/* | |
* Licensed to the Apache Software Foundation (ASF) under one or more | |
* contributor license agreements. See the NOTICE file distributed with | |
* this work for additional information regarding copyright ownership. | |
* The ASF licenses this file to You 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 org.apache.struts2.jasper.util; | |
import java.util.Vector; | |
/** | |
* A simple FIFO queue class which causes the calling thread to wait | |
* if the queue is empty and notifies threads that are waiting when it | |
* is not empty. | |
* | |
* @author Anil V (akv@eng.sun.com) | |
*/ | |
public class Queue { | |
private Vector vector = new Vector(); | |
/** | |
* Put the object into the queue. | |
* | |
* @param object the object to be appended to the | |
* queue. | |
*/ | |
public synchronized void put(Object object) { | |
vector.addElement(object); | |
notify(); | |
} | |
/** | |
* Pull the first object out of the queue. Wait if the queue is | |
* empty. | |
*/ | |
public synchronized Object pull() { | |
while (isEmpty()) | |
try { | |
wait(); | |
} catch (InterruptedException ex) { | |
} | |
return get(); | |
} | |
/** | |
* Get the first object out of the queue. Return null if the queue | |
* is empty. | |
*/ | |
public synchronized Object get() { | |
Object object = peek(); | |
if (object != null) | |
vector.removeElementAt(0); | |
return object; | |
} | |
/** | |
* Peek to see if something is available. | |
*/ | |
public Object peek() { | |
if (isEmpty()) | |
return null; | |
return vector.elementAt(0); | |
} | |
/** | |
* Is the queue empty? | |
*/ | |
public boolean isEmpty() { | |
return vector.isEmpty(); | |
} | |
/** | |
* How many elements are there in this queue? | |
*/ | |
public int size() { | |
return vector.size(); | |
} | |
} |