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554310186f
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fix(hardlink): content freshness moved switches, it was not withdrawn
CI / shellcheck + selftests (pull_request) Successful in 1m17s
`unshare_mutable_paths`' comment recorded that upstream had stopped rewriting `dep-<target>` in place, on a measurement taken against 1.100.0-nightly. It had not. Two unrelated cargo changes landed within four days of each other and between them moved the switch that turns the behaviour on and the path it writes to: - cargo PR #17382 (2026-08-22) demoted `-Z checksum-freshness` to a gate and gave `build.fingerprint` the choice, defaulting to `mtime`. Setting only the gate is accepted and does nothing, which is exactly the result that was read as a withdrawal. - build-dir layout v2 (cargo PR #17354, stable 1.100.0 on 2026-11-12, nightly default since 1.99) moved the file from `.fingerprint/<unit>/dep-*` to `build/<pkg>/<hash>/fingerprint/dep-*`. Measured 2026-08-26 on 1.100.0-nightly (e8cb624d5): same toolchain, same clone procedure, one env var apart — with the gate alone a `cp -al` clone mutates only the build/ and *.d families; add `CARGO_BUILD_FINGERPRINT=content` and the source's dep-info file is mutated through the shared inode again. The hazard is intact. So the suite now exports both switches, and its strongest scenario runs again on current nightlies — verified passing against both layouts. Its control note learned the v2 path too: it looked for the v1 path only, and so printed "does NOT rewrite ... in place" three lines beneath a listing that showed the rewrite. Every claim these comments make is now dated and cited, because the defect being fixed is a comment that cited one measurement and silently stopped reproducing. Layout v2 also drags the artifacts under `build/`, which collapses this function's real-copy set from 21.3% of a target dir to 99.998%. That is a live cost, not a correctness problem, and it is filed as gitdan-actions#14 rather than fixed here. Part of daniel/gitdan#62. |
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e94c46f2ec
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test(hardlink): move the probe's INACTIVE answer off bash's error codes
CI / shellcheck + selftests (pull_request) Successful in 1m21s
Review finding on #13, and the last change to this function. A typo'd variable name on a line that HAS its `|| exit 2` guard — `$CONTNET_B` for `$CONTENT_B` — fails in EXPANSION, before the command runs, so neither the guard nor the ERR trap ever sees it. Under `set -u` that exits 1, which was the code meaning "measured, and the answer is mtime". Not a live defect: the probe references only set variables today, and the 1 gitdan-ci reports is a genuine measurement. The defect is that the answer codes and the error codes overlapped at all. Three rounds on this function each found a narrower way for a shell-generated 1 to be read as a measurement — an unguarded command, then a guarded line whose guard could not fire — and each was closed by narrowing the failure surface, which is a game with no last move. INACTIVE is now 3, and anything that is not 0 or 3 is NOT MEASURED. Bash generates 1, 2, 126, 127 and 128+n for its own errors and never 3, so "not an answer" is decided by a property of the shell rather than by an enumeration of the ways a step can go wrong. A step added later without a guard, or with a guard that cannot fire, lands on NOT MEASURED by construction. The guards and the trap stay, with their job restated: reporting rather than correctness. They put a failed step on 2 with both probe logs printed instead of on some incidental status — nicer to debug, and the same destination either way. The `set +e` bracket at the call site keeps its own note, since a `set -e` that cannot fire is the kind of thing a reader assumes works. The not-measured message now quotes the actual exit code, so the two ways to reach it are distinguishable in a log without reading this file. Red-proven with the reviewer's own mutation, A/B: with INACTIVE at 1 the typo reports `mode: off — resolves freshness by mtime`, a false measurement; at 3 it reports `mode: unmeasured — the probe exited 1`. All four paths re-verified — unmodified 4 assertions; env stripped inside the probe, measured INACTIVE with the mtime reason; a broken probe build, unmeasured via a guard; an unguarded `false`, unmeasured via the trap. |
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5b46986cd7
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test(hardlink): make the errexit invariant real, and stop gpg deciding a gate
CI / shellcheck + selftests (pull_request) Successful in 1m23s
