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| 1 | +/* | |
| 2 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 3 | + * | |
| 4 | + * This code is free software; you can redistribute it and/or modify it | |
| 5 | + * under the terms of the GNU General Public License version 2 only, as | |
| 6 | + * published by the Free Software Foundation. Oracle designates this | |
| 7 | + * particular file as subject to the "Classpath" exception as provided | |
| 8 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 9 | + * | |
| 10 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 11 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 12 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 13 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 14 | + * accompanied this code). | |
| 15 | + * | |
| 16 | + * You should have received a copy of the GNU General Public License version | |
| 17 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 18 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 19 | + * | |
| 20 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 21 | + * or visit www.oracle.com if you need additional information or have any | |
| 22 | + * questions. | |
| 23 | + */ | |
| 24 | + | |
| 25 | +/* | |
| 26 | + * This file is available under and governed by the GNU General Public | |
| 27 | + * License version 2 only, as published by the Free Software Foundation. | |
| 28 | + * However, the following notice accompanied the original version of this | |
| 29 | + * file: | |
| 30 | + * | |
| 31 | + * Written by Doug Lea with assistance from members of JCP JSR-166 | |
| 32 | + * Expert Group and released to the public domain, as explained at | |
| 33 | + * http://creativecommons.org/publicdomain/zero/1.0/ | |
| 34 | + */ | |
| 35 | + | |
| 36 | +package java.util.concurrent; | |
| 37 | +import java.util.*; | |
| 38 | + | |
| 39 | +/** | |
| 40 | + * Provides default implementations of {@link ExecutorService} | |
| 41 | + * execution methods. This class implements the <tt>submit</tt>, | |
| 42 | + * <tt>invokeAny</tt> and <tt>invokeAll</tt> methods using a | |
| 43 | + * {@link RunnableFuture} returned by <tt>newTaskFor</tt>, which defaults | |
| 44 | + * to the {@link FutureTask} class provided in this package. For example, | |
| 45 | + * the implementation of <tt>submit(Runnable)</tt> creates an | |
| 46 | + * associated <tt>RunnableFuture</tt> that is executed and | |
| 47 | + * returned. Subclasses may override the <tt>newTaskFor</tt> methods | |
| 48 | + * to return <tt>RunnableFuture</tt> implementations other than | |
| 49 | + * <tt>FutureTask</tt>. | |
| 50 | + * | |
| 51 | + * <p> <b>Extension example</b>. Here is a sketch of a class | |
| 52 | + * that customizes {@link ThreadPoolExecutor} to use | |
| 53 | + * a <tt>CustomTask</tt> class instead of the default <tt>FutureTask</tt>: | |
| 54 | + * <pre> {@code | |
| 55 | + * public class CustomThreadPoolExecutor extends ThreadPoolExecutor { | |
| 56 | + * | |
| 57 | + * static class CustomTask<V> implements RunnableFuture<V> {...} | |
| 58 | + * | |
| 59 | + * protected <V> RunnableFuture<V> newTaskFor(Callable<V> c) { | |
| 60 | + * return new CustomTask<V>(c); | |
| 61 | + * } | |
| 62 | + * protected <V> RunnableFuture<V> newTaskFor(Runnable r, V v) { | |
| 63 | + * return new CustomTask<V>(r, v); | |
| 64 | + * } | |
| 65 | + * // ... add constructors, etc. | |
| 66 | + * }}</pre> | |
| 67 | + * | |
| 68 | + * @since 1.5 | |
| 69 | + * @author Doug Lea | |
| 70 | + */ | |
| 71 | +public abstract class AbstractExecutorService implements ExecutorService { | |
| 72 | + | |
| 73 | + /** | |
| 74 | + * Returns a <tt>RunnableFuture</tt> for the given runnable and default | |
| 75 | + * value. | |
| 76 | + * | |
| 77 | + * @param runnable the runnable task being wrapped | |
| 78 | + * @param value the default value for the returned future | |
| 79 | + * @return a <tt>RunnableFuture</tt> which when run will run the | |
| 80 | + * underlying runnable and which, as a <tt>Future</tt>, will yield | |
| 81 | + * the given value as its result and provide for cancellation of | |
| 82 | + * the underlying task. | |
| 83 | + * @since 1.6 | |
| 84 | + */ | |
