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index-pack: guard nr_resolved_deltas reads by lock

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The threaded parts of index-pack increment the number of resolved
deltas in nr_resolved_deltas guarded by counter_mutex.  However, the
per-thread outer loop accessed nr_resolved_deltas without any locks.

This is not wrong as such, since it doesn't matter all that much
whether we get an outdated value.  However, unless someone proves that
this one lock makes all the performance difference, it would be much
cleaner to guard _all_ accesses to the variable with the lock.

The only such use is display_progress() in the threaded section (all
others are in the conclude_pack() callchain outside the threaded
part).  To make it obvious that it cannot deadlock, move it out of
work_mutex.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Reviewed-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Thomas Rast 2013-03-19 15:16:41 +01:00 committed by Junio C Hamano
parent 3aba2fddcb
commit 8f82aad4e7
1 changed files with 3 additions and 1 deletions
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4
builtin/index-pack.c
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@ -967,8 +967,10 @@ static void *threaded_second_pass(void *data)
set_thread_data(data);
for (;;) {
int i;
work_lock();
counter_lock();
display_progress(progress, nr_resolved_deltas);
counter_unlock();
work_lock();
while (nr_dispatched < nr_objects &&
is_delta_type(objects[nr_dispatched].type))
nr_dispatched++;