content/common/host_discardable_shared_memory_manager.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_COMMON_HOST_DISCARDABLE_SHARED_MEMORY_MANAGER_H_
   6 #define CONTENT_COMMON_HOST_DISCARDABLE_SHARED_MEMORY_MANAGER_H_
   7
   8 #include <vector>
   9
  10 #include "base/containers/hash_tables.h"
  11 #include "base/format_macros.h"
  12 #include "base/memory/discardable_memory_allocator.h"
  13 #include "base/memory/discardable_shared_memory.h"
  14 #include "base/memory/memory_pressure_listener.h"
  15 #include "base/memory/ref_counted.h"
  16 #include "base/memory/shared_memory.h"
  17 #include "base/memory/weak_ptr.h"
  18 #include "base/process/process_handle.h"
  19 #include "base/synchronization/lock.h"
  20 #include "base/trace_event/memory_dump_provider.h"
  21 #include "content/common/content_export.h"
  22
  23 namespace content {
  24 typedef int32_t DiscardableSharedMemoryId;
  25
  26 // Implementation of DiscardableMemoryAllocator that allocates and manages
  27 // discardable memory segments for the browser process and child processes.
  28 // This class is thread-safe and instances can safely be used on any thread.
  29 class CONTENT_EXPORT HostDiscardableSharedMemoryManager
  30     : public base::DiscardableMemoryAllocator,
  31       public base::trace_event::MemoryDumpProvider {
  32  public:
  33   HostDiscardableSharedMemoryManager();
  34   ~HostDiscardableSharedMemoryManager() override;
  35
  36   // Returns a singleton instance.
  37   static HostDiscardableSharedMemoryManager* current();
  38
  39   // Overridden from base::DiscardableMemoryAllocator:
  40   scoped_ptr<base::DiscardableMemory> AllocateLockedDiscardableMemory(
  41       size_t size) override;
  42
  43   // Overridden from base::trace_event::MemoryDumpProvider:
  44   bool OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd) override;
  45
  46   // This allocates a discardable memory segment for |process_handle|.
  47   // A valid shared memory handle is returned on success.
  48   void AllocateLockedDiscardableSharedMemoryForChild(
  49       base::ProcessHandle process_handle,
  50       int child_process_id,
  51       size_t size,
  52       DiscardableSharedMemoryId id,
  53       base::SharedMemoryHandle* shared_memory_handle);
  54
  55   // Call this to notify the manager that child process associated with
  56   // |child_process_id| has deleted discardable memory segment with |id|.
  57   void ChildDeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
  58                                            int child_process_id);
  59
  60   // Call this to notify the manager that child process associated with
  61   // |child_process_id| has been removed. The manager will use this to release
  62   // memory segments allocated for child process to the OS.
  63   void ProcessRemoved(int child_process_id);
  64
  65   // The maximum number of bytes of memory that may be allocated. This will
  66   // cause memory usage to be reduced if currently above |limit|.
  67   void SetMemoryLimit(size_t limit);
  68
  69   // Reduce memory usage if above current memory limit.
  70   void EnforceMemoryPolicy();
  71
  72   // Returns bytes of allocated discardable memory.
  73   size_t GetBytesAllocated();
  74
  75  private:
  76   class MemorySegment : public base::RefCountedThreadSafe<MemorySegment> {
  77    public:
  78     MemorySegment(scoped_ptr<base::DiscardableSharedMemory> memory);
  79
  80     base::DiscardableSharedMemory* memory() const { return memory_.get(); }
  81
  82    private:
  83     friend class base::RefCountedThreadSafe<MemorySegment>;
  84
  85     ~MemorySegment();
  86
  87     scoped_ptr<base::DiscardableSharedMemory> memory_;
  88
  89     DISALLOW_COPY_AND_ASSIGN(MemorySegment);
  90   };
  91
  92   static bool CompareMemoryUsageTime(const scoped_refptr<MemorySegment>& a,
  93                                      const scoped_refptr<MemorySegment>& b) {
  94     // In this system, LRU memory segment is evicted first.
  95     return a->memory()->last_known_usage() > b->memory()->last_known_usage();
  96   }
  97
  98   void AllocateLockedDiscardableSharedMemory(
  99       base::ProcessHandle process_handle,
 100       int client_process_id,
 101       size_t size,
 102       DiscardableSharedMemoryId id,
 103       base::SharedMemoryHandle* shared_memory_handle);
 104   void DeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
 105                                       int client_process_id);
 106   void OnMemoryPressure(
 107       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
 108   void ReduceMemoryUsageUntilWithinMemoryLimit();
 109   void ReduceMemoryUsageUntilWithinLimit(size_t limit);
 110   void ReleaseMemory(base::DiscardableSharedMemory* memory);
 111   void BytesAllocatedChanged(size_t new_bytes_allocated) const;
 112
 113   // Virtual for tests.
 114   virtual base::Time Now() const;
 115   virtual void ScheduleEnforceMemoryPolicy();
 116
 117   base::Lock lock_;
 118   typedef base::hash_map<DiscardableSharedMemoryId,
 119                          scoped_refptr<MemorySegment>> MemorySegmentMap;
 120   typedef base::hash_map<int, MemorySegmentMap> ProcessMap;
 121   ProcessMap processes_;
 122   // Note: The elements in |segments_| are arranged in such a way that they form
 123   // a heap. The LRU memory segment always first.
 124   typedef std::vector<scoped_refptr<MemorySegment>> MemorySegmentVector;
 125   MemorySegmentVector segments_;
 126   size_t memory_limit_;
 127   size_t bytes_allocated_;
 128   scoped_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 129   bool enforce_memory_policy_pending_;
 130   base::WeakPtrFactory<HostDiscardableSharedMemoryManager> weak_ptr_factory_;
 131
 132   DISALLOW_COPY_AND_ASSIGN(HostDiscardableSharedMemoryManager);
 133 };
 134
 135 }  // namespace content
 136
 137 #endif  // CONTENT_COMMON_HOST_DISCARDABLE_SHARED_MEMORY_MANAGER_H_