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

mojo/public/cpp/bindings/lib/multiplex_router.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_MULTIPLEX_ROUTER_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_MULTIPLEX_ROUTER_H_
 
 #include <stdint.h>
 
 #include <deque>
@@ skipping 20 matching lines @@
 class SingleThreadTaskRunner;
 }
 
 namespace mojo {
 
 class AssociatedGroup;
 
 namespace internal {
 
 class InterfaceEndpointClient;
+class InterfaceEndpointController;
 
 // MultiplexRouter supports routing messages for multiple interfaces over a
 // single message pipe.
 //
 // It is created on the thread where the master interface of the message pipe
 // lives. Although it is ref-counted, it is guarateed to be destructed on the
 // same thread.
 // Some public methods are only allowed to be called on the creating thread;
 // while the others are safe to call from any threads. Please see the method
 // comments for more details.
@@ skipping 19 matching lines @@
   // Creates an interface endpoint handle from a given interface ID. The handle
   // is used locally.
   // Typically, this method is used to (1) create an endpoint handle for the
   // master interface; or (2) create an endpoint handle on receiving an
   // interface ID from the message pipe.
   ScopedInterfaceEndpointHandle CreateLocalEndpointHandle(InterfaceId id);
 
   // Closes an interface endpoint handle.
   void CloseEndpointHandle(InterfaceId id, bool is_local);
 
   // Attaches an client to the specified endpoint to send and receive messages.

[Ken Rockot(use gerrit already), 2016/03/29 06:36:49]

nit: While you're here, "Attaches a client"

[yzshen1, 2016/03/29 16:19:01]

Done.

-  void AttachEndpointClient(const ScopedInterfaceEndpointHandle& handle,
-                            InterfaceEndpointClient* endpoint_client);
+  // The returned object is still owned by the router. It should only be used on

[Ken Rockot(use gerrit already), 2016/03/29 06:36:49]

nit: should = must?

[yzshen1, 2016/03/29 16:19:01]

Done.

+  // the same thread as this call, and only before the client is detached using
+  // DetachEndpointClient().
+  InterfaceEndpointController* AttachEndpointClient(
+      const ScopedInterfaceEndpointHandle& handle,
+      InterfaceEndpointClient* endpoint_client);
+
   // Detaches the client attached to the specified endpoint. It should be called
   // on the same thread as the corresponding AttachEndpointClient() call.
   void DetachEndpointClient(const ScopedInterfaceEndpointHandle& handle);
 
-  bool SendMessage(const ScopedInterfaceEndpointHandle& handle,
-                   Message* message);
-
   // Raises an error on the underlying message pipe. It disconnects the pipe
   // and notifies all interfaces running on this pipe.
   void RaiseError();
 
   scoped_ptr<AssociatedGroup> CreateAssociatedGroup();
 
   static MultiplexRouter* GetRouter(AssociatedGroup* associated_group);
 
   // ---------------------------------------------------------------------------
   // The following public methods are called on the creating thread.
 
   // Please note that this method shouldn't be called unless it results from an
   // explicit request of the user of bindings (e.g., the user sets an
   // InterfacePtr to null or closes a Binding).
-  void CloseMessagePipe() {
-    DCHECK(thread_checker_.CalledOnValidThread());
-    connector_.CloseMessagePipe();
-  }
+  void CloseMessagePipe();
 
   // Extracts the underlying message pipe.
   ScopedMessagePipeHandle PassMessagePipe() {
     DCHECK(thread_checker_.CalledOnValidThread());
     DCHECK(!HasAssociatedEndpoints());
     return connector_.PassMessagePipe();
   }
 
   // Blocks the current thread until the first incoming message, or |deadline|.
   bool WaitForIncomingMessage(MojoDeadline deadline) {
@@ skipping 42 matching lines @@
 
   // MessageReceiver implementation:
   bool Accept(Message* message) override;
 
   // PipeControlMessageHandlerDelegate implementation:
   bool OnPeerAssociatedEndpointClosed(InterfaceId id) override;
   bool OnAssociatedEndpointClosedBeforeSent(InterfaceId id) override;
 
   void OnPipeConnectionError();
 
