AbstractLifecycleAwareExchangeEventHandler.java

/*
 * Copyright 2012 Riccardo Sirchia
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.github.camel.component.disruptor;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

/**
 * This abstract base class is used to implement the {@link LifecycleAwareExchangeEventHandler} interface with added
 * support to await starting/stopping by the Disruptor framework.
 */
abstract class AbstractLifecycleAwareExchangeEventHandler implements LifecycleAwareExchangeEventHandler {

    private volatile boolean started = false;
    private volatile CountDownLatch startedLatch = new CountDownLatch(1);
    private volatile CountDownLatch stoppedLatch = new CountDownLatch(1);

    @Override
    public abstract void onEvent(final ExchangeEvent event, long sequence, boolean endOfBatch) throws Exception;

    @Override
    public void awaitStarted() throws InterruptedException {
        if (!started) {
            startedLatch.await();
        }
    }

    @Override
    public boolean awaitStarted(final long timeout, final TimeUnit unit) throws InterruptedException {
        return started || startedLatch.await(timeout, unit);
    }

    @Override
    public void awaitStopped() throws InterruptedException {
        if (started) {
            stoppedLatch.await();
        }
    }

    @Override
    public boolean awaitStopped(final long timeout, final TimeUnit unit) throws InterruptedException {
        return !started || stoppedLatch.await(timeout, unit);
    }

    @Override
    public void onStart() {
        stoppedLatch = new CountDownLatch(1);
        startedLatch.countDown();
        started = true;
    }

    @Override
    public void onShutdown() {
        startedLatch = new CountDownLatch(1);
        stoppedLatch.countDown();
        started = false;
    }
}