Merge pull request #651 from magodo/master

wait nats drain since it's asynchronous

broker/nats/nats.go

@@ -13,18 +13,19 @@ import (
 )
 
 type natsBroker struct {
+	sync.Once
 	sync.RWMutex
 	addrs   []string
 	conn    *nats.Conn
 	opts    broker.Options
 	nopts   nats.Options
 	drain   bool
+	closeCh chan (error)
 }
 
 type subscriber struct {
 	s    *nats.Subscription
 	opts broker.SubscribeOptions
-	drain bool
 }
 
 type publication struct {
@@ -54,9 +55,6 @@ func (s *subscriber) Topic() string {
 }
 
 func (s *subscriber) Unsubscribe() error {
-	if s.drain {
-		return s.s.Drain()
-	}
 	return s.s.Unsubscribe()
 }
 
@@ -122,20 +120,17 @@ func (n *natsBroker) Connect() error {
 
 func (n *natsBroker) Disconnect() error {
 	n.RLock()
+	defer n.RUnlock()
 	if n.drain {
 		n.conn.Drain()
-	} else {
-		n.conn.Close()
+		return <-n.closeCh
 	}
-	n.RUnlock()
+	n.conn.Close()
 	return nil
 }
 
 func (n *natsBroker) Init(opts ...broker.Option) error {
-	for _, o := range opts {
-		o(&n.opts)
-	}
-	n.addrs = setAddrs(n.opts.Addrs)
+	n.setOption(opts...)
 	return nil
 }
 
@@ -167,11 +162,6 @@ func (n *natsBroker) Subscribe(topic string, handler broker.Handler, opts ...bro
 		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 {
@@ -193,7 +183,7 @@ func (n *natsBroker) Subscribe(topic string, handler broker.Handler, opts ...bro
 	if err != nil {
 		return nil, err
 	}
-	return &subscriber{s: sub, opts: opt, drain: drain}, nil
+	return &subscriber{s: sub, opts: opt}, nil
 }
 
 func (n *natsBroker) String() string {
@@ -207,39 +197,59 @@ func NewBroker(opts ...broker.Option) broker.Broker {
 		Context: context.Background(),
 	}
 
+	n := &natsBroker{
+		opts: options,
+	}
+	n.setOption(opts...)
+
+	return n
+}
+
+func (n *natsBroker) setOption(opts ...broker.Option) {
 	for _, o := range opts {
-		o(&options)
+		o(&n.opts)
 	}
 
-	natsOpts := nats.GetDefaultOptions()
-	if n, ok := options.Context.Value(optionsKey{}).(nats.Options); ok {
-		natsOpts = n
-	}
+	n.Once.Do(func() {
+		n.nopts = nats.GetDefaultOptions()
+	})
 
-	var drain bool
-	if _, ok := options.Context.Value(drainSubscriptionKey{}).(bool); ok {
-		drain = true
+	if nopts, ok := n.opts.Context.Value(optionsKey{}).(nats.Options); ok {
+		n.nopts = nopts
 	}
 
 	// 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 len(n.opts.Addrs) == 0 {
+		n.opts.Addrs = n.nopts.Servers
 	}
 
-	if !options.Secure {
-		options.Secure = natsOpts.Secure
+	if !n.opts.Secure {
+		n.opts.Secure = n.nopts.Secure
 	}
 
-	if options.TLSConfig == nil {
-		options.TLSConfig = natsOpts.TLSConfig
+	if n.opts.TLSConfig == nil {
+		n.opts.TLSConfig = n.nopts.TLSConfig
 	}
+	n.addrs = setAddrs(n.opts.Addrs)
 
-	return &natsBroker{
-		opts:  options,
-		nopts: natsOpts,
-		addrs: setAddrs(options.Addrs),
-		drain: drain,
+	if n.opts.Context.Value(drainConnectionKey{}) != nil {
+		n.drain = true
+		n.closeCh = make(chan error)
+		n.nopts.ClosedCB = n.onClose
+		n.nopts.AsyncErrorCB = n.onAsyncError
+	}
+}
+
+func (n *natsBroker) onClose(conn *nats.Conn) {
+	n.closeCh <- nil
+}
+
+func (n *natsBroker) onAsyncError(conn *nats.Conn, sub *nats.Subscription, err error) {
+	// There are kinds of different async error nats might callback, but we are interested
+	// in ErrDrainTimeout only here.
+	if err == nats.ErrDrainTimeout {
+		n.closeCh <- err
 	}
 }

broker/nats/options.go

@@ -7,7 +7,6 @@ import (
 
 type optionsKey struct{}
 type drainConnectionKey struct{}
-type drainSubscriptionKey struct{}
 
 // Options accepts nats.Options
 func Options(opts nats.Options) broker.Option {
@@ -16,10 +15,5 @@ func Options(opts nats.Options) broker.Option {
 
 // 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)
+	return setBrokerOption(drainConnectionKey{}, struct{}{})
 }