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dl |
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/* |
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* @test |
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* @summary Checks for responsiveness of futures to cancellation. |
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* Runs under |
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* the assumption that ITERS computations require more than TIMEOUT |
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* msecs to complete. |
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*/ |
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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain. Use, modify, and |
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* redistribute this code in any way without acknowledgement. |
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*/ |
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import java.util.concurrent.*; |
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import java.util.concurrent.locks.*; |
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import java.util.*; |
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public final class CancelledFutureLoops { |
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static final ExecutorService pool = Executors.newCachedThreadPool(); |
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static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom(); |
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static boolean print = false; |
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static final int ITERS = 10000000; |
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static final long TIMEOUT = 100; |
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public static void main(String[] args) throws Exception { |
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int maxThreads = 100; |
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if (args.length > 0) |
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maxThreads = Integer.parseInt(args[0]); |
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print = true; |
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for (int i = 2; i <= maxThreads; i += (i+1) >>> 1) { |
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System.out.print("Threads: " + i); |
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new FutureLoop(i).test(); |
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Thread.sleep(TIMEOUT); |
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} |
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pool.shutdown(); |
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} |
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static final class FutureLoop implements Callable { |
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private int v = rng.next(); |
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private final ReentrantLock lock = new ReentrantLock(); |
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private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer(); |
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private final CyclicBarrier barrier; |
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private final int nthreads; |
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FutureLoop(int nthreads) { |
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this.nthreads = nthreads; |
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barrier = new CyclicBarrier(nthreads+1, timer); |
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} |
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final void test() throws Exception { |
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Future[] futures = new Future[nthreads]; |
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for (int i = 0; i < nthreads; ++i) |
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futures[i] = pool.submit(this); |
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barrier.await(); |
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Thread.sleep(TIMEOUT); |
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boolean tooLate = false; |
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for (int i = 1; i < nthreads; ++i) { |
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if (!futures[i].cancel(true)) |
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tooLate = true; |
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// Unbunch some of the cancels |
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if ( (i & 3) == 0) |
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Thread.sleep(1 + rng.next() % 10); |
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} |
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Object f0 = futures[0].get(); |
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if (!tooLate) { |
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for (int i = 1; i < nthreads; ++i) { |
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if (!futures[i].isDone() || !futures[i].isCancelled()) |
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throw new Error("Only one thread should complete"); |
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} |
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} |
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else |
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System.out.print("(cancelled too late) "); |
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long endTime = System.nanoTime(); |
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long time = endTime - timer.startTime; |
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if (print) { |
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double secs = (double)(time) / 1000000000.0; |
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System.out.println("\t " + secs + "s run time"); |
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} |
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} |
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public final Object call() throws Exception { |
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barrier.await(); |
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int sum = v; |
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int x = 0; |
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int n = ITERS; |
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while (n-- > 0) { |
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lock.lockInterruptibly(); |
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try { |
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v = x = LoopHelpers.compute1(v); |
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} |
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finally { |
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lock.unlock(); |
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} |
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sum += LoopHelpers.compute2(LoopHelpers.compute2(x)); |
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} |
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return new Integer(sum); |
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} |
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} |
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} |
