Example usage for java.util.concurrent.locks Lock newCondition

Introduction

In this page you can find the example usage for java.util.concurrent.locks Lock newCondition.

Prototype

Condition newCondition();

Source Link

Document

Returns a new Condition instance that is bound to this Lock instance.

Usage

From source file:org.jactr.core.production.action.SleepAction.java

/**
 * wait until the goal buffer isn't empty
 * /*from  www  .  j  av  a  2  s.  co  m*/
 * @see org.jactr.core.production.action.IAction#fire(org.jactr.core.production.IInstantiation, double)
 */
public double fire(IInstantiation instantiation, double firingTime) {
    IActivationBuffer goalBuffer = instantiation.getModel().getActivationBuffer(IActivationBuffer.GOAL);

    if (goalBuffer.getSourceChunk() == null) {
        final Lock goalLock = new ReentrantLock();
        final Condition gotAGoal = goalLock.newCondition();

        /*
         * merely signal when the goal buffer gets something
         */
        IActivationBufferListener listener = new ActivationBufferListenerAdaptor() {
            @Override
            public void sourceChunkAdded(ActivationBufferEvent event) {
                try {
                    goalLock.lock();
                    if (LOGGER.isDebugEnabled())
                        LOGGER.debug("Signaling goal insertion");
                    gotAGoal.signalAll();
                } finally {
                    goalLock.unlock();
                }
            }
        };

        /*
         * attach the listener with the inline executor - this ensures that
         * regardless of what thread adds the source chunk to the buffer we will
         * be notified
         */
        goalBuffer.addListener(listener, ExecutorServices.INLINE_EXECUTOR);

        try {
            goalLock.lock();
            while (goalBuffer.getSourceChunk() == null) {
                if (LOGGER.isDebugEnabled())
                    LOGGER.debug("Waiting for goal");
                gotAGoal.await();
            }
        } catch (Exception e) {
            if (LOGGER.isDebugEnabled())
                LOGGER.debug("Could not wait for goal ", e);
        }

        if (LOGGER.isDebugEnabled())
            LOGGER.debug("Resuming from wait");

        goalLock.unlock();

        /*
         * remove the listener
         */
        goalBuffer.removeListener(listener);
    } else if (LOGGER.isDebugEnabled())
        LOGGER.debug("Goal is already present, no need to sleep");

    return 0;
}

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