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- // 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/callback.h"
- #include "base/memory/discardable_memory.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;
- DiscardableMemoryAllocator(const DiscardableMemoryAllocator&) = delete;
- DiscardableMemoryAllocator& operator=(const DiscardableMemoryAllocator&) =
- delete;
- 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;
- // Allocates discardable memory the same way |AllocateLockedDiscardableMemory|
- // does. In case of failure, calls |on_no_memory| and retries once. As a
- // consequence, |on_no_memory| should free some memory, and importantly,
- // address space as well.
- //
- // In case of allocation failure after retry, terminates the process with
- // an Out Of Memory status (for triage in crash reports).
- //
- // As a consequence, does *not* return nullptr.
- std::unique_ptr<DiscardableMemory>
- AllocateLockedDiscardableMemoryWithRetryOrDie(size_t size,
- OnceClosure on_no_memory);
- // 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;
- };
- } // namespace base
- #endif // BASE_MEMORY_DISCARDABLE_MEMORY_ALLOCATOR_H_
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