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/* |
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* Written by Doug Lea and Martin Buchholz with assistance from members of |
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* JCP JSR-166 Expert Group and released to the public domain, as explained |
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* at http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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|
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import java.util.concurrent.*; |
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import java.util.concurrent.atomic.*; |
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|
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/** |
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* Tries to demonstrate a leaked interrupt from FutureTask.cancel(true). |
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*/ |
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public class FutureTaskCancelLoops { |
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static long millisElapsedSince(long startTimeNanos) { |
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return (System.nanoTime() - startTimeNanos)/(1000L*1000L); |
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} |
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|
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public static void main(String[] args) throws Exception { |
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|
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long startTime = System.nanoTime(); |
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|
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final BlockingQueue<Runnable> q = new LinkedBlockingQueue<Runnable>(10000); |
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|
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final ThreadPoolExecutor pool = |
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new ThreadPoolExecutor(1, 1, 0L, TimeUnit.MILLISECONDS, q); |
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|
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final AtomicLong count = new AtomicLong(0); |
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|
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final AtomicReference<Future<?>> cancelMe |
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= new AtomicReference<Future<?>>(null); |
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|
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final AtomicBoolean leakedInterrupt = new AtomicBoolean(false); |
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final AtomicBoolean goHome = new AtomicBoolean(false); |
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|
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class InterruptMeTask extends FutureTask<Void> { |
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InterruptMeTask() { this(new AtomicReference<Future<?>>()); } |
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InterruptMeTask(final AtomicReference<Future<?>> myFuture) { |
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super(new Runnable() { |
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public void run() { |
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if (cancelMe.get() != null) { |
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// We're likely to get the interrupt meant for previous task. |
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// Clear interrupts first to prove *we* got interrupted. |
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Thread.interrupted(); |
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while (cancelMe.get() != null && !goHome.get()) { |
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if (Thread.interrupted()) { |
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leakedInterrupt.set(true); |
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goHome.set(true); |
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System.err.println("leaked interrupt!"); |
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} |
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} |
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} else { |
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cancelMe.set(myFuture.get()); |
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do {} while (! myFuture.get().isCancelled() && |
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!goHome.get()); |
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} |
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count.getAndIncrement(); |
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|
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if (q.isEmpty()) |
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for (int i = 0, n = q.remainingCapacity(); i < n; i++) |
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pool.execute(new InterruptMeTask()); |
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}}, null); |
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myFuture.set(this); |
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} |
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} |
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|
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pool.execute(new InterruptMeTask()); // "starter" task |
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|
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while (!goHome.get() && millisElapsedSince(startTime) < 1000L) { |
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Future<?> future = cancelMe.get(); |
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if (future != null) { |
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future.cancel(true); |
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cancelMe.set(null); |
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} |
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} |
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|
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goHome.set(true); |
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pool.shutdown(); |
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|
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if (leakedInterrupt.get()) { |
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String msg = String.format |
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("%d tasks run, %d millis elapsed, till leaked interrupt%n", |
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count.get(), millisElapsedSince(startTime)); |
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throw new IllegalStateException(msg); |
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} else { |
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System.out.printf |
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("%d tasks run, %d millis elapsed%n", |
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count.get(), millisElapsedSince(startTime)); |
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} |
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} |
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} |
