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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.nio.channels.Channel; | |
| 29 | +import java.nio.channels.AsynchronousChannelGroup; | |
| 30 | +import java.nio.channels.spi.AsynchronousChannelProvider; | |
| 31 | +import java.io.IOException; | |
| 32 | +import java.io.FileDescriptor; | |
| 33 | +import java.util.Queue; | |
| 34 | +import java.util.concurrent.*; | |
| 35 | +import java.util.concurrent.atomic.AtomicInteger; | |
| 36 | +import java.util.concurrent.atomic.AtomicBoolean; | |
| 37 | +import java.security.PrivilegedAction; | |
| 38 | +import java.security.AccessController; | |
| 39 | +import java.security.AccessControlContext; | |
| 40 | +import sun.security.action.GetIntegerAction; | |
| 41 | + | |
| 42 | +/** | |
| 43 | + * Base implementation of AsynchronousChannelGroup | |
| 44 | + */ | |
| 45 | + | |
| 46 | +abstract class AsynchronousChannelGroupImpl | |
| 47 | + extends AsynchronousChannelGroup implements Executor | |
| 48 | +{ | |
| 49 | + // number of internal threads handling I/O events when using an unbounded | |
| 50 | + // thread pool. Internal threads do not dispatch to completion handlers. | |
| 51 | + private static final int internalThreadCount = AccessController.doPrivileged( | |
| 52 | + new GetIntegerAction("sun.nio.ch.internalThreadPoolSize", 1)); | |
| 53 | + | |
| 54 | + // associated thread pool | |
| 55 | + private final ThreadPool pool; | |
| 56 | + | |
| 57 | + // number of tasks running (including internal) | |
| 58 | + private final AtomicInteger threadCount = new AtomicInteger(); | |
| 59 | + | |
| 60 | + // associated Executor for timeouts | |
| 61 | + private ScheduledThreadPoolExecutor timeoutExecutor; | |
| 62 | + | |
| 63 | + // task queue for when using a fixed thread pool. In that case, thread | |
| 64 | + // waiting on I/O events must be awokon to poll tasks from this queue. | |
| 65 | + private final Queue<Runnable> taskQueue; | |
| 66 | + | |
| 67 | + // group shutdown | |
| 68 | + private final AtomicBoolean shutdown = new AtomicBoolean(); | |
| 69 | + private final Object shutdownNowLock = new Object(); | |
| 70 | + private volatile boolean terminateInitiated; | |
| 71 | + | |
| 72 | + AsynchronousChannelGroupImpl(AsynchronousChannelProvider provider, | |
| 73 | + ThreadPool pool) | |
| 74 | + { | |
| 75 | + super(provider); | |
| 76 | + this.pool = pool; | |
| 77 | + | |
| 78 | + if (pool.isFixedThreadPool()) { | |
| 79 | + taskQueue = new ConcurrentLinkedQueue<Runnable>(); | |
| 80 | + } else { | |
| 81 | + taskQueue = null; // not used | |
| 82 | + } | |
| 83 | + | |
| 84 | + // use default thread factory as thread should not be visible to | |
| 85 | + // application (it doesn't execute completion handlers). | |
| 86 | + this.timeoutExecutor = (ScheduledThreadPoolExecutor) | |
| 87 | + Executors.newScheduledThreadPool(1, ThreadPool.defaultThreadFactory()); | |
| 88 | + this.timeoutExecutor.setRemoveOnCancelPolicy(true); | |
| 89 | + } | |
| 90 | + | |
| 91 | + final ExecutorService executor() { | |
| 92 | + return pool.executor(); | |
| 93 | + } | |
| 94 | + | |
| 95 | + final boolean isFixedThreadPool() { | |
| 96 | + return pool.isFixedThreadPool(); | |
| 97 | + } | |
| 98 | + | |
| 99 | + final int fixedThreadCount() { | |
| 100 | + if (isFixedThreadPool()) { | |
| 101 | + return pool.poolSize(); | |
| 102 | + } else { | |
| 103 | + return pool.poolSize() + internalThreadCount; | |
| 104 | + } | |
| 105 | + } | |
| 106 | + | |
| 107 | + private Runnable bindToGroup(final Runnable task) { | |
| 108 | + final AsynchronousChannelGroupImpl thisGroup = this; | |
| 109 | + return new Runnable() { | |
| 110 | + public void run() { | |
| 111 | + Invoker.bindToGroup(thisGroup); | |
| 112 | + task.run(); | |
| 113 | + } | |
| 114 | + }; | |
| 115 | + } | |
| 116 | + | |
| 117 | + private void startInternalThread(final Runnable task) { | |
