Use a channel based API for SendIQ

This makes sending IQ more idiomatic Go, but more importantly it solves
a problem with contexts that were not being cancelled correctly with
the previous API.

As a side-effect of this change `Route.route` must now be invoked in a
go-routine to prevent deadlocks. This also allows for stanzas to be processed
in parallel, which can result in a nice performance win.

client.go

@@ -231,18 +231,16 @@ func (c *Client) Send(packet stanza.Packet) error {
 // forever for an IQ result. For example:
 //
 //   ctx, _ := context.WithTimeout(context.Background(), 30 * time.Second)
-//   client.SendIQ(ctx, iq, func(s Sender, p stanza.Packet) {
-//           // Handle the result here
-//   })
+//   result := <- client.SendIQ(ctx, iq)
 //
-func (c *Client) SendIQ(ctx context.Context, iq stanza.IQ, handler IQResultHandlerFunc) (*IQResultRoute, error) {
+func (c *Client) SendIQ(ctx context.Context, iq stanza.IQ) (chan stanza.IQ, error) {
 	if iq.Attrs.Type != "set" && iq.Attrs.Type != "get" {
 		return nil, ErrCanOnlySendGetOrSetIq
 	}
 	if err := c.Send(iq); err != nil {
 		return nil, err
 	}
-	return c.router.NewIQResultRoute(ctx, iq.Attrs.Id).HandlerFunc(handler), nil
+	return c.router.NewIQResultRoute(ctx, iq.Attrs.Id), nil
 }
 
 // SendRaw sends an XMPP stanza as a string to the server.
@@ -295,7 +293,10 @@ func (c *Client) recv(state SMState, keepaliveQuit chan<- struct{}) (err error)
 			state.Inbound++
 		}
 
-		c.router.route(c, val)
+		// Do normal route processing in a go-routine so we can immediately
+		// start receiving other stanzas. This also allows route handlers to
+		// send and receive more stanzas.
+		go c.router.route(c, val)
 	}
 }
 

router.go

@@ -51,8 +51,8 @@ func (r *Router) route(s Sender, p stanza.Packet) {
 			r.IQResultRouteLock.Lock()
 			delete(r.IQResultRoutes, iq.Id)
 			r.IQResultRouteLock.Unlock()
-			close(route.matched)
-			route.handler.HandleIQ(route.context, s, iq)
+			route.result <- iq
+			close(route.result)
 			return
 		}
 	}
@@ -91,29 +91,22 @@ func (r *Router) NewRoute() *Route {
 // NewIQResultRoute register a route that will catch an IQ result stanza with
 // the given Id. The route will only match ones, after which it will automatically
 // be unregistered
-func (r *Router) NewIQResultRoute(ctx context.Context, id string) *IQResultRoute {
-	route := &IQResultRoute{
-		context: ctx,
-		matched: make(chan struct{}),
-	}
+func (r *Router) NewIQResultRoute(ctx context.Context, id string) chan stanza.IQ {
+	route := NewIQResultRoute(ctx)
 	r.IQResultRouteLock.Lock()
 	r.IQResultRoutes[id] = route
 	r.IQResultRouteLock.Unlock()
 
+	// Start a go function to make sure the route is unregistered when the context
+	// is done.
 	go func() {
-		select {
-		case <-route.context.Done():
-			r.IQResultRouteLock.Lock()
-			delete(r.IQResultRoutes, id)
-			r.IQResultRouteLock.Unlock()
-			if route.timeoutHandler != nil {
-				route.timeoutHandler(route.context.Err())
-			}
-		case <-route.matched:
-		}
+		<-route.context.Done()
+		r.IQResultRouteLock.Lock()
+		delete(r.IQResultRoutes, id)
+		r.IQResultRouteLock.Unlock()
 	}()
 
-	return route
+	return route.result
 }
 
 func (r *Router) Match(p stanza.Packet, match *RouteMatch) bool {
@@ -144,28 +137,16 @@ type TimeoutHandlerFunc func(err error)
 
 // IQResultRoute is a temporary route to match IQ result stanzas
 type IQResultRoute struct {
-	context        context.Context
-	matched        chan struct{}
-	handler        IQResultHandler
-	timeoutHandler TimeoutHandlerFunc
+	context context.Context
+	result  chan stanza.IQ
 }
 
