwrap.go

@@ -8,7 +8,7 @@ import (
 	"strconv"
 	"strings"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
 )
 
 const sf = "0-+# "

logger/unwrap/unwrap_test.go

@@ -5,7 +5,7 @@ import (
 	"strings"
 	"testing"
 
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
 )
 
 func TestUnwrap(t *testing.T) {

metadata/context.go

@@ -0,0 +1,179 @@
+// Package metadata is a way of defining message headers
+package metadata
+
+import (
+	"context"
+)
+
+type (
+	mdIncomingKey struct{}
+	mdOutgoingKey struct{}
+	mdKey         struct{}
+)
+
+// FromIncomingContext returns metadata from incoming ctx
+// returned metadata shoud not be modified or race condition happens
+func FromIncomingContext(ctx context.Context) (Metadata, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	md, ok := ctx.Value(mdIncomingKey{}).(*rawMetadata)
+	if !ok || md.md == nil {
+		return nil, false
+	}
+	return md.md, ok
+}
+
+// MustIncomingContext returns metadata from incoming ctx
+// returned metadata shoud not be modified or race condition happens.
+// If metadata not exists panics.
+func MustIncomingContext(ctx context.Context) Metadata {
+	md, ok := FromIncomingContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// FromOutgoingContext returns metadata from outgoing ctx
+// returned metadata shoud not be modified or race condition happens
+func FromOutgoingContext(ctx context.Context) (Metadata, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	md, ok := ctx.Value(mdOutgoingKey{}).(*rawMetadata)
+	if !ok || md.md == nil {
+		return nil, false
+	}
+	return md.md, ok
+}
+
+// MustOutgoingContext returns metadata from outgoing ctx
+// returned metadata shoud not be modified or race condition happens.
+// If metadata not exists panics.
+func MustOutgoingContext(ctx context.Context) Metadata {
+	md, ok := FromOutgoingContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// FromContext returns metadata from the given context
+// returned metadata shoud not be modified or race condition happens
+func FromContext(ctx context.Context) (Metadata, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	md, ok := ctx.Value(mdKey{}).(*rawMetadata)
+	if !ok || md.md == nil {
+		return nil, false
+	}
+	return md.md, ok
+}
+
+// MustContext returns metadata from the given context
+// returned metadata shoud not be modified or race condition happens
+func MustContext(ctx context.Context) Metadata {
+	md, ok := FromContext(ctx)
+	if !ok {
+		panic("missing metadata")
+	}
+	return md
+}
+
+// NewContext creates a new context with the given metadata
+func NewContext(ctx context.Context, md Metadata) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, mdKey{}, &rawMetadata{md})
+}
+
+// SetOutgoingContext modify outgoing context with given metadata
+func SetOutgoingContext(ctx context.Context, md Metadata) bool {
+	if ctx == nil {
+		return false
+	}
+	if omd, ok := ctx.Value(mdOutgoingKey{}).(*rawMetadata); ok {
+		omd.md = md
+		return true
+	}
+	return false
+}
+
+// SetIncomingContext modify incoming context with given metadata
+func SetIncomingContext(ctx context.Context, md Metadata) bool {
+	if ctx == nil {
+		return false
+	}
+	if omd, ok := ctx.Value(mdIncomingKey{}).(*rawMetadata); ok {
+		omd.md = md
+		return true
+	}
+	return false
+}
+
+// NewIncomingContext creates a new context with incoming metadata attached
+func NewIncomingContext(ctx context.Context, md Metadata) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, mdIncomingKey{}, &rawMetadata{md})
+}
+
+// NewOutgoingContext creates a new context with outcoming metadata attached
+func NewOutgoingContext(ctx context.Context, md Metadata) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, mdOutgoingKey{}, &rawMetadata{md})
+}
+
+// AppendOutgoingContext apends new md to context
+func AppendOutgoingContext(ctx context.Context, kv ...string) context.Context {
+	md, ok := Pairs(kv...)
+	if !ok {
+		return ctx
+	}
+	omd, ok := FromOutgoingContext(ctx)
+	if !ok {
+		return NewOutgoingContext(ctx, md)
+	}
+	for k, v := range md {
+		omd.Set(k, v)
+	}
+	return ctx
+}
+
+// AppendIncomingContext apends new md to context
+func AppendIncomingContext(ctx context.Context, kv ...string) context.Context {
+	md, ok := Pairs(kv...)
+	if !ok {
+		return ctx
+	}
+	omd, ok := FromIncomingContext(ctx)
+	if !ok {
+		return NewIncomingContext(ctx, md)
+	}
+	for k, v := range md {
+		omd.Set(k, v)
+	}
+	return ctx
+}
+
+// AppendContext apends new md to context
+func AppendContext(ctx context.Context, kv ...string) context.Context {
+	md, ok := Pairs(kv...)
+	if !ok {
+		return ctx
+	}
+	omd, ok := FromContext(ctx)
+	if !ok {
+		return NewContext(ctx, md)
+	}
+	for k, v := range md {
+		omd.Set(k, v)
+	}
+	return ctx
+}

metadata/context_test.go

@@ -0,0 +1,140 @@
+package metadata
+
+import (
+	"context"
+	"testing"
+)
+
+func TestFromNilContext(t *testing.T) {
+	// nolint: staticcheck
+	c, ok := FromContext(nil)
+	if ok || c != nil {
+		t.Fatal("FromContext not works")
+	}
+}
+
+func TestNewNilContext(t *testing.T) {
+	// nolint: staticcheck
+	ctx := NewContext(nil, New(0))
+
+	c, ok := FromContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewContext not works")
+	}
+}
+
+func TestFromContext(t *testing.T) {
+	ctx := context.WithValue(context.TODO(), mdKey{}, &rawMetadata{New(0)})
+
+	c, ok := FromContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("FromContext not works")
+	}
+}
+
+func TestNewContext(t *testing.T) {
+	ctx := NewContext(context.TODO(), New(0))
+
+	c, ok := FromContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewContext not works")
+	}
+}
+
+func TestFromIncomingContext(t *testing.T) {
+	ctx := context.WithValue(context.TODO(), mdIncomingKey{}, &rawMetadata{New(0)})
+
+	c, ok := FromIncomingContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("FromIncomingContext not works")
+	}
+}
+
+func TestFromOutgoingContext(t *testing.T) {
+	ctx := context.WithValue(context.TODO(), mdOutgoingKey{}, &rawMetadata{New(0)})
+
+	c, ok := FromOutgoingContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("FromOutgoingContext not works")
+	}
+}
+
+func TestSetIncomingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key", "val")
+	ctx := context.WithValue(context.TODO(), mdIncomingKey{}, &rawMetadata{})
+	if !SetIncomingContext(ctx, md) {
+		t.Fatal("SetIncomingContext not works")
+	}
+	md, ok := FromIncomingContext(ctx)
+	if md == nil || !ok {
+		t.Fatal("SetIncomingContext not works")
+	} else if v, ok := md.Get("key"); !ok || v != "val" {
+		t.Fatal("SetIncomingContext not works")
+	}
+}
+
+func TestSetOutgoingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key", "val")
+	ctx := context.WithValue(context.TODO(), mdOutgoingKey{}, &rawMetadata{})
+	if !SetOutgoingContext(ctx, md) {
+		t.Fatal("SetOutgoingContext not works")
+	}
+	md, ok := FromOutgoingContext(ctx)
+	if md == nil || !ok {
+		t.Fatal("SetOutgoingContext not works")
+	} else if v, ok := md.Get("key"); !ok || v != "val" {
+		t.Fatal("SetOutgoingContext not works")
+	}
+}
+
+func TestNewIncomingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key", "val")
+	ctx := NewIncomingContext(context.TODO(), md)
+
+	c, ok := FromIncomingContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewIncomingContext not works")
+	}
+}
+
+func TestNewOutgoingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key", "val")
+	ctx := NewOutgoingContext(context.TODO(), md)
+
+	c, ok := FromOutgoingContext(ctx)
+	if c == nil || !ok {
+		t.Fatal("NewOutgoingContext not works")
+	}
+}
+
+func TestAppendIncomingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key1", "val1")
+	ctx := AppendIncomingContext(context.TODO(), "key2", "val2")
+
+	nmd, ok := FromIncomingContext(ctx)
+	if nmd == nil || !ok {
+		t.Fatal("AppendIncomingContext not works")
+	}
+	if v, ok := nmd.Get("key2"); !ok || v != "val2" {
+		t.Fatal("AppendIncomingContext not works")
+	}
+}
+
+func TestAppendOutgoingContext(t *testing.T) {
+	md := New(1)
+	md.Set("key1", "val1")
+	ctx := AppendOutgoingContext(context.TODO(), "key2", "val2")
+
+	nmd, ok := FromOutgoingContext(ctx)
+	if nmd == nil || !ok {
+		t.Fatal("AppendOutgoingContext not works")
+	}
+	if v, ok := nmd.Get("key2"); !ok || v != "val2" {
+		t.Fatal("AppendOutgoingContext not works")
+	}
+}

metadata/headers.go

@@ -1,19 +0,0 @@
-// Package metadata is a way of defining message headers
-package metadata
-
-var (
-	// HeaderTopic is the header name that contains topic name
-	HeaderTopic = "Micro-Topic"
-	// HeaderContentType specifies content type of message
-	HeaderContentType = "Content-Type"
-	// HeaderEndpoint specifies endpoint in service
-	HeaderEndpoint = "Micro-Endpoint"
-	// HeaderService specifies service
-	HeaderService = "Micro-Service"
-	// HeaderTimeout specifies timeout of operation
-	HeaderTimeout = "Micro-Timeout"
-	// HeaderAuthorization specifies Authorization header
-	HeaderAuthorization = "Authorization"
-	// HeaderXRequestID specifies request id
-	HeaderXRequestID = "X-Request-Id"
-)

metadata/metadata.go

@@ -1,462 +1,41 @@
+// Package metadata is a way of defining message headers
 package metadata
 
 import (
-	"context"
-	"fmt"
 	"net/textproto"
 	"sort"
 	"strings"
 )
 
