Add mssql-tds support for incremental PLP parameter write path - #207
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Shiwani Gupta (shiwanigupta0809) wants to merge 4 commits into
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Add mssql-tds support for incremental PLP parameter write path#207Shiwani Gupta (shiwanigupta0809) wants to merge 4 commits into
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Shiwani Gupta (shiwanigupta0809)
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Extend the existing sp_executesql serialize flow with a data-at-execution pause point rather than adding a parallel send path. RpcParameter gains a data_at_exec marker; its serialize writes the parameter header and opens an unknown-length PLP value, then stops, reusing the same write_type_info the atomic path uses. begin_sp_executesql takes a single named_params list (some marked data_at_exec, mirroring ODBC SQL_DATA_AT_EXEC), partitions materialized vs streamed, sends materialized params through the normal path, and streams the rest via write_streamed_chunk/end_streamed_param. PacketWriter suspend/resume parks the in-progress message as owned client state, the write analogue of the incremental read pause. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
A failed write_streamed_chunk/end_streamed_param leaves a partial message on the wire, so re-parking it as Active let the caller keep appending to a corrupt message. Add abort_streamed_write to drop the message (state -> Idle, not resumable) and flag the connection for reset, matching msodbcsql's DAE teardown on a failed send. Add fault-injecting unit tests for both abort paths and e2e variations (empty value, many small chunks, connection reuse). Migrate the e2e test file to the current execute/ResultSet API. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Defer the PLP length field: the data-at-exec serialize now writes only the parameter header (status + TYPE_INFO), and the length field (PLP_UNKNOWN_LEN opener or PLP_NULL) is written lazily by the streaming driver. This lets a streamed parameter resolve to NULL before any data is sent, matching msodbcsql path 2 (SQLPutData(SQL_NULL_DATA)). Add write_streamed_null(); end_streamed_param emits PLP_NULL for a NULL-signalled param, the terminator for a value, or opener+terminator for an untouched (empty) param. Guard both orderings (chunk-after-null, null-after-chunk). Add unit and e2e tests. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Description
Adds a data-at-execution (streamed) PLP parameter write path to mssql-tds for large nvarchar(max) / varchar(max) / varbinary(max) values in sp_executesql. The value is streamed to the server in chunks instead of being materialized up front, mirroring msodbcsql's incremental PLP write. This is the TDS-layer foundation for a later ODBC SQLPutData / SQLParamData. Scope: mssql-tds only.
What this adds
Streaming entry points on TdsClient, mirroring ODBC's begin/put/end:
begin_sp_executesql — sends the RPC prefix (headers, positional args, materialized params) + the first streamed param's header, parks the half-written message, returns NeedData.
write_streamed_chunk — appends one length-prefixed chunk (empty chunks ignored — a zero-length header is the terminator). Writes the unknown-length opener lazily on the first chunk.
write_streamed_null — marks the current param SQL NULL instead of streaming chunks (the SQLPutData(SQL_NULL_DATA) case).
end_streamed_param — closes the value (PLP_NULL, terminator, or opener+terminator for an empty value), then opens the next streamed param (NeedData) or finalizes and positions on the response (Done).
RpcParameter::data_at_exec() marker; PacketWriter::suspend/resume to park a half-written message across calls; SqlRpc::serialize_prefix to serialize up to materialized params without finalizing.
Testing
Unit (offline mock): header serialization, non-MAX/encrypted rejection, single/multi-chunk framing, empty-chunk skip, two-param lifecycle, materialized+streamed mix, multi-packet chunk, streamed-NULL framing + ordering guards, usage-error guards, and two fault-injection tests for the mid-stream abort.
E2E (live SQL Server): round-trips for nvarchar/varbinary/varchar(max), two params, mixed, multi-row, materialized NULL, streamed NULL, empty value, many small chunks, and connection reuse.
Not covered (deferred)
Always Encrypted on the streamed path (rejected); ODBC SQLPutData / SQLParamData (the next layer).
Related Issues
https://sqlclientdrivers.visualstudio.com/mssql-rs/_backlogs/backlog/mssql-rs%20Team/Features?workitem=46139
Checklist
cargo bfmtpassescargo bclippypassescargo btestpasses