michael@0: // Copyright (c) 2008 The Chromium Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: 
michael@0: #ifndef BASE_SYSTEM_MONITOR_H_
michael@0: #define BASE_SYSTEM_MONITOR_H_
michael@0: 
michael@0: #include "base/observer_list_threadsafe.h"
michael@0: #include "base/singleton.h"
michael@0: 
michael@0: // Windows HiRes timers drain the battery faster so we need to know the battery
michael@0: // status.  This isn't true for other platforms.
michael@0: #if defined(OS_WIN)
michael@0: #define ENABLE_BATTERY_MONITORING 1
michael@0: #else
michael@0: #undef ENABLE_BATTERY_MONITORING
michael@0: #endif  // !OS_WIN
michael@0: 
michael@0: namespace base {
michael@0: 
michael@0: // Class for monitoring various system-related subsystems
michael@0: // such as power management, network status, etc.
michael@0: // TODO(mbelshe):  Add support beyond just power management.
michael@0: class SystemMonitor {
michael@0:  public:
michael@0:   // Access to the Singleton
michael@0:   static SystemMonitor* Get() {
michael@0:     // Uses the LeakySingletonTrait because cleanup is optional.
michael@0:     return
michael@0:         Singleton<SystemMonitor, LeakySingletonTraits<SystemMonitor> >::get();
michael@0:   }
michael@0: 
michael@0:   // Start the System Monitor within a process.  This method
michael@0:   // is provided so that the battery check can be deferred.
michael@0:   // The MessageLoop must be started before calling this
michael@0:   // method.
michael@0:   // This is a no-op on platforms for which ENABLE_BATTERY_MONITORING is
michael@0:   // disabled.
michael@0:   static void Start();
michael@0: 
michael@0:   //
michael@0:   // Power-related APIs
michael@0:   //
michael@0: 
michael@0:   // Is the computer currently on battery power.
michael@0:   // Can be called on any thread.
michael@0:   bool BatteryPower() {
michael@0:     // Using a lock here is not necessary for just a bool.
michael@0:     return battery_in_use_;
michael@0:   }
michael@0: 
michael@0:   // Normalized list of power events.
michael@0:   enum PowerEvent {
michael@0:     POWER_STATE_EVENT,  // The Power status of the system has changed.
michael@0:     SUSPEND_EVENT,      // The system is being suspended.
michael@0:     RESUME_EVENT        // The system is being resumed.
michael@0:   };
michael@0: 
michael@0:   // Callbacks will be called on the thread which creates the SystemMonitor.
michael@0:   // During the callback, Add/RemoveObserver will block until the callbacks
michael@0:   // are finished. Observers should implement quick callback functions; if
michael@0:   // lengthy operations are needed, the observer should take care to invoke
michael@0:   // the operation on an appropriate thread.
michael@0:   class PowerObserver {
michael@0:   public:
michael@0:     // Notification of a change in power status of the computer, such
michael@0:     // as from switching between battery and A/C power.
michael@0:     virtual void OnPowerStateChange(SystemMonitor*) = 0;
michael@0: 
michael@0:     // Notification that the system is suspending.
michael@0:     virtual void OnSuspend(SystemMonitor*) = 0;
michael@0: 
michael@0:     // Notification that the system is resuming.
michael@0:     virtual void OnResume(SystemMonitor*) = 0;
michael@0:   };
michael@0: 
michael@0:   // Add a new observer.
michael@0:   // Can be called from any thread.
michael@0:   // Must not be called from within a notification callback.
michael@0:   void AddObserver(PowerObserver* obs);
michael@0: 
michael@0:   // Remove an existing observer.
michael@0:   // Can be called from any thread.
michael@0:   // Must not be called from within a notification callback.
michael@0:   void RemoveObserver(PowerObserver* obs);
michael@0: 
michael@0: #if defined(OS_WIN)
michael@0:   // Windows-specific handling of a WM_POWERBROADCAST message.
michael@0:   // Embedders of this API should hook their top-level window
michael@0:   // message loop and forward WM_POWERBROADCAST through this call.
michael@0:   void ProcessWmPowerBroadcastMessage(int event_id);
michael@0: #endif
michael@0: 
michael@0:   // Cross-platform handling of a power event.
michael@0:   void ProcessPowerMessage(PowerEvent event_id);
michael@0: 
michael@0:   // Constructor.
michael@0:   // Don't use this; access SystemMonitor via the Singleton.
michael@0:   SystemMonitor();
michael@0: 
michael@0:  private:
michael@0:   // Platform-specific method to check whether the system is currently
michael@0:   // running on battery power.  Returns true if running on batteries,
michael@0:   // false otherwise.
michael@0:   bool IsBatteryPower();
michael@0: 
michael@0:   // Checks the battery status and notifies observers if the battery
michael@0:   // status has changed.
michael@0:   void BatteryCheck();
michael@0: 
michael@0:   // Functions to trigger notifications.
michael@0:   void NotifyPowerStateChange();
michael@0:   void NotifySuspend();
michael@0:   void NotifyResume();
michael@0: 
michael@0:   scoped_refptr<ObserverListThreadSafe<PowerObserver> > observer_list_;
michael@0:   bool battery_in_use_;
michael@0:   bool suspended_;
michael@0: 
michael@0: #if defined(ENABLE_BATTERY_MONITORING)
michael@0:   base::OneShotTimer<SystemMonitor> delayed_battery_check_;
michael@0: #endif
michael@0: 
michael@0:   DISALLOW_COPY_AND_ASSIGN(SystemMonitor);
michael@0: };
michael@0: 
michael@0: }
michael@0: 
michael@0: #endif  // BASE_SYSTEM_MONITOR_H_