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| 1 | +/* | |
| 2 | + * Copyright (c) 2008, 2009, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | + | |
| 26 | +package sun.nio.ch; | |
| 27 | + | |
| 28 | +import java.util.concurrent.*; | |
| 29 | +import java.security.AccessController; | |
| 30 | +import sun.security.action.GetPropertyAction; | |
| 31 | +import sun.security.action.GetIntegerAction; | |
| 32 | + | |
| 33 | +/** | |
| 34 | + * Encapsulates a thread pool associated with a channel group. | |
| 35 | + */ | |
| 36 | + | |
| 37 | +public class ThreadPool { | |
| 38 | + private static final String DEFAULT_THREAD_POOL_THREAD_FACTORY = | |
| 39 | + "java.nio.channels.DefaultThreadPool.threadFactory"; | |
| 40 | + private static final String DEFAULT_THREAD_POOL_INITIAL_SIZE = | |
| 41 | + "java.nio.channels.DefaultThreadPool.initialSize"; | |
| 42 | + private static final ThreadFactory defaultThreadFactory = new ThreadFactory() { | |
| 43 | + @Override | |
| 44 | + public Thread newThread(Runnable r) { | |
| 45 | + Thread t = new Thread(r); | |
| 46 | + t.setDaemon(true); | |
| 47 | + return t; | |
| 48 | + } | |
| 49 | + }; | |
| 50 | + | |
| 51 | + private final ExecutorService executor; | |
| 52 | + | |
| 53 | + // indicates if thread pool is fixed size | |
| 54 | + private final boolean isFixed; | |
| 55 | + | |
| 56 | + // indicates the pool size (for a fixed thread pool configuratin this is | |
| 57 | + // the maximum pool size; for other thread pools it is the initial size) | |
| 58 | + private final int poolSize; | |
| 59 | + | |
| 60 | + private ThreadPool(ExecutorService executor, | |
| 61 | + boolean isFixed, | |
| 62 | + int poolSize) | |
| 63 | + { | |
| 64 | + this.executor = executor; | |
| 65 | + this.isFixed = isFixed; | |
| 66 | + this.poolSize = poolSize; | |
| 67 | + } | |
| 68 | + | |
| 69 | + ExecutorService executor() { | |
| 70 | + return executor; | |
| 71 | + } | |
| 72 | + | |
| 73 | + boolean isFixedThreadPool() { | |
| 74 | + return isFixed; | |
| 75 | + } | |
| 76 | + | |
| 77 | + int poolSize() { | |
| 78 | + return poolSize; | |
| 79 | + } | |
| 80 | + | |
| 81 | + static ThreadFactory defaultThreadFactory() { | |
| 82 | + return defaultThreadFactory; | |
| 83 | + } | |
| 84 | + | |
| 85 | + private static class DefaultThreadPoolHolder { | |
| 86 | + final static ThreadPool defaultThreadPool = createDefault(); | |
| 87 | + } | |
| 88 | + | |
| 89 | + // return the default (system-wide) thread pool | |
| 90 | + static ThreadPool getDefault() { | |
| 91 | + return DefaultThreadPoolHolder.defaultThreadPool; | |
| 92 | + } | |
| 93 | + | |
| 94 | + // create thread using default settings (configured by system properties) | |
| 95 | + static ThreadPool createDefault() { | |
| 96 | + // default the number of fixed threads to the hardware core count | |
| 97 | + int initialSize = getDefaultThreadPoolInitialSize(); | |
| 98 | + if (initialSize < 0) | |
| 99 | + initialSize = Runtime.getRuntime().availableProcessors(); | |
| 100 | + // default to thread factory that creates daemon threads | |
| 101 | + ThreadFactory threadFactory = getDefaultThreadPoolThreadFactory(); | |
| 102 | + if (threadFactory == null) | |
