Example usage for java.util.concurrent Semaphore Semaphore

Introduction

In this page you can find the example usage for java.util.concurrent Semaphore Semaphore.

Prototype

public Semaphore(int permits) 

Source Link

Document

Creates a Semaphore with the given number of permits and nonfair fairness setting.

Usage

From source file:org.apache.kylin.storage.hbase.util.HbaseStreamingInput.java

public static void randomScan(String tableName) throws IOException {

    final Semaphore semaphore = new Semaphore(0);
    new Thread(new Runnable() {
        @Override//from   w  w w .j ava2  s .  c  om
        public void run() {
            scheduleJob(semaphore, 60000);//1 minutes a batch
        }
    }).start();

    while (true) {
        try {
            semaphore.acquire();
            int waiting = semaphore.drainPermits();
            if (waiting > 0) {
                logger.warn("Too many queries to handle! Blocking " + waiting + " sets of scan requests");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            e.printStackTrace();
        }

        Random r = new Random();
        Connection conn = getConnection();
        Table table = conn.getTable(TableName.valueOf(tableName));

        long leftBound = getFirstKeyTime(table);
        long rightBound = System.currentTimeMillis();

        for (int t = 0; t < 5; ++t) {
            long start = (long) (leftBound + r.nextDouble() * (rightBound - leftBound));
            long end = start + 600000;//a period of 10 minutes
            logger.info("A scan from " + formatTime(start) + " to " + formatTime(end));

            Scan scan = new Scan();
            scan.setStartRow(Bytes.toBytes(start));
            scan.setStopRow(Bytes.toBytes(end));
            scan.addFamily(CF);
            ResultScanner scanner = table.getScanner(scan);
            long hash = 0;
            int rowCount = 0;
            for (Result result : scanner) {
                Cell cell = result.getColumnLatestCell(CF, QN);
                byte[] value = cell.getValueArray();
                if (cell.getValueLength() != CELL_SIZE) {
                    logger.error("value size invalid!!!!!");
                }

                hash += Arrays.hashCode(Arrays.copyOfRange(value, cell.getValueOffset(),
                        cell.getValueLength() + cell.getValueOffset()));
                rowCount++;
            }
            scanner.close();
            logger.info("Scanned " + rowCount + " rows, the (meaningless) hash for the scan is " + hash);
        }
        table.close();
        conn.close();
    }
}

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From source file:ai.grakn.engine.loader.client.LoaderClient.java

/**
 * Set the size of the queue- this is equivalent to the size of the semaphore.
 * @param size the size of the queue/*  w  w  w .ja  va  2 s.  c om*/
 */
public Loader setQueueSize(int size) {
    // create availability map
    availability = new HashMap<>();
    hosts.forEach(h -> availability.put(h, new Semaphore(size)));
    return this;
}

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From source file:com.netflix.curator.framework.recipes.locks.TestInterProcessMutexBase.java

@Test
public void testKilledSession() throws Exception {
    final Timing timing = new Timing();

    CuratorFramework client = CuratorFrameworkFactory.newClient(server.getConnectString(), timing.session(),
            timing.connection(), new RetryOneTime(1));
    client.start();/*from   w ww  .j av  a 2  s  .  c  o  m*/
    try {
        final InterProcessLock mutex1 = makeLock(client);
        final InterProcessLock mutex2 = makeLock(client);

        final Semaphore semaphore = new Semaphore(0);
        ExecutorCompletionService<Object> service = new ExecutorCompletionService<Object>(
                Executors.newFixedThreadPool(2));
        service.submit(new Callable<Object>() {
            @Override
            public Object call() throws Exception {
                mutex1.acquire();
                semaphore.release();
                Thread.sleep(1000000);
                return null;
            }
        });

        service.submit(new Callable<Object>() {
            @Override
            public Object call() throws Exception {
                mutex2.acquire();
                semaphore.release();
                Thread.sleep(1000000);
                return null;
            }
        });

        Assert.assertTrue(timing.acquireSemaphore(semaphore, 1));
        KillSession.kill(client.getZookeeperClient().getZooKeeper(), server.getConnectString());
        Assert.assertTrue(timing.acquireSemaphore(semaphore, 1));
    } finally {
        client.close();
    }
}

