Generic bounded producer/consumer pipeline. The same shape applies to
sweep, patch, and mux today via three near-duplicate implementations
(or, in patch's and mux's case, no implementation at all). 0.18
collapses them onto one primitive. See
(internal)/memory/0_18_redesign.md for full context.
Single contributor: MattJackson.
The bounded-cache writeback wrapper (crate::io::Writer) was added in
0.17.10 and wired into Disc::sweep in 0.17.11, but the other two
paths in the crate that write large amounts of data sequentially —
Disc::patch and the MKV/M2TS mux — were still operating on raw
std::fs::File. That meant the dirty-page burst pathology the wrapper
exists to prevent could still bite on slow / network-attached staging
during recovery and mux phases.
This release plugs those gaps:
- Disc::patch (disc/mod.rs:1981) now wraps the reopened ISO in
Writer before any seek / write. sync_all on Writer cleanly drains
the in-flight chunk before the existing fsync.
- mux/resolve.rs MKV and M2TS branches wrap the output File in
Writer underneath BufWriter. UHD MKV mux routinely produces 70+ GB
of sequential output; the page cache no longer absorbs that as a
single hot blast on slow targets.
Mapfile, log, settings, history, and stream-pipeline byte buffers
remain unchanged: those are either small one-shot writes (where
the wrapper has zero benefit and adds a stream_position syscall) or
already use bounded persistence (mapfile time-batched in 0.17.12).
The principle: any path that writes substantial sequential data to
a single file uses Writer; trivial writes don't.
Pre-0.17.12 every Mapfile::record() persisted the full mapfile via
tempfile-create + write + atomic-rename. On local LVM that's
microseconds; on NFS each rename is multiple RPCs through the
unraid user-share fuse layer, dragging a Black Mass UHD rip from
~11 MB/s on local to ~1.5 MB/s on NFS — the mapfile path alone burned
multiple seconds of wall time per real-world second of work.
Mapfile now batches the rename to once per second:
- record() always updates in-memory state and stats; only fires
write_to_disk when last_flushed.elapsed() >= FLUSH_INTERVAL (1 s).
- New flush() API forces a persist; called by sweep_pipeline's
consumer at end-of-sweep and by Disc::patch at end-of-patch,
after the file's sync_all.
- Drop impl best-effort flushes so an early-return / unwind doesn't
silently lose pending state.
Crash-safety changes from "lose at most one block" to "lose at most
1 s of recorded progress" — the ISO file's payload bytes are unaffected;
only the mapfile's authority over which sectors are already-good is at
risk, and a resume re-reads anything Pass 1 had already covered.
Measured on the BU40N test bed against Black Mass UHD inner zone:
- NFS staging: 1.5 MB/s → 16.48 MB/s (10.9× recovery)
- Local LVM staging: 11.09 MB/s → 11.83 MB/s (+6.7 % bonus)
Internal round_trip_load test now flushes before reading back from
disk. External patch / copy tests are unaffected: patch and
sweep_pipeline flush at completion before returning.
Pre-0.17.11 sweep ran strictly serialised: SCSI read → decrypt → seek
+ write → mapfile.record → next read. Drive idled for the post-read
work; throughput capped at the sum of both costs. On a healthy disc
that's ~7-12 ms read + ~5-15 ms write/record per 64 KB batch, limiting
sustained throughput to ~10-12 MB/s on the test bed (BU40N + UHD inner
zone), well below the ~14-16 MB/s drive ceiling.
Decouples them: producer thread (caller's) owns SectorReader +
read_error state + decrypt + set_speed + halt; consumer thread (one
spawn) owns Writer + Mapfile, receives WorkItem messages, applies
file write + mapfile record. Bounded mpsc::sync_channel(4) gives
natural back-pressure. While the consumer writes batch N, the
producer is already reading batch N+1 — steady-state throughput is
now bound by the slower of the two pipelines (drive on healthy
discs), not their sum.
Side effects:
- Bisect path now decrypts. Pre-0.17.11 the bisect inner loop wrote
raw cyphertext for single-sector recoveries on encrypted discs —
quiet correctness bug exercised only by batch-fail-then-
bisect-succeed on encrypted media. New producer-side decrypt
covers main + bisect success paths uniformly.
- All read_ctx state stays single-threaded on producer (damage
window, jump multiplier, etc.). No locking added.
- Mapfile remains single-writer on consumer. No locking.
- Halt latency: producer breaks loop, sends Finish, consumer drains
≤4 in-flight items + sync_all. ~1 batch (~12 ms) typical.
- BU40N + Initio bridge wedge concern unchanged: still single SCSI
command in flight, error-path timing identical, no new retries.
