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(const base::trace_event::MemoryDumpArgs& args,
  45                     base::trace_event::ProcessMemoryDump* pmd) override;
  46
  47   // This allocates a discardable memory segment for |process_handle|.
  48   // A valid shared memory handle is returned on success.
  49   void AllocateLockedDiscardableSharedMemoryForChild(
  50       base::ProcessHandle process_handle,
  51       int child_process_id,
  52       size_t size,
  53       DiscardableSharedMemoryId id,
  54       base::SharedMemoryHandle* shared_memory_handle);
  55
  56   // Call this to notify the manager that child process associated with
  57   // |child_process_id| has deleted discardable memory segment with |id|.
  58   void ChildDeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
  59                                            int child_process_id);
  60
  61   // Call this to notify the manager that child process associated with
  62   // |child_process_id| has been removed. The manager will use this to release
  63   // memory segments allocated for child process to the OS.
  64   void ProcessRemoved(int child_process_id);
  65
  66   // The maximum number of bytes of memory that may be allocated. This will
  67   // cause memory usage to be reduced if currently above |limit|.
  68   void SetMemoryLimit(size_t limit);
  69
  70   // Reduce memory usage if above current memory limit.
  71   void EnforceMemoryPolicy();
  72
  73   // Returns bytes of allocated discardable memory.
  74   size_t GetBytesAllocated();
  75
  76  private:
  77   class MemorySegment : public base::RefCountedThreadSafe<MemorySegment> {
  78    public:
  79     MemorySegment(scoped_ptr<base::DiscardableSharedMemory> memory);
  80
  81     base::DiscardableSharedMemory* memory() const { return memory_.get(); }
  82
  83    private:
  84     friend class base::RefCountedThreadSafe<MemorySegment>;
  85
  86     ~MemorySegment();
  87
  88     scoped_ptr<base::DiscardableSharedMemory> memory_;
  89
  90     DISALLOW_COPY_AND_ASSIGN(MemorySegment);
  91   };
  92
  93   static bool CompareMemoryUsageTime(const scoped_refptr<MemorySegment>& a,
  94                                      const scoped_refptr<MemorySegment>& b) {
  95     // In this system, LRU memory segment is evicted first.
  96     return a->memory()->last_known_usage() > b->memory()->last_known_usage();
  97   }
  98
  99   void AllocateLockedDiscardableSharedMemory(
 100       base::ProcessHandle process_handle,
 101       int client_process_id,
 102       size_t size,
 103       DiscardableSharedMemoryId id,
 104       base::SharedMemoryHandle* shared_memory_handle);
 105   void DeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
 106                                       int client_process_id);
 107   void OnMemoryPressure(
 108       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
 109   void ReduceMemoryUsageUntilWithinMemoryLimit();
 110   void ReduceMemoryUsageUntilWithinLimit(size_t limit);
 111   void ReleaseMemory(base::DiscardableSharedMemory* memory);
 112   void BytesAllocatedChanged(size_t new_bytes_allocated) const;
 113
 114   // Virtual for tests.
 115   virtual base::Time Now() const;
 116   virtual void ScheduleEnforceMemoryPolicy();
 117
 118   base::Lock lock_;
 119   typedef base::hash_map<DiscardableSharedMemoryId,
 120                          scoped_refptr<MemorySegment>> MemorySegmentMap;
 121   typedef base::hash_map<int, MemorySegmentMap> ProcessMap;
 122   ProcessMap processes_;
 123   // Note: The elements in |segments_| are arranged in such a way that they form
 124   // a heap. The LRU memory segment always first.
 125   typedef std::vector<scoped_refptr<MemorySegment>> MemorySegmentVector;
 126   MemorySegmentVector segments_;
 127   size_t memory_limit_;
 128   size_t bytes_allocated_;
 129   scoped_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 130   bool enforce_memory_policy_pending_;
 131   base::WeakPtrFactory<HostDiscardableSharedMemoryManager> weak_ptr_factory_;
 132
 133   DISALLOW_COPY_AND_ASSIGN(HostDiscardableSharedMemoryManager);
 134 };
 135
 136 }  // namespace content
 137
 138 #endif  // CONTENT_COMMON_HOST_DISCARDABLE_SHARED_MEMORY_MANAGER_H_