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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 | } | ||