Commit Graph

3 Commits

Author SHA1 Message Date
f54ca2f81a IME: map commits against the whole buffer; drop the renderer-side model
The renderer kept a mirror of the pushed IME snippet (the 'IME model')
to translate commit positions, but it transiently desynced from the
buffer on fling/tap sequences (observed as a few-byte mapping drift on
both the x86_64 emulator and the ARM phone), corrupting text. The model
string also sat on the main goroutine next to the JNI render path,
where the app observed states that were impossible for Go memory
(string contents changing between reads microseconds apart), pointing
at corruption in the native bridge layer.

Restructure along the lines of the Android InputConnection contract
and Gio's own reference editor (widget/editor.go):

- Commits carry absolute file runes (the pushed snippet's coordinate
  space) straight to the logic goroutine, which maps them to bytes
  against the WHOLE buffer (runeToByteWhole, an 8 KiB-step scan).
  Scrolling moves the window, not the buffer, so the mapping is exact
  mid-fling by construction — no mirror to desync.
- Drift guard in HandleIMECommit: a small commit (range <= 2 runes)
  is always anchored at the caret the IME was last told about; if the
  IME reports it ending elsewhere, its snippet text is stale (a
  dropped restartInput, as Gboard does during flings) and its
  position is in the stale text's coordinates — snap the commit to
  the cursor, the only position it cannot drift from.
- FlushIME simplifies to: push the snippet when the frame's
  (context+window) text differs from the last push (gioui dedupes
  against its own cache), force the selection re-push in the same
  frame. After a commit the frame text equals what the IME already
  holds locally, so the restart is naturally suppressed; a fling
  re-anchors the IME once per text change.
- Remove the renderer model (adoptFrame/ModelTranslate/
  ApplyIMEEdit/ApplyIMEKey/IMECaret), the IME freeze/settle
  machinery (IMEFrozen, markIMEScrollActive, imeSettleChan), and the
  window-relative imeRuneToByte.

Also fixed along the way (both found while chasing the corruption):

- real.ReadFileAt: loop over short reads. A single ReadAt on Android
  FUSE can return a short read, silently truncating a chunk and
  shifting every byte offset after it.
- logic: a late lazy-chunk result no longer clobbers a buffer that
  SetContent has already fully loaded.
- e2e: large-file IME test (1.6 MB file, fling + commit).
- app icon (scripts/make_icon.py + cmd/pad/appicon.png) so gogio
  builds the mipmap/adaptive icon set.

Verified: go vet + staticcheck, go test -race (all packages), and the
emulator scenario loop (open moby excerpt, fling to mid-file, tap,
type 'a', byte-compare the saved file) 75/75 clean.
2026-09-13 11:57:38 -04:00
6c6a0c1a27 Fix write-concurrency race: per-file write protocol + unique temps
The review-identified race: saves are async (owner snapshots content,
worker pool writes), nothing serialized per file, and every write of a
file used the SAME deterministic temp ('.<name>.tmp'). Two overlapping
writes (autosave x autosave, retry x autosave, or the synchronous
FlushAll on GoToBrowser/Shutdown x a worker write) interleaved on the
shared temp and could rename a byte-mixture into place; even without
interleaving, last-rename-wins could promote a STALE snapshot.

Owner-side protocol (logic.go, requestSave + result handler):
- at most one write in flight per file (writeInFlight maps filename ->
  the file version whose content the in-flight write carries);
- a save requested while one is in flight is deferred (savePending) and
  re-issued by the write's result handler with a FRESH snapshot, so
  'last rename wins' coincides with 'newest snapshot wins';
- on success the SNAPSHOT version (not the current one) is recorded as
  written, so an edit that arrived during the write leaves the file
  dirty and triggers the re-issue;
- FlushAll (GoToBrowser, Shutdown) defers via the same protocol instead
  of writing concurrently on the shared temp;
- shutdown drain: on done the owner waits (bounded 5 s) for in-flight
  writes and armed retries to settle before exiting, so the post-exit
  synchronous FlushAll and workerPool.Stop cannot race a straggling
  worker write;
- retry timer now sends a non-blocking token (no timer-goroutine stall
  on a full channel); emitFrame no longer blocks on a slow/gone main
  (frames are snapshots; the next emission wins) - also required so the
  drain can never deadlock on frame delivery.