| 118 | + AccessController.doPrivileged(new PrivilegedAction<Void>() { | |
| 119 | + @Override | |
| 120 | + public Void run() { | |
| 121 | + // internal threads should not be visible to application so | |
| 122 | + // cannot use user-supplied thread factory | |
| 123 | + ThreadPool.defaultThreadFactory().newThread(task).start(); | |
| 124 | + return null; | |
| 125 | + } | |
| 126 | + }); | |
| 127 | + } | |
| 128 | + | |
| 129 | + protected final void startThreads(Runnable task) { | |
| 130 | + if (!isFixedThreadPool()) { | |
| 131 | + for (int i=0; i<internalThreadCount; i++) { | |
| 132 | + startInternalThread(task); | |
| 133 | + threadCount.incrementAndGet(); | |
| 134 | + } | |
| 135 | + } | |
| 136 | + if (pool.poolSize() > 0) { | |
| 137 | + task = bindToGroup(task); | |
| 138 | + try { | |
| 139 | + for (int i=0; i<pool.poolSize(); i++) { | |
| 140 | + pool.executor().execute(task); | |
| 141 | + threadCount.incrementAndGet(); | |
| 142 | + } | |
| 143 | + } catch (RejectedExecutionException x) { | |
| 144 | + // nothing we can do | |
| 145 | + } | |
| 146 | + } | |
| 147 | + } | |
| 148 | + | |
| 149 | + final int threadCount() { | |
| 150 | + return threadCount.get(); | |
| 151 | + } | |
| 152 | + | |
| 153 | + /** | |
| 154 | + * Invoked by tasks as they terminate | |
| 155 | + */ | |
| 156 | + final int threadExit(Runnable task, boolean replaceMe) { | |
| 157 | + if (replaceMe) { | |
| 158 | + try { | |
| 159 | + if (Invoker.isBoundToAnyGroup()) { | |
| 160 | + // submit new task to replace this thread | |
| 161 | + pool.executor().execute(bindToGroup(task)); | |
| 162 | + } else { | |
| 163 | + // replace internal thread | |
| 164 | + startInternalThread(task); | |
| 165 | + } | |
| 166 | + return threadCount.get(); | |
| 167 | + } catch (RejectedExecutionException x) { | |
| 168 | + // unable to replace | |
| 169 | + } | |
| 170 | + } | |
| 171 | + return threadCount.decrementAndGet(); | |
| 172 | + } | |
| 173 | + | |
| 174 | + /** | |
| 175 | + * Wakes up a thread waiting for I/O events to execute the given task. | |
| 176 | + */ | |
| 177 | + abstract void executeOnHandlerTask(Runnable task); | |
| 178 | + | |
| 179 | + /** | |
| 180 | + * For a fixed thread pool the task is queued to a thread waiting on I/O | |
| 181 | + * events. For other thread pools we simply submit the task to the thread | |
| 182 | + * pool. | |
| 183 | + */ | |
| 184 | + final void executeOnPooledThread(Runnable task) { | |
| 185 | + if (isFixedThreadPool()) { | |
| 186 | + executeOnHandlerTask(task); | |
| 187 | + } else { | |
| 188 | + pool.executor().execute(bindToGroup(task)); | |
| 189 | + } | |
| 190 | + } | |
| 191 | + | |
| 192 | + final void offerTask(Runnable task) { | |
| 193 | + taskQueue.offer(task); | |
| 194 | + } | |
| 195 | + | |
| 196 | + final Runnable pollTask() { | |
| 197 | + return (taskQueue == null) ? null : taskQueue.poll(); | |
| 198 | + } | |
| 199 | + | |
| 200 | + final Future<?> schedule(Runnable task, long timeout, TimeUnit unit) { | |
| 201 | + try { | |
| 202 | + return timeoutExecutor.schedule(task, timeout, unit); | |
| 203 | + } catch (RejectedExecutionException rej) { | |
| 204 | + if (terminateInitiated) { | |
| 205 | + // no timeout scheduled as group is terminating | |
| 206 | + return null; | |
| 207 | + } | |
| 208 | + throw new AssertionError(rej); | |
| 209 | + } | |
| 210 | + } | |
| 211 | + | |
| 212 | + @Override | |
| 213 | + public final boolean isShutdown() { | |
| 214 | + return shutdown.get(); | |
| 215 | + } | |
| 216 | + | |
| 217 | + @Override | |
| 218 | + public final boolean isTerminated() { | |
| 219 | + return pool.executor().isTerminated(); | |
| 220 | + } | |
| 221 | + | |
| 222 | + /** | |
| 223 | + * Returns true if there are no channels in the group | |
| 224 | + */ | |
| 225 | + abstract boolean isEmpty(); | |
| 226 | + | |
| 227 | + /** | |
| 228 | + * Attaches a foreign channel to this group. | |
| 229 | + */ | |
