Mojo: introducing a thread safe interface pointer.

mojo/public/cpp/bindings/lib/interface_ptr_state.h

Index: mojo/public/cpp/bindings/lib/interface_ptr_state.h
diff --git a/mojo/public/cpp/bindings/lib/interface_ptr_state.h b/mojo/public/cpp/bindings/lib/interface_ptr_state.h
index 78aa02e17635442ae394a7aa9d0109650fbbab1e..58fcdb493246f3ae1b4d8470bff3bf2d3d429483 100644
--- a/mojo/public/cpp/bindings/lib/interface_ptr_state.h
+++ b/mojo/public/cpp/bindings/lib/interface_ptr_state.h
@@ -18,6 +18,7 @@
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "mojo/public/cpp/bindings/associated_group.h"
 #include "mojo/public/cpp/bindings/connection_error_callback.h"
@@ -31,6 +32,7 @@
 #include "mojo/public/cpp/bindings/lib/router.h"
 #include "mojo/public/cpp/bindings/message_header_validator.h"
 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
+#include "mojo/public/cpp/bindings/thread_safe_interface_ptr.h"
 
 namespace mojo {
 namespace internal {
@@ -209,7 +211,7 @@ class InterfacePtrState<Interface, false> {
 template <typename Interface>
 class InterfacePtrState<Interface, true> {
  public:
-  InterfacePtrState() : version_(0u) {}
+  InterfacePtrState() : version_(0u), weak_ptr_factory_(this) {}
 
   ~InterfacePtrState() {
     endpoint_client_.reset();
@@ -331,6 +333,16 @@ class InterfacePtrState<Interface, true> {
     router_->EnableTestingMode();
   }
 
+  scoped_refptr<ThreadSafeInterfacePtr<Interface>> GetThreadSafePtr() {

[yzshen1, 2016/11/11 22:32:10]

One thing that seems a little weird about this is that the
ThreadSafeInterfacePtr is tied to the InterfacePtrState object itself, which is
not moved around like its contents. As a result, when an InterfacePtr x is moved
to y, although it behaves exactly the same, its connection with the
ThreadSafeInterfacePtr has gone.

[Jay Civelli, 2016/11/15 05:02:30]

Per our discussion, the  ThreadSafeInterfacePtr class is still thread safe ref
counted, but it now owns the InterfacePtr.

+    ConfigureProxyIfNecessary();
+    return new ThreadSafeInterfacePtr<Interface>(
+                     base::ThreadTaskRunnerHandle::Get(),
+                     base::Bind(&InterfacePtrState::ForwardMessage,
+                                weak_ptr_factory_.GetWeakPtr()),
+                     base::Bind(&InterfacePtrState::ForwardMessageWithResponder,
+                                weak_ptr_factory_.GetWeakPtr()));
+  }
+
  private:
   using Proxy = typename Interface::Proxy_;
 
@@ -371,6 +383,15 @@ class InterfacePtrState<Interface, true> {
     callback.Run(version);
   }
 
+  void ForwardMessage(Message message) {
+    endpoint_client_->Accept(&message);
+  }
+
+  void ForwardMessageWithResponder(Message message,
+                                   std::unique_ptr<MessageReceiver> responder) {
+    endpoint_client_->AcceptWithResponder(&message, responder.release());
+  }
+
   scoped_refptr<MultiplexRouter> router_;
 
   std::unique_ptr<InterfaceEndpointClient> endpoint_client_;
@@ -384,6 +405,8 @@ class InterfacePtrState<Interface, true> {
 
   uint32_t version_;
 
+  base::WeakPtrFactory<InterfacePtrState> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(InterfacePtrState);
 };