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Diffstat (limited to 'gcc-4.4.3/libjava/classpath/external/jsr166/java/util/concurrent/ScheduledThreadPoolExecutor.java')
| -rw-r--r-- | gcc-4.4.3/libjava/classpath/external/jsr166/java/util/concurrent/ScheduledThreadPoolExecutor.java | 626 |
1 files changed, 626 insertions, 0 deletions
diff --git a/gcc-4.4.3/libjava/classpath/external/jsr166/java/util/concurrent/ScheduledThreadPoolExecutor.java b/gcc-4.4.3/libjava/classpath/external/jsr166/java/util/concurrent/ScheduledThreadPoolExecutor.java new file mode 100644 index 000000000..d4da334c6 --- /dev/null +++ b/gcc-4.4.3/libjava/classpath/external/jsr166/java/util/concurrent/ScheduledThreadPoolExecutor.java @@ -0,0 +1,626 @@ +/* + * Written by Doug Lea with assistance from members of JCP JSR-166 + * Expert Group and released to the public domain, as explained at + * http://creativecommons.org/licenses/publicdomain + */ + +package java.util.concurrent; +import java.util.concurrent.atomic.*; +import java.util.*; + +/** + * A {@link ThreadPoolExecutor} that can additionally schedule + * commands to run after a given delay, or to execute + * periodically. This class is preferable to {@link java.util.Timer} + * when multiple worker threads are needed, or when the additional + * flexibility or capabilities of {@link ThreadPoolExecutor} (which + * this class extends) are required. + * + * <p> Delayed tasks execute no sooner than they are enabled, but + * without any real-time guarantees about when, after they are + * enabled, they will commence. Tasks scheduled for exactly the same + * execution time are enabled in first-in-first-out (FIFO) order of + * submission. + * + * <p>While this class inherits from {@link ThreadPoolExecutor}, a few + * of the inherited tuning methods are not useful for it. In + * particular, because it acts as a fixed-sized pool using + * <tt>corePoolSize</tt> threads and an unbounded queue, adjustments + * to <tt>maximumPoolSize</tt> have no useful effect. + * + * <p><b>Extension notes:</b> This class overrides {@link + * AbstractExecutorService} <tt>submit</tt> methods to generate + * internal objects to control per-task delays and scheduling. To + * preserve functionality, any further overrides of these methods in + * subclasses must invoke superclass versions, which effectively + * disables additional task customization. However, this class + * provides alternative protected extension method + * <tt>decorateTask</tt> (one version each for <tt>Runnable</tt> and + * <tt>Callable</tt>) that can be used to customize the concrete task + * types used to execute commands entered via <tt>execute</tt>, + * <tt>submit</tt>, <tt>schedule</tt>, <tt>scheduleAtFixedRate</tt>, + * and <tt>scheduleWithFixedDelay</tt>. By default, a + * <tt>ScheduledThreadPoolExecutor</tt> uses a task type extending + * {@link FutureTask}. However, this may be modified or replaced using + * subclasses of the form: + * + * <pre> + * public class CustomScheduledExecutor extends ScheduledThreadPoolExecutor { + * + * static class CustomTask<V> implements RunnableScheduledFuture<V> { ... } + * + * protected <V> RunnableScheduledFuture<V> decorateTask( + * Runnable r, RunnableScheduledFuture<V> task) { + * return new CustomTask<V>(r, task); + * } + * + * protected <V> RunnableScheduledFuture<V> decorateTask( + * Callable<V> c, RunnableScheduledFuture<V> task) { + * return new CustomTask<V>(c, task); + * } + * // ... add constructors, etc. + * } + * </pre> + * @since 1.5 + * @author Doug Lea + */ +public class ScheduledThreadPoolExecutor + extends ThreadPoolExecutor + implements ScheduledExecutorService { + + /** + * False if should cancel/suppress periodic tasks on shutdown. + */ + private volatile boolean continueExistingPeriodicTasksAfterShutdown; + + /** + * False if should cancel non-periodic tasks on shutdown. + */ + private volatile boolean executeExistingDelayedTasksAfterShutdown = true; + + /** + * Sequence number to break scheduling ties, and in turn to + * guarantee FIFO order among tied entries. + */ + private static final AtomicLong sequencer = new AtomicLong(0); + + /** Base of nanosecond timings, to avoid wrapping */ + private static final long NANO_ORIGIN = System.nanoTime(); + + /** + * Returns nanosecond time offset by origin + */ + final long now() { + return