broker: add BatchBroker interface to avoid breaking older brokers

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

broker/broker.go

@@ -8,31 +8,83 @@ import (
 	"github.com/unistack-org/micro/v3/metadata"
 )
 
-// DefaultBroker default broker
+// DefaultBroker default memory broker
 var DefaultBroker Broker = NewBroker()
 
+var (
+	// ErrNotConnected returns when broker used but not connected yet
+	ErrNotConnected = errors.New("broker not connected")
+	// ErrDisconnected returns when broker disconnected
+	ErrDisconnected = errors.New("broker disconnected")
+)
+
+type BatchBroker interface {
+	Broker
+	// 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)
+}
+
 // Broker is an interface used for asynchronous messaging.
 type Broker interface {
+	// Name returns broker instance name
 	Name() string
-	Init(...Option) error
+	// Init initilize broker
+	Init(opts ...Option) error
+	// Options returns broker options
 	Options() Options
+	// Address return configured address
 	Address() string
-	Connect(context.Context) error
-	Disconnect(context.Context) error
-	Publish(context.Context, string, *Message, ...PublishOption) error
-	Subscribe(context.Context, string, Handler, ...SubscribeOption) (Subscriber, error)
+	// Connect connects to broker
+	Connect(ctx context.Context) error
+	// Disconnect disconnect from broker
+	Disconnect(ctx context.Context) error
+	// Publish message to broker topic
+	Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error
+	// Subscribe subscribes to topic message via handler
+	Subscribe(ctx context.Context, topic string, h Handler, opts ...SubscribeOption) (Subscriber, error)
+	// String type of broker
 	String() string
 }
 
 // Handler is used to process messages via a subscription of a topic.
 type Handler func(Event) error
 
+// Events contains multiple events
+type Events []Event
+
+func (evs Events) Ack() error {
+	var err error
+	for _, ev := range evs {
+		if err = ev.Ack(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+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 {
+	// Topic returns event topic
 	Topic() string
+	// Message returns broker message
 	Message() *Message
+	// Ack acknowledge message
 	Ack() error
+	// Error returns message error (like decoding errors or some other)
 	Error() error
+	// SetError set event processing error
+	SetError(err error)
 }
 
 // RawMessage is a raw encoded JSON value.
@@ -58,13 +110,25 @@ func (m *RawMessage) UnmarshalJSON(data []byte) error {
 
 // Message is used to transfer data
 type Message struct {
-	Header metadata.Metadata // contains message metadata
-	Body   RawMessage        // contains message body
+	// Header contains message metadata
+	Header metadata.Metadata
+	// Body contains message body
+	Body 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
 type Subscriber interface {
+	// Options returns subscriber options
 	Options() SubscribeOptions
+	// Topic returns topic for subscription
 	Topic() string
-	Unsubscribe(context.Context) error
+	// Unsubscribe from topic
+	Unsubscribe(ctx context.Context) error
 }

broker/memory.go

@@ -2,20 +2,21 @@ package broker
 
 import (
 	"context"
-	"errors"
 	"sync"
 
 	"github.com/google/uuid"
 	"github.com/unistack-org/micro/v3/logger"
+	"github.com/unistack-org/micro/v3/metadata"
 	maddr "github.com/unistack-org/micro/v3/util/addr"
 	mnet "github.com/unistack-org/micro/v3/util/net"
 	"github.com/unistack-org/micro/v3/util/rand"
 )
 
 type memoryBroker struct {
-	Subscribers map[string][]*memorySubscriber
-	addr        string
-	opts        Options
+	subscribers      map[string][]*memorySubscriber
+	batchsubscribers map[string][]*memoryBatchSubscriber
+	addr             string
+	opts             Options
 	sync.RWMutex
 	connected bool
 }
@@ -36,6 +37,15 @@ type memorySubscriber struct {
 	opts    SubscribeOptions
 }
 
+type memoryBatchSubscriber struct {
+	ctx     context.Context
+	exit    chan bool
+	handler BatchHandler
+	id      string
+	topic   string
+	opts    SubscribeOptions
+}
+
 func (m *memoryBroker) Options() Options {
 	return m.opts
 }
@@ -77,7 +87,6 @@ func (m *memoryBroker) Disconnect(ctx context.Context) error {
 	}
 
 	m.connected = false
-
 	return nil
 }
 
@@ -88,14 +97,127 @@ func (m *memoryBroker) Init(opts ...Option) error {
 	return nil
 }
 
