Re: [PATCH 0/3] Make add_missing_tags() linear

"Derrick Stolee via GitGitGadget" [off-list ref] writes:

Add a new method in commit-reach.c called get_reachable_subset() which does
a many-to-many reachability test. Starting at the 'from' commits, walk until
the generation is below the smallest generation in the 'to' commits, or all
'to' commits have been discovered. This performs only one commit walk for
the entire add_missing_tags() method, giving linear performance in the worst
case.

;-)

I think in_merge_bases_many() was an attempt to do one half of this
(i.e. it checks only one 'to' against main 'from' to see if any of
them reach).  I wonder why we didn't extend it to multiple 'to' back
when we invented it.

In any case, good to see this code optimized.

Thanks.