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.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  19  * CA 95054 USA or visit www.sun.com if you need additional information or
  20  * have any questions.
  21  */
  22 
  23 /*
  24  * This file is available under and governed by the GNU General Public
  25  * License version 2 only, as published by the Free Software Foundation.
  26  * However, the following notice accompanied the original version of this
  27  * file:
  28  *
  29  * Written by Doug Lea with assistance from members of JCP JSR-166
  30  * Expert Group and released to the public domain, as explained at
  31  * http://creativecommons.org/licenses/publicdomain
  32  */
  33 
  34 /*
  35  * @test
  36  * @bug 4486658
  37  * @compile -source 1.5 CancelledFutureLoops.java
  38  * @run main/timeout=2000 CancelledFutureLoops
  39  * @summary Checks for responsiveness of futures to cancellation.
  40  * Runs under the assumption that ITERS computations require more than
  41  * TIMEOUT msecs to complete.
  42  */
  43 
  44 import java.util.concurrent.*;
  45 import java.util.concurrent.locks.*;
  46 import java.util.*;
  47 
  48 public final class CancelledFutureLoops {
  49     static final ExecutorService pool = Executors.newCachedThreadPool();
  50     static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
  51     static boolean print = false;
  52     static final int ITERS = 1000000;
  53     static final long TIMEOUT = 100;
  54 
  55     public static void main(String[] args) throws Exception {
  56         int maxThreads = 5;
  57         if (args.length > 0)
  58             maxThreads = Integer.parseInt(args[0]);
  59 
  60         print = true;
  61 
  62         for (int i = 2; i <= maxThreads; i += (i+1) >>> 1) {
  63             System.out.print("Threads: " + i);
  64             try {
  65                 new FutureLoop(i).test();
  66             }
  67             catch(BrokenBarrierException bb) {
  68                 // OK; ignore
  69             }
  70             catch(ExecutionException ee) {
  71                 // OK; ignore
  72             }
  73             Thread.sleep(TIMEOUT);
  74         }
  75         pool.shutdown();
  76         if (! pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS))
  77             throw new Error();
  78     }
  79 
  80     static final class FutureLoop implements Callable {
  81         private int v = rng.next();
  82         private final ReentrantLock lock = new ReentrantLock();
  83         private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
  84         private final CyclicBarrier barrier;
  85         private final int nthreads;
  86         FutureLoop(int nthreads) {
  87             this.nthreads = nthreads;
  88             barrier = new CyclicBarrier(nthreads+1, timer);
  89         }
  90 
  91         final void test() throws Exception {
  92             Future[] futures = new Future[nthreads];
  93             for (int i = 0; i < nthreads; ++i)
  94                 futures[i] = pool.submit(this);
  95 
  96             barrier.await();
  97             Thread.sleep(TIMEOUT);
  98             boolean tooLate = false;
  99             for (int i = 1; i < nthreads; ++i) {
 100                 if (!futures[i].cancel(true))
 101                     tooLate = true;
 102                 // Unbunch some of the cancels
 103                 if ( (i & 3) == 0)
 104                     Thread.sleep(1 + rng.next() % 10);
 105             }
 106 
 107             Object f0 = futures[0].get();
 108             if (!tooLate) {
 109                 for (int i = 1; i < nthreads; ++i) {
 110                     if (!futures[i].isDone() || !futures[i].isCancelled())
 111                         throw new Error("Only one thread should complete");
 112                 }
 113             }
 114             else
 115                 System.out.print("(cancelled too late) ");
 116 
 117             long endTime = System.nanoTime();
 118             long time = endTime - timer.startTime;
 119             if (print) {
 120                 double secs = (double)(time) / 1000000000.0;
 121                 System.out.println("\t " + secs + "s run time");
 122             }
 123 
 124         }
 125 
 126         public final Object call() throws Exception {
 127             barrier.await();
 128             int sum = v;
 129             int x = 0;
 130             int n = ITERS;
 131             while (n-- > 0) {
 132                 lock.lockInterruptibly();
 133                 try {
 134                     v = x = LoopHelpers.compute1(v);
 135                 }
 136                 finally {
 137                     lock.unlock();
 138                 }
 139                 sum += LoopHelpers.compute2(LoopHelpers.compute2(x));
 140             }
 141             return new Integer(sum);
 142         }
 143     }
 144 
 145 }