Move discardable memory to //components from //content

content/common/host_discardable_shared_memory_manager.h

-// 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 <stddef.h>
-#include <stdint.h>
-
-#include <memory>
-#include <vector>
-
-#include "base/callback.h"
-#include "base/containers/hash_tables.h"
-#include "base/format_macros.h"
-#include "base/macros.h"
-#include "base/memory/discardable_memory_allocator.h"
-#include "base/memory/discardable_shared_memory.h"
-#include "base/memory/memory_coordinator_client.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 "base/threading/thread_task_runner_handle.h"
-#include "base/trace_event/memory_dump_provider.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 base::trace_event::MemoryDumpProvider,
-      public base::MemoryCoordinatorClient {
- public:
-  HostDiscardableSharedMemoryManager();
-  ~HostDiscardableSharedMemoryManager() override;
-
-  // Returns a singleton instance.
-  static HostDiscardableSharedMemoryManager* current();
-
-  // Overridden from base::DiscardableMemoryAllocator:
-  std::unique_ptr<base::DiscardableMemory> AllocateLockedDiscardableMemory(
-      size_t size) override;
-
-  // Overridden from base::trace_event::MemoryDumpProvider:
-  bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
-                    base::trace_event::ProcessMemoryDump* pmd) 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,
-      int child_process_id,
-      size_t size,
-      DiscardableSharedMemoryId id,
-      base::SharedMemoryHandle* shared_memory_handle);
-
-  // Call this to notify the manager that child process associated with
-  // |child_process_id| has deleted discardable memory segment with |id|.
-  void ChildDeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
-                                           int child_process_id);
-
-  // Call this to notify the manager that child process associated with
-  // |child_process_id| has been removed. The manager will use this to release
-  // memory segments allocated for child process to the OS.
-  void ProcessRemoved(int child_process_id);
-
-  // 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(std::unique_ptr<base::DiscardableSharedMemory> memory);
-
-    base::DiscardableSharedMemory* memory() const { return memory_.get(); }
-
-   private:
-    friend class base::RefCountedThreadSafe<MemorySegment>;
-
-    ~MemorySegment();
-
-    std::unique_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();
-  }
-
-  // base::MemoryCoordinatorClient implementation:
-  void OnMemoryStateChange(base::MemoryState state) override;
-
-  void AllocateLockedDiscardableSharedMemory(
-      base::ProcessHandle process_handle,
-      int client_process_id,
-      size_t size,
-      DiscardableSharedMemoryId id,
-      base::SharedMemoryHandle* shared_memory_handle);
-  void DeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
-                                      int client_process_id);
-  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<int, 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 default_memory_limit_;
-  size_t memory_limit_;
-  size_t bytes_allocated_;
-  std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
-  scoped_refptr<base::SingleThreadTaskRunner>
-      enforce_memory_policy_task_runner_;
-  base::Closure enforce_memory_policy_callback_;
-  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_