Improve shared_ptr usage (#2030)

[xray] Improve shared_ptr usage

src/ray/object_manager/object_manager.h

@@ -110,7 +110,7 @@ class ObjectManager {
   ///
   /// \param conn The connection.
   /// \return Status of whether the connection was successfully established.
-  void ProcessNewClient(std::shared_ptr<TcpClientConnection> conn);
+  void ProcessNewClient(TcpClientConnection &conn);
 
   /// Process messages sent from other nodes. We only establish
   /// transfer connections using this method; all other transfer communication
@@ -119,7 +119,7 @@ class ObjectManager {
   /// \param conn The connection.
   /// \param message_type The message type.
   /// \param message A pointer set to the beginning of the message.
-  void ProcessClientMessage(std::shared_ptr<TcpClientConnection> conn,
+  void ProcessClientMessage(std::shared_ptr<TcpClientConnection> &conn,
                             int64_t message_type, const uint8_t *message);
 
   /// Cancels all requests (Push/Pull) associated with the given ObjectID.
@@ -226,7 +226,7 @@ class ObjectManager {
   /// Synchronously send a pull request via remote object manager connection.
   /// Executes on main_service_ thread.
   ray::Status PullSendRequest(const ObjectID &object_id,
-                              std::shared_ptr<SenderConnection> conn);
+                              std::shared_ptr<SenderConnection> &conn);
 
   std::shared_ptr<SenderConnection> CreateSenderConnection(
       ConnectionPool::ConnectionType type, RemoteConnectionInfo info);
@@ -241,23 +241,22 @@ class ObjectManager {
   /// Executes on send_service_ thread pool.
   ray::Status SendObjectHeaders(const ObjectID &object_id, uint64_t data_size,
                                 uint64_t metadata_size, uint64_t chunk_index,
-                                std::shared_ptr<SenderConnection> conn);
+                                std::shared_ptr<SenderConnection> &conn);
 
   /// This method initiates the actual object transfer.
   /// Executes on send_service_ thread pool.
   ray::Status SendObjectData(const ObjectID &object_id,
                              const ObjectBufferPool::ChunkInfo &chunk_info,
-                             std::shared_ptr<SenderConnection> conn);
+                             std::shared_ptr<SenderConnection> &conn);
 
   /// Invoked when a remote object manager pushes an object to this object manager.
   /// This will invoke the object receive on the receive_service_ thread pool.
-  void ReceivePushRequest(std::shared_ptr<TcpClientConnection> conn,
+  void ReceivePushRequest(std::shared_ptr<TcpClientConnection> &conn,
                           const uint8_t *message);
   /// Execute a receive on the receive_service_ thread pool.
   void ExecuteReceiveObject(const ClientID &client_id, const ObjectID &object_id,
                             uint64_t data_size, uint64_t metadata_size,
-                            uint64_t chunk_index,
-                            std::shared_ptr<TcpClientConnection> conn);
+                            uint64_t chunk_index, TcpClientConnection &conn);
 
   /// Handles receiving a pull request message.
   void ReceivePullRequest(std::shared_ptr<TcpClientConnection> &conn,