-// defaultMetadataSize used when need to init new Metadata
+var (
-var defaultMetadataSize = 2
+	// HeaderTopic is the header name that contains topic name
-
+	HeaderTopic = "Micro-Topic"
-// Metadata is a mapping from metadata keys to values. Users should use the following
+	// HeaderContentType specifies content type of message
-// two convenience functions New and Pairs to generate Metadata.
+	HeaderContentType = "Content-Type"
-type Metadata map[string][]string
+	// HeaderEndpoint specifies endpoint in service
-
+	HeaderEndpoint = "Micro-Endpoint"
-// New creates an zero Metadata.
+	// HeaderService specifies service
-func New(l int) Metadata {
+	HeaderService = "Micro-Service"
-	if l == 0 {
+	// HeaderTimeout specifies timeout of operation
-		l = defaultMetadataSize
+	HeaderTimeout = "Micro-Timeout"
-	}
+	// HeaderAuthorization specifies Authorization header
-	md := make(Metadata, l)
+	HeaderAuthorization = "Authorization"
-	return md
+	// HeaderXRequestID specifies request id
-}
+	HeaderXRequestID = "X-Request-Id"
-
-// NewWithMetadata creates an Metadata from a given key-value map.
-func NewWithMetadata(m map[string]string) Metadata {
-	md := make(Metadata, len(m))
-	for key, val := range m {
-		md[key] = append(md[key], val)
-	}
-	return md
-}
-
-// Pairs returns an Metadata formed by the mapping of key, value ...
-// Pairs panics if len(kv) is odd.
-func Pairs(kv ...string) Metadata {
-	if len(kv)%2 == 1 {
-		panic(fmt.Sprintf("metadata: Pairs got the odd number of input pairs for metadata: %d", len(kv)))
-	}
-	md := make(Metadata, len(kv)/2)
-	for i := 0; i < len(kv); i += 2 {
-		md[kv[i]] = append(md[kv[i]], kv[i+1])
-	}
-	return md
-}
-
-// Len returns the number of items in Metadata.
-func (md Metadata) Len() int {
-	return len(md)
-}
-
-// Copy returns a copy of Metadata.
-func Copy(src Metadata) Metadata {
-	out := make(Metadata, len(src))
-	for k, v := range src {
-		out[k] = copyOf(v)
-	}
-	return out
-}
-
-// Copy returns a copy of Metadata.
-func (md Metadata) Copy() Metadata {
-	out := make(Metadata, len(md))
-	for k, v := range md {
-		out[k] = copyOf(v)
-	}
-	return out
-}
-
-// AsHTTP1 returns a copy of Metadata
-// with CanonicalMIMEHeaderKey.
-func (md Metadata) AsHTTP1() map[string][]string {
-	out := make(map[string][]string, len(md))
-	for k, v := range md {
-		out[textproto.CanonicalMIMEHeaderKey(k)] = copyOf(v)
-	}
-	return out
-}
-
-// AsHTTP1 returns a copy of Metadata
-// with strings.ToLower.
-func (md Metadata) AsHTTP2() map[string][]string {
-	out := make(map[string][]string, len(md))
-	for k, v := range md {
-		out[strings.ToLower(k)] = copyOf(v)
-	}
-	return out
-}
-
-// CopyTo copies Metadata to out.
-func (md Metadata) CopyTo(out Metadata) {
-	for k, v := range md {
-		out[k] = copyOf(v)
-	}
-}
-
-// Get obtains the values for a given key.
-func (md Metadata) MustGet(k string) []string {
-	v, ok := md.Get(k)
-	if !ok {
-		panic("missing metadata key")
-	}
-	return v
-}
-
-// Get obtains the values for a given key.
-func (md Metadata) Get(k string) ([]string, bool) {
-	v, ok := md[k]
-	if !ok {
-		v, ok = md[strings.ToLower(k)]
-	}
-	if !ok {
-		v, ok = md[textproto.CanonicalMIMEHeaderKey(k)]
-	}
-	return v, ok
-}
-
-// MustGetJoined obtains the values for a given key
-// with joined values with "," symbol
-func (md Metadata) MustGetJoined(k string) string {
-	v, ok := md.GetJoined(k)
-	if !ok {
-		panic("missing metadata key")
-	}
-	return v
-}
-
-// GetJoined obtains the values for a given key
-// with joined values with "," symbol
-func (md Metadata) GetJoined(k string) (string, bool) {
-	v, ok := md.Get(k)
-	if !ok {
-		return "", ok
-	}
-	return strings.Join(v, ","), true
-}
-
-// Set sets the value of a given key with a slice of values.
-func (md Metadata) Add(key string, vals ...string) {
-	if len(vals) == 0 {
-		return
-	}
-	md[key] = vals
-}
-
-// Set sets the value of a given key with a slice of values.
-func (md Metadata) Set(kvs ...string) {
-	if len(kvs)%2 == 1 {
-		panic(fmt.Sprintf("metadata: Set got an odd number of input pairs for metadata: %d", len(kvs)))
-	}
-
-	for i := 0; i < len(kvs); i += 2 {
-		md[kvs[i]] = append(md[kvs[i]], kvs[i+1])
-	}
-}
-
-// Append adds the values to key k, not overwriting what was already stored at
-// that key.
-func (md Metadata) Append(key string, vals ...string) {
-	if len(vals) == 0 {
-		return
-	}
-	md[key] = append(md[key], vals...)
-}
-
-// Del removes the values for a given keys k.
-func (md Metadata) Del(k ...string) {
-	for i := range k {
-		delete(md, k[i])
-		delete(md, strings.ToLower(k[i]))
-		delete(md, textproto.CanonicalMIMEHeaderKey(k[i]))
-	}
-}
-
-// Join joins any number of Metadatas into a single Metadata.
-//
-// The order of values for each key is determined by the order in which the Metadatas
-// containing those values are presented to Join.
-func Join(mds ...Metadata) Metadata {
-	out := Metadata{}
-	for _, Metadata := range mds {
-		for k, v := range Metadata {
-			out[k] = append(out[k], v...)
-		}
-	}
-	return out
-}
-
-type (
-	metadataIncomingKey struct{}
-	metadataOutgoingKey struct{}
-	metadataCurrentKey  struct{}
 )
 