+func (m *memoryBroker) BatchPublish(ctx context.Context, msgs []*Message, opts ...PublishOption) error {
+	m.RLock()
+	if !m.connected {
+		m.RUnlock()
+		return ErrNotConnected
+	}
+	m.RUnlock()
+
+	type msgWrapper struct {
+		topic string
+		body  interface{}
+	}
+
+	vs := make([]msgWrapper, 0, len(msgs))
+	if m.opts.Codec == nil {
+		m.RLock()
+		for _, msg := range msgs {
+			topic, _ := msg.Header.Get(metadata.HeaderTopic)
+			vs = append(vs, msgWrapper{topic: topic, body: m})
+		}
+		m.RUnlock()
+	} else {
+		m.RLock()
+		for _, msg := range msgs {
+			topic, _ := msg.Header.Get(metadata.HeaderTopic)
+			buf, err := m.opts.Codec.Marshal(msg)
+			if err != nil {
+				m.RUnlock()
+				return err
+			}
+			vs = append(vs, msgWrapper{topic: topic, body: buf})
+		}
+		m.RUnlock()
+	}
+
+	if len(m.batchsubscribers) > 0 {
+		eh := m.opts.BatchErrorHandler
+
+		msgTopicMap := make(map[string]Events)
+		for _, v := range vs {
+			p := &memoryEvent{
+				topic:   v.topic,
+				message: v.body,
+				opts:    m.opts,
+			}
+			msgTopicMap[p.topic] = append(msgTopicMap[p.topic], p)
+		}
+
+		for t, ms := range msgTopicMap {
+			m.RLock()
+			subs, ok := m.batchsubscribers[t]
+			m.RUnlock()
+			if !ok {
+				continue
+			}
+			for _, sub := range subs {
+				if err := sub.handler(ms); err != nil {
+					ms.SetError(err)
+					if sub.opts.BatchErrorHandler != nil {
+						eh = sub.opts.BatchErrorHandler
+					}
+					if eh != nil {
+						eh(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.Errorf(m.opts.Context, "ack failed: %v", err)
+					}
+				}
+			}
+		}
+
+	}
+
+	eh := m.opts.ErrorHandler
+
+	for _, v := range vs {
+		p := &memoryEvent{
+			topic:   v.topic,
+			message: v.body,
+			opts:    m.opts,
+		}
+
+		m.RLock()
+		subs, ok := m.subscribers[p.topic]
+		m.RUnlock()
+		if !ok {
+			continue
+		}
+		for _, sub := range subs {
+			if err := sub.handler(p); err != nil {
+				p.SetError(err)
+				if sub.opts.ErrorHandler != nil {
+					eh = sub.opts.ErrorHandler
+				}
+				if eh != nil {
+					eh(p)
+				} else if m.opts.Logger.V(logger.ErrorLevel) {
+					m.opts.Logger.Error(m.opts.Context, err.Error())
+				}
+			} else if sub.opts.AutoAck {
+				if err := p.Ack(); err != nil {
+					m.opts.Logger.Errorf(m.opts.Context, "ack failed: %v", err)
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
 func (m *memoryBroker) Publish(ctx context.Context, topic string, msg *Message, opts ...PublishOption) error {
 	m.RLock()
 	if !m.connected {
 		m.RUnlock()
-		return errors.New("not connected")
+		return ErrNotConnected
 	}
 
-	subs, ok := m.Subscribers[topic]
+	subs, ok := m.subscribers[topic]
 	m.RUnlock()
 	if !ok {
 		return nil
@@ -138,11 +260,56 @@ func (m *memoryBroker) Publish(ctx context.Context, topic string, msg *Message,
 	return nil
 }
 
