feat: wire --compress-threads=N through to zstd ZSTD_c_nbWorkers (3.4.2 parity)#4100
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Plumb the value parsed in #4095 into the actual zstd encoder via `ZSTD_c_nbWorkers`, matching upstream `token.c:701` so a non-zero `--compress-threads=N` engages real worker threads instead of being silently dropped. - `compress::zstd::CountingZstdEncoder` gains `new_with_workers` / `with_sink_workers` constructors and a `SUPPORTS_MULTITHREAD` const. - `engine::ActiveCompressor::new_with_workers` and `transfer::CompressedWriter::with_workers` thread the value end to end. `LocalCopyOptions` gains `compression_threads` and is populated from `ClientConfig::compression_threads` in `apply_compression`. - Multithreaded zstd lives behind a `zstdmt` Cargo feature on the `compress` crate (off by default to avoid a forced C build cost). Requesting workers without the feature returns `Unsupported` so callers can fall back to single-threaded compression instead of silently discarding the user's request. upstream: options.c:89 do_compression_threads, token.c:701. Refs #2239, #2217.
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….2 parity) (#4100) * feat: wire --compress-threads=N through to zstd ZSTD_c_nbWorkers Plumb the value parsed in #4095 into the actual zstd encoder via `ZSTD_c_nbWorkers`, matching upstream `token.c:701` so a non-zero `--compress-threads=N` engages real worker threads instead of being silently dropped. - `compress::zstd::CountingZstdEncoder` gains `new_with_workers` / `with_sink_workers` constructors and a `SUPPORTS_MULTITHREAD` const. - `engine::ActiveCompressor::new_with_workers` and `transfer::CompressedWriter::with_workers` thread the value end to end. `LocalCopyOptions` gains `compression_threads` and is populated from `ClientConfig::compression_threads` in `apply_compression`. - Multithreaded zstd lives behind a `zstdmt` Cargo feature on the `compress` crate (off by default to avoid a forced C build cost). Requesting workers without the feature returns `Unsupported` so callers can fall back to single-threaded compression instead of silently discarding the user's request. upstream: options.c:89 do_compression_threads, token.c:701. Refs #2239, #2217. * style: apply rustfmt to zstd worker wiring * fix(compress): avoid Result::unwrap_err since encoder lacks Debug * fix(engine): wire compression_threads through options builder + Debug-safe unwrap * fix(engine): gate unused ActiveCompressor::new behind #[cfg(test)] * fix(transfer): avoid expect_err on CompressedWriter lacking Debug
oferchen
added a commit
that referenced
this pull request
May 18, 2026
….2 parity) (#4100) * feat: wire --compress-threads=N through to zstd ZSTD_c_nbWorkers Plumb the value parsed in #4095 into the actual zstd encoder via `ZSTD_c_nbWorkers`, matching upstream `token.c:701` so a non-zero `--compress-threads=N` engages real worker threads instead of being silently dropped. - `compress::zstd::CountingZstdEncoder` gains `new_with_workers` / `with_sink_workers` constructors and a `SUPPORTS_MULTITHREAD` const. - `engine::ActiveCompressor::new_with_workers` and `transfer::CompressedWriter::with_workers` thread the value end to end. `LocalCopyOptions` gains `compression_threads` and is populated from `ClientConfig::compression_threads` in `apply_compression`. - Multithreaded zstd lives behind a `zstdmt` Cargo feature on the `compress` crate (off by default to avoid a forced C build cost). Requesting workers without the feature returns `Unsupported` so callers can fall back to single-threaded compression instead of silently discarding the user's request. upstream: options.c:89 do_compression_threads, token.c:701. Refs #2239, #2217. * style: apply rustfmt to zstd worker wiring * fix(compress): avoid Result::unwrap_err since encoder lacks Debug * fix(engine): wire compression_threads through options builder + Debug-safe unwrap * fix(engine): gate unused ActiveCompressor::new behind #[cfg(test)] * fix(transfer): avoid expect_err on CompressedWriter lacking Debug
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Summary
PR #4095 added
--compress-threads=Nparsing and stored the value inClientConfig::compression_threads, but nothing actually consumed it.This change wires the value through to the zstd encoder so the flag
takes effect.
compress::zstd::CountingZstdEncodergainsnew_with_workers/with_sink_workersconstructors that callmultithread(n)(i.e.ZSTD_c_nbWorkers). A newSUPPORTS_MULTITHREADconstant exposeswhether the build has the underlying C support compiled in.
engine::ActiveCompressor::new_with_workersandtransfer::CompressedWriter::with_workerspropagate the valueend-to-end.
LocalCopyOptionsgainscompression_threads, populatedfrom
ClientConfig::compression_threadsinapply_compression.zstdmtCargo feature on thecompresscrate (off by default to keep minimal builds lean andavoid a forced C build cost). Requesting workers without the
feature returns
io::ErrorKind::Unsupported, so callers fail loudlyinstead of silently discarding the user's setting.
Mirrors upstream:
options.c:89-do_compression_threads = 0(single-threaded default).token.c:701-ZSTD_CCtx_setParameter(zstd_cctx, ZSTD_c_nbWorkers, do_compression_threads).Refs #2239, parent #2217.
Test plan
compress::zstd::workers_path_round_trip_and_smoke-round-trips
Noneand verifiesSome(_)either compresses orsurfaces
Unsupported.engine::compressor::active_compressor_zstd_workers_dispatches_to_encoder-same dispatch contract at the engine layer.
transfer::compressed_writer::zstd_tests::with_workers_round_trip_and_smoke-end-to-end through the multiplexed writer.
engine::options::compression::with_compression_threads_round_trips-builder round-trip for the new option field.