xpcom/base/AvailableMemoryWatcher.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_AvailableMemoryWatcher_h
   8 #define mozilla_AvailableMemoryWatcher_h
   9
  10 #include "mozilla/ipc/CrashReporterHost.h"
  11 #include "mozilla/UniquePtr.h"
  12 #include "MemoryPressureLevelMac.h"
  13 #include "nsCOMPtr.h"
  14 #include "nsIAvailableMemoryWatcherBase.h"
  15 #include "nsIObserver.h"
  16 #include "nsIObserverService.h"
  17
  18 namespace mozilla {
  19
  20 // This class implements a platform-independent part to watch the system's
  21 // memory situation and invoke the registered callbacks when we detect
  22 // a low-memory situation or a high-memory situation.
  23 // The actual logic to monitor the memory status is implemented in a subclass
  24 // of nsAvailableMemoryWatcherBase per platform.
  25 class nsAvailableMemoryWatcherBase : public nsIAvailableMemoryWatcherBase,
  26                                      public nsIObserver {
  27   static StaticRefPtr<nsAvailableMemoryWatcherBase> sSingleton;
  28   static const char* const kObserverTopics[];
  29
  30   TimeStamp mLowMemoryStart;
  31
  32  protected:
  33   // On Windows the publicly available methods (::Observe() and ::Notify()) are
  34   // called on the main thread while the ::LowMemoryCallback() method is called
  35   // by an external thread. All functions called from those must acquire a lock
  36   // on this mutex before accessing the object's fields to prevent races.
  37   //
  38   // On Linux we might tell polling to start/stop from our polling thread
  39   // or from the main thread during ::Observe().
  40   Mutex mMutex;
  41
  42   uint32_t mNumOfTabUnloading MOZ_GUARDED_BY(mMutex);
  43   uint32_t mNumOfMemoryPressure MOZ_GUARDED_BY(mMutex);
  44
  45   nsCOMPtr<nsITabUnloader> mTabUnloader;
  46   nsCOMPtr<nsIObserverService> mObserverSvc;
  47   // Do not change this value off the main thread.
  48   bool mInteracting;
  49
  50   virtual ~nsAvailableMemoryWatcherBase() = default;
  51   virtual nsresult Init();
  52   void Shutdown();
  53   void UpdateLowMemoryTimeStamp();
  54   void RecordTelemetryEventOnHighMemory(const MutexAutoLock&)
  55       MOZ_REQUIRES(mMutex);
  56
  57  public:
  58   static already_AddRefed<nsAvailableMemoryWatcherBase> GetSingleton();
  59
  60   nsAvailableMemoryWatcherBase();
  61
  62 #if defined(XP_DARWIN)
  63   virtual void OnMemoryPressureChanged(MacMemoryPressureLevel aNewLevel) {};
  64   virtual void AddChildAnnotations(
  65       const UniquePtr<ipc::CrashReporterHost>& aCrashReporter) {};
  66 #endif
  67
  68   NS_DECL_THREADSAFE_ISUPPORTS
  69   NS_DECL_NSIAVAILABLEMEMORYWATCHERBASE
  70   NS_DECL_NSIOBSERVER
  71 };
  72
  73 // Method to create a platform-specific object
  74 already_AddRefed<nsAvailableMemoryWatcherBase> CreateAvailableMemoryWatcher();
  75
  76 }  // namespace mozilla
  77
  78 #endif  // ifndef mozilla_AvailableMemoryWatcher_h