+func (m *memoryBroker) BatchSubscribe(ctx context.Context, topic string, handler BatchHandler, opts ...SubscribeOption) (Subscriber, error) {
+	m.RLock()
+	if !m.connected {
+		m.RUnlock()
+		return nil, ErrNotConnected
+	}
+	m.RUnlock()
+
+	options := NewSubscribeOptions(opts...)
+
+	id, err := uuid.NewRandom()
+	if err != nil {
+		return nil, err
+	}
+
+	sub := &memoryBatchSubscriber{
+		exit:    make(chan bool, 1),
+		id:      id.String(),
+		topic:   topic,
+		handler: handler,
+		opts:    options,
+		ctx:     ctx,
+	}
+
+	m.Lock()
+	m.batchsubscribers[topic] = append(m.batchsubscribers[topic], sub)
+	m.Unlock()
+
+	go func() {
+		<-sub.exit
+		m.Lock()
+		var newSubscribers []*memoryBatchSubscriber
+		for _, sb := range m.batchsubscribers[topic] {
+			if sb.id == sub.id {
+				continue
+			}
+			newSubscribers = append(newSubscribers, sb)
+		}
+		m.batchsubscribers[topic] = newSubscribers
+		m.Unlock()
+	}()
+
+	return sub, nil
+}
+
 func (m *memoryBroker) Subscribe(ctx context.Context, topic string, handler Handler, opts ...SubscribeOption) (Subscriber, error) {
 	m.RLock()
 	if !m.connected {
 		m.RUnlock()
-		return nil, errors.New("not connected")
+		return nil, ErrNotConnected
 	}
 	m.RUnlock()
 
@@ -163,20 +330,20 @@ func (m *memoryBroker) Subscribe(ctx context.Context, topic string, handler Hand
 	}
 
 	m.Lock()
-	m.Subscribers[topic] = append(m.Subscribers[topic], sub)
+	m.subscribers[topic] = append(m.subscribers[topic], sub)
 	m.Unlock()
 
 	go func() {
 		<-sub.exit
 		m.Lock()
 		var newSubscribers []*memorySubscriber
-		for _, sb := range m.Subscribers[topic] {
+		for _, sb := range m.subscribers[topic] {
 			if sb.id == sub.id {
 				continue
 			}
 			newSubscribers = append(newSubscribers, sb)
 		}
-		m.Subscribers[topic] = newSubscribers
+		m.subscribers[topic] = newSubscribers
 		m.Unlock()
 	}()
 
@@ -221,6 +388,23 @@ func (m *memoryEvent) Error() error {
 	return m.err
 }
 
+func (m *memoryEvent) SetError(err error) {
+	m.err = err
+}
+
+func (m *memoryBatchSubscriber) Options() SubscribeOptions {
+	return m.opts
+}
+
+func (m *memoryBatchSubscriber) Topic() string {
+	return m.topic
+}
+
+func (m *memoryBatchSubscriber) Unsubscribe(ctx context.Context) error {
+	m.exit <- true
+	return nil
+}
+
 func (m *memorySubscriber) Options() SubscribeOptions {
 	return m.opts
 }
@@ -235,9 +419,10 @@ func (m *memorySubscriber) Unsubscribe(ctx context.Context) error {
 }
 
 // NewBroker return new memory broker
-func NewBroker(opts ...Option) Broker {
+func NewBroker(opts ...Option) BatchBroker {
 	return &memoryBroker{
-		opts:        NewOptions(opts...),
-		Subscribers: make(map[string][]*memorySubscriber),
+		opts:             NewOptions(opts...),
+		subscribers:      make(map[string][]*memorySubscriber),
+		batchsubscribers: make(map[string][]*memoryBatchSubscriber),
 	}
 }

broker/memory_test.go

@@ -4,8 +4,55 @@ import (
 	"context"
 	"fmt"
 	"testing"
+
+	"github.com/unistack-org/micro/v3/metadata"
 )
 
+func TestMemoryBatchBroker(t *testing.T) {
+	b := NewBroker()
+	ctx := context.Background()
+
+	if err := b.Connect(ctx); err != nil {
+		t.Fatalf("Unexpected connect error %v", err)
+	}
+
+	topic := "test"
+	count := 10
+
+	fn := func(evts Events) error {
+		return evts.Ack()
+	}
+
+	sub, err := b.BatchSubscribe(ctx, topic, fn)
+	if err != nil {
+		t.Fatalf("Unexpected error subscribing %v", err)
+	}
+
+	msgs := make([]*Message, 0, 0)
+	for i := 0; i < count; i++ {
+		message := &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.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)
+	}
+}
 func TestMemoryBroker(t *testing.T) {
 	b := NewBroker()
 	ctx := context.Background()
@@ -26,20 +73,27 @@ func TestMemoryBroker(t *testing.T) {
 		t.Fatalf("Unexpected error subscribing %v", err)
 	}
 