-// NewContext creates a new context with Metadata attached. Metadata must
+// Metadata is our way of representing request headers internally.
-// not be modified after calling this function.
+// They're used at the RPC level and translate back and forth
-func NewContext(ctx context.Context, md Metadata) context.Context {
+// from Transport headers.
-	return context.WithValue(ctx, metadataCurrentKey{}, rawMetadata{md: md})
+type Metadata map[string]string
-}
-
-// NewIncomingContext creates a new context with incoming Metadata attached. Metadata must
-// not be modified after calling this function.
-func NewIncomingContext(ctx context.Context, md Metadata) context.Context {
-	return context.WithValue(ctx, metadataIncomingKey{}, rawMetadata{md: md})
-}
-
-// NewOutgoingContext creates a new context with outgoing Metadata attached. If used
-// in conjunction with AppendOutgoingContext, NewOutgoingContext will
-// overwrite any previously-appended metadata. Metadata must not be modified after
-// calling this function.
-func NewOutgoingContext(ctx context.Context, md Metadata) context.Context {
-	return context.WithValue(ctx, metadataOutgoingKey{}, rawMetadata{md: md})
-}
-
-// AppendContext returns a new context with the provided kv merged
-// with any existing metadata in the context. Please refer to the documentation
-// of Pairs for a description of kv.
-func AppendContext(ctx context.Context, kv ...string) context.Context {
-	if len(kv)%2 == 1 {
-		panic(fmt.Sprintf("metadata: AppendContext got an odd number of input pairs for metadata: %d", len(kv)))
-	}
-	md, _ := ctx.Value(metadataCurrentKey{}).(rawMetadata)
-	added := make([][]string, len(md.added)+1)
-	copy(added, md.added)
-	kvCopy := make([]string, 0, len(kv))
-	for i := 0; i < len(kv); i += 2 {
-		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
-	}
-	added[len(added)-1] = kvCopy
-	return context.WithValue(ctx, metadataCurrentKey{}, rawMetadata{md: md.md, added: added})
-}
-
-// AppendIncomingContext returns a new context with the provided kv merged
-// with any existing metadata in the context. Please refer to the documentation
-// of Pairs for a description of kv.
-func AppendIncomingContext(ctx context.Context, kv ...string) context.Context {
-	if len(kv)%2 == 1 {
-		panic(fmt.Sprintf("metadata: AppendIncomingContext got an odd number of input pairs for metadata: %d", len(kv)))
-	}
-	md, _ := ctx.Value(metadataIncomingKey{}).(rawMetadata)
-	added := make([][]string, len(md.added)+1)
-	copy(added, md.added)
-	kvCopy := make([]string, 0, len(kv))
-	for i := 0; i < len(kv); i += 2 {
-		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
-	}
-	added[len(added)-1] = kvCopy
-	return context.WithValue(ctx, metadataIncomingKey{}, rawMetadata{md: md.md, added: added})
-}
-
-// AppendOutgoingContext returns a new context with the provided kv merged
-// with any existing metadata in the context. Please refer to the documentation
-// of Pairs for a description of kv.
-func AppendOutgoingContext(ctx context.Context, kv ...string) context.Context {
-	if len(kv)%2 == 1 {
-		panic(fmt.Sprintf("metadata: AppendOutgoingContext got an odd number of input pairs for metadata: %d", len(kv)))
-	}
-	md, _ := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
-	added := make([][]string, len(md.added)+1)
-	copy(added, md.added)
-	kvCopy := make([]string, 0, len(kv))
-	for i := 0; i < len(kv); i += 2 {
-		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
-	}
-	added[len(added)-1] = kvCopy
-	return context.WithValue(ctx, metadataOutgoingKey{}, rawMetadata{md: md.md, added: added})
-}
-
-// FromContext returns the metadata in ctx if it exists.
-func FromContext(ctx context.Context) (Metadata, bool) {
-	raw, ok := ctx.Value(metadataCurrentKey{}).(rawMetadata)
-	if !ok {
-		return nil, false
-	}
-	metadataSize := len(raw.md)
-	for i := range raw.added {
-		metadataSize += len(raw.added[i]) / 2
-	}
-
-	out := make(Metadata, metadataSize)
-	for k, v := range raw.md {
-		out[k] = copyOf(v)
-	}
-	for _, added := range raw.added {
-		if len(added)%2 == 1 {
-			panic(fmt.Sprintf("metadata: FromContext got an odd number of input pairs for metadata: %d", len(added)))
-		}
-
-		for i := 0; i < len(added); i += 2 {
-			out[added[i]] = append(out[added[i]], added[i+1])
-		}
-	}
-	return out, true
-}
-
-// MustContext returns the metadata in ctx.
-func MustContext(ctx context.Context) Metadata {
-	md, ok := FromContext(ctx)
-	if !ok {
-		panic("missing metadata")
-	}
-	return md
-}
-
-// FromIncomingContext returns the incoming metadata in ctx if it exists.
-func FromIncomingContext(ctx context.Context) (Metadata, bool) {
-	raw, ok := ctx.Value(metadataIncomingKey{}).(rawMetadata)
-	if !ok {
-		return nil, false
-	}
-	metadataSize := len(raw.md)
-	for i := range raw.added {
-		metadataSize += len(raw.added[i]) / 2
-	}
-
-	out := make(Metadata, metadataSize)
-	for k, v := range raw.md {
-		out[k] = copyOf(v)
-	}
-	for _, added := range raw.added {
-		if len(added)%2 == 1 {
-			panic(fmt.Sprintf("metadata: FromIncomingContext got an odd number of input pairs for metadata: %d", len(added)))
-		}
-
-		for i := 0; i < len(added); i += 2 {
-			out[added[i]] = append(out[added[i]], added[i+1])
-		}
-	}
-	return out, true
-}
-
-// MustIncomingContext returns the incoming metadata in ctx.
-func MustIncomingContext(ctx context.Context) Metadata {
-	md, ok := FromIncomingContext(ctx)
-	if !ok {
-		panic("missing metadata")
-	}
-	return md
-}
-
-// ValueFromIncomingContext returns the metadata value corresponding to the metadata
-// key from the incoming metadata if it exists. Keys are matched in a case insensitive
-// manner.
-func ValueFromIncomingContext(ctx context.Context, key string) []string {
-	raw, ok := ctx.Value(metadataIncomingKey{}).(rawMetadata)
-	if !ok {
-		return nil
-	}
-
-	if v, ok := raw.md[key]; ok {
-		return copyOf(v)
-	}
-	for k, v := range raw.md {
-		// Case insensitive comparison: Metadata is a map, and there's no guarantee
-		// that the Metadata attached to the context is created using our helper
-		// functions.
-		if strings.EqualFold(k, key) {
-			return copyOf(v)
-		}
-	}
-	return nil
-}
-
-// ValueFromCurrentContext returns the metadata value corresponding to the metadata
-// key from the incoming metadata if it exists. Keys are matched in a case insensitive
-// manner.
-func ValueFromCurrentContext(ctx context.Context, key string) []string {
-	md, ok := ctx.Value(metadataCurrentKey{}).(rawMetadata)
-	if !ok {
-		return nil
-	}
-
-	if v, ok := md.md[key]; ok {
-		return copyOf(v)
-	}
-	for k, v := range md.md {
-		// Case insensitive comparison: Metadata is a map, and there's no guarantee
-		// that the Metadata attached to the context is created using our helper
-		// functions.
-		if strings.EqualFold(k, key) {
-			return copyOf(v)
-		}
-	}
-	return nil
-}
-
-// MustOutgoingContext returns the outgoing metadata in ctx.
-func MustOutgoingContext(ctx context.Context) Metadata {
-	md, ok := FromOutgoingContext(ctx)
-	if !ok {
-		panic("missing metadata")
-	}
-	return md
-}
-
-// ValueFromOutgoingContext returns the metadata value corresponding to the metadata
-// key from the incoming metadata if it exists. Keys are matched in a case insensitive
-// manner.
-func ValueFromOutgoingContext(ctx context.Context, key string) []string {
-	md, ok := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
-	if !ok {
-		return nil
-	}
-
-	if v, ok := md.md[key]; ok {
-		return copyOf(v)
-	}
-	for k, v := range md.md {
-		// Case insensitive comparison: Metadata is a map, and there's no guarantee
-		// that the Metadata attached to the context is created using our helper
-		// functions.
-		if strings.EqualFold(k, key) {
-			return copyOf(v)
-		}
-	}
-	return nil
-}
-
-func copyOf(v []string) []string {
-	vals := make([]string, len(v))
-	copy(vals, v)
-	return vals
-}
-
-// FromOutgoingContext returns the outgoing metadata in ctx if it exists.
-func FromOutgoingContext(ctx context.Context) (Metadata, bool) {
-	raw, ok := ctx.Value(metadataOutgoingKey{}).(rawMetadata)
-	if !ok {
-		return nil, false
-	}
-
-	metadataSize := len(raw.md)
-	for i := range raw.added {
-		metadataSize += len(raw.added[i]) / 2
-	}
-
-	out := make(Metadata, metadataSize)
-	for k, v := range raw.md {
-		out[k] = copyOf(v)
-	}
-	for _, added := range raw.added {
-		if len(added)%2 == 1 {
-			panic(fmt.Sprintf("metadata: FromOutgoingContext got an odd number of input pairs for metadata: %d", len(added)))
-		}
-
-		for i := 0; i < len(added); i += 2 {
-			out[added[i]] = append(out[added[i]], added[i+1])
-		}
-	}
-	return out, ok
-}
 
 type rawMetadata struct {
-	md    Metadata
+	md Metadata
-	added [][]string
 }
 
+// defaultMetadataSize used when need to init new Metadata
+var defaultMetadataSize = 2
+
 // Iterator used to iterate over metadata with order
 type Iterator struct {
 	md   Metadata
@@ -466,18 +45,14 @@ type Iterator struct {
 }
 
 // Next advance iterator to next element
-func (iter *Iterator) Next(k *string, v *[]string) bool {
+func (iter *Iterator) Next(k, v *string) bool {
 	if iter.cur+1 > iter.cnt {
 		return false
 	}
 
-	if k != nil && v != nil {
+	*k = iter.keys[iter.cur]
-		*k = iter.keys[iter.cur]
+	*v = iter.md[*k]
-		vv := iter.md[*k]
+	iter.cur++
-		*v = make([]string, len(vv))
-		copy(*v, vv)
-		iter.cur++
-	}
 	return true
 }
 
@@ -491,3 +66,102 @@ func (md Metadata) Iterator() *Iterator {
 	sort.Strings(iter.keys)
 	return iter
 }
+
+func (md Metadata) MustGet(key string) string {
+	val, ok := md.Get(key)
+	if !ok {
+		panic("missing metadata key")
+	}
+	return val
+}
+
+// Get returns value from metadata by key
+func (md Metadata) Get(key string) (string, bool) {
+	// fast path
+	val, ok := md[key]
+	if !ok {
+		// slow path
+		val, ok = md[textproto.CanonicalMIMEHeaderKey(key)]
+		if !ok {
+			val, ok = md[strings.ToLower(key)]
+		}
+	}
+	return val, ok
+}
+
+// Set is used to store value in metadata
+func (md Metadata) Set(kv ...string) {
+	if len(kv)%2 == 1 {
+		kv = kv[:len(kv)-1]
+	}
+	for idx := 0; idx < len(kv); idx += 2 {
+		md[textproto.CanonicalMIMEHeaderKey(kv[idx])] = kv[idx+1]
+	}
+}
+
+// Del is used to remove value from metadata
+func (md Metadata) Del(keys ...string) {
+	for _, key := range keys {
+		// fast path
+		delete(md, key)
+		// slow path
+		delete(md, textproto.CanonicalMIMEHeaderKey(key))
+		// very slow path
+		delete(md, strings.ToLower(key))
+	}
+}
+
+// Copy makes a copy of the metadata
+func (md Metadata) CopyTo(dst Metadata) {
+	for k, v := range md {
+		dst[k] = v
+	}
+}
+
+// Copy makes a copy of the metadata
+func Copy(md Metadata, exclude ...string) Metadata {
+	nmd := New(len(md))
+	for k, v := range md {
+		nmd[k] = v
+	}
+	nmd.Del(exclude...)
+	return nmd
+}
+
+// New return new sized metadata
+func New(size int) Metadata {
+	if size == 0 {
+		size = defaultMetadataSize
+	}
+	return make(Metadata, size)
+}
+
+// Merge merges metadata to existing metadata, overwriting if specified
+func Merge(omd Metadata, mmd Metadata, overwrite bool) Metadata {
+	var ok bool
+	nmd := Copy(omd)
+	for key, val := range mmd {
+		_, ok = nmd[key]
+		switch {
+		case ok && !overwrite:
+			continue
+		case val != "":
+			nmd[key] = val
+		case ok && val == "":
+			nmd.Del(key)
+		}
+	}
+	return nmd
+}
+
+// Pairs from which metadata created
+func Pairs(kv ...string) (Metadata, bool) {
+	if len(kv)%2 == 1 {
+		return nil, false
+	}
+	md := New(len(kv) / 2)
+	for idx := 0; idx < len(kv); idx += 2 {
+		md[kv[idx]] = kv[idx+1]
+	}
+	return md, true
+}

metadata/metadata_test.go

@@ -5,21 +5,10 @@ import (
 	"testing"
 )
 
-/*
-func TestAppendOutgoingContextModify(t *testing.T) {
-	md := Pairs("key1", "val1")
-	ctx := NewOutgoingContext(context.TODO(), md)
-	nctx := AppendOutgoingContext(ctx, "key1", "val3", "key2", "val2")
-	_ = nctx
-	omd := MustOutgoingContext(nctx)
-	fmt.Printf("%#+v\n", omd)
-}
-*/
-
 func TestLowercase(t *testing.T) {
 	md := New(1)
-	md["x-request-id"] = []string{"12345"}
+	md["x-request-id"] = "12345"
-	v, ok := md.GetJoined("X-Request-Id")
+	v, ok := md.Get("X-Request-Id")
 	if !ok || v == "" {
 		t.Fatalf("metadata invalid %#+v", md)
 	}
@@ -49,12 +38,15 @@ func TestMultipleUsage(t *testing.T) {
 
 func TestMetadataSetMultiple(t *testing.T) {
 	md := New(4)
-	md.Set("key1", "val1", "key2", "val2")
+	md.Set("key1", "val1", "key2", "val2", "key3")
 
-	if v, ok := md.GetJoined("key1"); !ok || v != "val1" {
+	if v, ok := md.Get("key1"); !ok || v != "val1" {
 		t.Fatalf("invalid kv %#+v", md)
 	}
-	if v, ok := md.GetJoined("key2"); !ok || v != "val2" {
+	if v, ok := md.Get("key2"); !ok || v != "val2" {
+		t.Fatalf("invalid kv %#+v", md)
+	}
+	if _, ok := md.Get("key3"); ok {
 		t.Fatalf("invalid kv %#+v", md)
 	}
 }
@@ -72,12 +64,22 @@ func TestAppend(t *testing.T) {
 }
 
 func TestPairs(t *testing.T) {
-	md := Pairs("key1", "val1", "key2", "val2")
+	md, ok := Pairs("key1", "val1", "key2", "val2")
-	if _, ok := md.Get("key1"); !ok {
+	if !ok {
+		t.Fatal("odd number of kv")
+	}
+	if _, ok = md.Get("key1"); !ok {
 		t.Fatal("key1 not found")
 	}
 }
 
