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package org.eclipse.swt.widgets;
/*
* Licensed Materials - Property of IBM,
* (c) Copyright IBM Corp. 1998, 2001 All Rights Reserved
*/
/**
* 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 messagesSize;
RunnableLock [] messages;
Object messageLock = new Object ();
Thread syncThread;
public Synchronizer (Display display) {
this.display = display;
}
void addLast (RunnableLock entry) {
synchronized (messageLock) {
if (messages == null) messages = new RunnableLock [4];
if (messagesSize == messages.length) {
RunnableLock[] newMessages = new RunnableLock [messagesSize + 4];
System.arraycopy (messages, 0, newMessages, 0, messagesSize);
messages = newMessages;
}
messages [messagesSize++] = entry;
}
}
/**
* 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) addLast (new RunnableLock (runnable));
display.wake ();
}
void releaseSynchronizer () {
display = null;
messages = null;
messageLock = null;
syncThread = null;
}
RunnableLock removeFirst () {
synchronized (messageLock) {
if (messagesSize == 0) return null;
RunnableLock lock = messages [0];
System.arraycopy (messages, 1, messages, 0, --messagesSize);
messages [messagesSize] = null;
if (messagesSize == 0) messages = null;
return lock;
}
}
boolean runAsyncMessages () {
if (messagesSize == 0) return false;
do {
RunnableLock lock = removeFirst ();
if (lock == null) return true;
synchronized (lock) {
syncThread = lock.thread;
try {
lock.run ();
} finally {
syncThread = null;
}
lock.notifyAll ();
};
} while (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.
*
* @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);
display.wake ();
boolean interrupted = false;
while (!lock.done ()) {
try {
lock.wait ();
} catch (InterruptedException e) {
interrupted = true;
}
}
if (interrupted) {
Thread.currentThread ().interrupt ();
}
}
}
}
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