+	msgs := make([]*Message, 0, 0)
 	for i := 0; i < count; i++ {
 		message := &Message{
 			Header: map[string]string{
-				"foo": "bar",
-				"id":  fmt.Sprintf("%d", i),
+				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", i)
+			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)
 	}

broker/options.go

@@ -29,6 +29,8 @@ type Options struct {
 	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
 	// Name holds the broker name
 	Name string
 	// Addrs holds the broker address
@@ -85,6 +87,8 @@ type SubscribeOptions struct {
 	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
@@ -175,6 +179,14 @@ func ErrorHandler(h Handler) Option {
 	}
 }
 
+// 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 {
@@ -183,6 +195,14 @@ func SubscribeErrorHandler(h Handler) SubscribeOption {
 	}
 }
 
+// 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 {

client/noop.go

@@ -190,8 +190,8 @@ func (n *noopClient) Publish(ctx context.Context, p Message, opts ...PublishOpti
 	if !ok {
 		md = metadata.New(0)
 	}
-	md["Content-Type"] = p.ContentType()
-	md["Micro-Topic"] = p.Topic()
+	md[metadata.HeaderContentType] = p.ContentType()
+	md[metadata.HeaderTopic] = p.Topic()
 
 	// passed in raw data
 	if d, ok := p.Payload().(*codec.Frame); ok {

metadata/metadata.go

@@ -6,8 +6,20 @@ import (
 	"sort"
 )
 
-// HeaderPrefix for all headers passed
-var HeaderPrefix = "Micro-"
+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"
+)
 
 // Metadata is our way of representing request headers internally.
 // They're used at the RPC level and translate back and forth

meter/meter.go

@@ -3,8 +3,9 @@ package meter
 
 import (
 	"io"
-	"reflect"
 	"sort"
+	"strconv"
+	"strings"
 	"time"
 )
 
@@ -77,36 +78,62 @@ type Summary interface {
 	UpdateDuration(time.Time)
 }
 
+// sort labels alphabeticaly by label name
 type byKey []string
 
 func (k byKey) Len() int           { return len(k) / 2 }
 func (k byKey) Less(i, j int) bool { return k[i*2] < k[j*2] }
 func (k byKey) Swap(i, j int) {
-	k[i*2], k[i*2+1], k[j*2], k[j*2+1] = k[j*2], k[j*2+1], k[i*2], k[i*2+1]
+	k[i*2], k[j*2] = k[j*2], k[i*2]
+	k[i*2+1], k[j*2+1] = k[j*2+1], k[i*2+1]
 }
 
-func Sort(slice *[]string) {
-	bk := byKey(*slice)
-	if bk.Len() <= 1 {
-		return
+// BuildLables used to sort labels and delete duplicates.
+// Last value wins in case of duplicate label keys.
+func BuildLabels(labels ...string) []string {
+	if len(labels)%2 == 1 {
+		labels = labels[:len(labels)-1]
 	}
-	sort.Sort(bk)
-	v := reflect.ValueOf(slice).Elem()
-	cnt := 0
-	key := 0
-	val := 1
-	for key < v.Len() {
-		if len(bk) > key+2 && bk[key] == bk[key+2] {
-			key += 2
-			val += 2
-			continue
-		}
-		v.Index(cnt).Set(v.Index(key))
-		cnt++
-		v.Index(cnt).Set(v.Index(val))
-		cnt++
-		key += 2
-		val += 2
-	}
-	v.SetLen(cnt)
+	sort.Sort(byKey(labels))
+	return labels
+}
+
+// BuildName used to combine metric with labels.
+// If labels count is odd, drop last element
+func BuildName(name string, labels ...string) string {
+	if len(labels)%2 == 1 {
+		labels = labels[:len(labels)-1]
+	}
+
+	if len(labels) > 2 {
+		sort.Sort(byKey(labels))
+
+		idx := 0
+		for {
+			if labels[idx] == labels[idx+2] {
+				copy(labels[idx:], labels[idx+2:])
+				labels = labels[:len(labels)-2]
+			} else {
+				idx += 2
+			}
+			if idx+2 >= len(labels) {
+				break
+			}
+		}
+	}
+
+	var b strings.Builder
+	_, _ = b.WriteString(name)
+	_, _ = b.WriteRune('{')
+	for idx := 0; idx < len(labels); idx += 2 {
+		if idx > 0 {
+			_, _ = b.WriteRune(',')
+		}
+		_, _ = b.WriteString(labels[idx])
+		_, _ = b.WriteString(`=`)
+		_, _ = b.WriteString(strconv.Quote(labels[idx+1]))
+	}
+	_, _ = b.WriteRune('}')
+
+	return b.String()
 }

