1 /*
2 * Copyright 2009 Red Hat, Inc.
3 *
4 * Red Hat licenses this file to you under the Apache License, version 2.0
5 * (the "License"); you may not use this file except in compliance with the
6 * License. You may obtain a copy of the License at:
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package org.jboss.netty.util.internal;
17
18 import java.util.concurrent.Executor;
19 import java.util.concurrent.ExecutorService;
20 import java.util.concurrent.TimeUnit;
21
22 /**
23 * Shuts down a list of {@link Executor}s. {@link #terminate(Executor...)} will
24 * shut down all specified {@link ExecutorService}s immediately and wait for
25 * their termination. An {@link Executor} which is not an {@link ExecutorService}
26 * will be ignored silently.
27 *
28 * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
29 * @author <a href="http://gleamynode.net/">Trustin Lee</a>
30 * @version $Rev: 2080 $, $Date: 2010-01-26 18:04:19 +0900 (Tue, 26 Jan 2010) $
31 */
32 public class ExecutorUtil {
33
34 /**
35 * Returns {@code true} if and only if the specified {@code executor}
36 * is an {@link ExecutorService} and is shut down. Please note that this
37 * method returns {@code false} if the specified {@code executor} is not an
38 * {@link ExecutorService}.
39 */
40 public static boolean isShutdown(Executor executor) {
41 if (executor instanceof ExecutorService) {
42 if (((ExecutorService) executor).isShutdown()) {
43 return true;
44 }
45 }
46 return false;
47 }
48
49 /**
50 * Shuts down the specified executors.
51 */
52 public static void terminate(Executor... executors) {
53 // Check nulls.
54 if (executors == null) {
55 throw new NullPointerException("executors");
56 }
57
58 Executor[] executorsCopy = new Executor[executors.length];
59 for (int i = 0; i < executors.length; i ++) {
60 if (executors[i] == null) {
61 throw new NullPointerException("executors[" + i + "]");
62 }
63 executorsCopy[i] = executors[i];
64 }
65
66 // Check dead lock.
67 final Executor currentParent = DeadLockProofWorker.PARENT.get();
68 if (currentParent != null) {
69 for (Executor e: executorsCopy) {
70 if (e == currentParent) {
71 throw new IllegalStateException(
72 "An Executor cannot be shut down from the thread " +
73 "acquired from itself. Please make sure you are " +
74 "not calling releaseExternalResources() from an " +
75 "I/O worker thread.");
76 }
77 }
78 }
79
80 // Shut down all executors.
81 boolean interrupted = false;
82 for (Executor e: executorsCopy) {
83 if (!(e instanceof ExecutorService)) {
84 continue;
85 }
86
87 ExecutorService es = (ExecutorService) e;
88 for (;;) {
89 try {
90 es.shutdownNow();
91 } catch (SecurityException ex) {
92 // Running in a restricted environment - fall back.
93 try {
94 es.shutdown();
95 } catch (SecurityException ex2) {
96 // Running in a more restricted environment.
97 // Can't shut down this executor - skip to the next.
98 break;
99 } catch (NullPointerException ex2) {
100 // Some JDK throws NPE here, but shouldn't.
101 }
102 } catch (NullPointerException ex) {
103 // Some JDK throws NPE here, but shouldn't.
104 }
105
106 try {
107 if (es.awaitTermination(100, TimeUnit.MILLISECONDS)) {
108 break;
109 }
110 } catch (InterruptedException ex) {
111 interrupted = true;
112 }
113 }
114 }
115
116 if (interrupted) {
117 Thread.currentThread().interrupt();
118 }
119 }
120
121 private ExecutorUtil() {
122 super();
123 }
124 }