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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 COMPONENTS_HTML_VIEWER_DISCARDABLE_MEMORY_ALLOCATOR_H_
#define COMPONENTS_HTML_VIEWER_DISCARDABLE_MEMORY_ALLOCATOR_H_
#include <list>
#include "base/memory/discardable_memory_allocator.h"
namespace html_viewer {
// A discarable memory allocator which will unallocate chunks on new
// allocations.
class DiscardableMemoryAllocator : public base::DiscardableMemoryAllocator {
public:
class OwnedMemoryChunk;
explicit DiscardableMemoryAllocator(size_t desired_max_memory);
~DiscardableMemoryAllocator() override;
// Overridden from DiscardableMemoryAllocator:
scoped_ptr<base::DiscardableMemory> AllocateLockedDiscardableMemory(
size_t size) override;
private:
friend class OwnedMemoryChunk;
// Called by OwnedMemoryChunks when they are unlocked. This puts them at the
// end of the live_unlocked_chunks_ list and passes an iterator to their
// position in the unlocked chunk list.
std::list<OwnedMemoryChunk*>::iterator NotifyUnlocked(
OwnedMemoryChunk* chunk);
// Called by OwnedMemoryChunks when they are locked. This removes the passed
// in unlocked chunk list.
void NotifyLocked(std::list<OwnedMemoryChunk*>::iterator it);
// The amount of memory we can allocate before we try to free unlocked
// chunks. We can go over this amount if all callers keep their discardable
// chunks locked.
const size_t desired_max_memory_;
// A count of the sum of memory. Used to trigger discarding the oldest
// memory.
size_t total_live_memory_;
// The number of locked chunks.
int locked_chunks_;
// A linked list of unlocked allocated chunks so that the tail is most
// recently accessed chunks.
std::list<OwnedMemoryChunk*> live_unlocked_chunks_;
DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryAllocator);
};
} // namespace html_viewer
#endif // COMPONENTS_HTML_VIEWER_DISCARDABLE_MEMORY_ALLOCATOR_H_
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