-// Handler adds an IQ handler to the route.
-func (r *IQResultRoute) Handler(handler IQResultHandler) *IQResultRoute {
-	r.handler = handler
-	return r
-}
-
-// HandlerFunc updates the route to call a handler function when an IQ result is received.
-func (r *IQResultRoute) HandlerFunc(f IQResultHandlerFunc) *IQResultRoute {
-	return r.Handler(f)
-}
-
-// TimeoutHandlerFunc registers a function that will be called automatically when
-// the IQ result route is cancelled (most likely due to a timeout on the context).
-func (r *IQResultRoute) TimeoutHandlerFunc(f TimeoutHandlerFunc) *IQResultRoute {
-	r.timeoutHandler = f
-	return r
+// NewIQResultRoute creates a new IQResultRoute instance
+func NewIQResultRoute(ctx context.Context) *IQResultRoute {
+	return &IQResultRoute{
+		context: ctx,
+		result:  make(chan stanza.IQ),
+	}
 }
 
 // ============================================================================

router_test.go

@@ -4,8 +4,8 @@ import (
 	"bytes"
 	"context"
 	"encoding/xml"
-	"runtime"
 	"testing"
+	"time"
 
 	"gosrc.io/xmpp/stanza"
 )
@@ -16,52 +16,41 @@ import (
 func TestIQResultRoutes(t *testing.T) {
 	t.Parallel()
 	router := NewRouter()
+	conn := NewSenderMock()
 
 	if router.IQResultRoutes == nil {
 		t.Fatal("NewRouter does not initialize isResultRoutes")
 	}
 
-	// Check other IQ does not matcah
-	conn := NewSenderMock()
-	iq := stanza.NewIQ(stanza.Attrs{Type: stanza.IQTypeResult, Id: "4321"})
-	router.NewIQResultRoute(context.Background(), "1234").HandlerFunc(func(ctx context.Context, s Sender, iq stanza.IQ) {
-		_ = s.SendRaw(successFlag)
-	})
-	if conn.String() == successFlag {
-		t.Fatal("IQ result with wrong ID was matched")
-	}
-
 	// Check if the IQ handler was called
-	conn = NewSenderMock()
-	iq = stanza.NewIQ(stanza.Attrs{Type: stanza.IQTypeResult, Id: "1234"})
-	router.route(conn, iq)
-	if conn.String() != successFlag {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Millisecond*100)
+	defer cancel()
+	iq := stanza.NewIQ(stanza.Attrs{Type: stanza.IQTypeResult, Id: "1234"})
+	res := router.NewIQResultRoute(ctx, "1234")
+	go router.route(conn, iq)
+	select {
+	case <-ctx.Done():
 		t.Fatal("IQ result was not matched")
+	case <-res:
+		// Success
 	}
 
-	// The match must only happen once, so we if receive the same package again it
-	// must not be matched.
-	conn = NewSenderMock()
-	router.route(conn, iq)
-	if conn.String() == successFlag {
-		t.Fatal("IQ result was matched twice")
+	// The match must only happen once, so the id should no longer be in IQResultRoutes
+	if _, ok := router.IQResultRoutes[iq.Attrs.Id]; ok {
+		t.Fatal("IQ ID was not removed from the route map")
 	}
 
-	// After cancelling a route it should no longer match
-	conn = NewSenderMock()
-	ctx, cancel := context.WithCancel(context.Background())
-	iq = stanza.NewIQ(stanza.Attrs{Type: stanza.IQTypeResult, Id: "1234"})
-	router.NewIQResultRoute(ctx, "1234").HandlerFunc(func(ctx context.Context, s Sender, iq stanza.IQ) {
-		_ = s.SendRaw(successFlag)
-	}).TimeoutHandlerFunc(func(err error) {
-		conn.SendRaw(cancelledFlag)
-	})
-	cancel()
-	// Yield the processor so the cancellation goroutine is triggered
-	runtime.Gosched()
-	router.route(conn, iq)
-	if conn.String() != cancelledFlag {
-		t.Fatal("IQ result route was matched after cancellation")
+	// Check other IQ does not matcah
+	ctx, cancel = context.WithTimeout(context.Background(), time.Millisecond*100)
+	defer cancel()
+	iq.Attrs.Id = "4321"
+	res = router.NewIQResultRoute(ctx, "1234")
+	go router.route(conn, iq)
+	select {
+	case <-ctx.Done():
+		// Success
+	case <-res:
+		t.Fatal("IQ result with wrong ID was matched")
 	}
 }