| /******************************************************************************* |
| * Copyright (c) 2003, 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.osgi.framework.eventmgr; |
| |
| /** |
| * The ListenerQueue is used to snapshot the set of listeners at the time the event |
| * is fired. The snapshot list is then used to dispatch |
| * events to those listeners. A ListenerQueue object is associated with a |
| * specific EventManager object. ListenerQueue objects that use the same |
| * EventManager object will get in order delivery of events |
| * within each delivery class: synchronous and asynchronous. |
| * |
| * <p>ListenerQueue objects are created as necesssary to build a set of listeners |
| * that should receive a specific event or events. Once the set is created, the event |
| * can then be synchronously or asynchronously delivered to the set of |
| * listeners. After the event has been dispatched for delivery, the |
| * ListenerQueue object should be discarded as it is likely the list of listeners is stale. |
| * A new ListenerQueue object should be created when it is time to deliver |
| * another event. |
| */ |
| |
| public class ListenerQueue { |
| /** |
| * EventManager with which this queue is associated. |
| */ |
| protected EventManager manager; |
| /** |
| * A list of listener lists. |
| */ |
| protected ElementList queue; |
| |
| /** |
| * Once the listener queue has been used to dispatch an event, |
| * you cannot add modify the queue. |
| */ |
| private boolean readOnly; |
| |
| /** |
| * ListenerQueue constructor. This method creates an empty event queue. |
| * |
| * @param manager The EventManager this queue is associated with. |
| * @throws IllegalArgumentException If manager is null. |
| */ |
| public ListenerQueue(EventManager manager) { |
| if (manager == null) { |
| throw new IllegalArgumentException(); |
| } |
| |
| this.manager = manager; |
| queue = new ElementList(); |
| readOnly = false; |
| } |
| |
| /** |
| * Build the set of listeners. This method can be called multiple times, prior to |
| * calling one of the dispatchEvent methods, to build the set of listeners for the |
| * delivery of a specific event. The current list of listeners in the specified EventListeners, |
| * at the time this method is called, is added to the set. |
| * |
| * @param listeners An EventListeners object to add to the queue. All listeners |
| * previously added to |
| * the EventListeners object will be called when an event is dispatched. |
| * @param dispatcher An EventDispatcher object to use when dispatching an event |
| * to the listeners on this ElementList. |
| * @throws IllegalStateException If called after one of the dispatch methods has been called. |
| */ |
| public synchronized void queueListeners(EventListeners listeners, EventDispatcher dispatcher) { |
| if (readOnly) { |
| throw new IllegalStateException(); |
| } |
| |
| if (listeners != null) { |
| ListElement[] list = listeners.getListeners(); |
| |
| if (list.length > 0) { |
| queue.addElement(new ListElement(list, dispatcher)); |
| } |
| } |
| } |
| |
| /** |
| * Asynchronously dispatch an event to the set of listeners. An event dispatch thread |
| * maintained by the associated EventManager is used to deliver the events. |
| * This method may return immediately to the caller. |
| * |
| * @param eventAction This value is passed to the EventDispatcher. |
| * @param eventObject This object is passed to the EventDispatcher. |
| */ |
| public void dispatchEventAsynchronous(int eventAction, Object eventObject) { |
| ListElement[] lists; |
| |
| synchronized (this) { |
| readOnly = true; |
| lists = queue.getElements(); |
| } |
| EventThread eventThread = manager.getEventThread(); |
| synchronized (eventThread) { /* synchronize on the EventThread to ensure no interleaving of posting to the event thread */ |
| int size = lists.length; |
| for (int i = 0; i < size; i++) { /* iterate over the list of listener lists */ |
| ListElement list = lists[i]; |
| eventThread.postEvent((ListElement[]) list.primary, (EventDispatcher) list.companion, eventAction, eventObject); |
| } |
| } |
| } |
| |
| /** |
| * Synchronously dispatch an event to the set of listeners. The event may |
| * be dispatched on the current thread or an event dispatch thread |
| * maintained by the associated EventManager. |
| * This method will not return to the caller until the EventDispatcher |
| * has been called (and returned) for each listener on the queue. |
| * |
| * @param eventAction This value is passed to the EventDispatcher. |
| * @param eventObject This object is passed to the EventDispatcher. |
| */ |
| public void dispatchEventSynchronous(int eventAction, Object eventObject) { |
| ListElement[] lists; |
| |
| synchronized (this) { |
| readOnly = true; |
| lists = queue.getElements(); |
| } |
| synchronized (manager) { /* synchronize on the EventManager to ensure no interleaving of event delivery */ |
| int size = lists.length; |
| for (int i = 0; i < size; i++) { /* iterate over the list of listener lists */ |
| ListElement list = lists[i]; |
| EventManager.dispatchEvent((ListElement[]) list.primary, (EventDispatcher) list.companion, eventAction, eventObject); |
| } |
| } |
| } |
| } |