Queue.java

00001 /*
00002  * Copyright (c) 2003, KNOPFLERFISH project
00003  * All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following
00007  * conditions are met:
00008  *
00009  * - Redistributions of source code must retain the above copyright
00010  *   notice, this list of conditions and the following disclaimer.
00011  *
00012  * - Redistributions in binary form must reproduce the above
00013  *   copyright notice, this list of conditions and the following
00014  *   disclaimer in the documentation and/or other materials
00015  *   provided with the distribution.
00016  *
00017  * - Neither the name of the KNOPFLERFISH project nor the names of its
00018  *   contributors may be used to endorse or promote products derived
00019  *   from this software without specific prior written permission.
00020  *
00021  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
00022  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00023  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00024  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
00025  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00026  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
00027  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
00028  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
00029  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
00030  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
00031  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
00032  * OF THE POSSIBILITY OF SUCH DAMAGE.
00033  */
00034 
00035 package org.knopflerfish.framework;
00036 
00037 import java.util.Vector;
00038 
00044 public class Queue extends Vector {
00045   private int m_nMaxSize = -1;
00046   private boolean queueClosed = false;
00047   
00048   //  ====================    Queue      ====================
00054   public Queue(int size)
00055   {
00056     m_nMaxSize = size;
00057   }
00058  
00059   //  ====================    insert      ====================
00067   public synchronized void insert(Object item) throws IndexOutOfBoundsException
00068   {
00069     // Check if queue is full
00070     if (m_nMaxSize > 0 && size() >= m_nMaxSize) 
00071       throw new IndexOutOfBoundsException("Queue full");
00072 
00073     addElement(item);
00074     notify();
00075   }
00076 
00077   //  ====================    insertFirst      ====================
00084   public synchronized void insertFirst(Object item)
00085   {
00086     insertElementAt(item, 0);
00087     notify();
00088   }
00089 
00090   //  ====================    remove      ====================
00100   public synchronized Object removeWait(float timeout)
00101   {
00102     Object obj = null;
00103 
00104     // If queue is empty wait for object to be inserted
00105     if (isEmpty() && !queueClosed) {
00106       try {
00107         if (timeout > 0) {
00108           wait(Math.round(timeout * 1000.0f));
00109         } else
00110           wait();
00111       } catch (InterruptedException e) {}
00112     }
00113 
00114     if (queueClosed) {
00115       return null;
00116     }    
00117     
00118     try {
00119       obj = firstElement();
00120       removeElementAt(0);
00121     } catch (Exception e) {}
00122  
00123     return obj;
00124   }
00125 
00126   //  ====================    remove      ====================
00134   public Object remove()
00135   {
00136     return removeWait(0);
00137   }
00138 
00139 
00140   //  ====================     close     ====================
00146   public synchronized void close() {
00147     queueClosed = true;
00148     notifyAll();
00149   }
00150   
00151 }
00152 

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