| 230 | + abstract Object attachForeignChannel(Channel channel, FileDescriptor fdo) | |
| 231 | + throws IOException; | |
| 232 | + | |
| 233 | + /** | |
| 234 | + * Detaches a foreign channel from this group. | |
| 235 | + */ | |
| 236 | + abstract void detachForeignChannel(Object key); | |
| 237 | + | |
| 238 | + /** | |
| 239 | + * Closes all channels in the group | |
| 240 | + */ | |
| 241 | + abstract void closeAllChannels() throws IOException; | |
| 242 | + | |
| 243 | + /** | |
| 244 | + * Shutdown all tasks waiting for I/O events. | |
| 245 | + */ | |
| 246 | + abstract void shutdownHandlerTasks(); | |
| 247 | + | |
| 248 | + private void shutdownExecutors() { | |
| 249 | + AccessController.doPrivileged(new PrivilegedAction<Void>() { | |
| 250 | + public Void run() { | |
| 251 | + pool.executor().shutdown(); | |
| 252 | + timeoutExecutor.shutdown(); | |
| 253 | + return null; | |
| 254 | + } | |
| 255 | + }); | |
| 256 | + } | |
| 257 | + | |
| 258 | + @Override | |
| 259 | + public final void shutdown() { | |
| 260 | + if (shutdown.getAndSet(true)) { | |
| 261 | + // already shutdown | |
| 262 | + return; | |
| 263 | + } | |
| 264 | + // if there are channels in the group then shutdown will continue | |
| 265 | + // when the last channel is closed | |
| 266 | + if (!isEmpty()) { | |
| 267 | + return; | |
| 268 | + } | |
| 269 | + // initiate termination (acquire shutdownNowLock to ensure that other | |
| 270 | + // threads invoking shutdownNow will block). | |
| 271 | + synchronized (shutdownNowLock) { | |
| 272 | + if (!terminateInitiated) { | |
| 273 | + terminateInitiated = true; | |
| 274 | + shutdownHandlerTasks(); | |
| 275 | + shutdownExecutors(); | |
| 276 | + } | |
| 277 | + } | |
| 278 | + } | |
| 279 | + | |
| 280 | + @Override | |
| 281 | + public final void shutdownNow() throws IOException { | |
| 282 | + shutdown.set(true); | |
| 283 | + synchronized (shutdownNowLock) { | |
| 284 | + if (!terminateInitiated) { | |
| 285 | + terminateInitiated = true; | |
| 286 | + closeAllChannels(); | |
| 287 | + shutdownHandlerTasks(); | |
| 288 | + shutdownExecutors(); | |
| 289 | + } | |
| 290 | + } | |
| 291 | + } | |
| 292 | + | |
| 293 | + /** | |
| 294 | + * For use by AsynchronousFileChannel to release resources without shutting | |
| 295 | + * down the thread pool. | |
| 296 | + */ | |
| 297 | + final void detachFromThreadPool() { | |
| 298 | + if (shutdown.getAndSet(true)) | |
| 299 | + throw new AssertionError("Already shutdown"); | |
| 300 | + if (!isEmpty()) | |
| 301 | + throw new AssertionError("Group not empty"); | |
| 302 | + shutdownHandlerTasks(); | |
| 303 | + } | |
| 304 | + | |
| 305 | + @Override | |
| 306 | + public final boolean awaitTermination(long timeout, TimeUnit unit) | |
| 307 | + throws InterruptedException | |
| 308 | + { | |
| 309 | + return pool.executor().awaitTermination(timeout, unit); | |
| 310 | + } | |
| 311 | + | |
| 312 | + /** | |
| 313 | + * Executes the given command on one of the channel group's pooled threads. | |
| 314 | + */ | |
| 315 | + @Override | |
| 316 | + public final void execute(Runnable task) { | |
| 317 | + SecurityManager sm = System.getSecurityManager(); | |
| 318 | + if (sm != null) { | |
| 319 | + // when a security manager is installed then the user's task | |
| 320 | + // must be run with the current calling context | |
| 321 | + final AccessControlContext acc = AccessController.getContext(); | |
| 322 | + final Runnable delegate = task; | |
| 323 | + task = new Runnable() { | |
| 324 | + @Override | |
| 325 | + public void run() { | |
| 326 | + AccessController.doPrivileged(new PrivilegedAction<Void>() { | |
| 327 | + @Override | |
| 328 | + public Void run() { | |
| 329 | + delegate.run(); | |
| 330 | + return null; | |
| 331 | + } | |
| 332 | + }, acc); | |
| 333 | + } | |
| 334 | + }; | |
| 335 | + } | |
| 336 | + executeOnPooledThread(task); | |
| 337 | + } | |
| 338 | +} | |