/*
* Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 David Berkman
*
* This file is part of the SmallMind Code Project.
*
* The SmallMind Code Project is free software, you can redistribute
* it and/or modify it under either, at your discretion...
*
* 1) The terms of GNU Affero General Public License as published by the
* Free Software Foundation, either version 3 of the License, or (at
* your option) any later version.
*
* ...or...
*
* 2) The terms of the Apache License, Version 2.0.
*
* The SmallMind Code Project is distributed in the hope that it will
* be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License or Apache License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* and the Apache License along with the SmallMind Code Project. If not, see
* <http://www.gnu.org/licenses/> or <http://www.apache.org/licenses/LICENSE-2.0>.
*
* Additional permission under the GNU Affero GPL version 3 section 7
* ------------------------------------------------------------------
* If you modify this Program, or any covered work, by linking or
* combining it with other code, such other code is not for that reason
* alone subject to any of the requirements of the GNU Affero GPL
* version 3.
*/
package org.smallmind.seda;
import java.util.LinkedList;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicBoolean;
import org.smallmind.scribe.pen.LoggerManager;
public class ThreadPool<I extends Event, O extends Event> {
private final LinkedList<EventProcessor<I, O>> processorList;
private CountDownLatch exitLatch;
private AtomicBoolean stopped = new AtomicBoolean(false);
private SedaConfiguration sedaConfiguration;
private EventQueue<I> eventQueue;
private DurationMonitor durationMonitor;
private HomeostaticRegulator<I, O> homeostaticRegulator;
public ThreadPool (EventQueue<I> eventQueue, SedaConfiguration sedaConfiguration) {
Thread regulatorThread;
this.sedaConfiguration = sedaConfiguration;
this.eventQueue = eventQueue;
durationMonitor = new DurationMonitor(sedaConfiguration.getMaxTrackedInvocations());
processorList = new LinkedList<EventProcessor<I, O>>();
regulatorThread = new Thread(homeostaticRegulator = new HomeostaticRegulator<I, O>(this, durationMonitor, processorList, sedaConfiguration));
regulatorThread.start();
exitLatch = new CountDownLatch(1);
}
public boolean isRunning () {
return !stopped.get();
}
protected synchronized void increase () {
synchronized (processorList) {
if (!stopped.get()) {
if ((sedaConfiguration.getMaxThreadPoolSize() == 0) || (processorList.size() < sedaConfiguration.getMaxThreadPoolSize())) {
Thread processorThread;
EventProcessor<I, O> eventProcessor;
eventProcessor = new EventProcessor<I, O>(eventQueue, durationMonitor, sedaConfiguration);
processorThread = new Thread(eventProcessor);
processorThread.start();
processorList.add(eventProcessor);
}
}
}
}
protected void decrease () {
synchronized (processorList) {
if (!stopped.get()) {
if ((!processorList.isEmpty()) && (processorList.size() > sedaConfiguration.getMinThreadPoolSize())) {
try {
processorList.removeFirst().stop();
// TODO: When the processor list is Empty (or 1), the processor should short circuit and decide how to upshift out of this state
}
catch (InterruptedException interruptedException) {
LoggerManager.getLogger(ThreadPool.class).error(interruptedException);
}
}
}
}
}
protected void stop ()
throws InterruptedException {
if (stopped.compareAndSet(false, true)) {
try {
homeostaticRegulator.stop();
}
catch (InterruptedException interruptedException) {
LoggerManager.getLogger(ThreadPool.class).error(interruptedException);
}
synchronized (processorList) {
while (!processorList.isEmpty()) {
try {
processorList.removeFirst().stop();
}
catch (InterruptedException interruptedException) {
LoggerManager.getLogger(ThreadPool.class).error(interruptedException);
}
}
}
exitLatch.countDown();
}
else {
exitLatch.await();
}
}
}