Re: [PATCH 2/2] for-each-ref: add --count-matches option

[Derrick Stolee <derrickstolee@github.com>]

On 6/27/2023 1:30 AM, Jeff King wrote:
>On Mon, Jun 26, 2023 at 03:09:57PM +0000, Derrick Stolee via GitGitGadget wrote:
>
>>+for pattern in "refs/heads/" "refs/tags/" "refs/remotes"
>>+do
>>+   test_perf "count $pattern: git for-each-ref | wc -l" "
>>+       git for-each-ref $pattern | wc -l
>>+   "
>>+
>>+   test_perf "count $pattern: git for-each-ref --count-match" "
>>+       git for-each-ref --count-matches $pattern
>>+   "
>>+done
>
>I don't think this is a very realistic perf test, because for-each-ref
>is doing a bunch of work to generate its default format, only to have
>"wc" throw most of it away. Doing:
>
>  git for-each-ref --format='%(refname)' | wc -l
>
>is much better (obviously you have to remember to do that if you care
>about optimizing your command, but that's true of --count-matches, too).
Thank you for pointing this out! I'll be sure to modify the test and the
analysis about it.
The other check I need to compare is when multiple refspecs are provided
at the same time, which I do believe still is a valuable thing to combine
into a single process instead of multiple pipes to 'wc'.
Did you have any thoughts on whether or not this works as an option in
'git for-each-ref' or would be better broken into a new builtin?
Thanks,
-Stolee