Two review findings on #13. THE STATED INVARIANT WAS NOT IN FORCE. The header claimed a `set -e` abort could never be mistaken for the `1` that means "measured, and the answer is mtime". It could not fire at all: `checksum_freshness_probe || probe_rc=$?` runs the left side with errexit suppressed, and that suppression propagates into the subshell. An unguarded step there fell through to `exit 0` and reported ACTIVE — a fourth outcome the header said was impossible. The guard audit was complete, so nothing was broken; the wrong mechanism had the credit, in a comment inviting the next editor to add an unguarded step and rely on it. The suggested fix — `set -e` as the first line of the subshell — does not work, and measured on bash 5.3 it makes things worse rather than not-better: set -e inside a subshell called via `||` or `if` still falls through: rc=0 set -e inside, called with errexit off at the site aborts, but with the FAILING COMMAND's status — `false` gives 1, which is exactly the value that means "mtime" So both halves are needed and neither is decoration: `set +e` around the call site, so the subshell can arm its own errexit at all, and `trap 'exit 2' ERR` inside it, so an abort lands on "not measured" instead of on an answer. The explicit `|| exit 2` guards stay as the first line of defence. All of that is now written down where the false claim was. Red-proven with one unguarded `false` between the `touch` and the second build, on a box where freshness is live: without the fix, mode `on` and 4 assertions — the reviewer's fourth outcome, reproduced; with it, mode `unmeasured`, the warning, 3 assertions; unmodified, mode `on` and 4. Recorded in the same block, since the next person to hit a `2` will ask: why it skips rather than fails. The gated scenario is the only thing here that depends on freshness mode, and failing would turn a statement about one machine into a red gate reading "the hardlink scheme is broken" across three consuming repos. What would change the answer is `2` becoming the everyday CI outcome, and run 2583 measures that it is not — gitdan-ci reports `1`. GPG. The two suites that commit in scratch repos inherited the developer's GLOBAL `commit.gpgsign`, so whether this gate passes could depend on their gpg agent — seen as a red `restore-mtimes-selftest.sh` caused by a full disk breaking gpg, in a suite with nothing to say about either. Pinned off locally, in the throwaway repos only: `git config commit.gpgsign false` beside the identity the scratch repo already sets, and `-c commit.gpgsign=false` on prune-cache-selftest's three commits, matching its existing `-c` style. Red-proven under a GIT_CONFIG_GLOBAL with gpgsign on and a nonexistent gpg program: without it `fatal: failed to write commit object`, with it both suites pass. |
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5a90d5c829
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test(hardlink): let the freshness probe report that it could not measure
CI / shellcheck + selftests (pull_request) Successful in 1m21s
Review finding on #13. `checksum_freshness_active()` returned non-zero for any reason — including its own `cargo build` failing — and the caller's `else` branch then announced "this nightly accepts -Z checksum-freshness but still resolves freshness by mtime" regardless. On a machine where content freshness IS live, breaking only the probe's build produced that sentence, which is false, and silently dropped the scenario, which is lost coverage. Reachable, not theoretical: it needs a half-installed toolchain, which is exactly the state a probe exists to notice. The whole point of the preceding commit was to settle this by experiment rather than by asking, and an experiment that cannot tell a negative result from a failed measurement is not settling it. "This toolchain resolves freshness by mtime" is a statement about Cargo; "a probe build failed" is a statement about this machine. They are not interchangeable. Three outcomes now, carried in an exit code: 0 measured ACTIVE both builds ran, the backdated rebuild recompiled 1 measured INACTIVE both builds ran, the backdated rebuild was Fresh 2 NOT MEASURED a probe step failed; nothing was learned Every step that could fail for a reason other than the experiment's own outcome exits 2 explicitly, so a `set -e` abort cannot be mistaken for the 1 that means "measured, and the answer is mtime". Outcome 2 emits a ::warning:: saying in those words that this is a failure to measure and not a finding about Cargo, and prints the tail of both probe logs. The scenario still skips for 1 and 2 alike — everything else the suite asserts is independent of freshness mode — but the reason is now carried to the skip line, so the two are distinguishable at a glance. Verified all three states on a machine where freshness is live: unmodified, mode `on` and 4 assertions; probe build broken with a bogus flag, mode `unmeasured` with the warning and 3 assertions, and no claim about mtime; CARGO_UNSTABLE_CHECKSUM_FRESHNESS stripped inside the probe — CI's condition — mode `off` naming mtime, and 3 assertions. |
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6a80423bd0
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test(hardlink): settle checksum freshness by experiment, not by asking
CI / shellcheck + selftests (pull_request) Successful in 1m17s
Third toolchain probe in this branch, and the first one that asks the
question the suite actually depends on. The two before it each let the suite
assert a property the toolchain did not have:
cargo +nightly -V answers "did a proxy called with
+nightly exit 0". `-V` short-circuits
before `-Z` is parsed at all.