System.nanoTime() - NANO_ORIGIN; + } + + private class ScheduledFutureTask<V> + extends FutureTask<V> implements RunnableScheduledFuture<V> { + + /** Sequence number to break ties FIFO */ + private final long sequenceNumber; + /** The time the task is enabled to execute in nanoTime units */ + private long time; + /** + * Period in nanoseconds for repeating tasks. A positive + * value indicates fixed-rate execution. A negative value + * indicates fixed-delay execution. A value of 0 indicates a + * non-repeating task. + */ + private final long period; + + /** + * Creates a one-shot action with given nanoTime-based trigger time. + */ + ScheduledFutureTask(Runnable r, V result, long ns) { + super(r, result); + this.time = ns; + this.period = 0; + this.sequenceNumber = sequencer.getAndIncrement(); + } + + /** + * Creates a periodic action with given nano time and period. + */ + ScheduledFutureTask(Runnable r, V result, long ns, long period) { + super(r, result); + this.time = ns; + this.period = period; + this.sequenceNumber = sequencer.getAndIncrement(); + } + + /** + * Creates a one-shot action with given nanoTime-based trigger. + */ + ScheduledFutureTask(Callable<V> callable, long ns) { + super(callable); + this.time = ns; + this.period = 0; + this.sequenceNumber = sequencer.getAndIncrement(); + } + + public long getDelay(TimeUnit unit) { + long d = unit.convert(time - now(), TimeUnit.NANOSECONDS); + return d; + } + + public int compareTo(Delayed other) { + if (other == this) // compare zero ONLY if same object + return 0; + if (other instanceof ScheduledFutureTask) { + ScheduledFutureTask<?> x = (ScheduledFutureTask<?>)other; + long diff = time - x.time; + if (diff < 0) + return -1; + else if (diff > 0) + return 1; + else if (sequenceNumber < x.sequenceNumber) + return -1; + else + return 1; + } + long d = (getDelay(TimeUnit.NANOSECONDS) - + other.getDelay(TimeUnit.NANOSECONDS)); + return (d == 0)? 0 : ((d < 0)? -1 : 1); + } + + /** + * Returns true if this is a periodic (not a one-shot) action. + * + * @return true if periodic + */ + public boolean isPeriodic() { + return period != 0; + } + + /** + * Runs a periodic task. + */ + private void runPeriodic() { + boolean ok = ScheduledFutureTask.super.runAndReset(); + boolean down = isShutdown(); + // Reschedule if not cancelled and not shutdown or policy allows + if (ok && (!down || + (getContinueExistingPeriodicTasksAfterShutdownPolicy() && + !isTerminating()))) { + long p = period; + if (p > 0) + time += p; + else + time = now() - p; + // Classpath local: ecj from eclipse 3.1 does not + // compile this. + // ScheduledThreadPoolExecutor.super.getQueue().add(this); + ScheduledThreadPoolExecutor.super.getQueue().add((Runnable) this); + } + // This might have been the final executed delayed + // task. Wake up threads to check. + else if (down) + interruptIdleWorkers(); + } + + /** + * Overrides FutureTask version so as to reset/requeue if periodic. + */ + public void run() { + if (isPeriodic()) + runPeriodic(); + else + ScheduledFutureTask.super.run(); + } + } + + /** + * Specialized variant of ThreadPoolExecutor.execute for delayed tasks. + */ + private void delayedExecute(Runnable command) { + if (isShutdown()) { + reject(command); + return; + } + // Prestart a thread if necessary. We cannot prestart it + // running the task because the task (probably) shouldn't be + // run yet, so thread will just idle until delay elapses. + if (getPoolSize() < getCorePoolSize()) + prestartCoreThread(); + + super.getQueue().add(command); + } + + /** + * Cancels and clears the queue of all tasks that should not be run + * due to shutdown policy. + */ + private void cancelUnwantedTasks() { + boolean keepDelayed = getExecuteExistingDelayedTasksAfterShutdownPolicy(); + boolean keepPeriodic = getContinueExistingPeriodicTasksAfterShutdownPolicy(); + if (!keepDelayed && !keepPeriodic) + super.getQueue().clear(); + else if (keepDelayed || keepPeriodic) { + Object[] entries = super.getQueue().toArray(); + for (int i = 0; i < entries.length; ++i) { + Object e = entries[i]; + if (e instanceof RunnableScheduledFuture) { + RunnableScheduledFuture<?> t = (RunnableScheduledFuture<?>)e; + if (t.isPeriodic()? !keepPeriodic : !keepDelayed) + t.cancel(false); + } + } + entries = null; + purge(); + } + } + + public boolean remove(Runnable task) { + if (!