+func testCtx(ctx context.Context) {
+	md := New(2)
+	md.Set("Key1", "Val1_new")
+	md.Set("Key3", "Val3")
+	SetOutgoingContext(ctx, md)
+}
+
 func TestPassing(t *testing.T) {
 	ctx := context.TODO()
 	md1 := New(2)
@@ -85,62 +87,69 @@ func TestPassing(t *testing.T) {
 	md1.Set("Key2", "Val2")
 
 	ctx = NewIncomingContext(ctx, md1)
-
+	testCtx(ctx)
 	_, ok := FromOutgoingContext(ctx)
 	if ok {
 		t.Fatalf("create outgoing context")
 	}
 
-	ctx = NewOutgoingContext(ctx, md1)
+	ctx = NewOutgoingContext(ctx, New(1))
-
+	testCtx(ctx)
 	md, ok := FromOutgoingContext(ctx)
 	if !ok {
 		t.Fatalf("missing metadata from outgoing context")
 	}
-	if v, ok := md.Get("Key1"); !ok || v[0] != "Val1" {
+	if v, ok := md.Get("Key1"); !ok || v != "Val1_new" {
 		t.Fatalf("invalid metadata value %#+v", md)
 	}
 }
 
-func TestIterator(t *testing.T) {
+func TestMerge(t *testing.T) {
-	md := Pairs(
+	omd := Metadata{
-		"1Last", "last",
+		"key1": "val1",
-		"2First", "first",
+	}
-		"3Second", "second",
+	mmd := Metadata{
-	)
+		"key2": "val2",
-
-	iter := md.Iterator()
-	var k string
-	var v []string
-	chk := New(3)
-	for iter.Next(&k, &v) {
-		chk[k] = v
 	}
 
-	for k, v := range chk {
+	nmd := Merge(omd, mmd, true)
-		if cv, ok := md[k]; !ok || len(cv) != len(v) || cv[0] != v[0] {
+	if len(nmd) != 2 {
-			t.Fatalf("XXXX %#+v %#+v", chk, md)
+		t.Fatalf("merge failed: %v", nmd)
-		}
+	}
+}
+
+func TestIterator(_ *testing.T) {
+	md := Metadata{
+		"1Last":   "last",
+		"2First":  "first",
+		"3Second": "second",
+	}
+
+	iter := md.Iterator()
+	var k, v string
+
+	for iter.Next(&k, &v) {
+		// fmt.Printf("k: %s, v: %s\n", k, v)
 	}
 }
 
 func TestMedataCanonicalKey(t *testing.T) {
 	md := New(1)
 	md.Set("x-request-id", "12345")
-	v, ok := md.GetJoined("x-request-id")
+	v, ok := md.Get("x-request-id")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
 	} else if v != "12345" {
 		t.Fatalf("invalid metadata value: %s != %s", "12345", v)
 	}
 
-	v, ok = md.GetJoined("X-Request-Id")
+	v, ok = md.Get("X-Request-Id")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
 	} else if v != "12345" {
 		t.Fatalf("invalid metadata value: %s != %s", "12345", v)
 	}
-	v, ok = md.GetJoined("X-Request-ID")
+	v, ok = md.Get("X-Request-ID")
 	if !ok {
 		t.Fatalf("failed to get x-request-id")
 	} else if v != "12345" {
@@ -153,7 +162,7 @@ func TestMetadataSet(t *testing.T) {
 
 	md.Set("Key", "val")
 
-	val, ok := md.GetJoined("Key")
+	val, ok := md.Get("Key")
 	if !ok {
 		t.Fatal("key Key not found")
 	}
@@ -164,8 +173,8 @@ func TestMetadataSet(t *testing.T) {
 
 func TestMetadataDelete(t *testing.T) {
 	md := Metadata{
-		"Foo": []string{"bar"},
+		"Foo": "bar",
-		"Baz": []string{"empty"},
+		"Baz": "empty",
 	}
 
 	md.Del("Baz")
@@ -175,16 +184,25 @@ func TestMetadataDelete(t *testing.T) {
 	}
 }
 
+func TestNilContext(t *testing.T) {
+	var ctx context.Context
+
+	_, ok := FromContext(ctx)
+	if ok {
+		t.Fatal("nil context")
+	}
+}
+
 func TestMetadataCopy(t *testing.T) {
 	md := Metadata{
-		"Foo": []string{"bar"},
+		"Foo": "bar",
-		"Bar": []string{"baz"},
+		"Bar": "baz",
 	}
 
 	cp := Copy(md)
 
 	for k, v := range md {
-		if cv := cp[k]; cv[0] != v[0] {
+		if cv := cp[k]; cv != v {
 			t.Fatalf("Got %s:%s for %s:%s", k, cv, k, v)
 		}
 	}
@@ -192,7 +210,7 @@ func TestMetadataCopy(t *testing.T) {
 
 func TestMetadataContext(t *testing.T) {
 	md := Metadata{
-		"Foo": []string{"bar"},
+		"Foo": "bar",
 	}
 
 	ctx := NewContext(context.TODO(), md)
@@ -202,7 +220,7 @@ func TestMetadataContext(t *testing.T) {
 		t.Errorf("Unexpected error retrieving metadata, got %t", ok)
 	}
 
-	if emd["Foo"][0] != md["Foo"][0] {
+	if emd["Foo"] != md["Foo"] {
 		t.Errorf("Expected key: %s val: %s, got key: %s val: %s", "Foo", md["Foo"], "Foo", emd["Foo"])
 	}
 
@@ -211,88 +229,13 @@ func TestMetadataContext(t *testing.T) {
 	}
 }
 
-func TestFromContext(t *testing.T) {
+func TestCopy(t *testing.T) {
-	ctx := context.WithValue(context.TODO(), metadataCurrentKey{}, rawMetadata{md: New(0)})
+	md := New(2)
-
+	md.Set("key1", "val1", "key2", "val2")
-	c, ok := FromContext(ctx)
+	nmd := Copy(md, "key2")
-	if c == nil || !ok {
+	if len(nmd) != 1 {
-		t.Fatal("FromContext not works")
+		t.Fatal("Copy exclude not works")
-	}
+	} else if nmd["Key1"] != "val1" {
-}
+		t.Fatal("Copy exclude not works")
-
-func TestNewContext(t *testing.T) {
-	ctx := NewContext(context.TODO(), New(0))
-
-	c, ok := FromContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("NewContext not works")
-	}
-}
-
-func TestFromIncomingContext(t *testing.T) {
-	ctx := context.WithValue(context.TODO(), metadataIncomingKey{}, rawMetadata{md: New(0)})
-
-	c, ok := FromIncomingContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("FromIncomingContext not works")
-	}
-}
-
-func TestFromOutgoingContext(t *testing.T) {
-	ctx := context.WithValue(context.TODO(), metadataOutgoingKey{}, rawMetadata{md: New(0)})
-
-	c, ok := FromOutgoingContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("FromOutgoingContext not works")
-	}
-}
-
-func TestNewIncomingContext(t *testing.T) {
-	md := New(1)
-	md.Set("key", "val")
-	ctx := NewIncomingContext(context.TODO(), md)
-
-	c, ok := FromIncomingContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("NewIncomingContext not works")
-	}
-}
-
-func TestNewOutgoingContext(t *testing.T) {
-	md := New(1)
-	md.Set("key", "val")
-	ctx := NewOutgoingContext(context.TODO(), md)
-
-	c, ok := FromOutgoingContext(ctx)
-	if c == nil || !ok {
-		t.Fatal("NewOutgoingContext not works")
-	}
-}
-
-func TestAppendIncomingContext(t *testing.T) {
-	md := New(1)
-	md.Set("key1", "val1")
-	ctx := AppendIncomingContext(context.TODO(), "key2", "val2")
-
-	nmd, ok := FromIncomingContext(ctx)
-	if nmd == nil || !ok {
-		t.Fatal("AppendIncomingContext not works")
-	}
-	if v, ok := nmd.GetJoined("key2"); !ok || v != "val2" {
-		t.Fatal("AppendIncomingContext not works")
-	}
-}
-
-func TestAppendOutgoingContext(t *testing.T) {
-	md := New(1)
-	md.Set("key1", "val1")
-	ctx := AppendOutgoingContext(context.TODO(), "key2", "val2")
-
-	nmd, ok := FromOutgoingContext(ctx)
-	if nmd == nil || !ok {
-		t.Fatal("AppendOutgoingContext not works")
-	}
-	if v, ok := nmd.GetJoined("key2"); !ok || v != "val2" {
-		t.Fatal("AppendOutgoingContext not works")
 	}
 }

meter/meter.go

@@ -4,8 +4,8 @@ package meter
 import (
 	"io"
 	"sort"
-	"strconv"
 	"strings"
+	"sync"
 	"time"
 )
 
@@ -49,9 +49,11 @@ type Meter interface {
 	Set(opts ...Option) Meter
 	// Histogram get or create histogram
 	Histogram(name string, labels ...string) Histogram
+	// HistogramExt get or create histogram with specified quantiles
+	HistogramExt(name string, quantiles []float64, labels ...string) Histogram
 	// Summary get or create summary
 	Summary(name string, labels ...string) Summary
-	// SummaryExt get or create summary with spcified quantiles and window time
+	// SummaryExt get or create summary with specified quantiles and window time
 	SummaryExt(name string, window time.Duration, quantiles []float64, labels ...string) Summary
 	// Write writes metrics to io.Writer
 	Write(w io.Writer, opts ...Option) error
@@ -59,6 +61,8 @@ type Meter interface {
 	Options() Options
 	// String return meter type
 	String() string
+	// Unregister metric name and drop all data
+	Unregister(name string, labels ...string) bool
 }
 
 // Counter is a counter
@@ -80,7 +84,11 @@ type FloatCounter interface {
 
 // Gauge is a float64 gauge
 type Gauge interface {
+	Add(float64)
 	Get() float64
+	Set(float64)
+	Dec()
+	Inc()
 }
 
 // Histogram is a histogram for non-negative values with automatically created buckets
@@ -117,6 +125,39 @@ func BuildLabels(labels ...string) []string {
 	return labels
 }
 
