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 * Try to call {@link ExecutorService#shutdownNow()}
32 */
33 public static void shutdownNow(Executor executor) {
34 if (executor instanceof ExecutorService) {
35 ExecutorService es = (ExecutorService) executor;
36 try {
37 es.shutdownNow();
38 } catch (SecurityException ex) {
39 // Running in a restricted environment - fall back.
40 try {
41 es.shutdown();
42 } catch (SecurityException ex2) {
43 // Running in a more restricted environment.
44 // Can't shut down this executor - skip to the next.
45 } catch (NullPointerException ex2) {
46 // Some JDK throws NPE here, but shouldn't.
47 }
48 } catch (NullPointerException ex) {
49 // Some JDK throws NPE here, but shouldn't.
50 }
51 }
52 }
53
54 /**
55 * Returns {@code true} if and only if the specified {@code executor}
56 * is an {@link ExecutorService} and is shut down. Please note that this
57 * method returns {@code false} if the specified {@code executor} is not an
58 * {@link ExecutorService}.
59 */
60 public static boolean isShutdown(Executor executor) {
61 if (executor instanceof ExecutorService) {
62 if (((ExecutorService) executor).isShutdown()) {
63 return true;
64 }
65 }
66 return false;
67 }
68
69 /**
70 * Shuts down the specified executors.
71 */
72 public static void terminate(Executor... executors) {
73 terminate(DeadLockProofWorker.PARENT, executors);
74 }
75 /**
76 * Shuts down the specified executors using the given {@link ThreadLocal} to check if there is a deadlock
77 */
78 public static void terminate(ThreadLocal<Executor> deadLockChecker, Executor... executors) {
79 // Check nulls.
80 if (executors == null) {
81 throw new NullPointerException("executors");
82 }
83
84 Executor[] executorsCopy = new Executor[executors.length];
85 for (int i = 0; i < executors.length; i ++) {
86 if (executors[i] == null) {
87 throw new NullPointerException("executors[" + i + ']');
88 }
89 executorsCopy[i] = executors[i];
90 }
91
92 // Check dead lock.
93 final Executor currentParent = deadLockChecker.get();
94 if (currentParent != null) {
95 for (Executor e: executorsCopy) {
96 if (e == currentParent) {
97 throw new IllegalStateException(
98 "An Executor cannot be shut down from the thread " +
99 "acquired from itself. Please make sure you are " +
100 "not calling releaseExternalResources() from an " +
101 "I/O worker thread.");
102 }
103 }
104 }
105
106 // Shut down all executors.
107 boolean interrupted = false;
108 for (Executor e: executorsCopy) {
109 if (!(e instanceof ExecutorService)) {
110 continue;
111 }
112
113 ExecutorService es = (ExecutorService) e;
114 for (;;) {
115 shutdownNow(es);
116
117 try {
118 if (es.awaitTermination(100, TimeUnit.MILLISECONDS)) {
119 break;
120 }
121 } catch (InterruptedException ex) {
122 interrupted = true;
123 }
124 }
125 }
126
127 if (interrupted) {
128 Thread.currentThread().interrupt();
129 }
130 }
131
132 private ExecutorUtil() {
133 }
134 }
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