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>
 #include <map>
+#include <queue>
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/ref_counted_delete_on_message_loop.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "mojo/public/cpp/bindings/callback.h"
@@ skipping 10 matching lines @@
 }
 
 namespace mojo {
 
 class AssociatedGroup;
 
 namespace internal {
 
 class InterfaceEndpointClient;
 
+class InterfaceEndpointController {
+ public:
+  virtual ~InterfaceEndpointController() {}
+
+  virtual bool SendMessage(Message* message) = 0;
+
+  virtual void AllowWokenUpBySyncWatchOnSameThread() = 0;
+  /*
+  // Requests to register |message_pipe_| with SyncHandleWatcher whenever this
+  // instance is expecting incoming messages.
+  //
+  // Please note that UnregisterSyncHandleWatch() needs to be called as many
+  // times as successful RegisterSyncHandleWatch() calls in order to cancel the
+  // effect.
+  virtual bool RegisterSyncHandleWatch() = 0;
+  virtual void UnregisterSyncHandleWatch() = 0;*/
+
+  // Watches all handles registered with SyncHandleWatcher on the same thread.
+  // The method returns true when |*should_stop| is set to true; returns false
+  // when any failure occurs during the watch, including |message_pipe_| is
+  // closed.
+  virtual bool SyncWatch(const bool* should_stop) = 0;
+};
+
 // 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.
 class MultiplexRouter
@@ skipping 19 matching lines @@
   // 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.
-  void AttachEndpointClient(const ScopedInterfaceEndpointHandle& handle,
-                            InterfaceEndpointClient* endpoint_client);
+  // The returned object is owned by the router. It should only be used on 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();
+    // CloseMessagePipe() above won't trigger connection error handler.
+    // Explicitly call OnPipeConnectionError() so that associated endpoints will
+    // get notified.
+    OnPipeConnectionError();
   }
 
   // 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|.
@@ skipping 43 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);
+
+  // Returns whether there are more in the queue.
+  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);
@@ skipping 14 matching lines @@
 
   // 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 testing_mode_;
 
   DISALLOW_COPY_AND_ASSIGN(MultiplexRouter);
 };
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_MULTIPLEX_ROUTER_H_