PausableExecutor.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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 org.apache.axis2.jaxws.sample.parallelasync.common;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

/**
 * A custom executor that can be paused for testing of exceptions that occur
 * before an item is executed. This executor provides absolue control over its
 * thread size via size parameter in the constructor
 */
public class PausableExecutor extends ThreadPoolExecutor {
    private boolean isPaused;

    private ReentrantLock pauseLock = new ReentrantLock();

    private Condition unpaused = pauseLock.newCondition();

    public PausableExecutor(int size) {
        super(size, size, 1, TimeUnit.SECONDS,
                new ArrayBlockingQueue<Runnable>(size));
    }
    
    protected void beforeExecute(Thread t, Runnable r) {
        super.beforeExecute(t, r);
        pauseLock.lock();
        try {
            while (isPaused)
                unpaused.await();
        } catch (InterruptedException ie) {
            t.interrupt();
        } finally {
            pauseLock.unlock();
        }
    }

    public void pause() {
        pauseLock.lock();
        try {
            isPaused = true;
        } finally {
            pauseLock.unlock();
        }
    }

    public void resume() {
        pauseLock.lock();
        try {
            isPaused = false;
            unpaused.signalAll();
        } finally {
            pauseLock.unlock();
        }
    }
}