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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 java.util.concurrent.TimeUnit.MILLISECONDS;
     20 import static java.util.concurrent.TimeUnit.NANOSECONDS;
     21 import static junit.framework.Assert.fail;
     22 
     23 import com.google.common.testing.TearDown;
     24 import com.google.common.testing.TearDownAccepter;
     25 
     26 import java.util.concurrent.TimeUnit;
     27 import java.util.logging.Logger;
     28 
     29 /**
     30  * Utilities for performing thread interruption in tests
     31  *
     32  * @author Kevin Bourrillion
     33  * @author Chris Povirk
     34  */
     35 final class InterruptionUtil {
     36   private static final Logger logger =
     37       Logger.getLogger(InterruptionUtil.class.getName());
     38 
     39   /**
     40    * Runnable which will interrupt the target thread repeatedly when run.
     41    */
     42   private static final class Interruptenator implements Runnable {
     43     private final long everyMillis;
     44     private final Thread interruptee;
     45     private volatile boolean shouldStop = false;
     46 
     47     Interruptenator(Thread interruptee, long everyMillis) {
     48       this.everyMillis = everyMillis;
     49       this.interruptee = interruptee;
     50     }
     51 
     52     @Override
     53     public void run() {
     54       while (true) {
     55         try {
     56           Thread.sleep(everyMillis);
     57         } catch (InterruptedException e) {
     58           // ok. just stop sleeping.
     59         }
     60         if (shouldStop) {
     61           break;
     62         }
     63         interruptee.interrupt();
     64       }
     65     }
     66 
     67     void stopInterrupting() {
     68       shouldStop = true;
     69     }
     70   }
     71 
     72   /**
     73    * Interrupts the current thread after sleeping for the specified delay.
     74    */
     75   static void requestInterruptIn(final long time, final TimeUnit unit) {
     76     final Thread interruptee = Thread.currentThread();
     77     new Thread(new Runnable() {
     78       @Override
     79       public void run() {
     80         try {
     81           unit.sleep(time);
     82         } catch (InterruptedException wontHappen) {
     83           throw new AssertionError(wontHappen);
     84         }
     85         interruptee.interrupt();
     86       }
     87     }).start();
     88   }
     89 
     90   static void repeatedlyInterruptTestThread(
     91       long interruptPeriodMillis, TearDownAccepter tearDownAccepter) {
     92     final Interruptenator interruptingTask =
     93         new Interruptenator(Thread.currentThread(), interruptPeriodMillis);
     94     final Thread interruptingThread = new Thread(interruptingTask);
     95     interruptingThread.start();
     96     tearDownAccepter.addTearDown(new TearDown() {
     97       @Override public void tearDown() throws Exception {
     98         interruptingTask.stopInterrupting();
     99         interruptingThread.interrupt();
    100         joinUninterruptibly(interruptingThread, 2500, MILLISECONDS);
    101         Thread.interrupted();
    102         if (interruptingThread.isAlive()) {
    103           // This will be hidden by test-output redirection:
    104           logger.severe(
    105               "InterruptenatorTask did not exit; future tests may be affected");
    106           /*
    107            * This won't do any good under JUnit 3, but I'll leave it around in
    108            * case we ever switch to JUnit 4:
    109            */
    110           fail();
    111         }
    112       }
    113     });
    114   }
    115 
    116   // TODO(cpovirk): promote to Uninterruptibles, and add untimed version
    117   private static void joinUninterruptibly(
    118       Thread thread, long timeout, TimeUnit unit) {
    119     boolean interrupted = false;
    120     try {
    121       long remainingNanos = unit.toNanos(timeout);
    122       long end = System.nanoTime() + remainingNanos;
    123 
    124       while (true) {
    125         try {
    126           // TimeUnit.timedJoin() treats negative timeouts just like zero.
    127           NANOSECONDS.timedJoin(thread, remainingNanos);
    128           return;
    129         } catch (InterruptedException e) {
    130           interrupted = true;
    131           remainingNanos = end - System.nanoTime();
    132         }
    133       }
    134     } finally {
    135       if (interrupted) {
    136         Thread.currentThread().interrupt();
    137       }
    138     }
    139   }
    140 }
    141