Example usage for com.liferay.portal.kernel.concurrent CompeteLatch await

Introduction

In this page you can find the example usage for com.liferay.portal.kernel.concurrent CompeteLatch await.

Prototype

public void await() throws InterruptedException 

Source Link

Document

This method should only be called by a loser thread.

Usage

From source file:com.liferay.counter.service.persistence.CounterFinderImpl.java

License:Open Source License

private long _competeIncrement(CounterRegister counterRegister, int size) throws SystemException {

    CounterHolder counterHolder = counterRegister.getCounterHolder();

    // Try to use the fast path

    long newValue = counterHolder.addAndGet(size);

    if (newValue <= counterHolder.getRangeMax()) {
        return newValue;
    }/* w  ww  .j  ava  2 s.c o  m*/

    // Use the slow path

    CompeteLatch completeLatch = counterRegister.getCompeteLatch();

    if (!completeLatch.compete()) {

        // Loser thread has to wait for the winner thread to finish its job

        try {
            completeLatch.await();
        } catch (InterruptedException ie) {
            throw processException(ie);
        }

        // Compete again

        return _competeIncrement(counterRegister, size);
    }

    // Winner thread

    try {

        // Double check

        counterHolder = counterRegister.getCounterHolder();
        newValue = counterHolder.addAndGet(size);

        if (newValue > counterHolder.getRangeMax()) {
            CounterHolder newCounterHolder = _obtainIncrement(counterRegister.getName(),
                    counterRegister.getRangeSize(), 0);

            newValue = newCounterHolder.addAndGet(size);

            counterRegister.setCounterHolder(newCounterHolder);
        }
    } catch (Exception e) {
        throw processException(e);
    } finally {

        // Winner thread opens the latch so that loser threads can continue

        completeLatch.done();
    }

    return newValue;
}

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