Mechanism (real/filesystem.go):
- WriteFileAtomic uses a unique per-call temp ('.<name>.tmp.<pid>.<seq>'),
  making same-file staging-file interleaving structurally impossible even
  if the serialization regressed (defense in depth);
- each successful write best-effort removes stale temps of the same file
  (crash leftovers, plus the legacy deterministic name for upgraded
  installs); a failed write removes its own temp.

Tests:
- write_serialization_test.go (e2e): a counting FS wrapper proves the
  peak concurrent same-file saves is 1 across two deliberately
  overlapping autosaves (2 s saves; the second edit lands inside the
  first save's window and its token is deferred, then re-issued with the
  newer content), and that a Flush during an in-flight save adds no
  concurrent writer and the newest snapshot still wins. Mutation-verified:
  disabling the deferral fails it with peak = 2. (The pool's WriteFileTask
  calls FS.WriteFile, not WriteFileAtomic - the real FS is atomic only
  because WriteFile delegates to WriteFileAtomic; the wrapper mirrors that
  delegation or the overlap window does not exist.)
- filesystem_test.go: stale-temp test updated to the new pattern, also
  covering the legacy name and asserting a different file's temp is
  untouched.
- real_file_fuzz_test.go: stray-temp check matches both patterns.

Docs: architecture.md 6.5 rewritten (protocol invariants), spec.md
autosave line, development_plan.md v11 + Phase 12.

On-device smoke: open, type, autosave lands exact content on disk, no
temp files left, clean relaunch. Full suite green under -race.

Residuals (documented): no fsync before rename (power-loss window only);
external-change detection absent; a drain-deadline exit with a straggling
write can only lose freshness (unique temps keep every rename a complete
snapshot).
2026-08-17 16:29:47 -04:00
5205906de4 Data-corruption test suite: differential fuzz + atomicity contract
Adds the corruption-proofing layer for the edit/persist path:

- chunked_buffer_fuzz_test.go: differential fuzz of ChunkedBuffer
  Insert/Delete against a plain []byte shadow model (arbitrary byte
  positions/text, chunk sizes 1..64KB, 500-2000 ops each) verifying
  FileLen, FullContent, Content probes and the chunk-size invariant
  after every op; rune-aligned variant adds UTF-8 validity and an
  independent RuneIndexToByte oracle.
- line_index_fuzz_test.go: differential fuzz of the incremental
  LineIndex updates against a full-recomputation oracle (mixed,
  no-newline, single-line, CRLF, trailing-newline shapes), plus a
  trailing-empty-line structural invariant test.
- state_api_fuzz_test.go: differential fuzz of the production edit
  entry points (HandleInsert/Backspace/Delete/ReplaceRange, incl.
  selection variants) checking content, UTF-8 validity, chunk
  invariant, line index and exact cursor after every op.
- real_file_fuzz_test.go (e2e): random edit sequences (incl.
  window-relative IME replaces) against the REAL filesystem with
  per-batch IME-window-consistency checks, forced-flush disk
  byte-comparison, then a second logic instance (restart simulation)
  must reload byte-identical content with a fresh line index;
  asserts no stray temp files.
- filesystem_test.go (real): atomicity contract - exact round trip
  at edge sizes, concurrent reader never sees a torn file across 150
  alternating 2MB writes, failed write (read-only dir) leaves the
  original byte-identical, stale temp file is consumed.

Fixes a real invariant violation the fuzzing exposed: Insert halved
an oversized spliced result once, so a large paste into a non-empty
buffer left chunks up to ~P/2 (8x target at 1MB/64KB), breaking the
documented 'no chunk > 2x target' invariant. Insert now re-chunks the
oversized result into pieces of at most chunkSize, making the
invariant hold after every edit. Mutation-tested: dropping one byte
in Insert and one entry in UpdateLineIndexAfterInsert are both
caught by the fuzz suite.
2026-08-17 12:43:17 -04:00