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author | Michael Haggerty <mhagger@alum.mit.edu> | 2017-06-12 10:06:13 +0200 |
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committer | Junio C Hamano <gitster@pobox.com> | 2017-06-12 10:11:36 -0700 |
commit | fed6ebebf132eb32478a5cbbebba3760c943970a (patch) | |
tree | 65dbc52e5e4da2e5b8fa9858e77ee416b62837e0 /t/perf/aggregate.perl | |
parent | cache_ref_iterator_begin(): avoid priming unneeded directories (diff) | |
download | tgif-fed6ebebf132eb32478a5cbbebba3760c943970a.tar.xz |
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>
Diffstat (limited to 't/perf/aggregate.perl')
0 files changed, 0 insertions, 0 deletions