| /******************************************************************************* |
| * Copyright (c) 2005 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 |
| *******************************************************************************/ |
| /* |
| * $RCSfile$ |
| * $Revision$ $Date$ |
| */ |
| package org.eclipse.jem.internal.proxy.common; |
| |
| import java.util.LinkedList; |
| |
| /** |
| * A generic event queue. It runs on its own thread and will execute any queued up runnables. |
| * <p> |
| * When a runnable is added to the queue, the thread will be notified. If the thread is free it will |
| * run the runnable. If it is not free, the runnable will be added to the queue. The thread will process |
| * all intervening runnables and then execute the runnable in sequence with all of the rest. |
| * <p> |
| * This is used when you can't use the system widget (e.g. AWT event queue or SWT asyncExec) or when the |
| * runnable must be executed on a non-ui thread. |
| * <p> |
| * <b>Note:</b> It is required that {@link #close()} be called so that resources are cleared up. |
| * |
| * @since 1.1.0.1 |
| */ |
| public class GenericEventQueue { |
| |
| private LinkedList queue = new LinkedList(); |
| |
| private class EventThread extends Thread { |
| private boolean run = true; |
| |
| public EventThread(String title) { |
| super(title); |
| } |
| |
| public void close() { |
| synchronized (queue) { |
| run = false; |
| queue.clear(); |
| queue.notifyAll(); |
| } |
| } |
| |
| public void postEvent(Runnable run) { |
| if (!this.isAlive()) { |
| throw new IllegalStateException("Event queue thread is not executing."); //$NON-NLS-1$ |
| } |
| synchronized (queue) { |
| if (run != null) |
| queue.addLast(run); |
| queue.notifyAll(); |
| } |
| } |
| |
| public void run() { |
| while (true) { |
| Runnable runnable; |
| synchronized (queue) { |
| while (run && queue.isEmpty()) { |
| try { |
| queue.wait(); |
| } catch (InterruptedException e) { |
| } |
| } |
| if (!run) |
| return; // Done. |
| else { |
| runnable = (Runnable) queue.removeFirst(); |
| } |
| } |
| |
| try { |
| runnable.run(); |
| } catch (RuntimeException e) { |
| e.printStackTrace(); |
| } finally { |
| runnable = null; // Set this so that we don't hold onto resources in the runnable while waiting for next quy. |
| } |
| } |
| } |
| } |
| |
| private EventThread eventThread; |
| |
| /** |
| * Construct with a title. (This title will be the title on the Thread for the queue). |
| * The thread will have the same priority as the current thread. |
| * @param queueTitle |
| * |
| * @since 1.1.0.1 |
| */ |
| public GenericEventQueue(String queueTitle) { |
| this(queueTitle, Thread.currentThread().getPriority()); |
| } |
| |
| /** |
| * Construct with a title. (This title will be the title on the Thread for the queue). |
| * And a priority for the event queue's processing thread. |
| * @param queueTitle |
| * @param priority priority to use for event queue's thread. |
| * |
| * @since 1.1.0.1 |
| */ |
| public GenericEventQueue(String queueTitle, int priority) { |
| eventThread = new EventThread(queueTitle); |
| eventThread.setPriority(priority); |
| synchronized(queue) { |
| eventThread.start(); |
| try { |
| queue.wait(100); // Wait for thread to start. |
| } catch (InterruptedException e) { |
| } |
| } |
| } |
| |
| /** |
| * Close the event queue. This will clear out any pending events. They will not |
| * be executed. |
| * |
| * |
| * @since 1.1.0.1 |
| */ |
| public void close() { |
| eventThread.close(); |
| } |
| |
| /** |
| * Post the event. |
| * @param runnable runnable to execute, or <code>null</code> to kick-start the thread if for some reason it may be waiting and it shouldn't be. |
| * |
| * @throws IllegalStateException thrown if the event queue thread has already been closed, or ended for some severe error. |
| * @since 1.1.0.1 |
| */ |
| public void postEvent(Runnable runnable) { |
| eventThread.postEvent(runnable); |
| } |
| |
| } |