lidavidm commented on a change in pull request #12465: URL: https://github.com/apache/arrow/pull/12465#discussion_r817061628
########## File path: cpp/src/arrow/flight/transport_impl.h ########## @@ -0,0 +1,220 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +// Internal (but not private) interface for implementing alternate +// transports in Flight. +// +// EXPERIMENTAL. Subject to change. + +#pragma once + +#include <chrono> +#include <functional> +#include <memory> +#include <string> +#include <utility> +#include <vector> + +#include "arrow/flight/type_fwd.h" +#include "arrow/flight/visibility.h" +#include "arrow/type_fwd.h" + +namespace arrow { +namespace ipc { +class Message; +} +namespace flight { +namespace internal { + +/// Internal, not user-visible type used for memory-efficient reads +struct FlightData { + /// Used only for puts, may be null + std::unique_ptr<FlightDescriptor> descriptor; + + /// Non-length-prefixed Message header as described in format/Message.fbs + std::shared_ptr<Buffer> metadata; + + /// Application-defined metadata + std::shared_ptr<Buffer> app_metadata; + + /// Message body + std::shared_ptr<Buffer> body; + + /// Open IPC message from the metadata and body + ::arrow::Result<std::unique_ptr<ipc::Message>> OpenMessage(); +}; + +/// \brief An transport-specific interface for reading/writing Arrow data. +/// +/// New transports will implement this to read/write IPC payloads to +/// the underlying stream. +class ARROW_FLIGHT_EXPORT TransportDataStream { + public: + virtual ~TransportDataStream() = default; + /// \brief Attemnpt to read the next FlightData message. + /// + /// \return success true if data was populated, false if there was + /// an error. For clients, the error can be retrieved from Finish. + virtual bool ReadData(FlightData* data); + /// \brief Attempt to write a FlightPayload. + virtual Status WriteData(const FlightPayload& payload); + /// \brief Attempt to write a non-data message. + /// + /// Only implemented for DoPut; mutually exclusive with Write(const + /// FlightPayload&). + virtual Status WritePutMetadata(const Buffer& payload); + /// \brief Indicate that there are no more writes on this stream. + /// + /// This is only a hint for the underlying transport and may not + /// actually do anything. + virtual Status WritesDone(); +}; + +/// \brief A transport-specific interface for reading/writing Arrow +/// data for a client. +class ARROW_FLIGHT_EXPORT ClientDataStream : public TransportDataStream { + public: + /// \brief Attempt to read a non-data message. + /// + /// Only implemented for DoPut; mutually exclusive with Read(FlightData*). + virtual bool ReadPutMetadata(std::shared_ptr<Buffer>* out); Review comment: Basically, some methods are only used by some RPCs, or only used by the server or the client. But I didn't want to subdivide things into too many little interfaces. I'll add a server-side interface for this method, though. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
