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


         // Reacquire the semaphore tickets; when we have them all
         // we know the threads are done
         for (int i = 0; i < count; i++)
         {
            boolean acquired = semaphore.tryAcquire(60, TimeUnit.SECONDS);
            if (!acquired) fail("failed to acquire semaphore " + i);
         }


         // allow any async calls to clear
         if (!sync)

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         // Reacquire the semaphore tickets; when we have them all
         // we know the threads are done
         for (int i = 0; i < cacheCount; i++)
         {
            boolean acquired = semaphore.tryAcquire(60, TimeUnit.SECONDS);
            if (!acquired)
            {
               fail("failed to acquire semaphore " + i);
            }
         }

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            for (CacheStressor stressor : stressors)
            {
               cacheA.getRegion(Fqn.fromString("/" + stressor.getName()), true).activate();
               stressor.stopPuts();
               // Reacquire one semaphore ticket
               boolean acquired = semaphore.tryAcquire(60, TimeUnit.SECONDS);
               if (!acquired)
               {
                  fail("failed to acquire semaphore " + stressor.getName());
               }

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                Thread.sleep(500);
            }
        }


        // Wait until all updates return
        sem.tryAcquire(15000, TimeUnit.MILLISECONDS);
        
        // Verify that server is following and has the same epoch as the leader
        assertTrue("Not following", qu.getPeer(index).peer.follower != null);
        long epochF = (qu.getPeer(index).peer.getActiveServer().getZxid() >> 32L);
        long epochL = (leader.getEpoch() >> 32L);

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                }, null);
            }
        }


        // Wait until all updates return
        if(!sem.tryAcquire(20000, TimeUnit.MILLISECONDS)) {
            LOG.warn("Did not aquire semaphore fast enough");
        }
        t.join(10000);
        Thread.sleep(1000);

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                Thread.sleep(1000);
            }
        }


        // Wait until all updates return
        if(!sem.tryAcquire(15000, TimeUnit.MILLISECONDS)) {
            LOG.warn("Did not aquire semaphore fast enough");
        }
        t.join(10000);
        Thread.sleep(1000);
        // Verify that server is following and has the same epoch as the leader

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        ConnectFuture connectFuture = vmPipeConnector.connect(vmPipeAddress);
        connectFuture.awaitUninterruptibly();
        connectFuture.getSession().write(IoBuffer.wrap(new byte[1])).awaitUninterruptibly();
        connectFuture.getSession().close(false).awaitUninterruptibly();


        semaphore.tryAcquire(1, TimeUnit.SECONDS);
        vmPipeAcceptor.unbind(vmPipeAddress);
        Assert.assertEquals(1, connectFuture.getSession().getWrittenBytes());
        Assert.assertEquals("ABCD", stringBuffer.toString());
    }
}

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        Thread thread = new Thread(getName()  + " - Shutdown Monitor Thread") {
            @Override
            public void run() {
                try {
                    LOGGER.debug("Waiting for " + shutdownTimeout + " milliseconds to a clean shutdown of SA " + ServiceAssemblyImpl.this.getName());
                    if (!semaphore.tryAcquire(shutdownTimeout, TimeUnit.MILLISECONDS)) {
                        LOGGER.warn("Unable to do a clean shutdown of SA " + ServiceAssemblyImpl.this.getName() + ", canceling all sync exchanges");
                        listener.cancelPendingSyncExchanges(ServiceAssemblyImpl.this);                        
                    }
                } catch (InterruptedException e) {
                    //let's assume things went OK if we got interrupted

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        dispatch(e);
        Thread thread = Thread.currentThread();
        String original = thread.getName();
        try {
            if (timeout > 0) {
                if (!lock.tryAcquire(timeout, TimeUnit.MILLISECONDS)) {
                    throw new TimeoutException();
                }
            } else {
                thread.setName(original + " (waiting for exchange " + exchange.getId() + ")");
                lock.acquire();

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            }
        });
        
        // wait for the renderer to run the worker
        try {
            if (!gs.tryAcquire(2, TimeUnit.SECONDS)) {
                out.append("Graphics information unavailable\n");
            }
        } catch (InterruptedException ie) {
            // ignore

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