Matthew Jackson
6e14fc0c0c
Security - Remove the unsafe Vec::set_len over recycled sector buffers — UB reachable from safe code (GHSA-j8ww-f5fg-9pmh, low). Uses Vec::resize; pooling unchanged. CI / tooling - clippy on stable with the MSRV single-sourced from Cargo.toml; cargo-deny dependency-audit gate with first-party git sources allowed (#15); audience-based comment-guard (#17). Docs - README (keydb ownership, BD-J parser count), drive-access transport/reset notes, mux timeline module-doc links.
1.3 KiB
file_sector_source::macos
macOS has no direct POSIX_FADV_SEQUENTIAL equivalent; the idiomatic hint is
fcntl(F_RDADVISE, &radvisory) describing the byte range you intend to read
soon. The open-time sequential hint points it at the whole file (clamped to
RDADVISE_MAX_BYTES so a multi-TB ISO doesn't ask the kernel to prefetch
everything at once).
RDADVISE_MAX_BYTES
Cap on the byte length passed to F_RDADVISE. Asking for a multi-GB
readahead window is counterproductive — the OS doesn't have that much cache
to throw at one fd. 64 MiB is generous for our use case (sweep, mux) so the
kernel's prefetch keeps pace with our app-level pipeline depth.
drop_window
macOS has no direct POSIX_FADV_DONTNEED equivalent for a byte range.
fcntl(F_NOCACHE) would disable caching globally on the fd (too coarse — we
want the unread region to still benefit). Best approximation: no-op.
macOS's unified buffer cache is generally less prone to the pin-everything
pathology that triggers the regression on Linux NFS clients.
prefetch
Async-prefetch the byte range [offset, offset+len). macOS uses the same
fcntl(F_RDADVISE, &radvisory) primitive as the open-time sequential hint,
just targeted at a moving window instead of the whole file. The kernel
queues I/O for the requested range and returns immediately.