claude
df6f1b91fb
Co-authored-by: Claude <claude@gitdan.com> Co-committed-by: Claude <claude@gitdan.com>
50 lines
2.2 KiB
Bash
Executable File
50 lines
2.2 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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#
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# `.ci-lock-<id>` IS A CROSS-REPO CONTRACT NAME with daniel/gitdan's
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# `scripts/ci-cache-reclaim.sh`: that host-level arbiter reads this same
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# marker (its `leftover_is_locked()`) to decide whether a leftover it is about
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# to reclaim is still held open by a live job. `cache-lib.sh`'s
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# `write_cache_lock()` writes the identical shape independently of this
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# script. Rename or reshape this marker here without a matching change on
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# gitdan's side and the arbiter's lock check silently stops matching — a live
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# job's staging tree loses its liveness guard and becomes an ordinary reclaim
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# candidate while still in use. See the "Scratch names in a cache root" section
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# in README.md, and daniel/gitdan's `DEPENDED-UPON NAMES CONTRACT` block in
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# `scripts/ci-cache-reclaim.sh`, for the full arrangement — this repo's half
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# is: don't rename `.ci-lock-` without telling that script.
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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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