---

From source file:lockstep.LockstepServer.java

public LockstepServer(int tcpPort, int clientsNumber, int tickrate, int maxUDPPayloadLength,
        int connectionTimeout) {
    //late fail left to Socket class
    this.tcpPort = tcpPort;

    if (clientsNumber <= 1)
        throw new IllegalArgumentException("clientsNumber must be at least 2");
    else//w w w.  j  a v  a 2 s.c om
        this.clientsNumber = clientsNumber;

    if (tickrate <= 0)
        throw new IllegalArgumentException("Tickrate must be an integer greater than 0");
    else
        this.tickrate = tickrate;

    if (maxUDPPayloadLength <= 0)
        throw new IllegalArgumentException("Max UDP payload length must be an integer greater than 0");
    else
        this.maxUDPPayloadLength = maxUDPPayloadLength;

    if (connectionTimeout < 0)
        throw new IllegalArgumentException("Connection timeout must be greater or equal than zero");
    else
        this.connectionTimeout = connectionTimeout;

    receivers = new HashMap<>();
    transmitters = new HashMap<>();

    executionSemaphore = new Semaphore(0);
    receivingQueues = new ConcurrentHashMap<>();
    transmissionFrameQueueTree = new ConcurrentHashMap<>();
    ackQueues = new HashMap<>();
    clientIDs = new ConcurrentSkipListSet<>();
    openSockets = new ArrayList<>();
}

---

From source file:com.gooddata.http.client.GoodDataHttpClientIntegrationTest.java

License:asdf

@Test
public void shouldRefreshTTConcurrent() throws Exception {
    mock401OnProjects();/*from ww w.  ja  va2s  .  co m*/

    // this serves to block second thread, until the first one gets 401 on projects, which causes TT refresh
    // the test aims to test the second thread is not cycling on 401 and cumulating wrong TT headers
    final Semaphore semaphore = new Semaphore(1);

    requestOnPath(GDC_PROJECTS_PATH, "TT1").respondUsing(new Responder() {
        boolean first = true;

        @Override
        public StubResponse nextResponse(Request request) {
            if (first) {
                first = false;
                return StubResponse.builder().status(200).body(BODY_PROJECTS, CHARSET)
                        .header(CONTENT_HEADER, CONTENT_TYPE_JSON_UTF).build();
            } else {
                semaphore.release();
                return StubResponse.builder().status(401).body(BODY_401, CHARSET)
                        .header(CONTENT_HEADER, CONTENT_TYPE_JSON_UTF)
                        .header(WWW_AUTHENTICATE_HEADER, GOODDATA_REALM + " " + TT_COOKIE)
                        .delay(5, TimeUnit.SECONDS).build();
            }
        }
    });
    mock200OnProjects("TT2");

    mock401OnPath(GDC_PROJECTS2_PATH, "TT1");
    mock200OnPath(GDC_PROJECTS2_PATH, "TT2");

    mock401OnToken();
    respond200OnToken(mock200OnToken("TT1").thenRespond(), "TT2");

    mockLogin();

    final HttpClient client = createGoodDataClient(jadlerLogin, jadlerPassword, jadlerHost);

    // one get at the beginning causing successful login
    performGet(client, jadlerHost, GDC_PROJECTS_PATH, 200);

    // to be able to finish when both threads finished
    final CountDownLatch countDown = new CountDownLatch(2);

    final ExecutorService executor = Executors.newFixedThreadPool(2);
    semaphore.acquire(); // will be released in jadler
    executor.submit(new PerformGetWithCountDown(client, GDC_PROJECTS_PATH, countDown));
    semaphore.acquire(); // causes waiting
    executor.submit(new PerformGetWithCountDown(client, GDC_PROJECTS2_PATH, countDown));

    countDown.await(10, TimeUnit.SECONDS);

    verifyThatRequest().havingMethodEqualTo("GET").havingPathEqualTo(GDC_TOKEN_PATH)
            .havingHeaderEqualTo(SST_HEADER, "SST")
            // if received more than twice, it means the second thread didn't wait, while the first was refreshing TT
            .receivedTimes(2);

    verifyThatRequest().havingMethodEqualTo("GET").havingPathEqualTo(GDC_PROJECTS2_PATH)
            .havingHeaderEqualTo(TT_HEADER, "TT1")
            // the second thread should try only once with expired TT1
            .receivedOnce();

    verifyThatRequest().havingMethodEqualTo("GET").havingPathEqualTo(GDC_PROJECTS2_PATH)
            .havingHeaderEqualTo(TT_HEADER, "TT1").havingHeaderEqualTo(TT_HEADER, "TT2")
            // the second thread should not set more than one X-GDC-AuthTT header
            .receivedNever();
}

---

From source file:org.onosproject.loadtest.DistributedConsensusLoadTest.java

private void startTest() {
    stopped.set(false);/*from www.  j  a  va2 s .  com*/
    RateLimiter limiter = RateLimiter.create(rate);
    Semaphore s = new Semaphore(100);
    while (!stopped.get()) {
        limiter.acquire();
        s.acquireUninterruptibly();
        counters.get(RandomUtils.nextInt(TOTAL_COUNTERS)).incrementAndGet().whenComplete((r, e) -> {
            s.release();
            if (e == null) {
                increments.incrementAndGet();
            }
        });
    }
}