cargo +nightly -Z checksum-freshness answers "is the flag still accepted".
locate-project 1.100.0-nightly (2026-08-25) accepts it
and resolves freshness by mtime anyway,
which is how CI reached the final
scenario and failed there.
The final scenario depends on exactly one property: that changed content with
an OLDER mtime rebuilds. Under mtime freshness the correct answer is Fresh, so
under mtime freshness that scenario asserts a bug — which is what CI reported.
So the probe performs that experiment, on its own crate and its own target
dir, with no clone anywhere near it. That separation is also what keeps it a
control rather than a restatement: the probe establishes that the toolchain
rebuilds on content, the scenario establishes that a hardlink clone did not
take that away.
Verified both ways locally: with a real content-freshness nightly, mode on and
4 assertions; with the env var stripped inside the probe — the runner's
condition, faithfully — the probe says so by name, mode goes off, the scenario
is skipped loudly and the remaining 3 assertions pass.
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5e8e773f78
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test(hardlink): report the mutation families, don't assert one of them
CI / shellcheck + selftests (pull_request) Failing after 1m21s
CI's nightly is 1.100.0-nightly (2026-08-25); the machine this suite was written on had 1.96.0-nightly (2026-02-24). On the newer one the control's `cp -al` clone mutates only the build/ and *.d families — upstream appears to have stopped rewriting `.fingerprint/*/dep-*` in place under checksum freshness — so the suite went red on the *absence* of a hazard. That is the wrong shape for a gate. The control's job is to prove the hazard exists at all, which a non-empty mutated set already does; naming one family as mandatory makes the suite red whenever upstream stops doing something we never wanted it to do, and red in the CONTROL, where a failure reads as "the hazard is gone" rather than "upstream changed". It is now a note either way. Nothing is given up. The fix scenario asserts the source is byte-identical after a full rebuild in the clone, which covers every family the running Cargo has, named or not — and the checksum-freshness scenario after it tests the stale-reuse hazard directly. The dep-* line only ever documented which family was in play. `unshare_mutable_paths` keeps unsharing dep-* regardless, and its measurement block now records both observations with their versions: 22 MB of a 6.9 GB tree against a failure mode that is a wrong answer rather than a slow one. |
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3f97d3d1e7
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fix(selftest): make the two compiler-backed suites survive a CI runner
CI / shellcheck + selftests (pull_request) Failing after 1m36s
The new gate's first run went red on both suites that drive a real Cargo.
Neither failure was a defect in what they test; both were assumptions about
the machine, which had only ever been a dev box with a nightly installed and
no colour forcing. Fixed here rather than waived — turning a gate on is what
obliges fixing what it finds.
COLOUR. Every assertion in restore-mtimes-selftest.sh, and one in
hardlink-clone-selftest.sh, reads cargo's own words out of a build log
(`Compiling libdep`, `Fresh probe`). gitdan-ci's runner image forces colour, so
cargo wrote `Compiling\e[0m libdep` into the log and `grep -q "Compiling
libdep"` stopped matching. The suite then reported the opposite of what
happened — the failure printed the log, and the log plainly said `Compiling
libdep`. Both suites now pin CARGO_TERM_COLOR=never, which is the format their
assertions are written against.
