Idle timeout can be disabled (#91)

* Idle timeout can be disabled

Author: gammazero

options.go

@@ -17,7 +17,7 @@ type Option func(*config)
 
 // WithIdleTimeout configures the the amount of time that the worker pool must
 // be idle before a worker is automatically stopped. If zero or unset the value
-// defaults to DefaultIdleTimeout.
+// defaults to DefaultIdleTimeout. A negative value disables the idle timeout.
 func WithIdleTimeout(timeout time.Duration) Option {
 	return func(c *config) {
 		if timeout != 0 {

workerpool.go

@@ -186,11 +186,18 @@ func (p *WorkerPool) Pause(ctx context.Context) {
 // dispatch sends the next queued task to an available worker.
 func (p *WorkerPool) dispatch(idleTimeout time.Duration) {
 	defer close(p.stoppedChan)
-	timeout := time.NewTimer(idleTimeout)
-	var workerCount int
 	var idle bool
+	var idleTO <-chan time.Time
+	var workerCount int
 	var wg sync.WaitGroup
 
+	var timeout *time.Timer
+	if idleTimeout > 0 {
+		timeout = time.NewTimer(idleTimeout)
+		defer timeout.Stop()
+		idleTO = timeout.C
+	}
+
 Loop:
 	for {
 		// As long as tasks are in the waiting queue, incoming tasks are put
@@ -225,7 +232,7 @@ Loop:
 				}
 			}
 			idle = false
-		case <-timeout.C:
+		case <-idleTO:
 			// Timed out waiting for work to arrive. Kill a ready worker if
 			// pool has been idle for a whole timeout.
 			if idle && workerCount > 0 {
@@ -249,8 +256,6 @@ Loop:
 		workerCount--
 	}
 	wg.Wait()
-
-	timeout.Stop()
 }
 
 // worker executes tasks and stops when it receives a nil task.

workerpool_test.go

@@ -152,6 +152,31 @@ func TestWorkerTimeout(t *testing.T) {
 	})
 }
 
+func TestWorkerNoTimeout(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		wp := New(max, WithIdleTimeout(-1))
+		defer wp.Stop()
+
+		// Start workers, and have them all wait on ctx before completing.
+		ctx, cancel := context.WithCancel(context.Background())
+		wp.Pause(ctx)
+		cancel()
+
+		// Check that a worker timed out.
+		time.Sleep(time.Hour)
+		synctest.Wait()
+		if countReady(wp) != max {
+			t.Fatal("no workers should have timed out")
+		}
+		// Check again.
+		time.Sleep(time.Hour)
+		synctest.Wait()
+		if countReady(wp) != max {
+			t.Fatal("no workers should have timed out")
+		}
+	})
+}
+
 func TestStop(t *testing.T) {
 	synctest.Test(t, func(t *testing.T) {
 		wp := New(max)