New module: src/disc/sweep_pipeline.rs (WorkItem, ProgressSnapshot,
ConsumerInputs, spawn_consumer, consumer_loop, helpers). Public API
unchanged — Disc::copy / CopyOptions / CopyResult identical.
Patch (Pass N) is NOT changed; it's bound by drive recovery time, not
the read/write serialisation.
Pass 1 sweep speed on a healthy disc previously dipped from ~15 MB/s
to ~1 MB/s every ~30 s on a host with default Linux dirty-page
settings. Empirical cause: the kernel's vm.dirty_ratio (~20% of RAM)
lets hundreds of MB of dirty pages accumulate, then bursts a flush at
99% disk utilisation that blocks app writes for ~1 s. Confirmed on
the BU40N test bed — dirty pages grew 112 → 563 MB between bursts;
lowering vm.dirty_bytes to 64 MB at the host sysctl level eliminated
the dips. Shipping the equivalent inside libfreemkv so users do not
need to tune the host kernel.
- New crate::io::Writer: drop-in File wrapper (impl Write + Seek).
Wraps a per-platform WritebackPipeline that on Linux schedules
sync_file_range(WRITE) + lagging sync_file_range(WAIT_AFTER) +
posix_fadvise(DONTNEED) in 32 MB chunks, bounding dirty cache at
~64 MB. macOS and Windows ship a no-op stub.
- Disc::sweep wraps its output File in Writer. Loop body unchanged.
- Module is purpose-built so any large sequential output (patch,
mux) can adopt the same wrapper as a one-line change later.
Version bump to keep the four freemkv crates at unified versioning
after autorip's v0.17.6 + v0.17.7 work today. No libfreemkv code
changes; republished to crates.io so downstream consumers stay
aligned on the latest patch version.
Direct-SATA BU40N + Dune Part Two UHD live testing exposed that the
v0.17.3 single-shot SCSI READ path matched 0/22 of the small bad-
sector LBAs that dd if=/dev/sr0 recovers on the same drive. This
release closes that gap and fixes adjacent bugs silently capping
recovery.
- /dev/sr0 pread fallback in Drive::read (Linux only): on SCSI READ
Err, fall back to posix_fadvise(DONTNEED) + pread() against the
corresponding block device. Kernel sr_mod runs ~5 internal retries
with no per-attempt mid-layer escalation overhead — the mechanism
behind dd's recovery advantage. End-to-end byte verification
confirms the fallback path returns real disc data.
- Disc::patch per-range watchdog fix: MAX_RANGE_SECS was breaking
'outer (one slow range killed the entire patch). Now skips to the
next range. Pre-fix patch died after 4 sectors of range 1 of 47.
- Per-sector range budget: range_budget = sectors × 25 s, capped at
1800 s. Replaces the flat 180 s/range that was unfair to medium
ranges and pointlessly generous to single-sector ones.
- consecutive_failures resets per range. The wedge-exit detector is
for stuck-on-one-range, not many-small-ranges-with-one-fail-each.
- Reverted inline 5× retry experiment (was hurting: each retry paid
kernel SCSI escalation overhead). Restored READ_RECOVERY_TIMEOUT_MS
to 60 s. The kernel-auto-retry pattern is now provided by sr0
fallback.
Empirical: pass 1 recovered 94.6 MB / 11 s of main title (33 sr0
saves). Pass 2 added 0.6 MB. Remaining ~233 MB on the test disc
appears physically unrecoverable on this hardware.
tests/scsi_recovery.rs:
- Add `use std::time::Duration` inside both `#[cfg(target_os = "linux")]`
blocks. Locally on macOS the linux blocks are cfg-out so the missing
import was invisible to precommit on macOS.
- Bug pre-dated this branch but only surfaced when v0.17.2 release CI
ran the test compile on Linux.
Cargo.toml: 0.17.2 -> 0.17.3.
Cargo.toml: 0.17.1 -> 0.17.2. Functionally identical to the prior
commit; 0.17.1 was never published to crates.io but a tag exists on
the remote pointing at an unrelated commit. Bumping past it.
src/disc/mod.rs:
- Cache priming (3-sector lookback) before patch's single-sector reads.
Drive read-ahead pulls in adjacent pages so the target may already be
cached when we ask for it. Throwaway reads — failures here don't
update mapfile state.
- When patch hits skip-limit on a range, leave remaining sectors
NonTrimmed instead of marking Unreadable. We never tried to read those
sectors, so don't give them terminal status — drive state evolves
between passes (cache, mechanical settle), and a later pass may
succeed.
tests/pass_n_patch_fix.rs:
- New regression test for the decrypt key inversion bug at
src/disc/mod.rs:1938-1942. Asserts decrypt_sectors is invoked with
the correct key when opts.decrypt=true.
tests/pass_n_size_aware_skip.rs:
- rustfmt-only changes.
