claudeandClaude Opus 5
248af3061e
Replaces the phase-0 resolution probe with the real actions, merging the two independent per-branch Cargo cache implementations on this forge into the design neither of them had. ## The merge - zemyna seeds a PR branch by `cp -al` hardlink clone (near-free: cost scales with inode count, not bytes) from the base branch's LIVE target dir — a torn read waiting for a second job slot (its own #911). - emowheel seeds from a PUBLISHED IMMUTABLE SNAPSHOT (no race by construction) but with `cp -a`, duplicating ~35 GB per branch. This ships hardlink-clone FROM a published snapshot: zemyna's cost profile, emowheel's soundness, and #911 closed structurally rather than by the runner happening to have one execution slot. ## The bug both implementations have A build inside a `cp -al` clone DOES mutate the directory it was cloned from. Cargo replaces real artifacts, but writes its metadata — and build scripts write their OUT_DIR — with a plain truncating write, straight through the shared inode. Measured set: `.fingerprint/<unit>/dep-<target>` (under CARGO_UNSTABLE_CHECKSUM_FRESHNESS), `build/<pkg>/{output,root-output,out/**}`, `deps/*.d` and `<profile>/*.d`. The checksum-freshness case is a wrong answer, not a slow build: a PR clone rewrites the base's dep-info to describe the PR's sources while the base's cache still holds the artifact built from the base's; once the PR merges, the base's next run finds the checksums match, reports `Fresh`, and links a binary built from the pre-merge code. Reproduced end to end. Fix: hardlink the artifacts (the GB), real-copy the metadata (the MB) — about 3.7% of a 6.9 GB Bevy target dir, against 100% for a full copy. ## Contents - `cargo-cache/action.yml` — consume: resolve keys, seed from the base's snapshot via staging + one atomic rename, strip Cargo lock files, unshare the mutable paths, restore mtimes from git history, lock, prune. - `cargo-cache-publish/action.yml` — publish: record the build watermark, atomically republish the snapshot on a protected branch, release the lock (`mode: release-lock` for the `if: always()` step). - `scripts/` — all logic, so it is testable standalone; the YAML is wiring. - `scripts/*selftest.sh` + `selftest.sh` — five suites, 63 assertions, every fix paired with a control that reproduces the bug. All green locally. Eviction merges emowheel's liveness pass (dead branches pruned unconditionally, not gated on disk pressure) with LRU-under-pressure, but inverts the order within the pressure pass: `target-*` before `snapshot-*`, because a snapshot is hardlinked to everything cloned from it, so evicting one frees almost no real bytes while costing every future PR its warm start. restore-mtimes.sh is ported from emowheel (the watermark variant, which closes the merge hazard zemyna's copy still has) with its provenance de-projectised. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01Sqh2vscfzisk83VuPVQX9L
37 lines
1.4 KiB
Bash
Executable File
37 lines
1.4 KiB
Bash
Executable File
#!/usr/bin/env bash
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# Marks a cache directory as held open by a running job, so ANY job's prune
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# pass (including this run's own) skips it.
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#
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# Usage: cache-lock.sh acquire|release <dir> <lock-id>
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#
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# Without this, a directory's only protection from a concurrently running
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# job's eviction pass is "it happens to also be that job's own target dir",
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# which is true for the job that owns it and false for everyone else. The
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# marker is per-job (not just per-run) so two jobs sharing one cache key each
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# hold an independent lock rather than one clobbering the other's.
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#
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# A lock is a timestamp file, not a real mutex: prune-cache.sh honours it only
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# until STALE_LOCK_SECONDS, after which it is treated as abandoned by a job
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# the runner killed before it reached its own release step. Honouring a lock
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# forever would let one crashed job pin a directory permanently.
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set -euo pipefail
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MODE="${1:?usage: cache-lock.sh acquire|release <dir> <lock-id>}"
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DIR="${2:?}"; ID="${3:?}"
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case "$MODE" in
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acquire)
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mkdir -p "$DIR"
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date +%s > "$DIR/.ci-lock-${ID}"
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echo "lock: acquired .ci-lock-${ID} on $(basename "$DIR")"
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;;
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release)
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rm -f "$DIR/.ci-lock-${ID}" 2>/dev/null || true
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echo "lock: released .ci-lock-${ID} on $(basename "$DIR")"
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;;
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*)
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echo "::error::cache-lock.sh: unknown mode '$MODE' (expected acquire or release)" >&2
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exit 1
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;;
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esac
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