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// 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 CONTENT_COMMON_HOST_DISCARDABLE_SHARED_MEMORY_MANAGER_H_
#define CONTENT_COMMON_HOST_DISCARDABLE_SHARED_MEMORY_MANAGER_H_
#include <vector>
#include "base/containers/hash_tables.h"
#include "base/memory/discardable_memory_allocator.h"
#include "base/memory/discardable_shared_memory.h"
#include "base/memory/memory_pressure_listener.h"
#include "base/memory/ref_counted.h"
#include "base/memory/shared_memory.h"
#include "base/memory/weak_ptr.h"
#include "base/process/process_handle.h"
#include "base/synchronization/lock.h"
#include "content/common/content_export.h"
namespace content {
typedef int32_t DiscardableSharedMemoryId;
// Implementation of DiscardableMemoryAllocator that allocates and manages
// discardable memory segments for the browser process and child processes.
// This class is thread-safe and instances can safely be used on any thread.
class CONTENT_EXPORT HostDiscardableSharedMemoryManager
: public base::DiscardableMemoryAllocator {
public:
HostDiscardableSharedMemoryManager();
~HostDiscardableSharedMemoryManager() override;
// Returns a singleton instance.
static HostDiscardableSharedMemoryManager* current();
// Overridden from base::DiscardableMemoryAllocator:
scoped_ptr<base::DiscardableMemory> AllocateLockedDiscardableMemory(
size_t size) override;
// This allocates a discardable memory segment for |process_handle|.
// A valid shared memory handle is returned on success.
void AllocateLockedDiscardableSharedMemoryForChild(
base::ProcessHandle process_handle,
size_t size,
DiscardableSharedMemoryId id,
base::SharedMemoryHandle* shared_memory_handle);
// Call this to notify the manager that child process associated with
// |process_handle| has deleted discardable memory segment with |id|.
void ChildDeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
base::ProcessHandle process_handle);
// Call this to notify the manager that child process associated with
// |process_handle| has been removed. The manager will use this to release
// memory segments allocated for child process to the OS.
void ProcessRemoved(base::ProcessHandle process_handle);
// The maximum number of bytes of memory that may be allocated. This will
// cause memory usage to be reduced if currently above |limit|.
void SetMemoryLimit(size_t limit);
// Reduce memory usage if above current memory limit.
void EnforceMemoryPolicy();
// Returns bytes of allocated discardable memory.
size_t GetBytesAllocated();
private:
class MemorySegment : public base::RefCountedThreadSafe<MemorySegment> {
public:
MemorySegment(scoped_ptr<base::DiscardableSharedMemory> memory);
base::DiscardableSharedMemory* memory() const { return memory_.get(); }
private:
friend class base::RefCountedThreadSafe<MemorySegment>;
~MemorySegment();
scoped_ptr<base::DiscardableSharedMemory> memory_;
DISALLOW_COPY_AND_ASSIGN(MemorySegment);
};
static bool CompareMemoryUsageTime(const scoped_refptr<MemorySegment>& a,
const scoped_refptr<MemorySegment>& b) {
// In this system, LRU memory segment is evicted first.
return a->memory()->last_known_usage() > b->memory()->last_known_usage();
}
void AllocateLockedDiscardableSharedMemory(
base::ProcessHandle process_handle,
size_t size,
DiscardableSharedMemoryId id,
base::SharedMemoryHandle* shared_memory_handle);
void DeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
base::ProcessHandle process_handle);
void OnMemoryPressure(
base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
void ReduceMemoryUsageUntilWithinMemoryLimit();
void ReduceMemoryUsageUntilWithinLimit(size_t limit);
void ReleaseMemory(base::DiscardableSharedMemory* memory);
void BytesAllocatedChanged(size_t new_bytes_allocated) const;
// Virtual for tests.
virtual base::Time Now() const;
virtual void ScheduleEnforceMemoryPolicy();
base::Lock lock_;
typedef base::hash_map<DiscardableSharedMemoryId,
scoped_refptr<MemorySegment>> MemorySegmentMap;
typedef base::hash_map<base::ProcessHandle, MemorySegmentMap> ProcessMap;
ProcessMap processes_;
// Note: The elements in |segments_| are arranged in such a way that they form
// a heap. The LRU memory segment always first.
typedef std::vector<scoped_refptr<MemorySegment>> MemorySegmentVector;
MemorySegmentVector segments_;
size_t memory_limit_;
size_t bytes_allocated_;
scoped_ptr<base::MemoryPressureListener> memory_pressure_listener_;
bool enforce_memory_policy_pending_;
base::WeakPtrFactory<HostDiscardableSharedMemoryManager> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(HostDiscardableSharedMemoryManager);
};
} // namespace content
#endif // CONTENT_COMMON_HOST_DISCARDABLE_SHARED_MEMORY_MANAGER_H_
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