discovery: using the new basesheads()
Our ultimate goal is to switch eventually to a Rust implementation, but
this move actually seems to increase the performance in a pure Python
build.
What follows is a quick measurement done on PyPy on repos prepared with
`contrib/discovery-helper.sh 50 100`.
Before:
! wall 0.894384 comb 0.890000 user 0.890000 sys 0.000000 (best of 11)
! wall 0.971199 comb 0.970000 user 0.950000 sys 0.020000 (max of 11)
! wall 0.927993 comb 0.925455 user 0.919091 sys 0.006364 (avg of 11)
! wall 0.921619 comb 0.920000 user 0.910000 sys 0.010000 (median of 11)
After:
! wall 0.614278 comb 0.610000 user 0.610000 sys 0.000000 (best of 14)
! wall 0.789459 comb 0.790000 user 0.770000 sys 0.020000 (max of 14)
! wall 0.722765 comb 0.720000 user 0.715714 sys 0.004286 (avg of 14)
! wall 0.734448 comb 0.720000 user 0.720000 sys 0.000000 (median of 14)
Differential Revision: https://phab.mercurial-scm.org/D5583
Our full contribution guidelines are in our wiki, please see:
https://www.mercurial-scm.org/wiki/ContributingChanges
If you just want a checklist to follow, you can go straight to
https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist
If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).