| 85 | + protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) { | |
| 86 | + return new FutureTask<T>(runnable, value); | |
| 87 | + } | |
| 88 | + | |
| 89 | + /** | |
| 90 | + * Returns a <tt>RunnableFuture</tt> for the given callable task. | |
| 91 | + * | |
| 92 | + * @param callable the callable task being wrapped | |
| 93 | + * @return a <tt>RunnableFuture</tt> which when run will call the | |
| 94 | + * underlying callable and which, as a <tt>Future</tt>, will yield | |
| 95 | + * the callable's result as its result and provide for | |
| 96 | + * cancellation of the underlying task. | |
| 97 | + * @since 1.6 | |
| 98 | + */ | |
| 99 | + protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) { | |
| 100 | + return new FutureTask<T>(callable); | |
| 101 | + } | |
| 102 | + | |
| 103 | + /** | |
| 104 | + * @throws RejectedExecutionException {@inheritDoc} | |
| 105 | + * @throws NullPointerException {@inheritDoc} | |
| 106 | + */ | |
| 107 | + public Future<?> submit(Runnable task) { | |
| 108 | + if (task == null) throw new NullPointerException(); | |
| 109 | + RunnableFuture<Void> ftask = newTaskFor(task, null); | |
| 110 | + execute(ftask); | |
| 111 | + return ftask; | |
| 112 | + } | |
| 113 | + | |
| 114 | + /** | |
| 115 | + * @throws RejectedExecutionException {@inheritDoc} | |
| 116 | + * @throws NullPointerException {@inheritDoc} | |
| 117 | + */ | |
| 118 | + public <T> Future<T> submit(Runnable task, T result) { | |
| 119 | + if (task == null) throw new NullPointerException(); | |
| 120 | + RunnableFuture<T> ftask = newTaskFor(task, result); | |
| 121 | + execute(ftask); | |
| 122 | + return ftask; | |
| 123 | + } | |
| 124 | + | |
| 125 | + /** | |
| 126 | + * @throws RejectedExecutionException {@inheritDoc} | |
| 127 | + * @throws NullPointerException {@inheritDoc} | |
| 128 | + */ | |
| 129 | + public <T> Future<T> submit(Callable<T> task) { | |
| 130 | + if (task == null) throw new NullPointerException(); | |
| 131 | + RunnableFuture<T> ftask = newTaskFor(task); | |
| 132 | + execute(ftask); | |
| 133 | + return ftask; | |
| 134 | + } | |
| 135 | + | |
| 136 | + /** | |
| 137 | + * the main mechanics of invokeAny. | |
| 138 | + */ | |
| 139 | + private <T> T doInvokeAny(Collection<? extends Callable<T>> tasks, | |
| 140 | + boolean timed, long nanos) | |
| 141 | + throws InterruptedException, ExecutionException, TimeoutException { | |
| 142 | + if (tasks == null) | |
| 143 | + throw new NullPointerException(); | |
| 144 | + int ntasks = tasks.size(); | |
| 145 | + if (ntasks == 0) | |
| 146 | + throw new IllegalArgumentException(); | |
| 147 | + List<Future<T>> futures= new ArrayList<Future<T>>(ntasks); | |
| 148 | + ExecutorCompletionService<T> ecs = | |
| 149 | + new ExecutorCompletionService<T>(this); | |
| 150 | + | |
| 151 | + // For efficiency, especially in executors with limited | |
| 152 | + // parallelism, check to see if previously submitted tasks are | |
| 153 | + // done before submitting more of them. This interleaving | |
| 154 | + // plus the exception mechanics account for messiness of main | |
| 155 | + // loop. | |
| 156 | + | |
| 157 | + try { | |
| 158 | + // Record exceptions so that if we fail to obtain any | |
| 159 | + // result, we can throw the last exception we got. | |
| 160 | + ExecutionException ee = null; | |
| 161 | + long lastTime = timed ? System.nanoTime() : 0; | |
| 162 | + Iterator<? extends Callable<T>> it = tasks.iterator(); | |
| 163 | + | |
| 164 | + // Start one task for sure; the rest incrementally | |
| 165 | + futures.add(ecs.submit(it.next())); | |
| 166 | + --ntasks; | |
| 167 | + int active = 1; | |
| 168 | + | |
| 169 | + for (;;) { | |
| 170 | + Future<T> f = ecs.poll(); | |
| 171 | + if (f == null) { | |
| 172 | + if (ntasks > 0) { | |
| 173 | + --ntasks; | |
| 174 | + futures.add(ecs.submit(it.next())); | |
| 175 | + ++active; | |
| 176 | + } | |
| 177 | + else if (active == 0) | |
| 178 | + break; | |
| 179 | + else if (timed) { | |
| 180 | + f = ecs.poll(nanos, TimeUnit.NANOSECONDS); | |
| 181 | + if (f == null) | |
| 182 | + throw new TimeoutException(); | |
| 183 | + long now = System.nanoTime(); | |
| 184 | + nanos -= now - lastTime; | |
| 185 | + lastTime = now; | |
