- Implement H2GlobalStreamCreator::ReplaceSocketForStream

- Set stream creator in serialize_request

src/brpc/details/controller_private_accessor.h

@@ -100,6 +100,7 @@ public:
         _cntl->_request_protocol = protocol;
         return *this;
     }
+    ProtocolType request_protocol() { return _cntl->_request_protocol; }
     
     Span* span() const { return _cntl->_span; }
 

src/brpc/socket.h

@@ -783,6 +783,8 @@ private:
 
     butil::Mutex _stream_mutex;
     std::set<StreamId> *_stream_set;
+
+    SocketUniquePtr _agent_socket;
 };
 
 } // namespace brpc