Mojo C++ bindings: sync call support for associated interfaces and master interfaces

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

 // Copyright 2015 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 MOJO_PUBLIC_CPP_BINDINGS_LIB_INTERFACE_ENDPOINT_CLIENT_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_INTERFACE_ENDPOINT_CLIENT_H_
 
 #include <stdint.h>
 
 #include <map>
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread_checker.h"
 #include "mojo/public/cpp/bindings/callback.h"
 #include "mojo/public/cpp/bindings/lib/scoped_interface_endpoint_handle.h"
 #include "mojo/public/cpp/bindings/message.h"
 #include "mojo/public/cpp/bindings/message_filter.h"
 
 namespace mojo {
 
 class AssociatedGroup;
 
 namespace internal {
 
 class MultiplexRouter;
+class InterfaceEndpointController;
 
 // InterfaceEndpointClient handles message sending and receiving of an interface
 // endpoint, either the implementation side or the client side.
 // It should only be accessed and destructed on the creating thread.
 class InterfaceEndpointClient : public MessageReceiverWithResponder {
  public:
   // |receiver| is okay to be null. If it is not null, it must outlive this
   // object.
   InterfaceEndpointClient(ScopedInterfaceEndpointHandle handle,
                           MessageReceiverWithResponderStatus* receiver,
-                          scoped_ptr<MessageFilter> payload_validator);
+                          scoped_ptr<MessageFilter> payload_validator,
+                          bool expect_sync_requests);
   ~InterfaceEndpointClient() override;
 
   // Sets the error handler to receive notifications when an error is
   // encountered.
   void set_connection_error_handler(const Closure& error_handler) {
     DCHECK(thread_checker_.CalledOnValidThread());
     error_handler_ = error_handler;
   }
 
   // Returns true if an error was encountered.
   bool encountered_error() const {
     DCHECK(thread_checker_.CalledOnValidThread());
     return encountered_error_;
   }
 
   // Returns true if this endpoint has any pending callbacks.
   bool has_pending_responders() const {
     DCHECK(thread_checker_.CalledOnValidThread());
-    return !responders_.empty();
+    return !async_responders_.empty() || !sync_responses_.empty();
   }
 
   MultiplexRouter* router() const { return handle_.router(); }
   AssociatedGroup* associated_group();
   uint32_t interface_id() const;
 
   // After this call the object is in an invalid state and shouldn't be reused.
   ScopedInterfaceEndpointHandle PassHandle();
 
   // Raises an error on the underlying message pipe. It disconnects the pipe
   // and notifies all interfaces running on this pipe.
   void RaiseError();
 
   // MessageReceiverWithResponder implementation:
   bool Accept(Message* message) override;
   bool AcceptWithResponder(Message* message,
                            MessageReceiver* responder) override;
 
   // The following methods are called by the router. They must be called
   // outside of the router's lock.
 
   // NOTE: |message| must have passed message header validation.
   bool HandleIncomingMessage(Message* message);
   void NotifyError();
 
  private:
-  using ResponderMap = std::map<uint64_t, MessageReceiver*>;
+  // Maps from the id of a response to the MessageReceiver that handles the
+  // response.
+  using AsyncResponderMap = std::map<uint64_t, scoped_ptr<MessageReceiver>>;
+
+  struct SyncResponseInfo {
+   public:
+    explicit SyncResponseInfo(bool* in_response_received);
+    ~SyncResponseInfo();
+
+    scoped_ptr<Message> response;
+
+    // Points to a stack-allocated variable.
+    bool* response_received;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(SyncResponseInfo);
+  };
+
+  using SyncResponseMap = std::map<uint64_t, scoped_ptr<SyncResponseInfo>>;
 
   // Used as the sink for |payload_validator_| and forwards messages to
   // HandleValidatedMessage().
   class HandleIncomingMessageThunk : public MessageReceiver {
    public:
     explicit HandleIncomingMessageThunk(InterfaceEndpointClient* owner);
     ~HandleIncomingMessageThunk() override;
 
     // MessageReceiver implementation:
     bool Accept(Message* message) override;
 
    private:
     InterfaceEndpointClient* const owner_;
 
     DISALLOW_COPY_AND_ASSIGN(HandleIncomingMessageThunk);
   };
 
   bool HandleValidatedMessage(Message* message);
 
   ScopedInterfaceEndpointHandle handle_;
   scoped_ptr<AssociatedGroup> associated_group_;
+  InterfaceEndpointController* controller_;
 
   MessageReceiverWithResponderStatus* const incoming_receiver_;
   scoped_ptr<MessageFilter> payload_validator_;
   HandleIncomingMessageThunk thunk_;
 
-  // Maps from the ID of a response to the MessageReceiver that handles the
-  // response.
-  ResponderMap responders_;
+  AsyncResponderMap async_responders_;
+  SyncResponseMap sync_responses_;
+
   uint64_t next_request_id_;
 
   Closure error_handler_;
   bool encountered_error_;
 
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<InterfaceEndpointClient> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InterfaceEndpointClient);
 };
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_INTERFACE_ENDPOINT_CLIENT_H_