1 /*
2 * Copyright 2012 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the 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 public final class ExecutorUtil {
29
30 /**
31 * Returns {@code true} if and only if the specified {@code executor}
32 * is an {@link ExecutorService} and is shut down. Please note that this
33 * method returns {@code false} if the specified {@code executor} is not an
34 * {@link ExecutorService}.
35 */
36 public static boolean isShutdown(Executor executor) {
37 if (executor instanceof ExecutorService) {
38 if (((ExecutorService) executor).isShutdown()) {
39 return true;
40 }
41 }
42 return false;
43 }
44
45 /**
46 * Shuts down the specified executors.
47 */
48 public static void terminate(Executor... executors) {
49 terminate(DeadLockProofWorker.PARENT, executors);
50 }
51 /**
52 * Shuts down the specified executors using the given {@link ThreadLocal} to check if there is a deadlock
53 */
54 public static void terminate(ThreadLocal<Executor> deadLockChecker, Executor... executors) {
55 // Check nulls.
56 if (executors == null) {
57 throw new NullPointerException("executors");
58 }
59
60 Executor[] executorsCopy = new Executor[executors.length];
61 for (int i = 0; i < executors.length; i ++) {
62 if (executors[i] == null) {
63 throw new NullPointerException("executors[" + i + ']');
64 }
65 executorsCopy[i] = executors[i];
66 }
67
68 // Check dead lock.
69 final Executor currentParent = deadLockChecker.get();
70 if (currentParent != null) {
71 for (Executor e: executorsCopy) {
72 if (e == currentParent) {
73 throw new IllegalStateException(
74 "An Executor cannot be shut down from the thread " +
75 "acquired from itself. Please make sure you are " +
76 "not calling releaseExternalResources() from an " +
77 "I/O worker thread.");
78 }
79 }
80 }
81
82 // Shut down all executors.
83 boolean interrupted = false;
84 for (Executor e: executorsCopy) {
85 if (!(e instanceof ExecutorService)) {
86 continue;
87 }
88
89 ExecutorService es = (ExecutorService) e;
90 for (;;) {
91 try {
92 es.shutdownNow();
93 } catch (SecurityException ex) {
94 // Running in a restricted environment - fall back.
95 try {
96 es.shutdown();
97 } catch (SecurityException ex2) {
98 // Running in a more restricted environment.
99 // Can't shut down this executor - skip to the next.
100 break;
101 } catch (NullPointerException ex2) {
102 // Some JDK throws NPE here, but shouldn't.
103 }
104 } catch (NullPointerException ex) {
105 // Some JDK throws NPE here, but shouldn't.
106 }
107
108 try {
109 if (es.awaitTermination(100, TimeUnit.MILLISECONDS)) {
110 break;
111 }
112 } catch (InterruptedException ex) {
113 interrupted = true;
114 }
115 }
116 }
117
118 if (interrupted) {
119 Thread.currentThread().interrupt();
120 }
121 }
122
123 private ExecutorUtil() {
124 }
125 }