(task instanceof RunnableScheduledFuture)) + return false; + return getQueue().remove(task); + } + + /** + * Modifies or replaces the task used to execute a runnable. + * This method can be used to override the concrete + * class used for managing internal tasks. + * The default implementation simply returns the given task. + * + * @param runnable the submitted Runnable + * @param task the task created to execute the runnable + * @return a task that can execute the runnable + * @since 1.6 + */ + protected <V> RunnableScheduledFuture<V> decorateTask( + Runnable runnable, RunnableScheduledFuture<V> task) { + return task; + } + + /** + * Modifies or replaces the task used to execute a callable. + * This method can be used to override the concrete + * class used for managing internal tasks. + * The default implementation simply returns the given task. + * + * @param callable the submitted Callable + * @param task the task created to execute the callable + * @return a task that can execute the callable + * @since 1.6 + */ + protected <V> RunnableScheduledFuture<V> decorateTask( + Callable<V> callable, RunnableScheduledFuture<V> task) { + return task; + } + + /** + * Creates a new ScheduledThreadPoolExecutor with the given core + * pool size. + * + * @param corePoolSize the number of threads to keep in the pool, + * even if they are idle + * @throws IllegalArgumentException if <tt>corePoolSize < 0</tt> + */ + public ScheduledThreadPoolExecutor(int corePoolSize) { + super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, + new DelayedWorkQueue()); + } + + /** + * Creates a new ScheduledThreadPoolExecutor with the given + * initial parameters. + * + * @param corePoolSize the number of threads to keep in the pool, + * even if they are idle + * @param threadFactory the factory to use when the executor + * creates a new thread + * @throws IllegalArgumentException if <tt>corePoolSize < 0</tt> + * @throws NullPointerException if threadFactory is null + */ + public ScheduledThreadPoolExecutor(int corePoolSize, + ThreadFactory threadFactory) { + super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, + new DelayedWorkQueue(), threadFactory); + } + + /** + * Creates a new ScheduledThreadPoolExecutor with the given + * initial parameters. + * + * @param corePoolSize the number of threads to keep in the pool, + * even if they are idle + * @param handler the handler to use when execution is blocked + * because the thread bounds and queue capacities are reached + * @throws IllegalArgumentException if <tt>corePoolSize < 0</tt> + * @throws NullPointerException if handler is null + */ + public ScheduledThreadPoolExecutor(int corePoolSize, + RejectedExecutionHandler handler) { + super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, + new DelayedWorkQueue(), handler); + } + + /** + * Creates a new ScheduledThreadPoolExecutor with the given + * initial parameters. + * + * @param corePoolSize the number of threads to keep in the pool, + * even if they are idle + * @param threadFactory the factory to use when the executor + * creates a new thread + * @param handler the handler to use when execution is blocked + * because the thread bounds and queue capacities are reached. + * @throws IllegalArgumentException if <tt>corePoolSize < 0</tt> + * @throws NullPointerException if threadFactory or handler is null + */ + public ScheduledThreadPoolExecutor(int corePoolSize, + ThreadFactory threadFactory, + RejectedExecutionHandler handler) { + super(corePoolSize, Integer.MAX_VALUE, 0, TimeUnit.NANOSECONDS, + new DelayedWorkQueue(), threadFactory, handler); + } + + public ScheduledFuture<?> schedule(Runnable command, + long delay, + TimeUnit unit) { + if (command == null || unit == null) + throw new NullPointerException(); + long triggerTime = now() + unit.toNanos(delay); + RunnableScheduledFuture<?> t = decorateTask(command, + new ScheduledFutureTask<Boolean>(command, null, triggerTime)); + delayedExecute(t); + return t; + } + + public <V> ScheduledFuture<V> schedule(Callable<V> callable, + long delay, + TimeUnit unit) { + if (callable == null || unit == null) + throw new NullPointerException(); + if (delay < 0) delay = 0; + long triggerTime = now() + unit.toNanos(delay); + RunnableScheduledFuture<V> t = decorateTask(callable, + new ScheduledFutureTask<V>(callable, triggerTime)); + delayedExecute(t); + return t; + } + + public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, + long initialDelay, + long period, + TimeUnit unit) { + if (command == null || unit == null) + throw new NullPointerException(); + if (period <= 0) + throw new IllegalArgumentException(); + if (initialDelay < 0) initialDelay = 0; + long triggerTime = now() + unit.toNanos(initialDelay); + RunnableScheduledFuture<?