Fix non-deterministic behavior in last-use repopulation #12958
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This fixes an issue where some last-use tests would fail sporadically because the code that populates missing database entries was using the current time as it was iterating over the files. If the clock happened to roll over while it was iterating, then different files would get different timestamps non-deterministically. The fix is to snapshot the current time when it starts, and reuse that time while repopulating. I didn't do this originally just because I was reluctant to pass yet another argument around. However, it seems like this is necessary. In rust-lang#12634, we discussed other options such as having some kind of process-global "now" snapshot (like in `Config`), but I'm reluctant to do that because I am uneasy dealing with long-lived programs, or handling before/after relationships (like different parts of the code not considering that all timestamps might be equal). It might be something that we could consider in the future, but I'm not sure I want to try right now.
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Update cargo 15 commits in 6790a5127895debec95c24aefaeb18e059270df3..87ee3e96285e0142b71d8c11c02b18647e43974d 2023-11-10 17:09:35 +0000 to 2023-11-14 18:00:46 +0000 - fix error message for duplicate links (rust-lang/cargo#12973) - Only filter out target if its in the package root (rust-lang/cargo#12944) - Ignore changing_spec_relearns_crate_types on windows-gnu (rust-lang/cargo#12972) - fix: do not panic when failed to parse rustc commit-hash (rust-lang/cargo#12965) - query{_vec} use IndexSummary (rust-lang/cargo#12970) - Bump to 0.77.0; update changelog (rust-lang/cargo#12966) - Improve about information of `cargo search` (rust-lang/cargo#12962) - Fix --quiet being used with nested subcommands. (rust-lang/cargo#12959) - make some debug assertion failures more informative (rust-lang/cargo#12963) - refactor(toml): Consistently lead with 'Toml' prefix (rust-lang/cargo#12960) - refactor(toml): Remove unused method (rust-lang/cargo#12961) - Fix non-deterministic behavior in last-use repopulation (rust-lang/cargo#12958) - Add cache garbage collection (rust-lang/cargo#12634) - refactor(toml): Improve consistency (rust-lang/cargo#12954) - Fix typo (rust-lang/cargo#12956) r? ghost
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Nov 15, 2023
Update cargo 15 commits in 6790a5127895debec95c24aefaeb18e059270df3..87ee3e96285e0142b71d8c11c02b18647e43974d 2023-11-10 17:09:35 +0000 to 2023-11-14 18:00:46 +0000 - fix error message for duplicate links (rust-lang/cargo#12973) - Only filter out target if its in the package root (rust-lang/cargo#12944) - Ignore changing_spec_relearns_crate_types on windows-gnu (rust-lang/cargo#12972) - fix: do not panic when failed to parse rustc commit-hash (rust-lang/cargo#12965) - query{_vec} use IndexSummary (rust-lang/cargo#12970) - Bump to 0.77.0; update changelog (rust-lang/cargo#12966) - Improve about information of `cargo search` (rust-lang/cargo#12962) - Fix --quiet being used with nested subcommands. (rust-lang/cargo#12959) - make some debug assertion failures more informative (rust-lang/cargo#12963) - refactor(toml): Consistently lead with 'Toml' prefix (rust-lang/cargo#12960) - refactor(toml): Remove unused method (rust-lang/cargo#12961) - Fix non-deterministic behavior in last-use repopulation (rust-lang/cargo#12958) - Add cache garbage collection (rust-lang/cargo#12634) - refactor(toml): Improve consistency (rust-lang/cargo#12954) - Fix typo (rust-lang/cargo#12956) r? ghost
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Update cargo 19 commits in 6790a5127895debec95c24aefaeb18e059270df3..2c03e0e2dcd05dd064fcf10cc1050d342eaf67e3 2023-11-10 17:09:35 +0000 to 2023-11-16 04:21:44 +0000 - docs(ref): Find a place to comment on --cap-lints (rust-lang/cargo#12976) - Switch from AtomicU64 to Mutex. (rust-lang/cargo#12981) - If the only path is a loop then counted as the shortest path. (rust-lang/cargo#12977) - fix(resolver): Prefer MSRV, rather than ignore incompatible (rust-lang/cargo#12950) - fix error message for duplicate links (rust-lang/cargo#12973) - Only filter out target if its in the package root (rust-lang/cargo#12944) - Ignore changing_spec_relearns_crate_types on windows-gnu (rust-lang/cargo#12972) - fix: do not panic when failed to parse rustc commit-hash (rust-lang/cargo#12965) - query{_vec} use IndexSummary (rust-lang/cargo#12970) - Bump to 0.77.0; update changelog (rust-lang/cargo#12966) - Improve about information of `cargo search` (rust-lang/cargo#12962) - Fix --quiet being used with nested subcommands. (rust-lang/cargo#12959) - make some debug assertion failures more informative (rust-lang/cargo#12963) - refactor(toml): Consistently lead with 'Toml' prefix (rust-lang/cargo#12960) - refactor(toml): Remove unused method (rust-lang/cargo#12961) - Fix non-deterministic behavior in last-use repopulation (rust-lang/cargo#12958) - Add cache garbage collection (rust-lang/cargo#12634) - refactor(toml): Improve consistency (rust-lang/cargo#12954) - Fix typo (rust-lang/cargo#12956)
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This fixes an issue where some last-use tests would fail sporadically because the code that populates missing database entries was using the current time as it was iterating over the files. If the clock happened to roll over while it was iterating, then different files would get different timestamps non-deterministically.
The fix is to snapshot the current time when it starts, and reuse that time while repopulating. I didn't do this originally just because I was reluctant to pass yet another argument around. However, it seems like this is necessary. In #12634, we discussed other options such as having some kind of process-global "now" snapshot (like in
Config), but I'm reluctant to do that because I am uneasy dealing with long-lived programs, or handling before/after relationships (like different parts of the code not considering that all timestamps might be equal). It might be something that we could consider in the future, but I'm not sure I want to try right now.