| commit | fed6ebebf132eb32478a5cbbebba3760c943970a | [log] [tgz] |
|---|---|---|
| author | Michael Haggerty <mhagger@alum.mit.edu> | Mon Jun 12 10:06:13 2017 +0200 |
| committer | Junio C Hamano <gitster@pobox.com> | Mon Jun 12 10:11:36 2017 -0700 |
| tree | 65dbc52e5e4da2e5b8fa9858e77ee416b62837e0 | |
| parent | f23092f19e73f5d8c3480ef02104af627a90361f [diff] |
lock_packed_refs(): fix cache validity check Commit 28ed9830b1 (get_packed_ref_cache(): assume "packed-refs" won't change while locked, 2017-05-22) assumes that the "packed-refs" file cannot change while we hold the lock. That assumption is justified *if* the lock has been held the whole time since the "packed-refs" file was last read. But in `lock_packed_refs()`, we ourselves lock the "packed-refs" file and then call `get_packed_ref_cache()` to ensure that the cache agrees with the file. The intent is to guard against the possibility that another process changed the "packed-refs" file the moment before we locked it. This check was defeated because `get_packed_ref_cache()` saw that the file was locked, and therefore didn't do the `stat_validity_check()` that we want. The mistake was compounded with a misleading comment in `lock_packed_refs()` claiming that it was doing the right thing. That comment came from an earlier draft of the mh/packed-ref-store-prep patch series when the commits were in a different order. So instead: * Extract a function `validate_packed_ref_cache()` that does the validity check independent of whether the lock is held. * Change `get_packed_ref_cache()` to call the new function, but only if the lock *isn't* held. * Change `lock_packed_refs()` to call the new function in any case before calling `get_packed_ref_cache()`. * Fix the comment in `lock_packed_refs()`. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
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