+var spool = newStringsPool(500)
+
+type stringsPool struct {
+	p *sync.Pool
+	c int
+}
+
+func newStringsPool(size int) *stringsPool {
+	p := &stringsPool{c: size}
+	p.p = &sync.Pool{
+		New: func() interface{} {
+			return &strings.Builder{}
+		},
+	}
+	return p
+}
+
+func (p *stringsPool) Cap() int {
+	return p.c
+}
+
+func (p *stringsPool) Get() *strings.Builder {
+	return p.p.Get().(*strings.Builder)
+}
+
+func (p *stringsPool) Put(b *strings.Builder) {
+	if b.Cap() > p.c {
+		return
+	}
+	b.Reset()
+	p.p.Put(b)
+}
+
 // BuildName used to combine metric with labels.
 // If labels count is odd, drop last element
 func BuildName(name string, labels ...string) string {
@@ -125,8 +166,6 @@ func BuildName(name string, labels ...string) string {
 	}
 
 	if len(labels) > 2 {
-		sort.Sort(byKey(labels))
-
 		idx := 0
 		for {
 			if labels[idx] == labels[idx+2] {
@@ -141,7 +180,9 @@ func BuildName(name string, labels ...string) string {
 		}
 	}
 
-	var b strings.Builder
+	b := spool.Get()
+	defer spool.Put(b)
+
 	_, _ = b.WriteString(name)
 	_, _ = b.WriteRune('{')
 	for idx := 0; idx < len(labels); idx += 2 {
@@ -149,8 +190,9 @@ func BuildName(name string, labels ...string) string {
 			_, _ = b.WriteRune(',')
 		}
 		_, _ = b.WriteString(labels[idx])
-		_, _ = b.WriteString(`=`)
+		_, _ = b.WriteString(`="`)
-		_, _ = b.WriteString(strconv.Quote(labels[idx+1]))
+		_, _ = b.WriteString(labels[idx+1])
+		_, _ = b.WriteRune('"')
 	}
 	_, _ = b.WriteRune('}')
 

meter/meter_test.go

@@ -50,11 +50,12 @@ func TestBuildName(t *testing.T) {
 	data := map[string][]string{
 		`my_metric{firstlabel="value2",zerolabel="value3"}`: {
 			"my_metric",
-			"zerolabel", "value3", "firstlabel", "value2",
+			"firstlabel", "value2",
+			"zerolabel", "value3",
 		},
 		`my_metric{broker="broker2",register="mdns",server="tcp"}`: {
 			"my_metric",
-			"broker", "broker1", "broker", "broker2", "server", "http", "server", "tcp", "register", "mdns",
+			"broker", "broker1", "broker", "broker2", "register", "mdns", "server", "http", "server", "tcp",
 		},
 		`my_metric{aaa="aaa"}`: {
 			"my_metric",

meter/noop.go

@@ -28,6 +28,10 @@ func (r *noopMeter) Name() string {
 	return r.opts.Name
 }
 
+func (r *noopMeter) Unregister(name string, labels ...string) bool {
+	return true
+}
+
 // Init initialize options
 func (r *noopMeter) Init(opts ...Option) error {
 	for _, o := range opts {
@@ -66,6 +70,11 @@ func (r *noopMeter) Histogram(_ string, labels ...string) Histogram {
 	return &noopHistogram{labels: labels}
 }
 
+// HistogramExt implements the Meter interface
+func (r *noopMeter) HistogramExt(_ string, quantiles []float64, labels ...string) Histogram {
+	return &noopHistogram{labels: labels}
+}
+
 // Set implements the Meter interface
 func (r *noopMeter) Set(opts ...Option) Meter {
 	m := &noopMeter{opts: r.opts}
@@ -132,6 +141,18 @@ type noopGauge struct {
 	labels []string
 }
 
+func (r *noopGauge) Add(float64) {
+}
+
+func (r *noopGauge) Set(float64) {
+}
+
+func (r *noopGauge) Inc() {
+}
+
+func (r *noopGauge) Dec() {
+}
+
 func (r *noopGauge) Get() float64 {
 	return 0
 }

meter/options.go

@@ -4,6 +4,8 @@ import (
 	"context"
 )
 
+var DefaultQuantiles = []float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}
+
 // Option powers the configuration for metrics implementations:
 type Option func(*Options)
 
@@ -23,6 +25,8 @@ type Options struct {
 	WriteProcessMetrics bool
 	// WriteFDMetrics flag to write fd metrics
 	WriteFDMetrics bool
+	// Quantiles specifies buckets for histogram
+	Quantiles []float64
 }
 
 // NewOptions prepares a set of options:
@@ -61,14 +65,12 @@ func Address(value string) Option {
 	}
 }
 
-/*
+// Quantiles defines the desired spread of statistics for histogram metrics:
-// TimingObjectives defines the desired spread of statistics for histogram / timing metrics:
+func Quantiles(quantiles []float64) Option {
-func TimingObjectives(value map[float64]float64) Option {
 	return func(o *Options) {
-		o.TimingObjectives = value
+		o.Quantiles = quantiles
 	}
 }
-*/
 
 // Labels add the meter labels
 func Labels(ls ...string) Option {

micro.go

@@ -3,21 +3,21 @@ package micro
 import (
 	"reflect"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/client"
+	"go.unistack.org/micro/v3/client"
-	"go.unistack.org/micro/v4/codec"
+	"go.unistack.org/micro/v3/codec"
-	"go.unistack.org/micro/v4/flow"
+	"go.unistack.org/micro/v3/flow"
-	"go.unistack.org/micro/v4/fsm"
+	"go.unistack.org/micro/v3/fsm"
-	"go.unistack.org/micro/v4/logger"
+	"go.unistack.org/micro/v3/logger"
-	"go.unistack.org/micro/v4/meter"
+	"go.unistack.org/micro/v3/meter"
-	"go.unistack.org/micro/v4/register"
+	"go.unistack.org/micro/v3/register"
-	"go.unistack.org/micro/v4/resolver"
+	"go.unistack.org/micro/v3/resolver"
-	"go.unistack.org/micro/v4/router"
+	"go.unistack.org/micro/v3/router"
-	"go.unistack.org/micro/v4/selector"
+	"go.unistack.org/micro/v3/selector"
-	"go.unistack.org/micro/v4/server"
+	"go.unistack.org/micro/v3/server"
-	"go.unistack.org/micro/v4/store"
+	"go.unistack.org/micro/v3/store"
-	"go.unistack.org/micro/v4/sync"
+	"go.unistack.org/micro/v3/sync"
-	"go.unistack.org/micro/v4/tracer"
+	"go.unistack.org/micro/v3/tracer"
 )
 
 func As(b any, target any) bool {

micro_test.go

@@ -6,9 +6,8 @@ import (
 	"reflect"
 	"testing"
 
-	"go.unistack.org/micro/v4/broker"
+	"go.unistack.org/micro/v3/broker"
-	"go.unistack.org/micro/v4/fsm"
+	"go.unistack.org/micro/v3/fsm"
-	"go.unistack.org/micro/v4/metadata"
 )
 
 func TestAs(t *testing.T) {
@@ -62,8 +61,6 @@ func TestAs(t *testing.T) {
 	}
 }
 
-var _ broker.Broker = (*bro)(nil)
-
 type bro struct {
 	name string
 }
@@ -90,18 +87,23 @@ func (p *bro) Connect(_ context.Context) error { return nil }
 // Disconnect disconnect from broker
 func (p *bro) Disconnect(_ context.Context) error { return nil }
 
-// NewMessage creates new message
-func (p *bro) NewMessage(_ context.Context, _ metadata.Metadata, _ interface{}, _ ...broker.PublishOption) (broker.Message, error) {
-	return nil, nil
-}
-
 // Publish message, msg can be single broker.Message or []broker.Message
-func (p *bro) Publish(_ context.Context, _ string, _ ...broker.Message) error {
+func (p *bro) Publish(_ context.Context, _ string, _ *broker.Message, _ ...broker.PublishOption) error {
 	return nil
 }
 
+// BatchPublish messages to broker with multiple topics
+func (p *bro) BatchPublish(_ context.Context, _ []*broker.Message, _ ...broker.PublishOption) error {
+	return nil
+}
+
+// BatchSubscribe subscribes to topic messages via handler
+func (p *bro) BatchSubscribe(_ context.Context, _ string, _ broker.BatchHandler, _ ...broker.SubscribeOption) (broker.Subscriber, error) {
+	return nil, nil
+}
+
 // Subscribe subscribes to topic message via handler
-func (p *bro) Subscribe(_ context.Context, _ string, _ interface{}, _ ...broker.SubscribeOption) (broker.Subscriber, error) {
+func (p *bro) Subscribe(_ context.Context, _ string, _ broker.Handler, _ ...broker.SubscribeOption) (broker.Subscriber, error) {
 	return nil, nil
 }
 

network/network.go

@@ -0,0 +1,55 @@
+// Package network is for creating internetworks
+package network
+
+import (
+	"go.unistack.org/micro/v3/client"
+	"go.unistack.org/micro/v3/server"
+)
+
+// Error is network node errors
+type Error interface {
+	// Count is current count of errors
+	Count() int
+	// Msg is last error message
+	Msg() string
+}
+
+// Status is node status
+type Status interface {
+	// Error reports error status
+	Error() Error
+}
+
+// Node is network node
+type Node interface {
+	// Id is node id
+	Id() string
+	// Address is node bind address
+	Address() string
+	// Peers returns node peers
+	Peers() []Node
+	// Network is the network node is in
+	Network() Network
+	// Status returns node status
+	Status() Status
+}
+
+// Network is micro network
+type Network interface {
+	// Node is network node
+	Node
+	// Initialise options
+	Init(...Option) error
+	// Options returns the network options
+	Options() Options
+	// Name of the network
+	Name() string
+	// Connect starts the resolver and tunnel server
+	Connect() error
+	// Close stops the tunnel and resolving
+	Close() error
+	// Client is micro client
+	Client() client.Client
+	// Server is micro server
+	Server() server.Server
+}