| 186 | + } | |
| 187 | + else | |
| 188 | + f = ecs.take(); | |
| 189 | + } | |
| 190 | + if (f != null) { | |
| 191 | + --active; | |
| 192 | + try { | |
| 193 | + return f.get(); | |
| 194 | + } catch (ExecutionException eex) { | |
| 195 | + ee = eex; | |
| 196 | + } catch (RuntimeException rex) { | |
| 197 | + ee = new ExecutionException(rex); | |
| 198 | + } | |
| 199 | + } | |
| 200 | + } | |
| 201 | + | |
| 202 | + if (ee == null) | |
| 203 | + ee = new ExecutionException(); | |
| 204 | + throw ee; | |
| 205 | + | |
| 206 | + } finally { | |
| 207 | + for (Future<T> f : futures) | |
| 208 | + f.cancel(true); | |
| 209 | + } | |
| 210 | + } | |
| 211 | + | |
| 212 | + public <T> T invokeAny(Collection<? extends Callable<T>> tasks) | |
| 213 | + throws InterruptedException, ExecutionException { | |
| 214 | + try { | |
| 215 | + return doInvokeAny(tasks, false, 0); | |
| 216 | + } catch (TimeoutException cannotHappen) { | |
| 217 | + assert false; | |
| 218 | + return null; | |
| 219 | + } | |
| 220 | + } | |
| 221 | + | |
| 222 | + public <T> T invokeAny(Collection<? extends Callable<T>> tasks, | |
| 223 | + long timeout, TimeUnit unit) | |
| 224 | + throws InterruptedException, ExecutionException, TimeoutException { | |
| 225 | + return doInvokeAny(tasks, true, unit.toNanos(timeout)); | |
| 226 | + } | |
| 227 | + | |
| 228 | + public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) | |
| 229 | + throws InterruptedException { | |
| 230 | + if (tasks == null) | |
| 231 | + throw new NullPointerException(); | |
| 232 | + List<Future<T>> futures = new ArrayList<Future<T>>(tasks.size()); | |
| 233 | + boolean done = false; | |
| 234 | + try { | |
| 235 | + for (Callable<T> t : tasks) { | |
| 236 | + RunnableFuture<T> f = newTaskFor(t); | |
| 237 | + futures.add(f); | |
| 238 | + execute(f); | |
| 239 | + } | |
| 240 | + for (Future<T> f : futures) { | |
| 241 | + if (!f.isDone()) { | |
| 242 | + try { | |
| 243 | + f.get(); | |
| 244 | + } catch (CancellationException ignore) { | |
| 245 | + } catch (ExecutionException ignore) { | |
| 246 | + } | |
| 247 | + } | |
| 248 | + } | |
| 249 | + done = true; | |
| 250 | + return futures; | |
| 251 | + } finally { | |
| 252 | + if (!done) | |
| 253 | + for (Future<T> f : futures) | |
| 254 | + f.cancel(true); | |
| 255 | + } | |
| 256 | + } | |
| 257 | + | |
| 258 | + public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, | |
| 259 | + long timeout, TimeUnit unit) | |
| 260 | + throws InterruptedException { | |
| 261 | + if (tasks == null || unit == null) | |
| 262 | + throw new NullPointerException(); | |
| 263 | + long nanos = unit.toNanos(timeout); | |
| 264 | + List<Future<T>> futures = new ArrayList<Future<T>>(tasks.size()); | |
| 265 | + boolean done = false; | |
| 266 | + try { | |
| 267 | + for (Callable<T> t : tasks) | |
| 268 | + futures.add(newTaskFor(t)); | |
| 269 | + | |
| 270 | + long lastTime = System.nanoTime(); | |
| 271 | + | |
| 272 | + // Interleave time checks and calls to execute in case | |
| 273 | + // executor doesn't have any/much parallelism. | |
| 274 | + Iterator<Future<T>> it = futures.iterator(); | |
| 275 | + while (it.hasNext()) { | |
| 276 | + execute((Runnable)(it.next())); | |
| 277 | + long now = System.nanoTime(); | |
| 278 | + nanos -= now - lastTime; | |
| 279 | + lastTime = now; | |
| 280 | + if (nanos <= 0) | |
| 281 | + return futures; | |
| 282 | + } | |
| 283 | + | |
| 284 | + for (Future<T> f : futures) { | |
| 285 | + if (!f.isDone()) { | |
| 286 | + if (nanos <= 0) | |
| 287 | + return futures; | |
| 288 | + try { | |
| 289 | + f.get(nanos, TimeUnit.NANOSECONDS); | |
| 290 | + } catch (CancellationException ignore) { | |
| 291 | + } catch (ExecutionException ignore) { | |
| 292 | + } catch (TimeoutException toe) { | |
| 293 | + return futures; | |
| 294 | + } | |
| 295 | + long now = System.nanoTime(); | |
| 296 | + nanos -= now - lastTime; | |
| 297 | + lastTime = now; | |
| 298 | + } | |
| 299 | + } | |
| 300 | + done = true; | |
| 301 | + return futures; | |
| 302 | + } finally { | |
| 303 | + if (!done) | |
| 304 | + for (Future<T> f : futures) | |
| 305 | + f.cancel(true); | |
| 306 | + } | |
| 307 | + } | |
| 308 | + | |
| 309 | +} | |