MT worker execution used to combine CCtx acquisition, raw-sequence-store
acquisition, destination-buffer allocation, frame-header publication, and the
LDM resource check in one C callback. That made the resource order and
short-circuit policy another C-owned implementation boundary even though the
operations themselves must remain private to C.
Project the scalar LDM and destination-presence inputs into Rust and let Rust
own the ordering and error normalization. The C callbacks now only acquire
private resources, report readiness, allocate the destination buffer, and
publish the frame-header destination. The ordering remains compatible with the
worker cleanup path: both pool gets happen first, CCtx failure stops before
destination work, destination failure stops before publication, and the LDM
sequence-store check runs after publication.
Test Plan:
- `ulimit -v 41943040; CARGO_BUILD_JOBS=1 cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings` -- passed
- `ulimit -v 41943040; cargo +nightly fmt --manifest-path rust/Cargo.toml --all -- --check` -- passed
- Capped GCC and Clang syntax-only checks for `lib/compress/zstdmt_compress.c` -- passed by the worker
- `git diff --cached --check` -- passed
- Native build and full upstream tests are deferred to the post-batch serial verification.
ddidderr
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