network/options.go

@@ -0,0 +1,135 @@
+package network
+
+import (
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/network/tunnel"
+	"go.unistack.org/micro/v3/proxy"
+	"go.unistack.org/micro/v3/router"
+	"go.unistack.org/micro/v3/tracer"
+	"go.unistack.org/micro/v3/util/id"
+)
+
+// Option func
+type Option func(*Options)
+
+// Options configure network
+type Options struct {
+	// Router used for routing
+	Router router.Router
+	// Proxy holds the proxy
+	Proxy proxy.Proxy
+	// Logger used for logging
+	Logger logger.Logger
+	// Meter used for metrics
+	Meter meter.Meter
+	// Tracer used for tracing
+	Tracer tracer.Tracer
+	// Tunnel used for transfer data
+	Tunnel tunnel.Tunnel
+	// ID of the node
+	ID string
+	// Name of the network
+	Name string
+	// Address to bind to
+	Address string
+	// Advertise sets the address to advertise
+	Advertise string
+	// Nodes is a list of nodes to connect to
+	Nodes []string
+}
+
+// ID sets the id of the network node
+func ID(id string) Option {
+	return func(o *Options) {
+		o.ID = id
+	}
+}
+
+// Name sets the network name
+func Name(n string) Option {
+	return func(o *Options) {
+		o.Name = n
+	}
+}
+
+// Address sets the network address
+func Address(a string) Option {
+	return func(o *Options) {
+		o.Address = a
+	}
+}
+
+// Advertise sets the address to advertise
+func Advertise(a string) Option {
+	return func(o *Options) {
+		o.Advertise = a
+	}
+}
+
+// Nodes is a list of nodes to connect to
+func Nodes(n ...string) Option {
+	return func(o *Options) {
+		o.Nodes = n
+	}
+}
+
+// Tunnel sets the network tunnel
+func Tunnel(t tunnel.Tunnel) Option {
+	return func(o *Options) {
+		o.Tunnel = t
+	}
+}
+
+// Router sets the network router
+func Router(r router.Router) Option {
+	return func(o *Options) {
+		o.Router = r
+	}
+}
+
+// Proxy sets the network proxy
+func Proxy(p proxy.Proxy) Option {
+	return func(o *Options) {
+		o.Proxy = p
+	}
+}
+
+// Logger sets the network logger
+func Logger(l logger.Logger) Option {
+	return func(o *Options) {
+		o.Logger = l
+	}
+}
+
+// Meter sets the meter
+func Meter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
+// Tracer to be used for tracing
+func Tracer(t tracer.Tracer) Option {
+	return func(o *Options) {
+		o.Tracer = t
+	}
+}
+
+// NewOptions returns network default options
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		ID:      id.MustNew(),
+		Name:    "go.micro",
+		Address: ":0",
+		Logger:  logger.DefaultLogger,
+		Meter:   meter.DefaultMeter,
+		Tracer:  tracer.DefaultTracer,
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}

network/transport/context.go

@@ -0,0 +1,34 @@
+package transport
+
+import (
+	"context"
+)
+
+type transportKey struct{}
+
+// FromContext get transport from context
+func FromContext(ctx context.Context) (Transport, bool) {
+	if ctx == nil {
+		return nil, false
+	}
+	c, ok := ctx.Value(transportKey{}).(Transport)
+	return c, ok
+}
+
+// NewContext put transport in context
+func NewContext(ctx context.Context, c Transport) context.Context {
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	return context.WithValue(ctx, transportKey{}, c)
+}
+
+// SetOption returns a function to setup a context with given value
+func SetOption(k, v interface{}) Option {
+	return func(o *Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, k, v)
+	}
+}

network/transport/memory.go

@@ -0,0 +1,258 @@
+package transport
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	maddr "go.unistack.org/micro/v3/util/addr"
+	mnet "go.unistack.org/micro/v3/util/net"
+	"go.unistack.org/micro/v3/util/rand"
+)
+
+type memorySocket struct {
+	ctx     context.Context
+	recv    chan *Message
+	exit    chan bool
+	lexit   chan bool
+	send    chan *Message
+	local   string
+	remote  string
+	timeout time.Duration
+	sync.RWMutex
+}
+
+type memoryClient struct {
+	*memorySocket
+	opts DialOptions
+}
+
+type memoryListener struct {
+	lopts ListenOptions
+	ctx   context.Context
+	exit  chan bool
+	conn  chan *memorySocket
+	addr  string
+	topts Options
+	sync.RWMutex
+}
+
+type memoryTransport struct {
+	listeners map[string]*memoryListener
+	opts      Options
+	sync.RWMutex
+}
+
+func (ms *memorySocket) Recv(m *Message) error {
+	ms.RLock()
+	defer ms.RUnlock()
+
+	ctx := ms.ctx
+	if ms.timeout > 0 {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ms.ctx, ms.timeout)
+		defer cancel()
+	}
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-ms.exit:
+		return errors.New("connection closed")
+	case <-ms.lexit:
+		return errors.New("server connection closed")
+	case cm := <-ms.recv:
+		*m = *cm
+	}
+	return nil
+}
+
+func (ms *memorySocket) Local() string {
+	return ms.local
+}
+
+func (ms *memorySocket) Remote() string {
+	return ms.remote
+}
+
+func (ms *memorySocket) Send(m *Message) error {
+	ms.RLock()
+	defer ms.RUnlock()
+
+	ctx := ms.ctx
+	if ms.timeout > 0 {
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ms.ctx, ms.timeout)
+		defer cancel()
+	}
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case <-ms.exit:
+		return errors.New("connection closed")
+	case <-ms.lexit:
+		return errors.New("server connection closed")
+	case ms.send <- m:
+	}
+	return nil
+}
+
+func (ms *memorySocket) Close() error {
+	ms.Lock()
+	defer ms.Unlock()
+	select {
+	case <-ms.exit:
+		return nil
+	default:
+		close(ms.exit)
+	}
+	return nil
+}
+
+func (m *memoryListener) Addr() string {
+	return m.addr
+}
+
+func (m *memoryListener) Close() error {
+	m.Lock()
+	defer m.Unlock()
+	select {
+	case <-m.exit:
+		return nil
+	default:
+		close(m.exit)
+	}
+	return nil
+}
+
+func (m *memoryListener) Accept(fn func(Socket)) error {
+	for {
+		select {
+		case <-m.exit:
+			return nil
+		case c := <-m.conn:
+			go fn(&memorySocket{
+				lexit:   c.lexit,
+				exit:    c.exit,
+				send:    c.recv,
+				recv:    c.send,
+				local:   c.Remote(),
+				remote:  c.Local(),
+				timeout: m.topts.Timeout,
+				ctx:     m.topts.Context,
+			})
+		}
+	}
+}
+
+func (m *memoryTransport) Dial(ctx context.Context, addr string, opts ...DialOption) (Client, error) {
+	m.RLock()
+	defer m.RUnlock()
+
+	listener, ok := m.listeners[addr]
+	if !ok {
+		return nil, errors.New("could not dial " + addr)
+	}
+
+	options := NewDialOptions(opts...)
+
+	client := &memoryClient{
+		&memorySocket{
+			send:    make(chan *Message),
+			recv:    make(chan *Message),
+			exit:    make(chan bool),
+			lexit:   listener.exit,
+			local:   addr,
+			remote:  addr,
+			timeout: m.opts.Timeout,
+			ctx:     m.opts.Context,
+		},
+		options,
+	}
+
+	// pseudo connect
+	select {
+	case <-listener.exit:
+		return nil, errors.New("connection error")
+	case listener.conn <- client.memorySocket:
+	}
+
+	return client, nil
+}
+
+func (m *memoryTransport) Listen(ctx context.Context, addr string, opts ...ListenOption) (Listener, error) {
+	m.Lock()
+	defer m.Unlock()
+
+	options := NewListenOptions(opts...)
+
+	host, port, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, err
+	}
+
+	addr, err = maddr.Extract(host)
+	if err != nil {
+		return nil, err
+	}
+
+	// if zero port then randomly assign one
+	if len(port) > 0 && port == "0" {
+		var rng rand.Rand
+		i := rng.Intn(20000)
+		port = fmt.Sprintf("%d", 10000+i)
+	}
+
+	// set addr with port
+	addr = mnet.HostPort(addr, port)
+
+	if _, ok := m.listeners[addr]; ok {
+		return nil, errors.New("already listening on " + addr)
+	}
+
+	listener := &memoryListener{
+		lopts: options,
+		topts: m.opts,
+		addr:  addr,
+		conn:  make(chan *memorySocket),
+		exit:  make(chan bool),
+		ctx:   m.opts.Context,
+	}
+
+	m.listeners[addr] = listener
+
+	return listener, nil
+}
+
+func (m *memoryTransport) Init(opts ...Option) error {
+	for _, o := range opts {
+		o(&m.opts)
+	}
+	return nil
+}
+
+func (m *memoryTransport) Options() Options {
+	return m.opts
+}
+
+func (m *memoryTransport) String() string {
+	return "memory"
+}
+
+func (m *memoryTransport) Name() string {
+	return m.opts.Name
+}
+
+// NewTransport returns new memory transport with options
+func NewTransport(opts ...Option) Transport {
+	options := NewOptions(opts...)
+
+	return &memoryTransport{
+		opts:      options,
+		listeners: make(map[string]*memoryListener),
+	}
+}

network/transport/memory_test.go

@@ -0,0 +1,100 @@
+package transport
+
+import (
+	"context"
+	"os"
+	"testing"
+)
+
+func TestMemoryTransport(t *testing.T) {
+	tr := NewTransport()
+	ctx := context.Background()
+	// bind / listen
+	l, err := tr.Listen(ctx, "127.0.0.1:8080")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l.Close()
+
+	cherr := make(chan error, 1)
+	// accept
+	go func() {
+		if nerr := l.Accept(func(sock Socket) {
+			for {
+				var m Message
+				if rerr := sock.Recv(&m); rerr != nil {
+					cherr <- rerr
+					return
+				}
+				if len(os.Getenv("INTEGRATION_TESTS")) == 0 {
+					t.Logf("Server Received %s", string(m.Body))
+				}
+				if cerr := sock.Send(&Message{
+					Body: []byte(`pong`),
+				}); cerr != nil {
+					cherr <- cerr
+					return
+				}
+			}
+		}); nerr != nil {
+			cherr <- err
+		}
+	}()
+
+	// dial
+	c, err := tr.Dial(ctx, "127.0.0.1:8080")
+	if err != nil {
+		t.Fatalf("Unexpected error dialing %v", err)
+	}
+	defer c.Close()
+
+	select {
+	case err := <-cherr:
+		t.Fatal(err)
+	default:
+		// send <=> receive
+		for i := 0; i < 3; i++ {
+			if err := c.Send(&Message{
+				Body: []byte(`ping`),
+			}); err != nil {
+				return
+			}
+			var m Message
+			if err := c.Recv(&m); err != nil {
+				return
+			}
+			if len(os.Getenv("INTEGRATION_TESTS")) == 0 {
+				t.Logf("Client Received %s", string(m.Body))
+			}
+		}
+	}
+}
+
+func TestListener(t *testing.T) {
+	tr := NewTransport()
+	ctx := context.Background()
+	// bind / listen on random port
+	l, err := tr.Listen(ctx, ":0")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l.Close()
+
+	// try again
+	l2, err := tr.Listen(ctx, ":0")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l2.Close()
+
+	// now make sure it still fails
+	l3, err := tr.Listen(ctx, ":8080")
+	if err != nil {
+		t.Fatalf("Unexpected error listening %v", err)
+	}
+	defer l3.Close()
+
+	if _, err := tr.Listen(ctx, ":8080"); err == nil {
+		t.Fatal("Expected error binding to :8080 got nil")
+	}
+}