meter/meter_test.go

@@ -14,11 +14,57 @@ func TestNoopMeter(t *testing.T) {
 	cnt.Inc()
 }
 
-func TestLabelsSort(t *testing.T) {
-	ls := []string{"server", "http", "register", "mdns", "broker", "broker1", "broker", "broker2", "server", "tcp"}
-	Sort(&ls)
+func testEq(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
 
-	if ls[0] != "broker" || ls[1] != "broker2" {
-		t.Fatalf("sort error: %v", ls)
+func TestBuildLabels(t *testing.T) {
+	type testData struct {
+		src []string
+		dst []string
+	}
+
+	data := []testData{
+		testData{
+			src: []string{"zerolabel", "value3", "firstlabel", "value2"},
+			dst: []string{"firstlabel", "value2", "zerolabel", "value3"},
+		},
+	}
+
+	for _, d := range data {
+		if !testEq(d.dst, BuildLabels(d.src...)) {
+			t.Fatalf("slices not properly sorted: %v %v", d.dst, d.src)
+		}
+	}
+}
+
+func TestBuildName(t *testing.T) {
+	data := map[string][]string{
+		`my_metric{firstlabel="value2",zerolabel="value3"}`: []string{
+			"my_metric",
+			"zerolabel", "value3", "firstlabel", "value2",
+		},
+		`my_metric{broker="broker2",register="mdns",server="tcp"}`: []string{
+			"my_metric",
+			"broker", "broker1", "broker", "broker2", "server", "http", "server", "tcp", "register", "mdns",
+		},
+		`my_metric{aaa="aaa"}`: []string{
+			"my_metric",
+			"aaa", "aaa",
+		},
+	}
+
+	for e, d := range data {
+		if x := BuildName(d[0], d[1:]...); x != e {
+			t.Fatalf("expect: %s, result: %s", e, x)
+		}
 	}
 }

network/tunnel/broker/broker.go

@@ -24,9 +24,18 @@ type tunSubscriber struct {
 	opts     broker.SubscribeOptions
 }
 
+type tunBatchSubscriber struct {
+	listener tunnel.Listener
+	handler  broker.BatchHandler
+	closed   chan bool
+	topic    string
+	opts     broker.SubscribeOptions
+}
+
 type tunEvent struct {
 	message *broker.Message
 	topic   string
+	err     error
 }
 
 // used to access tunnel from options context
@@ -62,6 +71,36 @@ func (t *tunBroker) Disconnect(ctx context.Context) error {
 	return t.tunnel.Close(ctx)
 }
 
+func (t *tunBroker) BatchPublish(ctx context.Context, msgs []*broker.Message, opts ...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, opts ...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
@@ -77,6 +116,26 @@ func (t *tunBroker) Publish(ctx context.Context, topic string, m *broker.Message
 	})
 }
 
+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 {
@@ -101,6 +160,49 @@ 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.V(logger.ErrorLevel) {
+				logger.Error(t.opts.Context, err.Error())
+			}
+			if err = c.Close(); err != nil {
+				if logger.V(logger.ErrorLevel) {
+					logger.Error(t.opts.Context, err.Error())
+				}
+			}
+			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 t.handler(evts)
+
+	}
+}
+
 func (t *tunSubscriber) run() {
 	for {
 		// accept a new connection
@@ -142,6 +244,24 @@ func (t *tunSubscriber) run() {
 	}
 }
 
