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      1 /*
      2  * Copyright (C) 2011 The Guava Authors
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  * http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.google.common.util.concurrent;
     18 
     19 import static com.google.common.base.Preconditions.checkNotNull;
     20 import static java.util.concurrent.TimeUnit.MILLISECONDS;
     21 import static java.util.concurrent.TimeUnit.NANOSECONDS;
     22 import static junit.framework.Assert.fail;
     23 
     24 import com.google.common.testing.TearDown;
     25 import com.google.common.testing.TearDownAccepter;
     26 
     27 import java.util.concurrent.TimeUnit;
     28 import java.util.logging.Logger;
     29 
     30 /**
     31  * Utilities for performing thread interruption in tests
     32  *
     33  * @author Kevin Bourrillion
     34  * @author Chris Povirk
     35  */
     36 final class InterruptionUtil {
     37   private static final Logger logger =
     38       Logger.getLogger(InterruptionUtil.class.getName());
     39 
     40   /**
     41    * Runnable which will interrupt the target thread repeatedly when run.
     42    */
     43   private static final class Interruptenator implements Runnable {
     44     private final long everyMillis;
     45     private final Thread interruptee;
     46     private volatile boolean shouldStop = false;
     47 
     48     Interruptenator(Thread interruptee, long everyMillis) {
     49       this.everyMillis = everyMillis;
     50       this.interruptee = interruptee;
     51     }
     52 
     53     @Override
     54     public void run() {
     55       while (true) {
     56         try {
     57           Thread.sleep(everyMillis);
     58         } catch (InterruptedException e) {
     59           // ok. just stop sleeping.
     60         }
     61         if (shouldStop) {
     62           break;
     63         }
     64         interruptee.interrupt();
     65       }
     66     }
     67 
     68     void stopInterrupting() {
     69       shouldStop = true;
     70     }
     71   }
     72 
     73   /**
     74    * Interrupts the current thread after sleeping for the specified delay.
     75    */
     76   static void requestInterruptIn(final long time, final TimeUnit unit) {
     77     checkNotNull(unit);
     78     final Thread interruptee = Thread.currentThread();
     79     new Thread(new Runnable() {
     80       @Override
     81       public void run() {
     82         try {
     83           unit.sleep(time);
     84         } catch (InterruptedException wontHappen) {
     85           throw new AssertionError(wontHappen);
     86         }
     87         interruptee.interrupt();
     88       }
     89     }).start();
     90   }
     91 
     92   static void repeatedlyInterruptTestThread(
     93       long interruptPeriodMillis, TearDownAccepter tearDownAccepter) {
     94     final Interruptenator interruptingTask =
     95         new Interruptenator(Thread.currentThread(), interruptPeriodMillis);
     96     final Thread interruptingThread = new Thread(interruptingTask);
     97     interruptingThread.start();
     98     tearDownAccepter.addTearDown(new TearDown() {
     99       @Override public void tearDown() throws Exception {
    100         interruptingTask.stopInterrupting();
    101         interruptingThread.interrupt();
    102         joinUninterruptibly(interruptingThread, 2500, MILLISECONDS);
    103         Thread.interrupted();
    104         if (interruptingThread.isAlive()) {
    105           // This will be hidden by test-output redirection:
    106           logger.severe(
    107               "InterruptenatorTask did not exit; future tests may be affected");
    108           /*
    109            * This won't do any good under JUnit 3, but I'll leave it around in
    110            * case we ever switch to JUnit 4:
    111            */
    112           fail();
    113         }
    114       }
    115     });
    116   }
    117 
    118   // TODO(cpovirk): promote to Uninterruptibles, and add untimed version
    119   private static void joinUninterruptibly(
    120       Thread thread, long timeout, TimeUnit unit) {
    121     boolean interrupted = false;
    122     try {
    123       long remainingNanos = unit.toNanos(timeout);
    124       long end = System.nanoTime() + remainingNanos;
    125 
    126       while (true) {
    127         try {
    128           // TimeUnit.timedJoin() treats negative timeouts just like zero.
    129           NANOSECONDS.timedJoin(thread, remainingNanos);
    130           return;
    131         } catch (InterruptedException e) {
    132           interrupted = true;
    133           remainingNanos = end - System.nanoTime();
    134         }
    135       }
    136     } finally {
    137       if (interrupted) {
    138         Thread.currentThread().interrupt();
    139       }
    140     }
    141   }
    142 }
    143