/*
* Copyright 2012 Red Hat, Inc. and/or its affiliates.
*
* 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 org.dashbuilder.scheduler;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
/**
* A scheduler implementation that adds pause/resume capabilities to the standard scheduler.
*/
public class PausableThreadPoolExecutor extends ScheduledThreadPoolExecutor {
protected boolean isPaused;
protected ReentrantLock pauseLock = new ReentrantLock();
protected Condition unpaused = pauseLock.newCondition();
public PausableThreadPoolExecutor(int corePoolSize) {
super(corePoolSize);
}
public PausableThreadPoolExecutor(int corePoolSize, RejectedExecutionHandler handler) {
super(corePoolSize, handler);
}
public PausableThreadPoolExecutor(int corePoolSize, ThreadFactory threadFactory) {
super(corePoolSize, threadFactory);
}
public PausableThreadPoolExecutor(int corePoolSize, ThreadFactory threadFactory, RejectedExecutionHandler handler) {
super(corePoolSize, threadFactory, handler);
}
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();
}
}
public boolean isPaused() {
return isPaused;
}
}