Manager: fixed panic in TimeoutAfter func when timeout channel was closed

packages/flamenco-manager-go/src/flamenco-manager/flamenco/scheduler_test.go

@@ -156,6 +156,7 @@ func (s *SchedulerTestSuite) TestSchedulerVerifyUpstreamCanceled(t *check.C) {
 	}
 
 	timeout := TimeoutAfter(1 * time.Second)
+	defer close(timeout)
 
 	// Mock that the task with highest priority was actually canceled on the Server.
 	httpmock.RegisterResponder(
@@ -207,6 +208,7 @@ func (s *SchedulerTestSuite) TestSchedulerVerifyUpstreamPrioChange(t *check.C) {
 	}
 
 	timeout := TimeoutAfter(1 * time.Second)
+	defer close(timeout)
 
 	// Mock that the task with highest priority was actually canceled on the Server.
 	httpmock.RegisterResponder(
@@ -264,6 +266,7 @@ func (s *SchedulerTestSuite) TestSchedulerVerifyUpstreamDeleted(t *check.C) {
 	}
 
 	timeout := TimeoutAfter(1 * time.Second)
+	defer close(timeout)
 
 	// Mock that the task with highest priority was actually canceled on the Server.
 	httpmock.RegisterResponder(

packages/flamenco-manager-go/src/flamenco-manager/flamenco/task_updates_test.go

@@ -53,6 +53,7 @@ func (s *TaskUpdatesTestSuite) TestCancelRunningTasks(t *check.C) {
 	}
 
 	timeout := TimeoutAfter(1 * time.Second)
+	defer close(timeout)
 
 	// Mock that the task with highest priority was actually canceled on the Server.
 	httpmock.RegisterResponder(
@@ -81,7 +82,6 @@ func (s *TaskUpdatesTestSuite) TestCancelRunningTasks(t *check.C) {
 
 	timedout := <-timeout
 	assert.False(t, timedout, "HTTP POST to Flamenco Server not performed")
-	close(timeout)
 
 	// Give the tup.Go() coroutine (and subsequent calls) time to run.
 	// the "timeout <- false" call in the responder is triggered before

packages/flamenco-manager-go/src/flamenco-manager/flamenco/timer.go

@@ -88,11 +88,23 @@ func UtcNow() *time.Time {
 	return &now
 }
 
+/* Sends a 'true' to the channel after the given timeout.
+ * Send a 'false' to the channel yourself if you want to notify the receiver that
+ * a timeout didn't happen.
+ *
+ * The channel is buffered with size 2, so both your 'false' and this routine's 'true'
+ * write won't block.
+ */
 func TimeoutAfter(duration time.Duration) chan bool {
-	timeout := make(chan bool, 1)
+	timeout := make(chan bool, 2)
 
 	go func() {
 		time.Sleep(duration)
+		defer func() {
+			// Recover from a panic. This panic can happen when the caller closed the
+			// channel while we were sleeping.
+			recover()
+		}()
 		timeout <- true
 	}()