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/*
* Copyright 2015 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef COBALT_BASE_POLLER_H_
#define COBALT_BASE_POLLER_H_
#include "base/callback.h"
#include "base/message_loop.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/thread.h"
#include "base/timer.h"
namespace base {
// Poller is a wrapper around a base::RepeatingTimer, with simplified semantics.
class Poller {
public:
Poller(const Closure& user_task, TimeDelta period) : message_loop_(NULL) {
StartTimer(user_task, period);
}
// Using this constructor, you can specify the message loop you would like
// the poll task to be run on.
Poller(MessageLoop* message_loop, const Closure& user_task, TimeDelta period)
: message_loop_(message_loop) {
message_loop_->PostTask(
FROM_HERE, base::Bind(&Poller::StartTimer, base::Unretained(this),
user_task, period));
}
~Poller() {
// If our timer is running on an explicit message loop, post a task to
// have it shut down on that message loop before completing the destruction
// of the Poller.
if (!message_loop_) {
StopTimer();
} else {
message_loop_->PostTask(
FROM_HERE, base::Bind(&Poller::StopTimer, base::Unretained(this)));
// Wait for the timer to actually be stopped.
base::WaitableEvent timer_stopped(true, false);
message_loop_->PostTask(FROM_HERE,
base::Bind(&base::WaitableEvent::Signal,
base::Unretained(&timer_stopped)));
timer_stopped.Wait();
}
}
private:
void StartTimer(const Closure& user_task, TimeDelta period) {
timer_.reset(new RepeatingTimer<Poller>());
timer_->Start(FROM_HERE, period, user_task);
}
void StopTimer() {
timer_.reset();
}
MessageLoop* message_loop_;
scoped_ptr<RepeatingTimer<Poller> > timer_;
DISALLOW_COPY_AND_ASSIGN(Poller);
};
class PollerWithThread {
public:
PollerWithThread(const Closure& user_task, TimeDelta period)
: thread_("PollerThread") {
// Start the dedicated thread and run the Poller on that thread's
// message loop.
thread_.Start();
poller_.reset(new Poller(thread_.message_loop(), user_task, period));
}
private:
base::Thread thread_;
scoped_ptr<Poller> poller_;
};
} // namespace base
#endif // COBALT_BASE_POLLER_H_