+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
 }
@@ -173,7 +293,11 @@ func (t *tunEvent) Ack() error {
 }
 
 func (t *tunEvent) Error() error {
-	return nil
+	return t.err
+}
+
+func (t *tunEvent) SetError(err error) {
+	t.err = err
 }
 
 // NewBroker returns new tunnel broker

server/server.go

@@ -15,8 +15,8 @@ import (
 var DefaultServer Server = NewServer()
 
 var (
-	// DefaultAddress will be used if no address passed
-	DefaultAddress = ":0"
+	// DefaultAddress will be used if no address passed, use secure localhost
+	DefaultAddress = "127.0.0.1:0"
 	// DefaultName will be used if no name passed
 	DefaultName = "server"
 	// DefaultVersion will be used if no version passed

util/fn/fn.go

@@ -1,15 +0,0 @@
-package fn
-
-type Initer interface {
-	Init(opts ...interface{}) error
-}
-
-func Init(ifaces ...Initer) error {
-	var err error
-	for _, iface := range ifaces {
-		if err = iface.Init(); err != nil {
-			return err
-		}
-	}
-	return nil
-}

util/reflect/struct.go

@@ -7,7 +7,6 @@ import (
 	"reflect"
 	"regexp"
 	"strings"
-	"time"
 )
 
 // ErrInvalidParam specifies invalid url query params
@@ -15,11 +14,12 @@ var ErrInvalidParam = errors.New("invalid url query param provided")
 
 var bracketSplitter = regexp.MustCompile(`\[|\]`)
 
-var timeKind = reflect.TypeOf(time.Time{}).Kind()
+//var timeKind = reflect.ValueOf(time.Time{}).Kind()
 
 type StructField struct {
 	Field reflect.StructField
 	Value reflect.Value
+	Path  string
 }
 
 func StructFieldByTag(src interface{}, tkey string, tval string) (interface{}, error) {
@@ -35,7 +35,7 @@ func StructFieldByTag(src interface{}, tkey string, tval string) (interface{}, e
 	for idx := 0; idx < typ.NumField(); idx++ {
 		fld := typ.Field(idx)
 		val := sv.Field(idx)
-		if !val.CanSet() || len(fld.PkgPath) != 0 {
+		if len(fld.PkgPath) != 0 {
 			continue
 		}
 
@@ -66,6 +66,17 @@ func StructFieldByTag(src interface{}, tkey string, tval string) (interface{}, e
 	return nil, ErrNotFound
 }
 
+func StructFieldByPath(src interface{}, path string) (interface{}, error) {
+	var err error
+	for _, p := range strings.Split(path, ".") {
+		src, err = StructFieldByName(src, p)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return src, err
+}
+
 func StructFieldByName(src interface{}, tkey string) (interface{}, error) {
 	sv := reflect.ValueOf(src)
 	if sv.Kind() == reflect.Ptr {
@@ -79,7 +90,7 @@ func StructFieldByName(src interface{}, tkey string) (interface{}, error) {
 	for idx := 0; idx < typ.NumField(); idx++ {
 		fld := typ.Field(idx)
 		val := sv.Field(idx)
-		if !val.CanSet() || len(fld.PkgPath) != 0 {
+		if len(fld.PkgPath) != 0 {
 			continue
 		}
 		if fld.Name == tkey {
@@ -105,6 +116,19 @@ func StructFieldByName(src interface{}, tkey string) (interface{}, error) {
 	return nil, ErrNotFound
 }
 