Cargo.toml: 0.17.0 -> 0.17.1.
New disc/read_error.rs as the single entry point all read failures flow
through. Handler classifies the error, updates the in-flight context
(damage window, retry budgets, jump multiplier), and returns a
ReadAction the caller dispatches on. Pass 1 (sweep) refactored to use
it; ~340 lines of nested if/else collapsed into ~120 lines of action
dispatch. Adding a new error class = one match arm. Logging is in one
place. Bisect inner failures don't poison the damage window. Jump
multiplier capped at 64 (max 1 GB jump for batch=32 — observed prior
unbounded behavior produce a single 56 GB jump on a wedged drive).
Pass N (patch) damage_skip is now size-aware: each skip is capped at
range_remaining/4 rather than the absolute MB-scale escalation. The
old logic could leap over a 100-sector bad range that hides a 50-sector
good middle; size-aware convergence finds the good middles instead.
Tests in tests/pass_n_size_aware_skip.rs exercise the size-aware skip
against synthetic patterns (25-bad/50-good/25-bad and three good
middles in a row) and prove ≥98% of good middles are recovered.
Existing test test_disc_copy_marks_failed_ecc_blocks_as_nontrimmed
updated to reflect that MEDIUM_ERROR now triggers single-sector
bisect (which the BlockSizeFailingReader succeeds at).
- Fix unwrap in disc/mod.rs sweep() hot path using pattern matching
- Patch pass excludes Unreadable sectors from work list
- Expose bytes_bad_in_title for accurate UI reporting
- All 256 tests pass, cargo clippy clean with -D warnings
- DAMAGE_WINDOW 50→16, DAMAGE_THRESHOLD_PCT 25→12: triggers on 2nd scattered failure
- Previous 50/25% was too diluted by good reads between sparse failures
- copy() dispatch checks mapfile total_size == disc capacity_bytes (covers_disc)
- NonTried regions → sweep with resume=true (preserves mapfile)
- Only NonTrimmed/NonScraped/Unreadable → patch
- sweep_internal takes resume param: true when dispatching from existing mapfile
- Verified: Pass 1 from 30-100% completes in ~20 min with correct jumps through 3 damage zones
- CopyOptions: replace resume/skip_on_error/batch_sectors with single multipass bool
- Disc::copy() auto-detects pass from mapfile state: no mapfile or NonTried → sweep, only NonTrimmed/Unreadable → patch
- Fix bug where mapfile with NonTried regions incorrectly dispatched to patch mode
- SectorReader::set_speed() default method, Drive impl sends SET CD SPEED
- On damage zone entry: set_speed(0x0000) for better error recovery
- On damage zone exit (50 consecutive good): set_speed(0xFFFF) to restore max speed
- Disc::mapfile_for() returns /tmp/<name>.mapfile for null:// output
- patch_internal/sweep_internal as private helpers, CopyResult gains recovered_this_pass
- Adaptive probe algorithm in Disc::copy skip_on_error mode: after 4
consecutive errors, probe 1 sector at 256x batch (8 MB) ahead. If
good, zero-fill gap, mark NonTrimmed, jump. Clears bad zones in
seconds instead of hours.
- NOT_READY sense key (0x02) now retries up to 3x with 3s pause before
marking NonTrimmed. BU40N returns NOT READY for bad sectors, not
MEDIUM ERROR.
- PassProgress struct gains bytes_bad_total field for consumer-side
bad/retryable byte counts.
- Mapfile header version string fix: no longer duplicates 'libfreemkv v'
prefix on each write.
- Structured sense_key/asc/ascq logging in copy error path.
macOS SCSI transport rewritten from hybrid MMC+pread to single-path
raw CDB dispatch through SCSITaskDeviceInterface. All CDBs (INQUIRY,
READ, REPORT KEY, etc.) now go through ExecuteTaskSync — 1:1 with
the Linux SG_IO backend.
Key changes:
- New macos_shim.c: diskutil unmount → find IOBDServices →
ObtainExclusiveAccess → raw CDB dispatch. Eliminates Rust-side
IOKit COM vtable complexity.
- build.rs compiles macos_shim.c via cc into static lib
- macos.rs simplified to three FFI calls (open/close/execute)
- disc/mod.rs: graduated batch restore after errors, skip-ahead
through bad zones, configurable error pause
- as_bytes() requires OsStrExt import which is platform-specific
- as_encoded_bytes() is the portable API available on all platforms
- Fixes CI failure on Linux (Ubuntu) in GitHub Actions
MattJackson