1 /*
2 * Copyright (C) 2008-2016, Google Inc.
3 * and other copyright owners as documented in the project's IP log.
4 *
5 * This program and the accompanying materials are made available
6 * under the terms of the Eclipse Distribution License v1.0 which
7 * accompanies this distribution, is reproduced below, and is
8 * available at http://www.eclipse.org/org/documents/edl-v10.php
9 *
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or
13 * without modification, are permitted provided that the following
14 * conditions are met:
15 *
16 * - Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 *
19 * - Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials provided
22 * with the distribution.
23 *
24 * - Neither the name of the Eclipse Foundation, Inc. nor the
25 * names of its contributors may be used to endorse or promote
26 * products derived from this software without specific prior
27 * written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
30 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
31 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
34 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
35 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
37 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
38 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
40 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
41 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
42 */
43
44 package org.eclipse.jgit.lib.internal;
45
46 import java.util.concurrent.Executors;
47 import java.util.concurrent.ScheduledThreadPoolExecutor;
48 import java.util.concurrent.ThreadFactory;
49
50 /**
51 * Simple work queue to run tasks in the background
52 */
53 public class WorkQueue {
54 private static final ScheduledThreadPoolExecutor executor;
55
56 static final Object executorKiller;
57
58 static {
59 // To support garbage collection, start our thread but
60 // swap out the thread factory. When our class is GC'd
61 // the executorKiller will finalize and ask the executor
62 // to shutdown, ending the worker.
63 //
64 int threads = 1;
65 executor = new ScheduledThreadPoolExecutor(threads,
66 new ThreadFactory() {
67 private final ThreadFactory baseFactory = Executors
68 .defaultThreadFactory();
69
70 @Override
71 public Thread newThread(Runnable taskBody) {
72 Thread thr = baseFactory.newThread(taskBody);
73 thr.setName("JGit-WorkQueue"); //$NON-NLS-1$
74 thr.setContextClassLoader(null);
75 thr.setDaemon(true);
76 return thr;
77 }
78 });
79 executor.setRemoveOnCancelPolicy(true);
80 executor.setContinueExistingPeriodicTasksAfterShutdownPolicy(false);
81 executor.setExecuteExistingDelayedTasksAfterShutdownPolicy(false);
82 executor.prestartAllCoreThreads();
83
84 // Now that the threads are running, its critical to swap out
85 // our own thread factory for one that isn't in the ClassLoader.
86 // This allows the class to GC.
87 //
88 executor.setThreadFactory(Executors.defaultThreadFactory());
89
90 executorKiller = new Object() {
91 @Override
92 protected void finalize() {
93 executor.shutdownNow();
94 }
95 };
96 }
97
98 /**
99 * Get the WorkQueue's executor
100 *
101 * @return the WorkQueue's executor
102 */
103 public static ScheduledThreadPoolExecutor getExecutor() {
104 return executor;
105 }
106 }