blob: e1301e9e947c9eb2d82e411b29bca720a40038fc [file] [log] [blame]
// Copyright 2014 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 <memory>
#include "base/files/file_descriptor_watcher_posix.h"
#include "base/files/scoped_file.h"
#include "base/macros.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/weak_ptr.h"
#include "base/threading/sequenced_task_runner_handle.h"
#include "base/time/time.h"
#include "base/timer/timer.h"
namespace base {
struct PendingTask;
namespace timers {
// The class implements a timer that is capable of waking the system up from a
// suspended state. For example, this is useful for running tasks that are
// needed for maintaining network connectivity, like sending heartbeat messages.
// Currently, this feature is only available on Chrome OS systems running linux
// version 3.11 or higher.
// A SimpleAlarmTimer instance can only be used from the sequence on which it
// was instantiated. Start() and Stop() must be called from a thread that
// supports FileDescriptorWatcher.
// A SimpleAlarmTimer only fires once but remembers the task that it was given
// even after it has fired. Useful if you want to run the same task multiple
// times but not at a regular interval.
class SimpleAlarmTimer : public base::RetainingOneShotTimer {
// Creates the SimpleAlarmTimer instance, or returns null on failure, e.g.,
// on a platform without timerfd_* system calls support, or missing
// capability (CAP_WAKE_ALARM).
static std::unique_ptr<SimpleAlarmTimer> Create();
// Similar to Create(), but for unittests without capability.
// Specifically, uses CLOCK_REALTIME instead of CLOCK_REALTIME_ALARM.
static std::unique_ptr<SimpleAlarmTimer> CreateForTesting();
~SimpleAlarmTimer() override;
// Timer overrides.
void Stop() override;
void Reset() override;
// Shared implementation of Create and CreateForTesting.
static std::unique_ptr<SimpleAlarmTimer> CreateInternal(int clockid);
explicit SimpleAlarmTimer(base::ScopedFD alarm_fd);
// Called when |alarm_fd_| is readable without blocking. Reads data from
// |alarm_fd_| and calls OnTimerFired().
void OnAlarmFdReadableWithoutBlocking();
// Called when the timer fires. Runs the callback.
void OnTimerFired();
// Timer file descriptor.
const base::ScopedFD alarm_fd_;
// Watches |alarm_fd_|.
std::unique_ptr<base::FileDescriptorWatcher::Controller> alarm_fd_watcher_;
// Posts tasks to the sequence on which this AlarmTimer was instantiated.
const scoped_refptr<base::SequencedTaskRunner> origin_task_runner_ =
// Keeps track of the user task we want to run. A new one is constructed every
// time Reset() is called.
std::unique_ptr<base::PendingTask> pending_task_;
// Used to invalidate pending callbacks.
base::WeakPtrFactory<SimpleAlarmTimer> weak_factory_;
} // namespace timers