Merge pull request #489 from micro/nats

Add nats broker as a default
This commit is contained in:
Asim Aslam 2019-05-31 13:12:38 +01:00 committed by GitHub
commit aeeb2b0010
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5 changed files with 408 additions and 0 deletions

37
broker/nats/context.go Normal file
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@ -0,0 +1,37 @@
package nats
import (
"context"
"github.com/micro/go-micro/broker"
)
// setSubscribeOption returns a function to setup a context with given value
func setSubscribeOption(k, v interface{}) broker.SubscribeOption {
return func(o *broker.SubscribeOptions) {
if o.Context == nil {
o.Context = context.Background()
}
o.Context = context.WithValue(o.Context, k, v)
}
}
// setBrokerOption returns a function to setup a context with given value
func setBrokerOption(k, v interface{}) broker.Option {
return func(o *broker.Options) {
if o.Context == nil {
o.Context = context.Background()
}
o.Context = context.WithValue(o.Context, k, v)
}
}
// setPublishOption returns a function to setup a context with given value
func setPublishOption(k, v interface{}) broker.PublishOption {
return func(o *broker.PublishOptions) {
if o.Context == nil {
o.Context = context.Background()
}
o.Context = context.WithValue(o.Context, k, v)
}
}

245
broker/nats/nats.go Normal file
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@ -0,0 +1,245 @@
// Package nats provides a NATS broker
package nats
import (
"context"
"errors"
"strings"
"sync"
"github.com/micro/go-micro/broker"
"github.com/micro/go-micro/codec/json"
nats "github.com/nats-io/nats.go"
)
type natsBroker struct {
sync.RWMutex
addrs []string
conn *nats.Conn
opts broker.Options
nopts nats.Options
drain bool
}
type subscriber struct {
s *nats.Subscription
opts broker.SubscribeOptions
drain bool
}
type publication struct {
t string
m *broker.Message
}
func (p *publication) Topic() string {
return p.t
}
func (p *publication) Message() *broker.Message {
return p.m
}
func (p *publication) Ack() error {
// nats does not support acking
return nil
}
func (s *subscriber) Options() broker.SubscribeOptions {
return s.opts
}
func (s *subscriber) Topic() string {
return s.s.Subject
}
func (s *subscriber) Unsubscribe() error {
if s.drain {
return s.s.Drain()
}
return s.s.Unsubscribe()
}
func (n *natsBroker) Address() string {
if n.conn != nil && n.conn.IsConnected() {
return n.conn.ConnectedUrl()
}
if len(n.addrs) > 0 {
return n.addrs[0]
}
return ""
}
func setAddrs(addrs []string) []string {
var cAddrs []string
for _, addr := range addrs {
if len(addr) == 0 {
continue
}
if !strings.HasPrefix(addr, "nats://") {
addr = "nats://" + addr
}
cAddrs = append(cAddrs, addr)
}
if len(cAddrs) == 0 {
cAddrs = []string{nats.DefaultURL}
}
return cAddrs
}
func (n *natsBroker) Connect() error {
n.Lock()
defer n.Unlock()
status := nats.CLOSED
if n.conn != nil {
status = n.conn.Status()
}
switch status {
case nats.CONNECTED, nats.RECONNECTING, nats.CONNECTING:
return nil
default: // DISCONNECTED or CLOSED or DRAINING
opts := n.nopts
opts.Servers = n.addrs
opts.Secure = n.opts.Secure
opts.TLSConfig = n.opts.TLSConfig
// secure might not be set
if n.opts.TLSConfig != nil {
opts.Secure = true
}
c, err := opts.Connect()
if err != nil {
return err
}
n.conn = c
return nil
}
}
func (n *natsBroker) Disconnect() error {
n.RLock()
if n.drain {
n.conn.Drain()
} else {
n.conn.Close()
}
n.RUnlock()
return nil
}
func (n *natsBroker) Init(opts ...broker.Option) error {
for _, o := range opts {
o(&n.opts)
}
n.addrs = setAddrs(n.opts.Addrs)
return nil
}
func (n *natsBroker) Options() broker.Options {
return n.opts
}
func (n *natsBroker) Publish(topic string, msg *broker.Message, opts ...broker.PublishOption) error {
b, err := n.opts.Codec.Marshal(msg)
if err != nil {
return err
}
n.RLock()
defer n.RUnlock()
return n.conn.Publish(topic, b)
}
func (n *natsBroker) Subscribe(topic string, handler broker.Handler, opts ...broker.SubscribeOption) (broker.Subscriber, error) {
if n.conn == nil {
return nil, errors.New("not connected")
}
opt := broker.SubscribeOptions{
AutoAck: true,
Context: context.Background(),
}
for _, o := range opts {
o(&opt)
}
var drain bool
if _, ok := opt.Context.Value(drainSubscriptionKey{}).(bool); ok {
drain = true
}
fn := func(msg *nats.Msg) {
var m broker.Message
if err := n.opts.Codec.Unmarshal(msg.Data, &m); err != nil {
return
}
handler(&publication{m: &m, t: msg.Subject})
}
var sub *nats.Subscription
var err error
n.RLock()
if len(opt.Queue) > 0 {
sub, err = n.conn.QueueSubscribe(topic, opt.Queue, fn)
} else {
sub, err = n.conn.Subscribe(topic, fn)
}
n.RUnlock()
if err != nil {
return nil, err
}
return &subscriber{s: sub, opts: opt, drain: drain}, nil
}
func (n *natsBroker) String() string {
return "nats"
}
func NewBroker(opts ...broker.Option) broker.Broker {
options := broker.Options{
// Default codec
Codec: json.Marshaler{},
Context: context.Background(),
}
for _, o := range opts {
o(&options)
}
natsOpts := nats.GetDefaultOptions()
if n, ok := options.Context.Value(optionsKey{}).(nats.Options); ok {
natsOpts = n
}
var drain bool
if _, ok := options.Context.Value(drainSubscriptionKey{}).(bool); ok {
drain = true
}
// broker.Options have higher priority than nats.Options
// only if Addrs, Secure or TLSConfig were not set through a broker.Option
// we read them from nats.Option
if len(options.Addrs) == 0 {
options.Addrs = natsOpts.Servers
}
if !options.Secure {
options.Secure = natsOpts.Secure
}
if options.TLSConfig == nil {
options.TLSConfig = natsOpts.TLSConfig
}
return &natsBroker{
opts: options,
nopts: natsOpts,
addrs: setAddrs(options.Addrs),
drain: drain,
}
}

