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 */
16package com.replica.replicaisland;
17
18import java.util.concurrent.Semaphore;
19import java.util.concurrent.TimeUnit;
20
21import android.util.Log;
22
23import 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 */
29public 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