| // Copyright 2014 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_ASHMEM_ALLOCATOR_H_ |
| #define BASE_MEMORY_DISCARDABLE_MEMORY_ASHMEM_ALLOCATOR_H_ |
| |
| #include <string> |
| |
| #include "base/base_export.h" |
| #include "base/basictypes.h" |
| #include "base/memory/scoped_ptr.h" |
| #include "base/memory/scoped_vector.h" |
| #include "base/synchronization/lock.h" |
| |
| namespace base { |
| namespace internal { |
| |
| class AshmemRegion; |
| |
| // Internal class, whose instances are returned to the client of the allocator |
| // (e.g. DiscardableMemoryAshmem), that mimicks the DiscardableMemory interface. |
| class BASE_EXPORT_PRIVATE DiscardableAshmemChunk { |
| public: |
| ~DiscardableAshmemChunk(); |
| |
| // Returns whether the memory is still resident. |
| bool Lock(); |
| |
| void Unlock(); |
| |
| void* Memory() const; |
| |
| private: |
| friend class AshmemRegion; |
| |
| DiscardableAshmemChunk(AshmemRegion* ashmem_region, |
| int fd, |
| void* address, |
| size_t offset, |
| size_t size); |
| |
| AshmemRegion* const ashmem_region_; |
| const int fd_; |
| void* const address_; |
| const size_t offset_; |
| const size_t size_; |
| bool locked_; |
| |
| DISALLOW_COPY_AND_ASSIGN(DiscardableAshmemChunk); |
| }; |
| |
| // Ashmem regions are backed by a file (descriptor) therefore they are a limited |
| // resource. This allocator minimizes the problem by allocating large ashmem |
| // regions internally and returning smaller chunks to the client. |
| // Allocated chunks are systematically aligned on a page boundary therefore this |
| // allocator should not be used for small allocations. |
| class BASE_EXPORT_PRIVATE DiscardableMemoryAshmemAllocator { |
| public: |
| // Note that |name| is only used for debugging/measurement purposes. |
| // |ashmem_region_size| is the size that will be used to create the underlying |
| // ashmem regions and is expected to be greater or equal than 32 MBytes. |
| DiscardableMemoryAshmemAllocator(const std::string& name, |
| size_t ashmem_region_size); |
| |
| ~DiscardableMemoryAshmemAllocator(); |
| |
| // Note that the allocator must outlive the returned DiscardableAshmemChunk |
| // instance. |
| scoped_ptr<DiscardableAshmemChunk> Allocate(size_t size); |
| |
| // Returns the size of the last ashmem region which was created. This is used |
| // for testing only. |
| size_t last_ashmem_region_size() const; |
| |
| private: |
| friend class AshmemRegion; |
| |
| void DeleteAshmemRegion_Locked(AshmemRegion* region); |
| |
| const std::string name_; |
| const size_t ashmem_region_size_; |
| mutable Lock lock_; |
| size_t last_ashmem_region_size_; |
| ScopedVector<AshmemRegion> ashmem_regions_; |
| |
| DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryAshmemAllocator); |
| }; |
| |
| } // namespace internal |
| } // namespace base |
| |
| #endif // BASE_MEMORY_DISCARDABLE_MEMORY_ASHMEM_ALLOCATOR_H_ |