+  // Specifies whether we are allowed to directly call into
+  // InterfaceEndpointClient (given that we are already on the same thread as
+  // the client).
+  enum ClientCallBehavior {
+    // Don't call any InterfaceEndpointClient methods directly.
+    NO_DIRECT_CLIENT_CALLS,
+    // Only call InterfaceEndpointClient::HandleIncomingMessage directly to
+    // handle sync messages.
+    ALLOW_DIRECT_CLIENT_CALLS_FOR_SYNC_MESSAGES,
+    // Allow to call any InterfaceEndpointClient methods directly.
+    ALLOW_DIRECT_CLIENT_CALLS
+  };
+
   // Processes enqueued tasks (incoming messages and error notifications).
-  // If |force_async| is true, it guarantees not to call any
-  // InterfaceEndpointClient methods directly.
   //
   // Note: Because calling into InterfaceEndpointClient may lead to destruction
-  // of this object, if |force_async| is set to false, the caller needs to hold
-  // on to a ref outside of |lock_| before calling this method.
-  void ProcessTasks(bool force_async);
+  // of this object, if direct calls are allowed, the caller needs to hold on to
+  // a ref outside of |lock_| before calling this method.
+  void ProcessTasks(ClientCallBehavior client_call_behavior);
+
+  // Processes the first queued sync message for the endpoint corresponding to
+  // |id|; returns whether there are more sync messages for that endpoint in the
+  // queue.
+  //
+  // This method is only used by enpoints during sync watching. Therefore, not
+  // all sync messages are handled by it.
+  bool ProcessFirstSyncMessageForEndpoint(InterfaceId id);
 
   // Returns true to indicate that |task|/|message| has been processed.
-  bool ProcessNotifyErrorTask(Task* task, bool force_async);
-  bool ProcessIncomingMessage(Message* message, bool force_async);
+  bool ProcessNotifyErrorTask(Task* task,
+                              ClientCallBehavior client_call_behavior);
+  bool ProcessIncomingMessage(Message* message,
+                              ClientCallBehavior client_call_behavior);
 
   void MaybePostToProcessTasks(base::SingleThreadTaskRunner* task_runner);
   void LockAndCallProcessTasks();
 
   // Updates the state of |endpoint|. If both the endpoint and its peer have
   // been closed, removes it from |endpoints_|.
   // NOTE: The method may invalidate |endpoint|.
   enum EndpointStateUpdateType { ENDPOINT_CLOSED, PEER_ENDPOINT_CLOSED };
   void UpdateEndpointStateMayRemove(InterfaceEndpoint* endpoint,
                                     EndpointStateUpdateType type);
 
   void RaiseErrorInNonTestingMode();
 
   InterfaceEndpoint* FindOrInsertEndpoint(InterfaceId id, bool* inserted);
 
   // Whether to set the namespace bit when generating interface IDs. Please see
   // comments of kInterfaceIdNamespaceMask.
   const bool set_interface_id_namespace_bit_;
 
   MessageHeaderValidator header_validator_;
   Connector connector_;
-  bool encountered_error_;
 
   base::ThreadChecker thread_checker_;
 
   // Protects the following members.
   mutable base::Lock lock_;
   PipeControlMessageHandler control_message_handler_;
   PipeControlMessageProxy control_message_proxy_;
 
   std::map<InterfaceId, scoped_refptr<InterfaceEndpoint>> endpoints_;
   uint32_t next_interface_id_value_;
 
   std::deque<scoped_ptr<Task>> tasks_;
+  // It refers to tasks in |tasks_| and doesn't own any of them.
+  std::map<InterfaceId, std::deque<Task*>> sync_message_tasks_;
 
   bool posted_to_process_tasks_;
 
+  bool encountered_error_;
+
   bool testing_mode_;
 
   DISALLOW_COPY_AND_ASSIGN(MultiplexRouter);
 };
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_MULTIPLEX_ROUTER_H_