network/transport/options.go

@@ -0,0 +1,175 @@
+package transport
+
+import (
+	"context"
+	"crypto/tls"
+	"time"
+
+	"go.unistack.org/micro/v3/codec"
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/tracer"
+)
+
+// Options struct holds the transport options
+type Options struct {
+	// Meter used for metrics
+	Meter meter.Meter
+	// Tracer used for tracing
+	Tracer tracer.Tracer
+	// Codec used for marshal/unmarshal messages
+	Codec codec.Codec
+	// Logger used for logging
+	Logger logger.Logger
+	// Context holds external options
+	Context context.Context
+	// TLSConfig holds tls.TLSConfig options
+	TLSConfig *tls.Config
+	// Name holds the transport name
+	Name string
+	// Addrs holds the transport addrs
+	Addrs []string
+	// Timeout holds the timeout
+	Timeout time.Duration
+}
+
+// NewOptions returns new options
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		Logger:  logger.DefaultLogger,
+		Meter:   meter.DefaultMeter,
+		Tracer:  tracer.DefaultTracer,
+		Context: context.Background(),
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}
+
+// DialOptions struct
+type DialOptions struct {
+	// Context holds the external options
+	Context context.Context
+	// Timeout holds the timeout
+	Timeout time.Duration
+	// Stream flag
+	Stream bool
+}
+
+// NewDialOptions returns new DialOptions
+func NewDialOptions(opts ...DialOption) DialOptions {
+	options := DialOptions{
+		Timeout: DefaultDialTimeout,
+		Context: context.Background(),
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}
+
+// ListenOptions struct
+type ListenOptions struct {
+	// TODO: add tls options when listening
+	// Currently set in global options
+	// Context holds the external options
+	Context context.Context
+	// TLSConfig holds the *tls.Config options
+	TLSConfig *tls.Config
+}
+
+// NewListenOptions returns new ListenOptions
+func NewListenOptions(opts ...ListenOption) ListenOptions {
+	options := ListenOptions{
+		Context: context.Background(),
+	}
+
+	for _, o := range opts {
+		o(&options)
+	}
+
+	return options
+}
+
+// Addrs to use for transport
+func Addrs(addrs ...string) Option {
+	return func(o *Options) {
+		o.Addrs = addrs
+	}
+}
+
+// Logger sets the logger
+func Logger(l logger.Logger) Option {
+	return func(o *Options) {
+		o.Logger = l
+	}
+}
+
+// Meter sets the meter
+func Meter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
+// Context sets the context
+func Context(ctx context.Context) Option {
+	return func(o *Options) {
+		o.Context = ctx
+	}
+}
+
+// Codec sets the codec used for encoding where the transport
+// does not support message headers
+func Codec(c codec.Codec) Option {
+	return func(o *Options) {
+		o.Codec = c
+	}
+}
+
+// Timeout sets the timeout for Send/Recv execution
+func Timeout(t time.Duration) Option {
+	return func(o *Options) {
+		o.Timeout = t
+	}
+}
+
+// TLSConfig to be used for the transport.
+func TLSConfig(t *tls.Config) Option {
+	return func(o *Options) {
+		o.TLSConfig = t
+	}
+}
+
+// WithStream indicates whether this is a streaming connection
+func WithStream() DialOption {
+	return func(o *DialOptions) {
+		o.Stream = true
+	}
+}
+
+// WithTimeout used when dialling the remote side
+func WithTimeout(d time.Duration) DialOption {
+	return func(o *DialOptions) {
+		o.Timeout = d
+	}
+}
+
+// Tracer to be used for tracing
+func Tracer(t tracer.Tracer) Option {
+	return func(o *Options) {
+		o.Tracer = t
+	}
+}
+
+// Name sets the name
+func Name(n string) Option {
+	return func(o *Options) {
+		o.Name = n
+	}
+}

network/transport/transport.go

@@ -0,0 +1,63 @@
+// Package transport is an interface for synchronous connection based communication
+package transport
+
+import (
+	"context"
+	"time"
+
+	"go.unistack.org/micro/v3/metadata"
+)
+
+var (
+	// DefaultTransport is the global default transport
+	DefaultTransport = NewTransport()
+	// DefaultDialTimeout the default dial timeout
+	DefaultDialTimeout = time.Second * 5
+)
+
+// Transport is an interface which is used for communication between
+// services. It uses connection based socket send/recv semantics and
+// has various implementations; http, grpc, quic.
+type Transport interface {
+	Init(...Option) error
+	Options() Options
+	Dial(ctx context.Context, addr string, opts ...DialOption) (Client, error)
+	Listen(ctx context.Context, addr string, opts ...ListenOption) (Listener, error)
+	String() string
+}
+
+// Message is used to transfer data
+type Message struct {
+	Header metadata.Metadata
+	Body   []byte
+}
+
+// Socket bastraction interface
+type Socket interface {
+	Recv(*Message) error
+	Send(*Message) error
+	Close() error
+	Local() string
+	Remote() string
+}
+
+// Client is the socket owner
+type Client interface {
+	Socket
+}
+
+// Listener is the interface for stream oriented messaging
+type Listener interface {
+	Addr() string
+	Close() error
+	Accept(func(Socket)) error
+}
+
+// Option is the option signature
+type Option func(*Options)
+
+// DialOption is the option signature
+type DialOption func(*DialOptions)
+
+// ListenOption is the option signature
+type ListenOption func(*ListenOptions)

