| // Copyright 2013 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. |
| |
| // MemoryPressure provides static APIs for handling memory pressure on |
| // platforms that have such signals, such as Android. |
| // The app will try to discard buffers that aren't deemed essential (individual |
| // modules will implement their own policy). |
| // |
| // Refer to memory_pressure_level_list.h for information about what sorts of |
| // signals can be sent under what conditions. |
| |
| #ifndef BASE_MEMORY_PRESSURE_LISTENER_H_ |
| #define BASE_MEMORY_PRESSURE_LISTENER_H_ |
| |
| #include "base/base_export.h" |
| #include "base/basictypes.h" |
| #include "base/callback.h" |
| |
| namespace base { |
| |
| // To start listening, create a new instance, passing a callback to a |
| // function that takes a MemoryPressureLevel parameter. To stop listening, |
| // simply delete the listener object. The implementation guarantees |
| // that the callback will always be called on the thread that created |
| // the listener. |
| // Note that even on the same thread, the callback is not guaranteed to be |
| // called synchronously within the system memory pressure broadcast. |
| // Please see notes on memory_pressure_level_list.h: some levels are absolutely |
| // critical, and if not enough memory is returned to the system, it'll |
| // potentially kill the app, and then later the app will have to be |
| // cold-started. |
| // |
| // |
| // Example: |
| // |
| // void OnMemoryPressure(MemoryPressureLevel memory_pressure_level) { |
| // ... |
| // } |
| // |
| // // Start listening. |
| // MemoryPressureListener* my_listener = |
| // new MemoryPressureListener(base::Bind(&OnMemoryPressure)); |
| // |
| // ... |
| // |
| // // Stop listening. |
| // delete my_listener; |
| // |
| class BASE_EXPORT MemoryPressureListener { |
| public: |
| enum MemoryPressureLevel { |
| #define DEFINE_MEMORY_PRESSURE_LEVEL(name, value) name = value, |
| #include "base/memory/memory_pressure_level_list.h" |
| #undef DEFINE_MEMORY_PRESSURE_LEVEL |
| }; |
| |
| typedef base::Callback<void(MemoryPressureLevel)> MemoryPressureCallback; |
| |
| explicit MemoryPressureListener( |
| const MemoryPressureCallback& memory_pressure_callback); |
| ~MemoryPressureListener(); |
| |
| // Intended for use by the platform specific implementation. |
| static void NotifyMemoryPressure(MemoryPressureLevel memory_pressure_level); |
| |
| private: |
| void Notify(MemoryPressureLevel memory_pressure_level); |
| |
| MemoryPressureCallback callback_; |
| |
| DISALLOW_COPY_AND_ASSIGN(MemoryPressureListener); |
| }; |
| |
| } // namespace base |
| |
| #endif // BASE_MEMORY_PRESSURE_LISTENER_H_ |