The Android Open Source Project | 9066cfe | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2007 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 | |
| 17 | package com.android.server; |
| 18 | |
| 19 | import android.os.SystemClock; |
| 20 | |
| 21 | import android.os.ConditionVariable; |
| 22 | |
| 23 | /** |
| 24 | * Utility class that you can call on with a timeout, and get called back |
| 25 | * after a given time, dealing correctly with restarting the timeout. |
| 26 | * |
| 27 | * <p>For example, this class is used by the android.os.Vibrator class. |
| 28 | */ |
| 29 | abstract class ResettableTimeout |
| 30 | { |
| 31 | /** |
| 32 | * Override this do what you need to do when it's starting |
| 33 | * This is called with the monitor on this method held, so be careful. |
| 34 | * |
| 35 | * @param alreadyOn is true if it's currently running |
| 36 | */ |
| 37 | public abstract void on(boolean alreadyOn); |
| 38 | |
| 39 | /** |
| 40 | * Override this to do what you need to do when it's stopping. |
| 41 | * This is called with the monitor on this method held, so be careful. |
| 42 | */ |
| 43 | public abstract void off(); |
| 44 | |
| 45 | /** |
| 46 | * Does the following steps. |
| 47 | * <p>1. Call on()</p> |
| 48 | * <p>2. Start the timer.</p> |
| 49 | * <p>3. At the timeout, calls off()<p> |
| 50 | * <p>If you call this again, the timeout is reset to the new one</p> |
| 51 | */ |
| 52 | public void go(long milliseconds) |
| 53 | { |
| 54 | synchronized (this) { |
| 55 | mOffAt = SystemClock.uptimeMillis() + milliseconds; |
| 56 | |
| 57 | boolean alreadyOn; |
| 58 | |
| 59 | // By starting the thread first and waiting, we ensure that if the |
| 60 | // thread to stop it can't start, we don't turn the vibrator on |
| 61 | // forever. This still isn't really sufficient, because we don't |
| 62 | // have another processor watching us. We really should have a |
| 63 | // service for this in case our process crashes. |
| 64 | if (mThread == null) { |
| 65 | alreadyOn = false; |
| 66 | mLock.close(); |
| 67 | mThread = new T(); |
| 68 | mThread.start(); |
| 69 | mLock.block(); |
| 70 | mOffCalled = false; |
| 71 | } else { |
| 72 | alreadyOn = true; |
| 73 | // poke the thread so it gets the new timeout. |
| 74 | mThread.interrupt(); |
| 75 | } |
| 76 | on(alreadyOn); |
| 77 | } |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Cancel the timeout and call off now. |
| 82 | */ |
| 83 | public void cancel() |
| 84 | { |
| 85 | synchronized (this) { |
| 86 | mOffAt = 0; |
| 87 | if (mThread != null) { |
| 88 | mThread.interrupt(); |
| 89 | mThread = null; |
| 90 | } |
| 91 | if (!mOffCalled) { |
| 92 | mOffCalled = true; |
| 93 | off(); |
| 94 | } |
| 95 | } |
| 96 | } |
| 97 | |
| 98 | private class T extends Thread |
| 99 | { |
| 100 | public void run() |
| 101 | { |
| 102 | mLock.open(); |
| 103 | while (true) { |
| 104 | long diff; |
| 105 | synchronized (this) { |
| 106 | diff = mOffAt - SystemClock.uptimeMillis(); |
| 107 | if (diff <= 0) { |
| 108 | mOffCalled = true; |
| 109 | off(); |
| 110 | mThread = null; |
| 111 | break; |
| 112 | } |
| 113 | } |
| 114 | try { |
| 115 | sleep(diff); |
| 116 | } |
| 117 | catch (InterruptedException e) { |
| 118 | } |
| 119 | } |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | private ConditionVariable mLock = new ConditionVariable(); |
| 124 | |
| 125 | // turn it off at this time. |
| 126 | private volatile long mOffAt; |
| 127 | private volatile boolean mOffCalled; |
| 128 | |
| 129 | private Thread mThread; |
| 130 | |
| 131 | } |
| 132 | |