Examples of java.util.concurrent.Semaphore.tryAcquire()

java.util.concurrent.Semaphore.tryAcquire()
Acquires a permit from this semaphore, only if one is available at the time of invocation.
Acquires a permit, if one is available and returns immediately, with the value {@code true}, reducing the number of available permits by one.
If no permit is available then this method will return immediately with the value {@code false}.
Even when this semaphore has been set to use a fair ordering policy, a call to {@code tryAcquire()} willimmediately acquire a permit if one is available, whether or not other threads are currently waiting. This "barging" behavior can be useful in certain circumstances, even though it breaks fairness. If you want to honor the fairness setting, then use {@link #tryAcquire(long,TimeUnit) tryAcquire(0, TimeUnit.SECONDS) }which is almost equivalent (it also detects interruption). @return {@code true} if a permit was acquired and {@code false}otherwise


            Util.blockUntilViewsReceived(30000, 500, tmp);
            System.out.println(">>>> all nodes have the same view <<<<");


            // Re-acquire the semaphore tickets; when we have them all we know the threads are done
            boolean acquired=semaphore.tryAcquire(count, 20, TimeUnit.SECONDS);
            if(!acquired) {
                log.warn("Most likely a bug, analyse the stack below:");
                log.warn(Util.dumpThreads());
            }

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            tmp[i] = receivers[i].getChannel();
        Util.blockUntilViewsReceived(60000, 1000, tmp);


        // Reacquire the semaphore tickets; when we have them all
        // we know the threads are done
        s.tryAcquire(1, 60, TimeUnit.SECONDS);
        receivers[0].cleanup();
        Util.sleep(1000);


        checkEventStateTransferSequence(receivers[0]);
    }

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                tmp[cnt++] = receiver.getChannel();
            Util.blockUntilViewsReceived(30000, 1000, tmp);


            // Reacquire the semaphore tickets; when we have them all
            // we know the threads are done
            semaphore.tryAcquire(count, 40, TimeUnit.SECONDS);


            Util.sleep(1000); //let all events propagate...
            for (FlushTestReceiver app : channels)
                app.getChannel().setReceiver(null);
            for (FlushTestReceiver app : channels)

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            Util.blockUntilViewsReceived(60000, 1000, tmp);


            // Reacquire the semaphore tickets; when we have them all
            // we know the threads are done
            boolean acquired=semaphore.tryAcquire(apps.length, 30, TimeUnit.SECONDS);
            if(!acquired) {
                log.warn("Most likely a bug, analyse the stack below:");
                log.warn(Util.dumpThreads());
            }

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      semaphore.release(numThreads);
      
      try
      {
         assertTrue("messages received within 15 seconds", semaphore.tryAcquire(numThreads, 15, TimeUnit.SECONDS));
         
         log.info("Messages received");
      }
      finally
      {

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    public Response load(final Request request, final CacheStrategy cacheStrategy, final long maxFileSize, final boolean checkBlacklist) throws IOException {
        final String url = request.url().toNormalform(true, false);
        Semaphore check = this.loaderSteering.get(url);
        if (check != null) {
            // a loading process may be going on for that url
            try { check.tryAcquire(5, TimeUnit.SECONDS);} catch (final InterruptedException e) {}
            // now the process may have terminated and we run a normal loading
            // which may be successful faster because of a cache hit
        }


        this.loaderSteering.put(url, new Semaphore(0));

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    Semaphore semaphore = _concurrentSemaphore;
    
    if (semaphore != null) {
      try {
        Thread.interrupted();
        if (! semaphore.tryAcquire(_concurrentTimeout, TimeUnit.MILLISECONDS))
          throw new RuntimeException(L.l("{0} concurrent max exceeded", this));
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }

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            server.stop();


            // test foreground retry
            client.checkExists().forPath("/hey");
            Assert.assertTrue(semaphore.tryAcquire(MAX_RETRIES, 10, TimeUnit.SECONDS));


            semaphore.drainPermits();
            retries.set(0);


            server.stop();

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            server.stop();


            // test background retry
            client.checkExists().inBackground().forPath("/hey");
            Assert.assertTrue(semaphore.tryAcquire(MAX_RETRIES, 10, TimeUnit.SECONDS));
        }
        catch ( Throwable e )
        {
            Assert.fail("Error", e);
        }

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        Activator a = new Activator();
        a.start(bctx);
        
        // Wait until the EndpointListener.endpointAdded call was made as the controlflow is asynchronous
        sema.tryAcquire(30, TimeUnit.SECONDS);
        
        c.verify();


    }

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