Merge pull request digitalocean#163 from digitalocean/drain_channel_on_disconnect

Drain channel on disconnect

Author: JenniGriesmann

.travis.yml

@@ -47,7 +47,7 @@ install:
   - rm qemu-${QEMU}.tar.${QEMU_EXT} libvirt-${LIBVIRT}.tar.${LIBVIRT_EXT}
 
 before_install:
-  - go get github.com/golang/lint/golint
+  - go get golang.org/x/lint/golint
   - go get golang.org/x/tools/cmd/stringer
 
 before_script:

qemu/domain.go

@@ -372,6 +372,14 @@ func (d *Domain) Events() (chan qmp.Event, chan struct{}, error) {
 	// handle disconnection
 	go func() {
 		<-done
+		// drain anything that gets sent on the channel
+		// because the disconnect won't be processed if the
+		// listenAndServe loop is waiting for the listener
+		// to read from the unbuffered channel.
+		go func() {
+			for range stream {
+			}
+		}()
 		d.disconnect <- stream
 		close(stream)
 		close(done)

qemu/domain_test.go

@@ -577,6 +577,28 @@ func TestEvents(t *testing.T) {
 	}
 }
 
+// Test when a listener connects, but disconnects without
+// receiving from the events channel returned.
+func TestEventsDerelictListener(t *testing.T) {
+	d, done := testDomain(t, nil)
+	defer done()
+
+	_, stop, err := d.Events()
+	if err != nil {
+		t.Error(err)
+	}
+
+	<-time.After(200 * time.Millisecond)
+
+	stop <- struct{}{}
+	select {
+	case <-stop:
+		return
+	case <-time.After(time.Millisecond * 20):
+		t.Error("shutdown failed to complete")
+	}
+}
+
 func TestEventsUnsupported(t *testing.T) {
 	d, done := testDomain(t, nil)
 	defer done()
@@ -589,6 +611,8 @@ func TestEventsUnsupported(t *testing.T) {
 }
 
 func testDomain(t *testing.T, fn func(qmp.Command) (interface{}, error)) (*Domain, func()) {
+	t.Helper()
+
 	mon := &testMonitor{fn: fn}
 	d, err := NewDomain(mon, "test")
 	if err != nil {