base/message_loop/message_pump_default.cc

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/message_loop/message_pump_default.h"

#include "base/logging.h"
#include "base/threading/thread_restrictions.h"
#include "build/build_config.h"

#if defined(OS_MACOSX)
#include "base/mac/scoped_nsautorelease_pool.h"
#endif

namespace base {

MessagePumpDefault::MessagePumpDefault()
    : keep_running_(true),
      event_(WaitableEvent::ResetPolicy::AUTOMATIC,
             WaitableEvent::InitialState::NOT_SIGNALED) {}

MessagePumpDefault::~MessagePumpDefault() {
}

void MessagePumpDefault::Run(Delegate* delegate) {
  DCHECK(keep_running_) << "Quit must have been called outside of Run!";

  for (;;) {
#if defined(OS_MACOSX)
    mac::ScopedNSAutoreleasePool autorelease_pool;
#endif

    bool did_work = delegate->DoWork();
    if (!keep_running_)
      break;

    did_work |= delegate->DoDelayedWork(&delayed_work_time_);
    if (!keep_running_)
      break;

    if (did_work)
      continue;

    did_work = delegate->DoIdleWork();
    if (!keep_running_)
      break;

    if (did_work)
      continue;

    ThreadRestrictions::ScopedAllowWait allow_wait;
    if (delayed_work_time_.is_null()) {
      event_.Wait();
    } else {
      // No need to handle already expired |delayed_work_time_| in any special
      // way. When |delayed_work_time_| is in the past TimeWaitUntil returns
      // promptly and |delayed_work_time_| will re-initialized on a next
      // DoDelayedWork call which has to be called in order to get here again.
      event_.TimedWaitUntil(delayed_work_time_);
    }
    // Since event_ is auto-reset, we don't need to do anything special here
    // other than service each delegate method.
  }

  keep_running_ = true;
}

void MessagePumpDefault::Quit() {
  keep_running_ = false;
}

void MessagePumpDefault::ScheduleWork() {
  // Since this can be called on any thread, we need to ensure that our Run
  // loop wakes up.
  event_.Signal();
}

void MessagePumpDefault::ScheduleDelayedWork(
    const TimeTicks& delayed_work_time) {
  // We know that we can't be blocked on Wait right now since this method can
  // only be called on the same thread as Run, so we only need to update our
  // record of how long to sleep when we do sleep.
  delayed_work_time_ = delayed_work_time;
}

}  // namespace base