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Java > Open Source Codes > net > jforum > util > concurrent > executor > QueuedExecutor


1 /*
2  * Copyright (c) 2003, Rafael Steil
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms,
6  * with or without modification, are permitted provided
7  * that the following conditions are met:
8  *
9  * 1) Redistributions of source code must retain the above
10  * copyright notice, this list of conditions and the
11  * following disclaimer.
12  * 2) Redistributions in binary form must reproduce the
13  * above copyright notice, this list of conditions and
14  * the following disclaimer in the documentation and/or
15  * other materials provided with the distribution.
16  * 3) Neither the name of "Rafael Steil" nor
17  * the names of its contributors may be used to endorse
18  * or promote products derived from this software without
19  * specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT
22  * HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
23  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
24  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
25  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR
26  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
27  * THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
29  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES
30  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
32  * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
33  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
34  * IN CONTRACT, STRICT LIABILITY, OR TORT
35  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
36  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
37  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
38  *
39  * This file creation date: Jan 28, 2004
40  * The JForum Project
41  * http://www.jforum.net
42  */
43 package net.jforum.util.concurrent.executor;
44
45 import net.jforum.util.concurrent.Executor;
46 import net.jforum.util.concurrent.Queue;
47 import net.jforum.util.concurrent.Result;
48 import net.jforum.util.concurrent.Task;
49 import net.jforum.util.concurrent.queue.UnboundedFifoQueue;
50 import net.jforum.util.preferences.ConfigKeys;
51 import net.jforum.util.preferences.SystemGlobals;
52
53 import org.apache.log4j.Logger;
54
55 /**
56  * @author Rodrigo Kumpera
57  * @version $Id: QueuedExecutor.java,v 1.11 2005/07/26 04:01:15 diegopires Exp $
58  */
59 public class QueuedExecutor implements Executor
60 {
61     private Thread JavaDoc currentThread;
62     private final Queue queue;
63     private final Object JavaDoc lock = new Object JavaDoc();
64     private static final Logger logger = Logger.getLogger(QueuedExecutor.class);
65     
66     private static QueuedExecutor instance = new QueuedExecutor(new UnboundedFifoQueue());
67     
68     private QueuedExecutor(Queue queue)
69     {
70         logger.info("Setting queue...");
71         this.queue = queue;
72     }
73     
74     public static QueuedExecutor getInstance()
75     {
76         return instance;
77     }
78     
79     private class WorkerThread extends AbstractWorker
80     {
81         protected Object JavaDoc take() throws InterruptedException JavaDoc
82         {
83             return queue.get();
84         }
85         
86         protected void cleanup()
87         {
88             synchronized(lock) {
89                 currentThread = null;
90                 logger.info("Cleaning up the thread...");
91             }
92         }
93     }
94
95     public void execute(Task task) throws InterruptedException JavaDoc
96     {
97         if (SystemGlobals.getBoolValue(ConfigKeys.BACKGROUND_TASKS)) {
98             queue.put(task);
99             synchronized(lock) {
100                 if(currentThread == null) {
101                     logger.info("Creating a new thread...");
102                     
103                     currentThread = new Thread JavaDoc(new WorkerThread(), "jforum");
104                     currentThread.setDaemon(true);
105                     currentThread.start();
106                 }
107             }
108         }
109         else {
110             try {
111                 task.execute();
112             }
113             catch (Exception JavaDoc e) {
114                 logger.warn("Error while executing a task: " + e);
115             }
116         }
117     }
118     
119     public Result executeWithResult(Task task) throws InterruptedException JavaDoc
120     {
121         SimpleResult result = new SimpleResult(task);
122         queue.put(result);
123         
124         synchronized(lock) {
125             if(currentThread == null) {
126                 currentThread = new Thread JavaDoc(new WorkerThread(), "jforum");
127                 currentThread.setDaemon(true);
128                 currentThread.setName(this.getClass().getName() + "Thread");
129
130                 currentThread.start();
131             }
132         }
133
134         return result;
135     }
136 }
137
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