raulcd commented on code in PR #47410:
URL: https://github.com/apache/arrow/pull/47410#discussion_r2298191512
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cpp/src/arrow/flight/transport_server.cc:
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@@ -160,25 +161,63 @@ class TransportMessageReader final : public
FlightMessageReader {
std::shared_ptr<Buffer> app_metadata_;
};
-// TODO(ARROW-10787): this should use the same writer/ipc trick as client
+/// \brief An IpcPayloadWriter for ServerDataStream.
+///
+/// To support app_metadata and reuse the existing IPC infrastructure,
+/// this takes a pointer to a buffer to be combined with the IPC
+/// payload when writing a Flight payload.
+class TransportMessagePayloadWriter : public ipc::internal::IpcPayloadWriter {
+ public:
+ TransportMessagePayloadWriter(ServerDataStream* stream,
+ std::shared_ptr<Buffer>* app_metadata)
+ : stream_(stream), app_metadata_(app_metadata) {}
+
+ Status Start() override { return Status::OK(); }
+ Status WritePayload(const ipc::IpcPayload& ipc_payload) override {
+ FlightPayload payload;
+ payload.ipc_message = ipc_payload;
+
+ if (ipc_payload.type == ipc::MessageType::RECORD_BATCH && *app_metadata_) {
+ payload.app_metadata = std::move(*app_metadata_);
+ }
+ ARROW_ASSIGN_OR_RAISE(auto success, stream_->WriteData(payload));
+ if (!success) {
+ return arrow::Status(arrow::StatusCode::IOError,
+ "Could not write record batch to stream");
+ }
+ return arrow::Status::OK();
+ }
+ Status Close() override {
+ // Closing is handled one layer up in TransportMessageWriter::Close
+ return Status::OK();
+ }
+
+ private:
+ ServerDataStream* stream_;
+ std::shared_ptr<Buffer>* app_metadata_;
+};
+
class TransportMessageWriter final : public FlightMessageWriter {
public:
explicit TransportMessageWriter(ServerDataStream* stream)
- : stream_(stream),
ipc_options_(::arrow::ipc::IpcWriteOptions::Defaults()) {}
+ : stream_(stream),
+ app_metadata_(nullptr),
+ ipc_options_(::arrow::ipc::IpcWriteOptions::Defaults()) {}
Status Begin(const std::shared_ptr<Schema>& schema,
const ipc::IpcWriteOptions& options) override {
- if (started_) {
+ ipc_options_ = options;
+ if (batch_writer_) {
Review Comment:
I should have removed `started_` from `CheckStarted` and just use the
`batch_writer_` as we do on the client. I've updated `CheckStarted` accordingly
and remove the now unnecessary `started_` flag.
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