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由 Michael Haggerty 提交于
Stop emitting an error message when deleting a packed reference if we find another dangling packed reference that is overridden by a loose reference. See the previous commit for a longer explanation of the issue. We have to be careful to make sure that the invalid packed reference really *is* overridden by a loose reference; otherwise what we have found is repository corruption, which we *should* report. Please note that this approach is vulnerable to a race condition similar to the race conditions already known to affect packed references [1]: * Process 1 tries to peel packed reference X as part of deleting another packed reference. It discovers that X does not refer to a valid object (because the object that it referred to has been garbage collected). * Process 2 tries to delete reference X. It starts by deleting the loose reference X. * Process 1 checks whether there is a loose reference X. There is not (it has just been deleted by process 2), so process 1 reports a spurious error "X does not point to a valid object!" The worst case seems relatively harmless, and the fix is identical to the fix that will be needed for the other race conditions (namely holding a lock on the packed-refs file during *all* reference deletions), so we leave the cleaning up of all of them as a future project. [1] http://thread.gmane.org/gmane.comp.version-control.git/211956Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu> Signed-off-by: NJunio C Hamano <gitster@pobox.com>
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