/*
* Copyright 2010-2011 Research In Motion Limited.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package blackberry.system.event;
import java.util.Vector;
import blackberry.system.event.SystemEventReturnValue;
/** Thread safe queue implementation based on Vector.
*
* @author ababut
*/
public class EventQueue {
private Vector _queue;
private Object _lock;
EventQueue() {
_queue = new Vector();
_lock = new Object();
}
/**
* Queues a SystemReturnValue object and signals the lock that there are items
* waiting.
*
* @param event the event to queue up
*/
public void enqueue(SystemEventReturnValue event) {
synchronized(_lock) {
_queue.addElement(event);
_lock.notify();
}
}
/**
* Removes first SystemReturnValue object in queue. If queue is empty, wait
* on lock until signalled.
*
* @param event the event to queue up
*/
public SystemEventReturnValue dequeueWaitIfEmpty() {
SystemEventReturnValue result = null;
if(_queue.isEmpty()) {
try {
synchronized(_lock) {
_lock.wait();
}
} catch(InterruptedException e) {
System.out.println("InterrupedException while waiting on event queue");
throw new RuntimeException("Polling thread interrupted while waiting.");
}
}
synchronized(_lock) {
result = (SystemEventReturnValue)_queue.elementAt(0);
_queue.removeElementAt(0);
}
return result;
}
}