Re: git tag --contains now takes a long time

Jerry Snitselaar [off-list ref] writes:

Is this known and being looked into? I've seen a jump from 12 seconds
to over 9 minutes with running git tag --contains on my kernel repo.

Thanks for a report.  Yes, it seems that there is a recent
regression on the 'master' branch, not yet in any released version,
and we can observe with a much smaller repository X-<.  E.g.

    git tag --contains v2.5.0~12

in git itself seems to have got 10 times slower.

snits ~/dev/linux> git --version
git version 2.6.1.145.gb27dacc

snits ~/dev/linux> time git tag --contains 825fcfc
next-20151012
next-20151013
v4.3-rc5

real	9m4.765s
user	8m56.157s
sys	0m2.450s



snits ~/dev/linux> git --version
git version 2.5.0.275.gac4cc86

snits ~/dev/linux> time git tag --contains 825fcfc
next-20151012
next-20151013
v4.3-rc5

real	0m12.842s
user	0m11.536s
sys	0m1.098s



b7cc53e92c806b73e14b03f60c17b7c29e52b4a4 is the first bad commit
commit b7cc53e92c806b73e14b03f60c17b7c29e52b4a4
Author: Karthik Nayak [off-list ref]
Date:   Fri Sep 11 20:36:16 2015 +0530

   tag.c: use 'ref-filter' APIs

   Make 'tag.c' use 'ref-filter' APIs for iterating through refs, sorting
   and printing of refs. This removes most of the code used in 'tag.c'
   replacing it with calls to the 'ref-filter' library.

   Make 'tag.c' use the 'filter_refs()' function provided by 'ref-filter'
   to filter out tags based on the options set.

   For printing tags we use 'show_ref_array_item()' function provided by
   'ref-filter'.

   We improve the sorting option provided by 'tag.c' by using the sorting
   options provided by 'ref-filter'. This causes the test 'invalid sort
   parameter on command line' in t7004 to fail, as 'ref-filter' throws an
   error for all sorting fields which are incorrect. The test is changed
   to reflect the same.

   Modify documentation for the same.

   Mentored-by: Christian Couder [off-list ref]
   Mentored-by: Matthieu Moy [off-list ref]
   Signed-off-by: Karthik Nayak [off-list ref]
   Signed-off-by: Junio C Hamano [off-list ref]