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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      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 package com.replica.replicaisland;
     17 
     18 import java.util.concurrent.Semaphore;
     19 import java.util.concurrent.TimeUnit;
     20 
     21 import android.util.Log;
     22 
     23 import junit.framework.Assert;
     24 
     25 /**
     26  * class for checking if rendering function is alive or not.
     27  * panic if watch-dog is not reset over certain amount of time
     28  */
     29 public class RenderingWatchDog implements Runnable {
     30     /** panic if watch-dog is not reset over this amount of time */
     31     private static final long DEFAULT_TIMEOUT_IN_MSECS = 10 * 1000;
     32     private static final String TAG = "RenderingWatchDog";
     33     private Thread mThread;
     34     private Semaphore mSemaphore;
     35     private volatile boolean mStopRequested;
     36     private final long mTimeoutInMilliSecs;
     37 
     38     public RenderingWatchDog() {
     39         this(DEFAULT_TIMEOUT_IN_MSECS);
     40     }
     41 
     42     public RenderingWatchDog(long timeoutInMilliSecs) {
     43         mTimeoutInMilliSecs = timeoutInMilliSecs;
     44     }
     45 
     46     /** start watch-dog */
     47     public void start() {
     48         Log.i(TAG, "start");
     49         mStopRequested = false;
     50         mSemaphore = new Semaphore(0);
     51         mThread = new Thread(this);
     52         mThread.start();
     53     }
     54 
     55     /** stop watch-dog */
     56     public void stop() {
     57         Log.i(TAG, "stop");
     58         if (mThread == null) {
     59             return; // already finished
     60         }
     61         mStopRequested = true;
     62         mSemaphore.release();
     63         try {
     64             mThread.join();
     65         } catch (InterruptedException e) {
     66             // ignore
     67         }
     68         mThread = null;
     69         mSemaphore = null;
     70     }
     71 
     72     /** resets watch-dog, thus prevent it from panic */
     73     public void reset() {
     74         if (!mStopRequested) { // stop requested, but rendering still on-going
     75             mSemaphore.release();
     76         }
     77     }
     78 
     79     @Override
     80     public void run() {
     81         while (!mStopRequested) {
     82             try {
     83                 Assert.assertTrue("Watchdog timed-out",
     84                         mSemaphore.tryAcquire(mTimeoutInMilliSecs, TimeUnit.MILLISECONDS));
     85             } catch (InterruptedException e) {
     86                 // this thread will not be interrupted,
     87                 // but if it happens, just check the exit condition.
     88             }
     89         }
     90     }
     91 }
     92