discardable_memory: Using mojo IPC to replace Chrome IPC

components/discardable_memory/client/client_discardable_shared_memory_manager.h

Index: components/discardable_memory/client/client_discardable_shared_memory_manager.h
diff --git a/components/discardable_memory/client/client_discardable_shared_memory_manager.h b/components/discardable_memory/client/client_discardable_shared_memory_manager.h
index 76215bc099f65ccd6cd36299f09ea531b29b1a4a..c3b1b4f0b07fbcdd3c2689e3aa7bef6a8170ea4d 100644
--- a/components/discardable_memory/client/client_discardable_shared_memory_manager.h
+++ b/components/discardable_memory/client/client_discardable_shared_memory_manager.h
@@ -15,7 +15,11 @@
 #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_heap.h"
-#include "components/discardable_memory/common/discardable_shared_memory_id.h"
+#include "components/discardable_memory/public/interfaces/discardable_memory.mojom.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}
 
 namespace discardable_memory {
 
@@ -25,20 +29,9 @@ class DISCARDABLE_MEMORY_EXPORT ClientDiscardableSharedMemoryManager
     : public base::DiscardableMemoryAllocator,
       public base::trace_event::MemoryDumpProvider {
  public:
-  class Delegate {
-   public:
-    virtual void AllocateLockedDiscardableSharedMemory(
-        size_t size,
-        DiscardableSharedMemoryId id,
-        base::SharedMemoryHandle* handle) = 0;
-    virtual void DeletedDiscardableSharedMemory(
-        DiscardableSharedMemoryId id) = 0;
-
-   protected:
-    virtual ~Delegate() {}
-  };
-
-  explicit ClientDiscardableSharedMemoryManager(Delegate* delegate);
+  ClientDiscardableSharedMemoryManager(
+      mojom::DiscardableSharedMemoryManagerPtrInfo info,
+      scoped_refptr<base::SingleThreadTaskRunner> io_task_runner);

[reveman, 2016/11/11 20:17:26]

s/scoped_refptr<base::SingleThreadTaskRunner>/base::SingleThreadTaskRunner*/ to
avoid unnecessary refcount churn

[Peng, 2016/11/11 22:50:35]

Done.

   ~ClientDiscardableSharedMemoryManager() override;
 
   // Overridden from base::DiscardableMemoryAllocator:
@@ -69,15 +62,18 @@ class DISCARDABLE_MEMORY_EXPORT ClientDiscardableSharedMemoryManager
   Statistics GetStatistics() const;
 
  private:
+  class ThreadSafeManagerProxy;
+
   std::unique_ptr<base::DiscardableSharedMemory>
-  AllocateLockedDiscardableSharedMemory(size_t size,
-                                        DiscardableSharedMemoryId id);
+  AllocateLockedDiscardableSharedMemory(size_t size, int32_t id);
+  void DeletedDiscardableSharedMemory(int32_t id);
+
   void MemoryUsageChanged(size_t new_bytes_allocated,
                           size_t new_bytes_free) const;
 
   mutable base::Lock lock_;
+  scoped_refptr<ThreadSafeManagerProxy> manager_;

[reveman, 2016/11/11 20:17:26]

why do we need a separate instance for this? Can the current manager class
contain the logic needed for IPC to be threads safe? Having a different manager
instance inside the manager class is awkward and makes the code harder to
understand imo

[Peng, 2016/11/11 22:50:35]

It is because I want to make manager_ a thread safe refcount ptr, So I can use
it in base::Bind() for some callbacks which will be called in io thread. I tried
using WeakPtrFactory in this class, but this class will be destroyed in main
thread, it causes problem (because WeakPtr is not thread safe, dereference and
invalidate have to be in the same thread).

   DiscardableSharedMemoryHeap heap_;
-  Delegate* const delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(ClientDiscardableSharedMemoryManager);
 };