Pass N now reads at 32 sectors per attempt and drops to 1 only on
batch-read failure to probe each sector individually. After 16
consecutive clean single-sector reads it climbs back to 32. Net
effect: NonTrimmed regions walk ~32x faster in clean stretches
without sacrificing per-sector recovery quality — the drop-to-1
retry from the same cursor position guarantees every sector in a
failed batch is individually attempted.
Design contract:
- A batch-read failure (count > 1) is NOT a recorded failure: no
NonTrimmed mark, no consecutive_failures bump, no damage_window
push, cursor stays put. We just drop current_batch to 1 and the
loop re-attempts the same position at single-sector granularity.
- A single-sector failure (count == 1) follows the existing path:
NonTrimmed mark, consecutive_failures++, damage_window.push(false),
post-failure pause, wedge probes.
- Backtrack always at count=1: this path fills a gap that the main
loop's damage-window skip jumped over. Using batched reads there
would lump good sectors into NonTrimmed marks when the gap
contains even one bad sector.
State machine adds:
- `initial_batch` (from opts.block_sectors, default 32 in patch_internal)
- `current_batch` (mutable, starts at initial_batch, drops to 1 on
batch failure)
- `consecutive_singles_ok` (counter, resets on upscale + failure)
- `ADAPTIVE_UPSCALE_THRESHOLD = 16` (matches sweep's pattern for
"16 consecutive good = back to fast mode")
Tests:
- pass_n_size_aware_skip.rs PatternedSectorReader now fills each
sector with its OWN LBA byte (not the starting LBA's byte). This
matches real drive behavior — the pre-0.18.13 fixture's
"fill whole batch with one byte" was a shortcut that only worked
when patch read 1 sector at a time. Existing recovery-quality
assertions all still pass under adaptive batching.
User spec: "try 32, pass, great, fail -> do 1 sector"
Foundation for label parsers that need structured access to .class
files inside /BDMV/JAR/<x>.jar. Replaces noak (~3KLOC dep) with a
~1000-line std-only reader.
Public API:
- ClassFile::parse(&[u8]) -> Result<ClassFile>
- ConstantPool::{get, utf8, class_name, string, integer, member_ref, iter}
- Member::code(&pool) -> Option<CodeAttribute>
- CodeAttribute::instructions() -> Instructions iterator
- Instruction::{name, operand_u8, operand_u16, cp_index}
- Opcode constants (LDC, AASTORE, NEW, GETSTATIC, INVOKESPECIAL, ...)
Spec coverage:
- Constant pool: all 17 tag types incl. Long/Double 2-slot quirk
- Modified UTF-8 incl. 0xC0 0x80 -> U+0000 special case
- Bytecode iteration with full opcode size table
- Variable-length tableswitch / lookupswitch / wide
12 unit tests cover the opcode table edge cases (padded switch tables,
wide-iinc 6-byte form), modified-UTF-8 decoder, and iterator
stop-on-truncated behaviour.
Module is currently #![allow(dead_code)] — the public API is staged
for labels::deluxe (Phases A-E bytecode walker) and a labels::dbp
refactor onto the constant-pool iterator. Tests exercise the API
in isolation. The allow comes off as those callers land.
Also fixes two pre-existing clippy lints that 1.86's stricter checks
flagged after I touched the labels module:
- src/mux/disc.rs: while-let-loop in test fixture
- tests/pass_n_size_aware_skip.rs: type_complexity in helper signature
Precommit (cargo +1.86 fmt + clippy + test) green.
Patch was strictly serial (per-sector recovery: read → seek+write
→ mapfile.record → next). Lifting the write+record onto a consumer
thread lets the drive issue the next per-sector retry while the
previous block's recovered bytes are being committed — small but
real win on damaged discs with many bad sectors, and uniform with
sweep's threading model.
- New PatchSink: Sink<PatchItem> impl in src/disc/patch.rs. Owns
WritebackFile + Mapfile. apply() seeks+writes recovered bytes
and records mapfile state per item; close() runs sync_all and
mapfile.flush.
- Channel depth: WRITE_THROUGH_DEPTH (1). Patch wants minimum
buffering — back-pressure should kick in immediately so the
drive's per-sector retry budget isn't ahead of the writer.
- Disc::patch: keeps every existing recovery decision on the
producer (reverse walk, damage-window skip, NOT_READY pauses,
bridge-degradation handling, wedge exit, range watchdog).
WritebackFile ownership moves to the sink.
Behaviour-preserving: per-sector single-shot read budget unchanged
(BU40N+Initio bridge wedge concern still respected); recovery
algorithm bit-identical.
See (internal)/memory/0_18_redesign.md.
Single contributor: MattJackson.
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).
MattJackson