1 /**
2 * Copyright (C) 2005-2009 Alfresco Software Limited.
3 *
4 * This file is part of the Spring Surf Extension project.
5 *
6 * Licensed under the Apache License, Version 2.0 (the "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19 package org.springframework.extensions.surf.task;
20
21 import java.util.Queue;
22
23 import org.apache.commons.logging.Log;
24 import org.apache.commons.logging.LogFactory;
25
26 /**
27 * Background thread that wakes up periodically to monitor the task manager's
28 * pool of tasks waiting to be processed. If it finds one, it notifies all
29 * worker threads so that someone will pick up the task and begin to work on it.
30 *
31 * @author muzquiano
32 */
33 public class TaskStarterThread extends Thread
34 {
35 private static Log logger = LogFactory.getLog(TaskStarterThread.class);
36
37 protected TaskManager taskManager;
38
39 /**
40 * Instantiates a new task starter thread.
41 */
42 public TaskStarterThread(TaskManager taskManager)
43 {
44 this.taskManager = taskManager;
45 }
46
47 /*
48 * (non-Javadoc)
49 *
50 * @see java.lang.Thread#run()
51 */
52 public void run()
53 {
54 while (true)
55 {
56 try
57 {
58 // sleep for a bit
59 Thread.sleep(taskManager.getWakeupPeriod());
60
61 // check whether the task queue has anything in it
62 Queue<AbstractTask> taskQueue = taskManager.getTaskQueue();
63
64 // if there are tasks to do
65 if (taskQueue.size() > 0)
66 {
67 // peek at the first tasks in the queue
68 AbstractTask task = (AbstractTask) taskQueue.peek();
69 if(task != null)
70 {
71 // in fact, there is a task...
72 if (logger.isDebugEnabled())
73 {
74 logger.debug("Found a job to start (" + task.getName() + ")");
75 logger.debug("Attempting to wake up threads");
76 }
77
78 // wake up all of the workers who are waiting
79 synchronized (taskManager.getClass())
80 {
81 taskManager.getClass().notifyAll();
82 }
83 }
84 }
85 }
86 catch (Throwable t)
87 {
88 t.printStackTrace();
89 }
90 }
91 }
92
93 }