text: // Copyright 2010-2014, Google Inc.
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  #include "base/timer.h"
  
  #include "base/logging.h"
  #include "base/thread.h"
  #include "base/unnamed_event.h"
  #include "base/util.h"
  
  namespace mozc {
  
  class Timer::TimerThread : public Thread {
   public:
    TimerThread(uint32 due_time, uint32 interval, Timer *timer)
        : Thread(),
          due_time_(due_time),
          interval_(interval),
          timer_(timer),
          event_(new UnnamedEvent) {}
  
    virtual ~TimerThread() {
      SignalQuit();
      Join();
    }
  
    virtual void Run() {
      if (event_->Wait(due_time_)) {
        VLOG(1) << "Received notification event";
        return;
      }
      VLOG(2) << "call TimerCallback()";
      timer_->TimerCallback();
  
      if (interval_ == 0) {
        VLOG(2) << "Run() end";
        return;
      } else {
        while (true) {
          if (event_->Wait(interval_)) {
            VLOG(1) << "Received notification event";
            return;
          }
          VLOG(2) << "call TimerCallback()";
          timer_->TimerCallback();
        }
      }
    }
  
    void SignalQuit() {
      const bool result = event_->Notify();
      DCHECK(result);
    }
  
   private:
    uint32 due_time_;
    uint32 interval_;
    Timer *timer_;
    scoped_ptr<UnnamedEvent> event_;
  
    DISALLOW_COPY_AND_ASSIGN(TimerThread);
  };
  
  void Timer::TimerCallback() {
    num_signaled_++;
    Signaled();
  }
  
  bool Timer::Start(uint32 due_time, uint32 interval) {
    VLOG(1) << "Starting " << due_time << " " << interval;
    // Note: We can simply destroy |*timer_thread_.get()| since
    // TimerThread::~TimerThread internally joins its background thread.
    timer_thread_.reset(new TimerThread(due_time, interval, this));
    timer_thread_->Start();
    return true;
  }
  
  void Timer::Stop() {
    // Note: We can simply destroy |*timer_thread_.get()| since
    // TimerThread::~TimerThread internally joins its background thread.
    timer_thread_.reset(NULL);
  }
  
  Timer::Timer()
      : num_signaled_(0) {}
  
  Timer::~Timer() {
    Stop();
  }
  
  void Timer::Signaled() {
    // Note: This code can be called back even if a subclass overrides this
    // method when the main thread reached to Timer::~Timer. Do not make this
    // method pure-virtual.
  }
  
  }  // namespace mozc
  