---

From source file:com.parse.ParseAnalyticsTest.java

@Test
public void testTrackEventInBackgroundNormalCallback() throws Exception {
    final Map<String, String> dimensions = new HashMap<>();
    dimensions.put("key", "value");
    final Semaphore done = new Semaphore(0);
    ParseAnalytics.trackEventInBackground("test", dimensions, new SaveCallback() {
        @Override//from   ww  w. ja va 2s.  c  o  m
        public void done(ParseException e) {
            assertNull(e);
            done.release();
        }
    });

    // Make sure the callback is called
    assertTrue(done.tryAcquire(1, 10, TimeUnit.SECONDS));
    verify(controller, times(1)).trackEventInBackground(eq("test"), eq(dimensions), isNull(String.class));

    final Semaphore doneAgain = new Semaphore(0);
    ParseAnalytics.trackEventInBackground("test", new SaveCallback() {
        @Override
        public void done(ParseException e) {
            assertNull(e);
            doneAgain.release();
        }
    });

    // Make sure the callback is called
    assertTrue(doneAgain.tryAcquire(1, 10, TimeUnit.SECONDS));
    verify(controller, times(1)).trackEventInBackground(eq("test"), Matchers.<Map<String, String>>eq(null),
            isNull(String.class));
}

---

From source file:org.hyperic.lather.server.LatherServlet.java

private ConnManager getConnManager(ServletConfig cfg) throws ServletException {
    @SuppressWarnings("unchecked")
    final Enumeration<String> paramNames = cfg.getInitParameterNames();
    final Map<String, Semaphore> maxConnMap = new HashMap<String, Semaphore>();
    while (paramNames.hasMoreElements()) {
        final String name = paramNames.nextElement();
        if (!name.startsWith(PROP_PREFIX) || name.contains(PROP_EXECTIMEOUT)) {
            continue;
        }/*from  w  w w  . ja  v  a  2  s  .  c o m*/
        final String param = cfg.getInitParameter(name);
        try {
            final int value = Integer.parseInt(param);
            maxConnMap.put(name.replace(PROP_PREFIX, ""), new Semaphore(value));
        } catch (NumberFormatException e) {
            log.error("could not initialize max conn setting for " + name + " value=" + param);
        }
    }
    if (!maxConnMap.containsKey(PROP_MAXCONNS)) {
        throw new ServletException("init-params do not contain key=" + PROP_MAXCONNS + ")");
    }
    return new ConnManager(maxConnMap);
}

---

From source file:ai.grakn.client.LoaderClient.java

/**
 * Number of active tasks running on the server at any one time.
 * Consider this a safeguard on system load.
 *
 * The Loader {@link #add(InsertQuery)} method will block on the value of this field.
 *
 * @param size number of tasks to allow to run at any given time
 *//*from  w w w. j  av a  2  s  .com*/
public LoaderClient setNumberActiveTasks(int size) {
    this.blockerSize = size;
    this.blocker = new Semaphore(size);
    return this;
}

---

From source file:io.hops.erasure_coding.ParallelStreamReader.java

/**
 * Reads data from multiple streams in parallel and puts the data in a queue.
 *
 * @param streams/*ww w  .  jav  a2s  . co m*/
 *     The input streams to read from.
 * @param bufSize
 *     The amount of data to read from each stream in each go.
 * @param numThreads
 *     Number of threads to use for parallelism.
 * @param boundedBuffer
 *     The queue to place the results in.
 */
public ParallelStreamReader(Progressable reporter, InputStream[] streams, int bufSize, int numThreads,
        int boundedBufferCapacity, long maxBytesPerStream) throws IOException {
    this.reporter = reporter;
    this.streams = new InputStream[streams.length];
    this.endOffsets = new long[streams.length];
    for (int i = 0; i < streams.length; i++) {
        this.streams[i] = streams[i];
        if (this.streams[i] instanceof DFSDataInputStream) {
            DFSDataInputStream stream = (DFSDataInputStream) this.streams[i];
            // in directory raiding, the block size for each input stream 
            // might be different, so we need to determine the endOffset of
            // each stream by their own block size.
            List<LocatedBlock> blocks = stream.getAllBlocks();
            if (blocks.size() == 0) {
                this.endOffsets[i] = Long.MAX_VALUE;
            } else {
                this.endOffsets[i] = stream.getPos() + blocks.get(0).getBlockSize();
            }
        } else {
            this.endOffsets[i] = Long.MAX_VALUE;
        }
        streams[i] = null; // Take over ownership of streams.
    }
    this.bufSize = bufSize;
    this.boundedBuffer = new ArrayBlockingQueue<ReadResult>(boundedBufferCapacity);
    if (numThreads > streams.length) {
        this.numThreads = streams.length;
    } else {
        this.numThreads = numThreads;
    }
    this.remainingBytesPerStream = maxBytesPerStream;
    this.slots = new Semaphore(this.numThreads);
    this.readPool = Executors.newFixedThreadPool(this.numThreads);
    this.mainThread = new MainThread();
}

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