| 103 | + threadFactory = defaultThreadFactory; | |
| 104 | + // create thread pool | |
| 105 | + ExecutorService executor = | |
| 106 | + new ThreadPoolExecutor(0, Integer.MAX_VALUE, | |
| 107 | + Long.MAX_VALUE, TimeUnit.MILLISECONDS, | |
| 108 | + new SynchronousQueue<Runnable>(), | |
| 109 | + threadFactory); | |
| 110 | + return new ThreadPool(executor, false, initialSize); | |
| 111 | + } | |
| 112 | + | |
| 113 | + // create using given parameters | |
| 114 | + static ThreadPool create(int nThreads, ThreadFactory factory) { | |
| 115 | + if (nThreads <= 0) | |
| 116 | + throw new IllegalArgumentException("'nThreads' must be > 0"); | |
| 117 | + ExecutorService executor = Executors.newFixedThreadPool(nThreads, factory); | |
| 118 | + return new ThreadPool(executor, true, nThreads); | |
| 119 | + } | |
| 120 | + | |
| 121 | + // wrap a user-supplied executor | |
| 122 | + public static ThreadPool wrap(ExecutorService executor, int initialSize) { | |
| 123 | + if (executor == null) | |
| 124 | + throw new NullPointerException("'executor' is null"); | |
| 125 | + // attempt to check if cached thread pool | |
| 126 | + if (executor instanceof ThreadPoolExecutor) { | |
| 127 | + int max = ((ThreadPoolExecutor)executor).getMaximumPoolSize(); | |
| 128 | + if (max == Integer.MAX_VALUE) { | |
| 129 | + if (initialSize < 0) { | |
| 130 | + initialSize = Runtime.getRuntime().availableProcessors(); | |
| 131 | + } else { | |
| 132 | + // not a cached thread pool so ignore initial size | |
| 133 | + initialSize = 0; | |
| 134 | + } | |
| 135 | + } | |
| 136 | + } else { | |
| 137 | + // some other type of thread pool | |
| 138 | + if (initialSize < 0) | |
| 139 | + initialSize = 0; | |
| 140 | + } | |
| 141 | + return new ThreadPool(executor, false, initialSize); | |
| 142 | + } | |
| 143 | + | |
| 144 | + private static int getDefaultThreadPoolInitialSize() { | |
| 145 | + String propValue = AccessController.doPrivileged(new | |
| 146 | + GetPropertyAction(DEFAULT_THREAD_POOL_INITIAL_SIZE)); | |
| 147 | + if (propValue != null) { | |
| 148 | + try { | |
| 149 | + return Integer.parseInt(propValue); | |
| 150 | + } catch (NumberFormatException x) { | |
| 151 | + throw new Error("Value of property '" + DEFAULT_THREAD_POOL_INITIAL_SIZE + | |
| 152 | + "' is invalid: " + x); | |
| 153 | + } | |
| 154 | + } | |
| 155 | + return -1; | |
| 156 | + } | |
| 157 | + | |
| 158 | + private static ThreadFactory getDefaultThreadPoolThreadFactory() { | |
| 159 | + String propValue = AccessController.doPrivileged(new | |
| 160 | + GetPropertyAction(DEFAULT_THREAD_POOL_THREAD_FACTORY)); | |
| 161 | + if (propValue != null) { | |
| 162 | + try { | |
| 163 | + Class<?> c = Class | |
| 164 | + .forName(propValue, true, ClassLoader.getSystemClassLoader()); | |
| 165 | + return ((ThreadFactory)c.newInstance()); | |
| 166 | + } catch (ClassNotFoundException x) { | |
| 167 | + throw new Error(x); | |
| 168 | + } catch (InstantiationException x) { | |
| 169 | + throw new Error(x); | |
| 170 | + } catch (IllegalAccessException x) { | |
| 171 | + throw new Error(x); | |
| 172 | + } | |
| 173 | + } | |
| 174 | + return null; | |
| 175 | + } | |
| 176 | +} | |