discardable_memory: Using mojo IPC to replace Chrome IPC

components/discardable_memory/service/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 COMPONENTS_DISCARDABLE_MEMORY_SERVICE_DISCARDABLE_SHARED_MEMORY_MANAGER_H_
 #define COMPONENTS_DISCARDABLE_MEMORY_SERVICE_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 "components/discardable_memory/common/discardable_memory_export.h"
-#include "components/discardable_memory/common/discardable_shared_memory_id.h"
+#include "components/discardable_memory/public/interfaces/discardable_shared_memory_manager.mojom.h"
 
 namespace discardable_memory {
 
 // Implementation of DiscardableMemoryAllocator that allocates and manages
 // discardable memory segments for the process which hosts this class, and
 // for remote processes which request discardable memory from this class via
 // IPC.
 // This class is thread-safe and instances can safely be used on any thread.
 class DISCARDABLE_MEMORY_EXPORT DiscardableSharedMemoryManager
     : public base::DiscardableMemoryAllocator,
       public base::trace_event::MemoryDumpProvider,
       public base::MemoryCoordinatorClient {
  public:
   DiscardableSharedMemoryManager();
   ~DiscardableSharedMemoryManager() override;
 
+  // Create a sigleton instance.
+  static DiscardableSharedMemoryManager* CreateInstance();
+
   // Returns a singleton instance.
   static DiscardableSharedMemoryManager* current();

[reveman, 2016/11/23 17:07:44]

Please rename this to GetInstance() now that we have CreateInstance?

[Peng, 2016/11/24 15:04:37]

Done.

 
+  // Bind the current manager to a mojo interface request.
+  static void Bind(mojom::DiscardableSharedMemoryManagerRequest request);

[reveman, 2016/11/23 17:07:44]

Please make this a member function instead of static.

[Peng, 2016/11/24 15:04:37]

Done.

+
   // 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;
 
-  // TODO(penghuang): Get ride of the |process_handle| when we switch to mojo.
   // This allocates a discardable memory segment for |process_handle|.
   // A valid shared memory handle is returned on success.
   void AllocateLockedDiscardableSharedMemoryForClient(
-      base::ProcessHandle process_handle,
       int client_id,
       size_t size,
-      DiscardableSharedMemoryId id,
+      int32_t id,
       base::SharedMemoryHandle* shared_memory_handle);
 
   // Call this to notify the manager that client process associated with
   // |client_id| has deleted discardable memory segment with |id|.
-  void ClientDeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
-                                            int client_id);
+  void ClientDeletedDiscardableSharedMemory(int32_t id, int client_id);
 
   // Call this to notify the manager that client associated with |client_id|
   // has been removed. The manager will use this to release memory segments
   // allocated for client to the OS.
   void ClientRemoved(int client_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);
 
@@ skipping 22 matching lines @@
 
   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;
 
-  // TODO(penghuang): Get ride of the |process_handle| when we switch to mojo.
   void AllocateLockedDiscardableSharedMemory(
-      base::ProcessHandle process_handle,
       int client_id,
       size_t size,
-      DiscardableSharedMemoryId id,
+      int32_t id,
       base::SharedMemoryHandle* shared_memory_handle);
-  void DeletedDiscardableSharedMemory(DiscardableSharedMemoryId id,
-                                      int client_id);
+  void DeletedDiscardableSharedMemory(int32_t id, int client_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();
 
+  int32_t last_client_id_;

[reveman, 2016/11/23 17:07:44]

nit (optional): it's more common in chromium to use next_client_id_ and post
increment. I don't feel strongly about it but I guess it makes more sense as
initially there's not really a "last" id..

[Peng, 2016/11/24 15:04:37]

Done.

+
   base::Lock lock_;
-  typedef base::hash_map<DiscardableSharedMemoryId,
-                         scoped_refptr<MemorySegment>>
+  typedef base::hash_map<int32_t, scoped_refptr<MemorySegment>>

[dcheng, 2016/11/25 00:07:08]

Nit: prefer using A = B; to typedef B A;

[Peng, 2016/11/25 16:41:53]

Done.

       MemorySegmentMap;
   typedef base::hash_map<int, MemorySegmentMap> ClientMap;
   ClientMap clients_;
   // 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<DiscardableSharedMemoryManager> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableSharedMemoryManager);
 };
 
 }  // namespace discardable_memory
 
 #endif  // COMPONENTS_DISCARDABLE_MEMORY_SERVICE_DISCARDABLE_SHARED_MEMORY_MANAGER_H_