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// 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 <algorithm>
#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 {
TimeDelta delay = delayed_work_time_ - TimeTicks::Now();
if (delay > TimeDelta()) {
#if defined(OS_WIN)
// TODO(stanisc): crbug.com/623223: Consider moving the OS_WIN specific
// logic into TimedWait implementation in waitable_event_win.cc.
// crbug.com/487724: on Windows, waiting for less than 1 ms results in
// returning from TimedWait promptly and spinning
// MessagePumpDefault::Run loop for up to 1 ms - until it is time to
// run a delayed task. |min_delay| is the minimum possible wait to
// to avoid the spinning.
constexpr TimeDelta min_delay = TimeDelta::FromMilliseconds(1);
do {
delay = std::max(delay, min_delay);
if (event_.TimedWait(delay))
break;
// TimedWait can time out earlier than the specified |delay| on
// Windows. It doesn't make sense to run the outer loop in that case
// because there isn't going to be any new work. It is less overhead
// to just go back to wait.
// In practice this inner wait loop might have up to 3 iterations.
delay = delayed_work_time_ - TimeTicks::Now();
} while (delay > TimeDelta());
#else
event_.TimedWait(delay);
#endif
} else {
// It looks like delayed_work_time_ indicates a time in the past, so we
// need to call DoDelayedWork now.
delayed_work_time_ = TimeTicks();
}
}
// 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
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