Optimize cycle in Acquire

semaphore.go

@@ -77,13 +77,16 @@ func (s *semaphore) Acquire(ctx context.Context, n int) error {
 	if n <= 0 {
 		panic("n must be positive number")
 	}
+	var ctxDoneCh <-chan struct{}
+	if ctx != nil {
+		ctxDoneCh = ctx.Done()
+	}
 	for {
-		if ctx != nil {
-			select {
-			case <-ctx.Done():
-				return ctx.Err()
-			default:
-			}
+		// check if context is done
+		select {
+		case <-ctxDoneCh:
+			return ctx.Err()
+		default:
 		}
 
 		// get current semaphore count and limit
@@ -108,18 +111,12 @@ func (s *semaphore) Acquire(ctx context.Context, n int) error {
 			broadcastCh := s.broadcastCh
 			s.lock.RUnlock()
 
-			if ctx != nil {
-				select {
-				case <-ctx.Done():
-					return ctx.Err()
-				// waiting for broadcast signal
-				case <-broadcastCh:
-				}
-			} else {
-				select {
-				// waiting for broadcast signal
-				case <-broadcastCh:
-				}
+			select {
+			// check if context is done
+			case <-ctxDoneCh:
+				return ctx.Err()
+			// waiting for broadcast signal
+			case <-broadcastCh:
 			}
 		}
 	}