| /******************************************************************************* |
| * Copyright (c) 2006, 2007 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.jface.internal.databinding.provisional.swt; |
| |
| import java.util.HashSet; |
| import java.util.LinkedList; |
| import java.util.Set; |
| |
| import org.eclipse.swt.SWT; |
| import org.eclipse.swt.widgets.Display; |
| import org.eclipse.swt.widgets.Event; |
| import org.eclipse.swt.widgets.Listener; |
| |
| /** |
| * NON-API - Helper class to manage a queue of runnables to be posted to the UI thread in a way |
| * that they are only run once. |
| * @since 1.1 |
| * |
| */ |
| public class WorkQueue { |
| |
| private boolean updateScheduled = false; |
| |
| private boolean paintListenerAttached = false; |
| |
| private LinkedList pendingWork = new LinkedList(); |
| |
| private Display d; |
| |
| private Set pendingWorkSet = new HashSet(); |
| |
| private Runnable updateJob = new Runnable() { |
| public void run() { |
| doUpdate(); |
| updateScheduled = false; |
| } |
| }; |
| |
| private Listener paintListener = new Listener() { |
| public void handleEvent(Event event) { |
| paintListenerAttached = false; |
| d.removeFilter(SWT.Paint, this); |
| doUpdate(); |
| } |
| }; |
| |
| /** |
| * @param targetDisplay |
| */ |
| public WorkQueue(Display targetDisplay) { |
| d = targetDisplay; |
| } |
| |
| private void doUpdate() { |
| for (;;) { |
| Runnable next; |
| synchronized (pendingWork) { |
| if (pendingWork.isEmpty()) { |
| break; |
| } |
| next = (Runnable) pendingWork.removeFirst(); |
| pendingWorkSet.remove(next); |
| } |
| |
| next.run(); |
| } |
| } |
| |
| /** |
| * Schedules some work to happen in the UI thread as soon as possible. If |
| * possible, the work will happen before the next control redraws. The given |
| * runnable will only be run once. Has no effect if this runnable has |
| * already been queued for execution. |
| * |
| * @param work |
| * runnable to execute |
| */ |
| public void runOnce(Runnable work) { |
| synchronized (pendingWork) { |
| if (pendingWorkSet.contains(work)) { |
| return; |
| } |
| |
| pendingWorkSet.add(work); |
| |
| asyncExec(work); |
| } |
| } |
| |
| /** |
| * Schedules some work to happen in the UI thread as soon as possible. If |
| * possible, the work will happen before the next control redraws. Unlike |
| * runOnce, calling asyncExec twice with the same runnable will cause that |
| * runnable to run twice. |
| * |
| * @param work |
| * runnable to execute |
| */ |
| public void asyncExec(Runnable work) { |
| synchronized (pendingWork) { |
| pendingWork.add(work); |
| if (!updateScheduled) { |
| updateScheduled = true; |
| d.asyncExec(updateJob); |
| } |
| |
| // If we're in the UI thread, add an event filter to ensure |
| // the work happens ASAP |
| if (Display.getCurrent() == d) { |
| if (!paintListenerAttached) { |
| paintListenerAttached = true; |
| d.addFilter(SWT.Paint, paintListener); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Cancels a previously-scheduled runnable. Has no effect if the given |
| * runnable was not previously scheduled or has already executed. |
| * |
| * @param toCancel |
| * runnable to cancel |
| */ |
| public void cancelExec(Runnable toCancel) { |
| synchronized (pendingWork) { |
| pendingWork.remove(toCancel); |
| pendingWorkSet.remove(toCancel); |
| } |
| } |
| |
| /** |
| * Cancels all pending work. |
| */ |
| public void cancelAll() { |
| synchronized (pendingWork) { |
| pendingWork.clear(); |
| pendingWorkSet.clear(); |
| } |
| } |
| } |