network/tunnel/broker/broker.go

@@ -0,0 +1,372 @@
+// Package broker is a tunnel broker
+package broker
+
+import (
+	"context"
+	"fmt"
+
+	"go.unistack.org/micro/v3/broker"
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/metadata"
+	"go.unistack.org/micro/v3/network/transport"
+	"go.unistack.org/micro/v3/network/tunnel"
+)
+
+type tunBroker struct {
+	tunnel tunnel.Tunnel
+	opts   broker.Options
+}
+
+type tunSubscriber struct {
+	listener tunnel.Listener
+	handler  broker.Handler
+	closed   chan bool
+	topic    string
+	opts     broker.SubscribeOptions
+}
+
+type tunBatchSubscriber struct {
+	listener tunnel.Listener
+	handler  broker.BatchHandler
+	closed   chan bool
+	topic    string
+	opts     broker.SubscribeOptions
+}
+
+type tunEvent struct {
+	err     error
+	message *broker.Message
+	topic   string
+}
+
+// used to access tunnel from options context
+type (
+	tunnelKey  struct{}
+	tunnelAddr struct{}
+)
+
+func (t *tunBroker) Live() bool {
+	return true
+}
+
+func (t *tunBroker) Ready() bool {
+	return true
+}
+
+func (t *tunBroker) Health() bool {
+	return true
+}
+
+func (t *tunBroker) Init(opts ...broker.Option) error {
+	for _, o := range opts {
+		o(&t.opts)
+	}
+	return nil
+}
+
+func (t *tunBroker) Name() string {
+	return t.opts.Name
+}
+
+func (t *tunBroker) Options() broker.Options {
+	return t.opts
+}
+
+func (t *tunBroker) Address() string {
+	return t.tunnel.Address()
+}
+
+func (t *tunBroker) Connect(ctx context.Context) error {
+	return t.tunnel.Connect(ctx)
+}
+
+func (t *tunBroker) Disconnect(ctx context.Context) error {
+	return t.tunnel.Close(ctx)
+}
+
+func (t *tunBroker) BatchPublish(ctx context.Context, msgs []*broker.Message, _ ...broker.PublishOption) error {
+	// TODO: this is probably inefficient, we might want to just maintain an open connection
+	// it may be easier to add broadcast to the tunnel
+	topicMap := make(map[string]tunnel.Session)
+
+	var err error
+	for _, msg := range msgs {
+		topic, _ := msg.Header.Get(metadata.HeaderTopic)
+		c, ok := topicMap[topic]
+		if !ok {
+			c, err = t.tunnel.Dial(ctx, topic, tunnel.DialMode(tunnel.Multicast))
+			if err != nil {
+				return err
+			}
+			defer c.Close()
+			topicMap[topic] = c
+		}
+
+		if err = c.Send(&transport.Message{
+			Header: msg.Header,
+			Body:   msg.Body,
+		}); err != nil {
+			//	msg.SetError(err)
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (t *tunBroker) Publish(ctx context.Context, topic string, m *broker.Message, _ ...broker.PublishOption) error {
+	// TODO: this is probably inefficient, we might want to just maintain an open connection
+	// it may be easier to add broadcast to the tunnel
+	c, err := t.tunnel.Dial(ctx, topic, tunnel.DialMode(tunnel.Multicast))
+	if err != nil {
+		return err
+	}
+	defer c.Close()
+
+	return c.Send(&transport.Message{
+		Header: m.Header,
+		Body:   m.Body,
+	})
+}
+
+func (t *tunBroker) BatchSubscribe(ctx context.Context, topic string, h broker.BatchHandler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	l, err := t.tunnel.Listen(ctx, topic, tunnel.ListenMode(tunnel.Multicast))
+	if err != nil {
+		return nil, err
+	}
+
+	tunSub := &tunBatchSubscriber{
+		topic:    topic,
+		handler:  h,
+		opts:     broker.NewSubscribeOptions(opts...),
+		closed:   make(chan bool),
+		listener: l,
+	}
+
+	// start processing
+	go tunSub.run()
+
+	return tunSub, nil
+}
+
+func (t *tunBroker) Subscribe(ctx context.Context, topic string, h broker.Handler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
+	l, err := t.tunnel.Listen(ctx, topic, tunnel.ListenMode(tunnel.Multicast))
+	if err != nil {
+		return nil, err
+	}
+
+	tunSub := &tunSubscriber{
+		topic:    topic,
+		handler:  h,
+		opts:     broker.NewSubscribeOptions(opts...),
+		closed:   make(chan bool),
+		listener: l,
+	}
+
+	// start processing
+	go tunSub.run()
+
+	return tunSub, nil
+}
+
+func (t *tunBroker) String() string {
+	return "tunnel"
+}
+
+func (t *tunBatchSubscriber) run() {
+	for {
+		// accept a new connection
+		c, err := t.listener.Accept()
+		if err != nil {
+			select {
+			case <-t.closed:
+				return
+			default:
+				continue
+			}
+		}
+
+		// receive message
+		m := new(transport.Message)
+		if err := c.Recv(m); err != nil {
+			if logger.DefaultLogger.V(logger.ErrorLevel) {
+				logger.DefaultLogger.Error(t.opts.Context, err.Error(), err)
+			}
+			if err = c.Close(); err != nil {
+				if logger.DefaultLogger.V(logger.ErrorLevel) {
+					logger.DefaultLogger.Error(t.opts.Context, err.Error(), err)
+				}
+			}
+			continue
+		}
+
+		// close the connection
+		c.Close()
+
+		evts := broker.Events{&tunEvent{
+			topic: t.topic,
+			message: &broker.Message{
+				Header: m.Header,
+				Body:   m.Body,
+			},
+		}}
+		// handle the message
+		go func() {
+			_ = t.handler(evts)
+		}()
+
+	}
+}
+
+func (t *tunSubscriber) run() {
+	for {
+		// accept a new connection
+		c, err := t.listener.Accept()
+		if err != nil {
+			select {
+			case <-t.closed:
+				return
+			default:
+				continue
+			}
+		}
+
+		// receive message
+		m := new(transport.Message)
+		if err := c.Recv(m); err != nil {
+			if logger.DefaultLogger.V(logger.ErrorLevel) {
+				logger.DefaultLogger.Error(t.opts.Context, err.Error(), err)
+			}
+			if err = c.Close(); err != nil {
+				if logger.DefaultLogger.V(logger.ErrorLevel) {
+					logger.DefaultLogger.Error(t.opts.Context, err.Error(), err)
+				}
+			}
+			continue
+		}
+
+		// close the connection
+		c.Close()
+
+		// handle the message
+		go func() {
+			_ = t.handler(&tunEvent{
+				topic: t.topic,
+				message: &broker.Message{
+					Header: m.Header,
+					Body:   m.Body,
+				},
+			})
+		}()
+	}
+}
+
+func (t *tunBatchSubscriber) Options() broker.SubscribeOptions {
+	return t.opts
+}
+
+func (t *tunBatchSubscriber) Topic() string {
+	return t.topic
+}
+
+func (t *tunBatchSubscriber) Unsubscribe(ctx context.Context) error {
+	select {
+	case <-t.closed:
+		return nil
+	default:
+		close(t.closed)
+		return t.listener.Close()
+	}
+}
+
+func (t *tunSubscriber) Options() broker.SubscribeOptions {
+	return t.opts
+}
+
+func (t *tunSubscriber) Topic() string {
+	return t.topic
+}
+
+func (t *tunSubscriber) Unsubscribe(ctx context.Context) error {
+	select {
+	case <-t.closed:
+		return nil
+	default:
+		close(t.closed)
+		return t.listener.Close()
+	}
+}
+
+func (t *tunEvent) Topic() string {
+	return t.topic
+}
+
+func (t *tunEvent) Message() *broker.Message {
+	return t.message
+}
+
+func (t *tunEvent) Ack() error {
+	return nil
+}
+
+func (t *tunEvent) Error() error {
+	return t.err
+}
+
+func (t *tunEvent) SetError(err error) {
+	t.err = err
+}
+
+func (t *tunEvent) Context() context.Context {
+	return context.TODO()
+}
+
+// NewBroker returns new tunnel broker
+func NewBroker(opts ...broker.Option) (broker.Broker, error) {
+	options := broker.NewOptions(opts...)
+
+	t, ok := options.Context.Value(tunnelKey{}).(tunnel.Tunnel)
+	if !ok {
+		return nil, fmt.Errorf("tunnel not set")
+	}
+
+	a, ok := options.Context.Value(tunnelAddr{}).(string)
+	if ok {
+		// initialise address
+		if err := t.Init(tunnel.Address(a)); err != nil {
+			return nil, err
+		}
+	}
+
+	if len(options.Addrs) > 0 {
+		// initialise nodes
+		if err := t.Init(tunnel.Nodes(options.Addrs...)); err != nil {
+			return nil, err
+		}
+	}
+
+	return &tunBroker{
+		opts:   options,
+		tunnel: t,
+	}, nil
+}
+
+// WithAddress sets the tunnel address
+func WithAddress(a string) broker.Option {
+	return func(o *broker.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, tunnelAddr{}, a)
+	}
+}
+
+// WithTunnel sets the internal tunnel
+func WithTunnel(t tunnel.Tunnel) broker.Option {
+	return func(o *broker.Options) {
+		if o.Context == nil {
+			o.Context = context.Background()
+		}
+		o.Context = context.WithValue(o.Context, tunnelKey{}, t)
+	}
+}

network/tunnel/options.go

@@ -0,0 +1,192 @@
+package tunnel
+
+import (
+	"time"
+
+	"go.unistack.org/micro/v3/logger"
+	"go.unistack.org/micro/v3/meter"
+	"go.unistack.org/micro/v3/network/transport"
+	"go.unistack.org/micro/v3/tracer"
+	"go.unistack.org/micro/v3/util/id"
+)
+
+var (
+	// DefaultAddress is default tunnel bind address
+	DefaultAddress = ":0"
+	// DefaultToken the shared default token
+	DefaultToken = "go.micro.tunnel"
+)
+
+// Option func signature
+type Option func(*Options)
+
+// Options provides network configuration options
+type Options struct {
+	// Logger used for logging
+	Logger logger.Logger
+	// Meter used for metrics
+	Meter meter.Meter
+	// Tracer used for tracing
+	Tracer tracer.Tracer
+	// Transport used for communication
+	Transport transport.Transport
+	// Token the shared auth token
+	Token string
+	// Name holds the tunnel name
+	Name string
+	// ID holds the tunnel id
+	ID string
+	// Address holds the tunnel address
+	Address string
+	// Nodes holds the tunnel nodes
+	Nodes []string
+}
+
+// DialOption func
+type DialOption func(*DialOptions)
+
+// DialOptions provides dial options
+type DialOptions struct {
+	// Link specifies the link to use
+	Link string
+	// specify mode of the session
+	Mode Mode
+	// Wait for connection to be accepted
+	Wait bool
+	// the dial timeout
+	Timeout time.Duration
+}
+
+// ListenOption func
+type ListenOption func(*ListenOptions)
+
+// ListenOptions provides listen options
+type ListenOptions struct {
+	// Mode specify mode of the session
+	Mode Mode
+	// Timeout the read timeout
+	Timeout time.Duration
+}
+
+// ID sets the tunnel id
+func ID(id string) Option {
+	return func(o *Options) {
+		o.ID = id
+	}
+}
+
+// Logger sets the logger
+func Logger(l logger.Logger) Option {
+	return func(o *Options) {
+		o.Logger = l
+	}
+}
+
+// Meter sets the meter
+func Meter(m meter.Meter) Option {
+	return func(o *Options) {
+		o.Meter = m
+	}
+}
+
+// Address sets the tunnel address
+func Address(a string) Option {
+	return func(o *Options) {
+		o.Address = a
+	}
+}
+
+// Nodes specify remote network nodes
+func Nodes(n ...string) Option {
+	return func(o *Options) {
+		o.Nodes = n
+	}
+}
+
+// Token sets the shared token for auth
+func Token(t string) Option {
+	return func(o *Options) {
+		o.Token = t
+	}
+}
+
+// Transport listens for incoming connections
+func Transport(t transport.Transport) Option {
+	return func(o *Options) {
+		o.Transport = t
+	}
+}
+
+// ListenMode option
+func ListenMode(m Mode) ListenOption {
+	return func(o *ListenOptions) {
+		o.Mode = m
+	}
+}
+
+// ListenTimeout for reads and writes on the listener session
+func ListenTimeout(t time.Duration) ListenOption {
+	return func(o *ListenOptions) {
+		o.Timeout = t
+	}
+}
+
+// DialMode multicast sets the multicast option to send only to those mapped
+func DialMode(m Mode) DialOption {
+	return func(o *DialOptions) {
+		o.Mode = m
+	}
+}
+
+// DialTimeout sets the dial timeout of the connection
+func DialTimeout(t time.Duration) DialOption {
+	return func(o *DialOptions) {
+		o.Timeout = t
+	}
+}
+
+// DialLink specifies the link to pin this connection to.
+// This is not applicable if the multicast option is set.
+func DialLink(id string) DialOption {
+	return func(o *DialOptions) {
+		o.Link = id
+	}
+}
+
+// DialWait specifies whether to wait for the connection
+// to be accepted before returning the session
+func DialWait(b bool) DialOption {
+	return func(o *DialOptions) {
+		o.Wait = b
+	}
+}
+
+// NewOptions returns router default options with filled values
+func NewOptions(opts ...Option) Options {
+	options := Options{
+		ID:      id.MustNew(),
+		Address: DefaultAddress,
+		Token:   DefaultToken,
+		Logger:  logger.DefaultLogger,
+		Meter:   meter.DefaultMeter,
+		Tracer:  tracer.DefaultTracer,
+	}
+	for _, o := range opts {
+		o(&options)
+	}
+	return options
+}
+
+// Tracer to be used for tracing
+func Tracer(t tracer.Tracer) Option {
+	return func(o *Options) {
+		o.Tracer = t
+	}
+}
+
+// Name sets the name
+func Name(n string) Option {
+	return func(o *Options) {
+		o.Name = n
+	}
+}

network/tunnel/transport/listener.go

@@ -0,0 +1,30 @@
+package transport
+
+import (
+	"go.unistack.org/micro/v3/network/transport"
+	"go.unistack.org/micro/v3/network/tunnel"
+)
+
+type tunListener struct {
+	l tunnel.Listener
+}
+
+func (t *tunListener) Addr() string {
+	return t.l.Channel()
+}
+
+func (t *tunListener) Close() error {
+	return t.l.Close()
+}
+
+func (t *tunListener) Accept(fn func(socket transport.Socket)) error {
+	for {
+		// accept connection
+		c, err := t.l.Accept()
+		if err != nil {
+			return err
+		}
+		// execute the function
+		go fn(c)
+	}
+}