99
broker/nats/nats_test.go Normal file
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@ -0,0 +1,99 @@
package nats
import (
"fmt"
"testing"
"github.com/micro/go-micro/broker"
nats "github.com/nats-io/nats.go"
)
var addrTestCases = []struct {
name string
description string
addrs map[string]string // expected address : set address
}{
{
"brokerOpts",
"set broker addresses through a broker.Option in constructor",
map[string]string{
"nats://192.168.10.1:5222": "192.168.10.1:5222",
"nats://10.20.10.0:4222": "10.20.10.0:4222"},
},
{
"brokerInit",
"set broker addresses through a broker.Option in broker.Init()",
map[string]string{
"nats://192.168.10.1:5222": "192.168.10.1:5222",
"nats://10.20.10.0:4222": "10.20.10.0:4222"},
},
{
"natsOpts",
"set broker addresses through the nats.Option in constructor",
map[string]string{
"nats://192.168.10.1:5222": "192.168.10.1:5222",
"nats://10.20.10.0:4222": "10.20.10.0:4222"},
},
{
"default",
"check if default Address is set correctly",
map[string]string{
"nats://127.0.0.1:4222": "",
},
},
}
// TestInitAddrs tests issue #100. Ensures that if the addrs is set by an option in init it will be used.
func TestInitAddrs(t *testing.T) {
for _, tc := range addrTestCases {
t.Run(fmt.Sprintf("%s: %s", tc.name, tc.description), func(t *testing.T) {
var br broker.Broker
var addrs []string
for _, addr := range tc.addrs {
addrs = append(addrs, addr)
}
switch tc.name {
case "brokerOpts":
// we know that there are just two addrs in the dict
br = NewBroker(broker.Addrs(addrs[0], addrs[1]))
br.Init()
case "brokerInit":
br = NewBroker()
// we know that there are just two addrs in the dict
br.Init(broker.Addrs(addrs[0], addrs[1]))
case "natsOpts":
nopts := nats.GetDefaultOptions()
nopts.Servers = addrs
br = NewBroker(Options(nopts))
br.Init()
case "default":
br = NewBroker()
br.Init()
}
natsBroker, ok := br.(*natsBroker)
if !ok {
t.Fatal("Expected broker to be of types *natsBroker")
}
// check if the same amount of addrs we set has actually been set, default
// have only 1 address nats://127.0.0.1:4222 (current nats code) or
// nats://localhost:4222 (older code version)
if len(natsBroker.addrs) != len(tc.addrs) && tc.name != "default" {
t.Errorf("Expected Addr count = %d, Actual Addr count = %d",
len(natsBroker.addrs), len(tc.addrs))
}
for _, addr := range natsBroker.addrs {
_, ok := tc.addrs[addr]
if !ok {
t.Errorf("Expected '%s' has not been set", addr)
}
}
})
}
}

25
broker/nats/options.go Normal file
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@ -0,0 +1,25 @@
package nats
import (
"github.com/micro/go-micro/broker"
nats "github.com/nats-io/nats.go"
)
type optionsKey struct{}
type drainConnectionKey struct{}
type drainSubscriptionKey struct{}
// Options accepts nats.Options
func Options(opts nats.Options) broker.Option {
return setBrokerOption(optionsKey{}, opts)
}
// DrainConnection will drain subscription on close
func DrainConnection() broker.Option {
return setBrokerOption(drainConnectionKey{}, true)
}
// DrainSubscription will drain pending messages when unsubscribe
func DrainSubscription() broker.SubscribeOption {
return setSubscribeOption(drainSubscriptionKey{}, true)
}

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@ -18,6 +18,7 @@ import (
"github.com/micro/go-micro/broker" "github.com/micro/go-micro/broker"
"github.com/micro/go-micro/broker/http" "github.com/micro/go-micro/broker/http"
"github.com/micro/go-micro/broker/memory" "github.com/micro/go-micro/broker/memory"
"github.com/micro/go-micro/broker/nats"
// registries // registries
"github.com/micro/go-micro/registry" "github.com/micro/go-micro/registry"
@ -170,6 +171,7 @@ var (
DefaultBrokers = map[string]func(...broker.Option) broker.Broker{ DefaultBrokers = map[string]func(...broker.Option) broker.Broker{
"http": http.NewBroker, "http": http.NewBroker,
"memory": memory.NewBroker, "memory": memory.NewBroker,
"nats": nats.NewBroker,
} }
DefaultClients = map[string]func(...client.Option) client.Client{ DefaultClients = map[string]func(...client.Option) client.Client{