Red-proven: with the export removed and CARGO_TERM_COLOR=always,
restore-mtimes-selftest reproduces the CI failure verbatim ("expected to find:
Compiling libdep"); with it, 14/14 pass under the same forced colour.
THE NIGHTLY PROBE ASKED THE WRONG QUESTION. `cargo +nightly -V` answers "did a
cargo proxy called with +nightly exit 0", which is not "will this build have
checksum freshness": `-V` short-circuits before `-Z` is validated at all. So
the probe said "on" on a runner where the flag was not in effect, and the
suite asserted the checksum-freshness mutation family against a build that
never had it — failing in the CONTROL, where a failure reads as "the hazard is
gone" rather than "the toolchain is wrong". It now probes the capability:
`cargo +nightly -Z checksum-freshness locate-project`, the narrowest command
that actually parses the flag. It rejects the stable channel and an unknown
flag name alike, needs no network and builds nothing.
Red-proven: the old channel probe, pointed at a cargo without the flag,
reproduces the CI failure exactly.
AND THE OFF PATH DID NOT WORK EITHER. The suite's header claimed that without
checksum freshness "the test still covers the build/ and *.d families". It did
not: the final scenario backdates the source to 2001 and asserts the rebuild
is not Fresh, which is checksum-freshness-only reasoning. Under Cargo's
ordinary mtime freshness a 2001 source IS older than the artifact and Fresh is
the correct answer, so the scenario asserted a bug. It is now gated on the
mode and skipped loudly, like the control's dep-* assertion already was: 5
assertions with a nightly, 3 without.
CI installs a nightly as well as stable (nightly first, so stable stays the
default) — that hazard is the one this whole scheme exists to close, and a CI
that skips it is checking the cheap half.
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f76789358d
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ci(gitea): gate scripts/ with shellcheck and the selftests
This repo had eight scripts, six selftest suites and nothing that ran any of
them. It is a composite action consumed at `@v1` — a moving tag — by three
repos' CI, so a bad edit here reaches zemyna, emowheel and lublub at once and
is discovered by whichever of them builds next.
One job: `shellcheck -x --source-path=scripts scripts/*.sh`, then
`bash scripts/selftest.sh`. `-x` follows the `. cache-lib.sh` every script
sources, which is where most of the logic being checked lives; without it
shellcheck reports SC1091 and analyses each file with a hole in it.
The full suite, not `--fast`: `hardlink-clone-selftest.sh` and
`restore-mtimes-selftest.sh` are the two that drive a real Cargo rather than a
fixture, and selftest.sh's own header says `--fast` is for iterating, not for
signing off a change. So the job installs a stable toolchain. The scratch
workspaces they build use path dependencies only, so nothing reaches
crates.io, and the job references no credentials at all.
Modelled on daniel/gitdan's workflow, including the two clauses of the
draft-skip guard (`github.event_name != 'pull_request' ||
!github.event.pull_request.draft` — the first is what stops the second from
also skipping pushes to `main`, where there is no `pull_request` context) and
the per-commit concurrency group for `push`.
No `container.volumes:` entry, deliberately: the suites want a cold target dir
every run, since "did this rebuild?" is exactly what restore-mtimes-selftest
asks. This job takes no share of the shared CI cache disk budget.
Turning the gate on surfaced three pre-existing findings, all fixed here
rather than suppressed or waived:
- `restore-mtimes-selftest.sh` SC2038: `find | xargs touch` -> `-print0 | xargs -0`.
- `hardlink-clone-selftest.sh` SC2295: `${f#$base_fix/}` -> `${f#"$base_fix"/}`.
- `cache-lib.sh` SC2016: a per-line disable with the rationale. The single
quotes are load-bearing — the program is for the inner shell, where `$f` is
its loop variable, `$rc` its accumulator and `$$` its pid — so this is the
documented-false-positive case, not a stopgap.
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248af3061e
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feat(cargo-cache): hardlink-clone a per-ref Cargo cache from a published snapshot
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 |