/*
* Copyright (c) 2013, grossmann
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the jo-widgets.org nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL jo-widgets.org BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*/
package org.jowidgets.util.concurrent;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import org.jowidgets.util.Assert;
import org.jowidgets.util.IFactory;
public final class SingleThreadAccess implements ISingleThreadAccess {
private static final long SLEEP_TIME = 200;
private final ThreadFactory threadFactory;
private final AtomicBoolean running;
private final AtomicBoolean paused;
private final BlockingQueue<Runnable> events;
private Thread singleThread;
private UncaughtExceptionHandler uncaughtExceptionHandler;
public SingleThreadAccess() {
this(new DaemonThreadFactory());
}
/**
* Creates a new single thread access that uses the given thread name factory for thread creation
*
* @param threadNameFactory The thread name factory to use
*/
public SingleThreadAccess(final IFactory<String> threadNameFactory) {
this(new DaemonThreadFactory(Assert.getParamNotNull(threadNameFactory, "threadNameFactory")));
}
/**
* Creates a new single thread access that uses the given thread name prefix for thread creation
*
* @param threadPrefix The thread name prefix to use
*/
public SingleThreadAccess(final String threadPrefix) {
this(new DaemonThreadFactory(Assert.getParamNotNull(threadPrefix, "threadPrefix")));
}
/**
* Creates a new single thread access that uses the given thread factory for thread creation
*
* @param threadFactory The thread factory to use
*/
public SingleThreadAccess(final ThreadFactory threadFactory) {
Assert.paramNotNull(threadFactory, "threadFactory");
this.threadFactory = threadFactory;
this.running = new AtomicBoolean(false);
this.paused = new AtomicBoolean(false);
this.events = new LinkedBlockingQueue<Runnable>();
this.uncaughtExceptionHandler = new DefaultUncaughtExeptionHandler();
}
@Override
public boolean isSingleThread() {
return Thread.currentThread() == singleThread;
}
@Override
public void invoke(final Runnable runnable) {
Assert.paramNotNull(runnable, "runnable");
events.add(runnable);
}
/**
* Starts the events loop
*/
public synchronized void start() {
if (running.getAndSet(true)) {
throw new IllegalStateException("Event queue is already running");
}
else {
singleThread = threadFactory.newThread(new EventLoop());
singleThread.start();
}
}
/**
* Pauses the event pump
*/
public synchronized void setPaused(final boolean paused) {
this.paused.set(paused);
}
/**
* Stops the events loop, refuses all events
*/
public synchronized void stop() {
//CHECKSTYLE:OFF
if (running.getAndSet(false)) {
//nothing else to do
}
//CHECKSTYLE:ON
else {
throw new IllegalStateException("Event queue is not running");
}
}
public boolean isRunning() {
return running.get();
}
public void setUncaughtExceptionHandler(final UncaughtExceptionHandler uncaughtExceptionHandler) {
Assert.paramNotNull(uncaughtExceptionHandler, "uncaughtExceptionHandler");
this.uncaughtExceptionHandler = uncaughtExceptionHandler;
}
private final class EventLoop implements Runnable {
@Override
public void run() {
try {
while (running.get()) {
if (paused.get()) {
Thread.sleep(SLEEP_TIME);
}
else {
final Runnable runnable = events.poll(SLEEP_TIME, TimeUnit.MILLISECONDS);
if (runnable != null) {
try {
runnable.run();
}
catch (final Exception e) {
uncaughtExceptionHandler.uncaughtException(Thread.currentThread(), e);
}
}
}
}
}
catch (final InterruptedException e) {
uncaughtExceptionHandler.uncaughtException(Thread.currentThread(), e);
}
finally {
running.set(false);
events.clear();
singleThread = null;
}
}
}
private final class DefaultUncaughtExeptionHandler implements UncaughtExceptionHandler {
@Override
public void uncaughtException(final Thread t, final Throwable e) {
//CHECKSTYLE:OFF
e.printStackTrace();
//CHECKSTYLE:ON
}
}
}