1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef COMPONENTS_TIMERS_ALARM_TIMER_CHROMEOS_H_ 6 #define COMPONENTS_TIMERS_ALARM_TIMER_CHROMEOS_H_ 7 8 #include <memory> 9 10 #include "base/files/file_descriptor_watcher_posix.h" 11 #include "base/macros.h" 12 #include "base/memory/scoped_refptr.h" 13 #include "base/memory/weak_ptr.h" 14 #include "base/threading/sequenced_task_runner_handle.h" 15 #include "base/time/time.h" 16 #include "base/timer/timer.h" 17 18 namespace base { 19 struct PendingTask; 20 } 21 22 namespace timers { 23 // The class implements a timer that is capable of waking the system up from a 24 // suspended state. For example, this is useful for running tasks that are 25 // needed for maintaining network connectivity, like sending heartbeat messages. 26 // Currently, this feature is only available on Chrome OS systems running linux 27 // version 3.11 or higher. On all other platforms, the SimpleAlarmTimer behaves 28 // exactly the same way as a regular Timer. 29 // 30 // A SimpleAlarmTimer instance can only be used from the sequence on which it 31 // was instantiated. Start() and Stop() must be called from a thread that 32 // supports FileDescriptorWatcher. 33 // 34 // A SimpleAlarmTimer only fires once but remembers the task that it was given 35 // even after it has fired. Useful if you want to run the same task multiple 36 // times but not at a regular interval. 37 class SimpleAlarmTimer : public base::RetainingOneShotTimer { 38 public: 39 SimpleAlarmTimer(); 40 ~SimpleAlarmTimer() override; 41 42 // Timer overrides. 43 void Stop() override; 44 void Reset() override; 45 46 private: 47 // Called when |alarm_fd_| is readable without blocking. Reads data from 48 // |alarm_fd_| and calls OnTimerFired(). 49 void OnAlarmFdReadableWithoutBlocking(); 50 51 // Called when the timer fires. Runs the callback. 52 void OnTimerFired(); 53 54 // Tracks whether the timer has the ability to wake the system up from 55 // suspend. This is a runtime check because we won't know if the system 56 // supports being woken up from suspend until the constructor actually tries 57 // to set it up. 58 bool CanWakeFromSuspend() const; 59 60 // Timer file descriptor. 61 const int alarm_fd_; 62 63 // Watches |alarm_fd_|. 64 std::unique_ptr<base::FileDescriptorWatcher::Controller> alarm_fd_watcher_; 65 66 // Posts tasks to the sequence on which this AlarmTimer was instantiated. 67 const scoped_refptr<base::SequencedTaskRunner> origin_task_runner_ = 68 base::SequencedTaskRunnerHandle::Get(); 69 70 // Keeps track of the user task we want to run. A new one is constructed every 71 // time Reset() is called. 72 std::unique_ptr<base::PendingTask> pending_task_; 73 74 // Used to invalidate pending callbacks. 75 base::WeakPtrFactory<SimpleAlarmTimer> weak_factory_; 76 77 DISALLOW_COPY_AND_ASSIGN(SimpleAlarmTimer); 78 }; 79 80 } // namespace timers 81 82 #endif // COMPONENTS_TIMERS_ALARM_TIMER_CHROMEOS_H_ 83