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      1 /*
      2  * Copyright 2018 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 #include "IdleTimer.h"
     18 
     19 #include <chrono>
     20 #include <thread>
     21 
     22 namespace android {
     23 namespace scheduler {
     24 
     25 IdleTimer::IdleTimer(const Interval& interval, const ResetCallback& resetCallback,
     26                      const TimeoutCallback& timeoutCallback)
     27       : mInterval(interval), mResetCallback(resetCallback), mTimeoutCallback(timeoutCallback) {}
     28 
     29 IdleTimer::~IdleTimer() {
     30     stop();
     31 }
     32 
     33 void IdleTimer::start() {
     34     {
     35         std::lock_guard<std::mutex> lock(mMutex);
     36         mState = TimerState::RESET;
     37     }
     38     mThread = std::thread(&IdleTimer::loop, this);
     39 }
     40 
     41 void IdleTimer::stop() {
     42     {
     43         std::lock_guard<std::mutex> lock(mMutex);
     44         mState = TimerState::STOPPED;
     45     }
     46     mCondition.notify_all();
     47     if (mThread.joinable()) {
     48         mThread.join();
     49     }
     50 }
     51 
     52 void IdleTimer::loop() {
     53     while (true) {
     54         bool triggerReset = false;
     55         bool triggerTimeout = false;
     56         {
     57             std::lock_guard<std::mutex> lock(mMutex);
     58             if (mState == TimerState::STOPPED) {
     59                 break;
     60             }
     61 
     62             if (mState == TimerState::IDLE) {
     63                 mCondition.wait(mMutex);
     64                 continue;
     65             }
     66 
     67             if (mState == TimerState::RESET) {
     68                 triggerReset = true;
     69             }
     70         }
     71         if (triggerReset && mResetCallback) {
     72             mResetCallback();
     73         }
     74 
     75         { // lock the mutex again. someone might have called stop meanwhile
     76             std::lock_guard<std::mutex> lock(mMutex);
     77             if (mState == TimerState::STOPPED) {
     78                 break;
     79             }
     80 
     81             auto triggerTime = std::chrono::steady_clock::now() + mInterval;
     82             mState = TimerState::WAITING;
     83             while (mState == TimerState::WAITING) {
     84                 constexpr auto zero = std::chrono::steady_clock::duration::zero();
     85                 auto waitTime = triggerTime - std::chrono::steady_clock::now();
     86                 if (waitTime > zero) mCondition.wait_for(mMutex, waitTime);
     87                 if (mState == TimerState::RESET) {
     88                     triggerTime = std::chrono::steady_clock::now() + mInterval;
     89                     mState = TimerState::WAITING;
     90                 } else if (mState == TimerState::WAITING &&
     91                            (triggerTime - std::chrono::steady_clock::now()) <= zero) {
     92                     triggerTimeout = true;
     93                     mState = TimerState::IDLE;
     94                 }
     95             }
     96         }
     97         if (triggerTimeout && mTimeoutCallback) {
     98             mTimeoutCallback();
     99         }
    100     }
    101 } // namespace scheduler
    102 
    103 void IdleTimer::reset() {
    104     {
    105         std::lock_guard<std::mutex> lock(mMutex);
    106         mState = TimerState::RESET;
    107     }
    108     mCondition.notify_all();
    109 }
    110 
    111 } // namespace scheduler
    112 } // namespace android
    113