> t = decorateTask(command, + new ScheduledFutureTask<Object>(command, + null, + triggerTime, + unit.toNanos(period))); + delayedExecute(t); + return t; + } + + public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, + long initialDelay, + long delay, + TimeUnit unit) { + if (command == null || unit == null) + throw new NullPointerException(); + if (delay <= 0) + throw new IllegalArgumentException(); + if (initialDelay < 0) initialDelay = 0; + long triggerTime = now() + unit.toNanos(initialDelay); + RunnableScheduledFuture<?> t = decorateTask(command, + new ScheduledFutureTask<Boolean>(command, + null, + triggerTime, + unit.toNanos(-delay))); + delayedExecute(t); + return t; + } + + + /** + * Executes command with zero required delay. This has effect + * equivalent to <tt>schedule(command, 0, anyUnit)</tt>. Note + * that inspections of the queue and of the list returned by + * <tt>shutdownNow</tt> will access the zero-delayed + * {@link ScheduledFuture}, not the <tt>command</tt> itself. + * + * @param command the task to execute + * @throws RejectedExecutionException at discretion of + * <tt>RejectedExecutionHandler</tt>, if task cannot be accepted + * for execution because the executor has been shut down. + * @throws NullPointerException if command is null + */ + public void execute(Runnable command) { + if (command == null) + throw new NullPointerException(); + schedule(command, 0, TimeUnit.NANOSECONDS); + } + + // Override AbstractExecutorService methods + + public Future<?> submit(Runnable task) { + return schedule(task, 0, TimeUnit.NANOSECONDS); + } + + public <T> Future<T> submit(Runnable task, T result) { + return schedule(Executors.callable(task, result), + 0, TimeUnit.NANOSECONDS); + } + + public <T> Future<T> submit(Callable<T> task) { + return schedule(task, 0, TimeUnit.NANOSECONDS); + } + + /** + * Sets the policy on whether to continue executing existing periodic + * tasks even when this executor has been <tt>shutdown</tt>. In + * this case, these tasks will only terminate upon + * <tt>shutdownNow</tt>, or after setting the policy to + * <tt>false</tt> when already shutdown. This value is by default + * false. + * + * @param value if true, continue after shutdown, else don't. + * @see #getContinueExistingPeriodicTasksAfterShutdownPolicy + */ + public void setContinueExistingPeriodicTasksAfterShutdownPolicy(boolean value) { + continueExistingPeriodicTasksAfterShutdown = value; + if (!value && isShutdown()) + cancelUnwantedTasks(); + } + + /** + * Gets the policy on whether to continue executing existing + * periodic tasks even when this executor has been + * <tt>shutdown</tt>. In this case, these tasks will only + * terminate upon <tt>shutdownNow</tt> or after setting the policy + * to <tt>false</tt> when already shutdown. This value is by + * default false. + * + * @return true if will continue after shutdown + * @see #setContinueExistingPeriodicTasksAfterShutdownPolicy + */ + public boolean getContinueExistingPeriodicTasksAfterShutdownPolicy() { + return continueExistingPeriodicTasksAfterShutdown; + } + + /** + * Sets the policy on whether to execute existing delayed + * tasks even when this executor has been <tt>shutdown</tt>. In + * this case, these tasks will only terminate upon + * <tt>shutdownNow</tt>, or after setting the policy to + * <tt>false</tt> when already shutdown. This value is by default + * true. + * + * @param value if true, execute after shutdown, else don't. + * @see #getExecuteExistingDelayedTasksAfterShutdownPolicy + */ + public void setExecuteExistingDelayedTasksAfterShutdownPolicy(boolean value) { + executeExistingDelayedTasksAfterShutdown = value; + if (!value && isShutdown()) + cancelUnwantedTasks(); + } + + /** + * Gets the policy on whether to execute existing delayed + * tasks even when this executor has been <tt>shutdown</tt>. In + * this case, these tasks will only terminate upon + * <tt>shutdownNow</tt>, or after setting the policy to + * <tt>false</tt> when already shutdown. This value is by default + * true. + * + * @return true if will execute after shutdown + * @see #setExecuteExistingDelayedTasksAfterShutdownPolicy + */ + public boolean getExecuteExistingDelayedTasksAfterShutdownPolicy() { + return executeExistingDelayedTasksAfterShutdown; + } + + + /** + * Initiates an orderly shutdown in which previously submitted + * tasks are executed, but no new tasks will be accepted. If the + * <tt>ExecuteExistingDelayedTasksAfterShutdownPolicy</tt> has + * been set <tt>false</tt>, existing delayed tasks whose delays + * have not yet elapsed are cancelled. And unless the + * <tt>ContinueExistingPeriodicTasksAfterShutdownPolicy</tt> has + * been set <tt>true</tt>, future executions of existing periodic + * tasks will be cancelled. + */ + public void shutdown() { + cancelUnwantedTasks(); + super.shutdown(); + } + + /** + * Attempts to stop all actively executing tasks, halts the + * processing of waiting tasks, and returns a list of the tasks + * that were awaiting execution. + * + * <p>There are no guarantees beyond best-effort attempts to stop + * processing actively executing tasks. This implementation + * cancels tasks via {@link Thread#interrupt}, so any task that + * fails to respond to interrupts may never terminate. + * + * @return list of tasks that never commenced execution. Each + * element of this list is a {@link ScheduledFuture}, + * including those tasks submitted using <tt>execute</tt>, which + * are for scheduling purposes used as the basis of a zero-delay + * <tt>ScheduledFuture</tt>. + * @throws SecurityException {@inheritDoc} + */ + public List<Runnable> shutdownNow() { + return super.shutdownNow(); + } + + /** + * Returns the task queue used by this executor. Each element of + * this queue is a {@link ScheduledFuture}, including those + * tasks submitted using <tt>execute</tt> which are for scheduling + * purposes used as the basis of a zero-delay + * <tt>ScheduledFuture</tt>. Iteration over this queue is + * <em>not</em> guaranteed to traverse tasks in the order in + * which they will execute. + * + * @return the task queue + */ + public BlockingQueue<Runnable> getQueue() { + return super.getQueue(); + } + + /** + * An annoying wrapper class to convince javac to use a + * DelayQueue<RunnableScheduledFuture> as a BlockingQueue<Runnable> + */ + private static class DelayedWorkQueue + extends AbstractCollection<Runnable> + implements BlockingQueue<Runnable> { + + private final DelayQueue<RunnableScheduledFuture> dq = new DelayQueue<RunnableScheduledFuture>(); + public Runnable poll() { return dq.poll(); } + public Runnable peek() { return dq.peek(); } + public Runnable take() throws InterruptedException { return dq.take(); } + public Runnable poll(long timeout, TimeUnit unit) throws InterruptedException { + return dq.poll(timeout, unit); + } + + public boolean add(Runnable x) { + return dq.add((RunnableScheduledFuture)x); + } + public boolean offer(Runnable x) { + return dq.offer((RunnableScheduledFuture)x); + } + public void put(Runnable x) { + dq.put((RunnableScheduledFuture)x); + } + public boolean offer(Runnable x, long timeout, TimeUnit unit) { + return dq.offer((RunnableScheduledFuture)x, timeout, unit); + } + + public Runnable remove() { return dq.remove(); } + public Runnable element() { return dq.element(); } + public void clear() { dq.clear(); } + public int drainTo(Collection<? super Runnable> c) { return dq.drainTo(c); } + public int drainTo(Collection<? super Runnable> c, int maxElements) { + return dq.drainTo(c, maxElements); + } + + public int remainingCapacity() { return dq.remainingCapacity(); } + public boolean remove(Object x) { return dq.remove(x); } + public boolean contains(Object x) { return dq.contains(x); } + public int size() { return dq.size(); } + public boolean isEmpty() { return dq.isEmpty(); } + public Object[] toArray() { return dq.toArray(); } + public <T> T[] toArray(T[] array) { return dq.toArray(array); } + public Iterator<Runnable> iterator() { + return new Iterator<Runnable>() { + private Iterator<RunnableScheduledFuture> it = dq.iterator(); + public boolean hasNext() { return it.hasNext(); } + public Runnable next() { return it.next(); } + public void remove() { it.remove(); } + }; + } + } +} |