java - How to throttle tasks such that only one runs at a time and rest are ignored -

i have object listens external events. upon receiving event, object needs execute task (a runnable). however, there restriction:

once task starts executing, should not start other tasks (i can ignore them) until original task finished , amount of time passed after (throttling).

here's suggested implementation using semaphore:

public class sample {      private final semaphore semaphore = new semaphore(1);      private final scheduledexecutorservice executor;      public sample(scheduledexecutorservice executor) {         this.executor = executor;         }      public void tryrun() {         if (semaphore.tryacquire()) {             try {                 executor.submit(                     new runnable() {                         @override                         public void run() {                             try {                                 doit();                             } {                                 try {                                     executor.schedule(                                         new runnable() {                                             @override                                             public void run() {                                                 semaphore.release();                                             }                                         },                                         1,                                          timeunit.minutes                                     );                                 } catch (throwable t) {                                     semaphore.release();                                 }                             }                         }                     }                 );             } catch (throwable t) {                 semaphore.release();                         }         }     }      private void doit() {         // exact task executing logic here     } } 

the code seems verbose me. there better way of doing this?

p.s. restriction scheduledexecutorservice interface have external executor , cannot start own threads/executors within object

just use threadpoolexecutor single thread. you'll have decide whether it's okay queue lot of other tasks. if not, pass own blockingqueue capacity 1, believe let @ 1 task queue up. i'm thinking how down zero.

one way create single threaded executor unbounded queue.

note need configure tpe discard rejected tasks via discardpolicy.