| // Copyright 2015 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. |
| |
| #ifndef BASE_MEMORY_DISCARDABLE_MEMORY_ALLOCATOR_H_ |
| #define BASE_MEMORY_DISCARDABLE_MEMORY_ALLOCATOR_H_ |
| |
| #include <stddef.h> |
| |
| #include <memory> |
| |
| #include "base/base_export.h" |
| #include "base/macros.h" |
| |
| namespace base { |
| class DiscardableMemory; |
| |
| // An allocator which creates and manages DiscardableMemory. The allocator |
| // itself should be created via CreateDiscardableMemoryAllocator, which |
| // selects an appropriate implementation depending on platform support. |
| class BASE_EXPORT DiscardableMemoryAllocator { |
| public: |
| DiscardableMemoryAllocator() = default; |
| virtual ~DiscardableMemoryAllocator() = default; |
| |
| // Returns the allocator instance. |
| static DiscardableMemoryAllocator* GetInstance(); |
| |
| // Sets the allocator instance. Can only be called once, e.g. on startup. |
| // Ownership of |instance| remains with the caller. |
| static void SetInstance(DiscardableMemoryAllocator* allocator); |
| |
| // Creates an initially-locked instance of discardable memory. |
| // If the platform supports Android ashmem or madvise(MADV_FREE), |
| // platform-specific techniques will be used to discard memory under pressure. |
| // Otherwise, discardable memory is emulated and manually discarded |
| // heuristicly (via memory pressure notifications). |
| virtual std::unique_ptr<DiscardableMemory> AllocateLockedDiscardableMemory( |
| size_t size) = 0; |
| |
| // Gets the total number of bytes allocated by this allocator which have not |
| // been discarded. |
| virtual size_t GetBytesAllocated() const = 0; |
| |
| // Release any memory used in the implementation of discardable memory that is |
| // not immediately being used. |
| virtual void ReleaseFreeMemory() = 0; |
| |
| private: |
| DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryAllocator); |
| }; |
| |
| } // namespace base |
| |
| #endif // BASE_MEMORY_DISCARDABLE_MEMORY_ALLOCATOR_H_ |