+// StructFieldsMap returns map[string]interface{} or error
+func StructFieldsMap(src interface{}) (map[string]interface{}, error) {
+	fields, err := StructFields(src)
+	if err != nil {
+		return nil, err
+	}
+	mp := make(map[string]interface{}, len(fields))
+	for _, field := range fields {
+		mp[field.Path] = field.Value.Interface()
+	}
+	return mp, nil
+}
+
 // StructFields returns slice of struct fields
 func StructFields(src interface{}) ([]StructField, error) {
 	var fields []StructField
@@ -116,25 +140,29 @@ func StructFields(src interface{}) ([]StructField, error) {
 	if sv.Kind() != reflect.Struct {
 		return nil, ErrInvalidStruct
 	}
-
 	typ := sv.Type()
 	for idx := 0; idx < typ.NumField(); idx++ {
 		fld := typ.Field(idx)
 		val := sv.Field(idx)
-		if !val.CanSet() || len(fld.PkgPath) != 0 {
+		if !val.IsValid() || len(fld.PkgPath) != 0 {
 			continue
 		}
+
 		switch val.Kind() {
-		case timeKind:
-			fields = append(fields, StructField{Field: fld, Value: val})
+		//case timeKind:
+		//fmt.Printf("GGG\n")
+		//fields = append(fields, StructField{Field: fld, Value: val, Path: fld.Name})
 		case reflect.Struct:
 			infields, err := StructFields(val.Interface())
 			if err != nil {
 				return nil, err
 			}
-			fields = append(fields, infields...)
+			for _, infield := range infields {
+				infield.Path = fmt.Sprintf("%s.%s", fld.Name, infield.Path)
+				fields = append(fields, infield)
+			}
 		default:
-			fields = append(fields, StructField{Field: fld, Value: val})
+			fields = append(fields, StructField{Field: fld, Value: val, Path: fld.Name})
 		}
 	}
 
@@ -194,7 +222,7 @@ func StructURLValues(src interface{}, pref string, tags []string) (url.Values, e
 	for idx := 0; idx < typ.NumField(); idx++ {
 		fld := typ.Field(idx)
 		val := sv.Field(idx)
-		if !val.CanSet() || len(fld.PkgPath) != 0 || !val.IsValid() {
+		if len(fld.PkgPath) != 0 || !val.IsValid() {
 			continue
 		}
 

util/reflect/struct_test.go

@@ -2,9 +2,80 @@ package reflect
 
 import (
 	"net/url"
+	"reflect"
+	rfl "reflect"
 	"testing"
 )
 
+func TestStructFieldsMap(t *testing.T) {
+	type NestedStr struct {
+		BBB string
+		CCC int
+	}
+	type Str struct {
+		Name   []string `json:"name" codec:"flatten"`
+		XXX    string   `json:"xxx"`
+		Nested NestedStr
+	}
+
+	val := &Str{Name: []string{"first", "second"}, XXX: "ttt", Nested: NestedStr{BBB: "ddd", CCC: 9}}
+	fields, err := StructFieldsMap(val)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if v, ok := fields["Nested.BBB"]; !ok || v != "ddd" {
+		t.Fatalf("invalid field from %v", fields)
+	}
+}
+
+func TestStructFields(t *testing.T) {
+	type NestedStr struct {
+		BBB string
+		CCC int
+	}
+	type Str struct {
+		Name   []string `json:"name" codec:"flatten"`
+		XXX    string   `json:"xxx"`
+		Nested NestedStr
+	}
+
+	val := &Str{Name: []string{"first", "second"}, XXX: "ttt", Nested: NestedStr{BBB: "ddd", CCC: 9}}
+	fields, err := StructFields(val)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var ok bool
+	for _, field := range fields {
+		if field.Path == "Nested.CCC" {
+			ok = true
+		}
+	}
+	if !ok {
+		t.Fatalf("struct fields returns invalid path: %v", fields)
+	}
+}
+
+func TestStructByPath(t *testing.T) {
+	type NestedStr struct {
+		BBB string
+		CCC int
+	}
+	type Str struct {
+		Name   []string `json:"name" codec:"flatten"`
+		XXX    string   `json:"xxx"`
+		Nested NestedStr
+	}
+
+	val := &Str{Name: []string{"first", "second"}, XXX: "ttt", Nested: NestedStr{BBB: "ddd", CCC: 9}}
+	field, err := StructFieldByPath(val, "Nested.CCC")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if rfl.Indirect(reflect.ValueOf(field)).Int() != 9 {
+		t.Fatalf("invalid elem returned: %v", field)
+	}
+}
+
 func TestStructByTag(t *testing.T) {
 	type Str struct {
 		Name []string `json:"name" codec:"flatten"`