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/*******************************************************************************
* Copyright (c) 2001, 2008 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.wst.validation.internal;
import java.util.Vector;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.wst.validation.internal.plugin.ValidationPlugin;
/**
* This class manages (queue, invoke, etc.) the Runnables that perform the validation for a
* particular validator.
*/
public class VThreadManager {
private static VThreadManager _manager = null;
private static final int MAX_NUM_OF_RESTART = 5; // the maximum number of times that the thread
// should attempt to ignore a Throwable and
// carry on
private Thread _validationThread = null; // This thread checks if the current Runnable is
// finished, and if so, loads the first Runnable off of
// the queue and starts it.
volatile int restart = 0; // how many times has the thread been restarted?
volatile Jobs _jobs = null;
private VThreadManager() {
_jobs = new Jobs();
// Start the validation thread to check for queued ValidationOperation
Runnable validationRunnable = new Runnable() {
public void run() {
while (true) {
try {
if (restart > MAX_NUM_OF_RESTART) {
// something has gone seriously, seriously wrong
String message = "restart = " + restart; //$NON-NLS-1$
ValidationPlugin.getPlugin().logMessage(IStatus.ERROR, message);
break;
}
Runnable job = getJobs().dequeue(); // If currentRunnable is null, there's
// nothing on the queue. Shouldn't
// happen with a semaphore.
if (job != null) {
getJobs().setActive(true);
job.run();
getJobs().setActive(false);
}
} catch (Exception e) {
restart++;
getJobs().setActive(false);
ValidationPlugin.getPlugin().handleException(e);
} finally {
//do nothing
}
}
}
};
_validationThread = new Thread(validationRunnable, "ValidationThread"); //$NON-NLS-1$
_validationThread.start();
}
public static VThreadManager getManager() {
if (_manager == null) {
_manager = new VThreadManager();
}
return _manager;
}
Jobs getJobs() {
return _jobs;
}
public void queue(Runnable runnable) {
getJobs().queue(runnable);
}
/**
* Return true if all of the Runnables have been run.
*/
public boolean isDone() {
return getJobs().isDone();
}
private class Jobs {
private Vector<Runnable> _queuedJobs; // The queued Runnables that need to be run.
private boolean _isActive; // Is a job being run in the validation thread?
public Jobs() {
_queuedJobs = new Vector<Runnable>();
}
public synchronized void queue(Runnable runnable) {
// If there is a thread running already, then it must finish before another validation
// thread is launched, or the validation messages could reflect the last thread
// finished,
// instead of the last state of changes.
// Have to wait for the current Runnable to finish, so add this to the end of the queue
_queuedJobs.add(runnable);
notifyAll();
}
/**
* Pop the Runnable off of the head of the queue.
*/
synchronized Runnable dequeue() {
while (_queuedJobs.size() == 0) {
try {
wait();
} catch (InterruptedException exc) {
//Ignore
}
} // Block on the semaphore; break when a job has been added to the queue.
Runnable job = null;
if (_queuedJobs.size() > 0) {
job = _queuedJobs.get(0);
if (job != null) {
_queuedJobs.remove(0);
}
}
return job;
}
public synchronized boolean isActive() {
return _isActive;
}
public synchronized void setActive(boolean active) {
_isActive = active;
}
/**
* Return true if all of the Runnables have been run.
*/
public synchronized boolean isDone() {
return ((_queuedJobs.size() == 0) && !isActive());
}
}
}
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