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

            Assert.assertEquals(cache.getCurrentData().getData(), "one".getBytes());


            client.delete().forPath("/test/foo");
            Assert.assertTrue(semaphore.tryAcquire(1, 10, TimeUnit.SECONDS));
            client.create().forPath("/test/foo", "two".getBytes());
            Assert.assertTrue(semaphore.tryAcquire(1, 10, TimeUnit.SECONDS));


            Throwable t = error.get();
            if ( t != null )
            {
                Assert.fail("Assert", t);

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            };
            selector = new LeaderSelector(client, "/leader", listener);
            selector.autoRequeue();
            selector.start();
            
            Assert.assertTrue(semaphore.tryAcquire(2, 10, TimeUnit.SECONDS));
        }
        finally
        {
            Closeables.closeQuietly(selector);
            Closeables.closeQuietly(client);

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            cache.addListener(listener);


            ServiceInstance<String>     instance1 = ServiceInstance.<String>builder().payload("thing").name("test").port(10064).build();
            ServiceInstance<String>     instance2 = ServiceInstance.<String>builder().payload("thing").name("test").port(10065).build();
            discovery.registerService(instance1);
            Assert.assertTrue(semaphore.tryAcquire(10, TimeUnit.SECONDS));


            discovery.registerService(instance2);
            Assert.assertTrue(semaphore.tryAcquire(3, TimeUnit.SECONDS));


            ServiceInstance<String>     instance3 = ServiceInstance.<String>builder().payload("thing").name("another").port(10064).build();

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            ServiceInstance<String>     instance2 = ServiceInstance.<String>builder().payload("thing").name("test").port(10065).build();
            discovery.registerService(instance1);
            Assert.assertTrue(semaphore.tryAcquire(10, TimeUnit.SECONDS));


            discovery.registerService(instance2);
            Assert.assertTrue(semaphore.tryAcquire(3, TimeUnit.SECONDS));


            ServiceInstance<String>     instance3 = ServiceInstance.<String>builder().payload("thing").name("another").port(10064).build();
            discovery.registerService(instance3);
            Assert.assertFalse(semaphore.tryAcquire(3, TimeUnit.SECONDS));  // should not get called for a different service
        }

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            discovery.registerService(instance2);
            Assert.assertTrue(semaphore.tryAcquire(3, TimeUnit.SECONDS));


            ServiceInstance<String>     instance3 = ServiceInstance.<String>builder().payload("thing").name("another").port(10064).build();
            discovery.registerService(instance3);
            Assert.assertFalse(semaphore.tryAcquire(3, TimeUnit.SECONDS));  // should not get called for a different service
        }
        finally
        {
            Collections.reverse(closeables);
            for ( Closeable c : closeables )

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                Thread.sleep(500);
            }
        }


        // Wait until all updates return
        sem.tryAcquire(15, TimeUnit.SECONDS);
        
        // 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(ClientBase.CONNECTION_TIMEOUT, TimeUnit.MILLISECONDS)) {
            LOG.warn("Did not aquire semaphore fast enough");
        }
        mytestfooThread.join(ClientBase.CONNECTION_TIMEOUT);
        if (mytestfooThread.isAlive()) {
            LOG.error("mytestfooThread is still alive");

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                Thread.sleep(1000);
            }
        }


        // Wait until all updates return
        if(!sem.tryAcquire(ClientBase.CONNECTION_TIMEOUT, TimeUnit.MILLISECONDS)) {
            LOG.warn("Did not aquire semaphore fast enough");
        }
        mytestfooThread.join(ClientBase.CONNECTION_TIMEOUT);
        if (mytestfooThread.isAlive()) {
            LOG.error("mytestfooThread is still alive");

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                                    //Long l = new Long(m.tag);
                                    Semaphore s = new Semaphore(0);
                                    synchronized (s) {
                                        challengeMutex.put(m.tag, s);
                                        s.tryAcquire((long) timeout, TimeUnit.MILLISECONDS);
                                        myChallenge = challengeMap
                                                .containsKey(m.tag);
                                    }
                                } catch (InterruptedException e) {
                                    LOG.warn("Challenge request exception: ", e);

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                            try {
                                Semaphore s = new Semaphore(0);
                                double timeout = ackWait
                                        * java.lang.Math.pow(10, attempts);
                                ackMutex.put(m.tag, s);
                                s.tryAcquire((int) timeout, TimeUnit.MILLISECONDS);
                            } catch (InterruptedException e) {
                                LOG.warn("Ack exception: ", e);
                            }
                            synchronized (acksqueue) {
                                for (int i = 0; i < acksqueue.size(); ++i) {

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