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/*******************************************************************************
* Copyright (c) 2000, 2004 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Common Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/cpl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.widgets;
import org.eclipse.swt.*;
import org.eclipse.swt.internal.Compatibility;
/**
* Instances of this class provide synchronization support
* for displays. A default instance is created automatically
* for each display, and this instance is sufficient for almost
* all applications.
* <p>
* <b>IMPORTANT:</b> Typical application code <em>never</em>
* needs to deal with this class. It is provided only to
* allow applications which require non-standard
* synchronization behavior to plug in the support they
* require. <em>Subclasses which override the methods in
* this class must ensure that the superclass methods are
* invoked in their implementations</em>
* </p>
*
* @see Display#setSynchronizer
*/
public class Synchronizer {
Display display;
int messageCount;
RunnableLock [] messages;
Object messageLock = new Object ();
Thread syncThread;
public Synchronizer (Display display) {
this.display = display;
}
void addLast (RunnableLock lock) {
synchronized (messageLock) {
if (messages == null) messages = new RunnableLock [4];
if (messageCount == messages.length) {
RunnableLock[] newMessages = new RunnableLock [messageCount + 4];
System.arraycopy (messages, 0, newMessages, 0, messageCount);
messages = newMessages;
}
messages [messageCount++] = lock;
if (messageCount == 1) display.wakeThread ();
}
}
/**
* Causes the <code>run()</code> method of the runnable to
* be invoked by the user-interface thread at the next
* reasonable opportunity. The caller of this method continues
* to run in parallel, and is not notified when the
* runnable has completed.
*
* @param runnable code to run on the user-interface thread.
*
* @see #syncExec
*/
protected void asyncExec (Runnable runnable) {
if (runnable == null) {
display.wake ();
return;
}
addLast (new RunnableLock (runnable));
}
int getMessageCount () {
return messageCount;
}
void releaseSynchronizer () {
display = null;
messages = null;
messageLock = null;
syncThread = null;
}
RunnableLock removeFirst () {
synchronized (messageLock) {
if (messageCount == 0) return null;
RunnableLock lock = messages [0];
System.arraycopy (messages, 1, messages, 0, --messageCount);
messages [messageCount] = null;
if (messageCount == 0) messages = null;
return lock;
}
}
boolean runAsyncMessages () {
if (messageCount == 0) return false;
RunnableLock lock = removeFirst ();
if (lock == null) return true;
synchronized (lock) {
syncThread = lock.thread;
try {
lock.run ();
} catch (Throwable t) {
lock.throwable = t;
SWT.error (SWT.ERROR_FAILED_EXEC, t);
} finally {
syncThread = null;
lock.notifyAll ();
}
}
return true;
}
/**
* Causes the <code>run()</code> method of the runnable to
* be invoked by the user-interface thread at the next
* reasonable opportunity. The thread which calls this method
* is suspended until the runnable completes.
*
* @param runnable code to run on the user-interface thread.
*
* @exception SWTException <ul>
* <li>ERROR_FAILED_EXEC - if an exception occured when executing the runnable</li>
* </ul>
*
* @see #asyncExec
*/
protected void syncExec (Runnable runnable) {
if (display.isValidThread ()) {
if (runnable != null) runnable.run ();
return;
}
if (runnable == null) {
display.wake ();
return;
}
RunnableLock lock = new RunnableLock (runnable);
/*
* Only remember the syncThread for syncExec.
*/
lock.thread = Thread.currentThread();
synchronized (lock) {
addLast (lock);
boolean interrupted = false;
while (!lock.done ()) {
try {
lock.wait ();
} catch (InterruptedException e) {
interrupted = true;
}
}
if (interrupted) {
Compatibility.interrupt();
}
if (lock.throwable != null) {
SWT.error (SWT.ERROR_FAILED_EXEC, lock.throwable);
}
}
}
}
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