AvailableMemoryWatcher.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_AvailableMemoryWatcher_h

#define mozilla_AvailableMemoryWatcher_h

#include "mozilla/ipc/CrashReporterHost.h"

#include "mozilla/UniquePtr.h"

#include "MemoryPressureLevelMac.h"

#include "nsCOMPtr.h"

#include "nsIAvailableMemoryWatcherBase.h"

#include "nsIObserver.h"

#include "nsIObserverService.h"

namespace mozilla {

// This class implements a platform-independent part to watch the system's

// memory situation and invoke the registered callbacks when we detect

// a low-memory situation or a high-memory situation.

// The actual logic to monitor the memory status is implemented in a subclass

// of nsAvailableMemoryWatcherBase per platform.

class nsAvailableMemoryWatcherBase : public nsIAvailableMemoryWatcherBase,

                                     public nsIObserver {

  static StaticRefPtr<nsAvailableMemoryWatcherBase> sSingleton;

  static const char* const kObserverTopics[];

  TimeStamp mLowMemoryStart;

 protected:

  // On Windows the publicly available methods (::Observe() and ::Notify()) are

  // called on the main thread while the ::LowMemoryCallback() method is called

  // by an external thread. All functions called from those must acquire a lock

  // on this mutex before accessing the object's fields to prevent races.

//

  // On Linux we might tell polling to start/stop from our polling thread

  // or from the main thread during ::Observe().

  Mutex mMutex;

  uint32_t mNumOfTabUnloading MOZ_GUARDED_BY(mMutex);

  uint32_t mNumOfMemoryPressure MOZ_GUARDED_BY(mMutex);

  nsCOMPtr<nsITabUnloader> mTabUnloader;

  nsCOMPtr<nsIObserverService> mObserverSvc;

  // Do not change this value off the main thread.

  bool mInteracting;

  virtual ~nsAvailableMemoryWatcherBase() = default;

  virtual nsresult Init();

  void Shutdown();

  void UpdateLowMemoryTimeStamp();

  void RecordTelemetryEventOnHighMemory(const MutexAutoLock&)

      MOZ_REQUIRES(mMutex);

 public:

  static already_AddRefed<nsAvailableMemoryWatcherBase> GetSingleton();

  nsAvailableMemoryWatcherBase();

#if defined(XP_DARWIN)

  virtual void OnMemoryPressureChanged(MacMemoryPressureLevel aNewLevel) {};

  virtual void AddChildAnnotations(

      const UniquePtr<ipc::CrashReporterHost>& aCrashReporter) {};

#endif

  NS_DECL_THREADSAFE_ISUPPORTS

  NS_DECL_NSIAVAILABLEMEMORYWATCHERBASE

  NS_DECL_NSIOBSERVER

};

// Method to create a platform-specific object

already_AddRefed<nsAvailableMemoryWatcherBase> CreateAvailableMemoryWatcher();

}  // namespace mozilla

#endif  // ifndef mozilla_AvailableMemoryWatcher_h