wrapping each of the onNext/onCompleted to ensure no overlapping calls

Author: abersnaze

src/main/java/rx/schedulers/ScheduleWhen.java

@@ -117,7 +117,9 @@ public void unsubscribe() {
 				// room for the next worker in the workerQueue.
 				if (unsubscribed.compareAndSet(false, true)) {
 					actualWorker.unsubscribe();
-					actionQueue.onCompleted();
+					synchronized (actionQueue) {
+						actionQueue.onCompleted();
+					}
 				}
 			}
 
@@ -130,21 +132,27 @@ public boolean isUnsubscribed() {
 			public Subscription schedule(final Action0 action, final long delayTime, final TimeUnit unit) {
 				// send a scheduled action to the actionQueue
 				DelayedAction delayedAction = new DelayedAction(action, delayTime, unit);
-				actionQueue.onNext(delayedAction);
+				synchronized (actionQueue) {
+					actionQueue.onNext(delayedAction);
+				}
 				return delayedAction;
 			}
 
 			@Override
 			public Subscription schedule(final Action0 action) {
 				// send a scheduled action to the actionQueue
 				ImmediateAction immediateAction = new ImmediateAction(action);
-				actionQueue.onNext(immediateAction);
+				synchronized (actionQueue) {
+					actionQueue.onNext(immediateAction);
+				}
 				return immediateAction;
 			}
 		};
 
 		// enqueue the completable that process actions put in reply subject
-		workerQueue.onNext(actions);
+		synchronized (workerQueue) {
+			workerQueue.onNext(actions);
+		}
 
 		// return the worker that adds actions to the reply subject
 		return worker;