branchmap-v3: introduce a "stop_rev" argument to `headsrevs`
The `headsrevs` method of the revlog already have a `revs` argument to compute
the headrevs of a limited set of heads. However, it disable the use of the
native compiled code to compute the heads, which slows down the branchmap v3
code a lot.
The branchmap v3 usage is actually quite constrained as we will always only
ignores a part at the top of the graph. So we could be significantly faster.
We start by making small change to the python side to improve the situation and
introduce the new API. More collaboration with the native code are coming later.
This massively speedup operation and close most of the remaining gaps between
branchmap-v3 and branchmap-v2. especially on repository with many revs like
mozilla-try. A small overhead remains mostly because the `headrevs` logic
currently has some inefficiently. We will look into them from there.
### benchmark.name = hg.command.unbundle
# bin-env-vars.hg.py-re2-module = default
# benchmark.variants.
issue6528 = disabled
# benchmark.variants.resource-usage = default
# benchmark.variants.reuse-external-delta-parent = yes
# benchmark.variants.revs = any-1-extra-rev
# benchmark.variants.source = unbundle
# benchmark.variants.validate = default
# benchmark.variants.verbosity = quiet
## data-env-vars.name = netbeans-2018-08-01-zstd-sparse-revlog
# bin-env-vars.hg.flavor = default
branch-v2: 0.233711 ~~~~~
branch-v3 before: 0.368769 (+57.79%, +0.14)
branch-v3 after: 0.239857 (+2.63%, +0.01)
# bin-env-vars.hg.flavor = rust
branch-v2: 0.235230 ~~~~~
branch-v3 before: 0.372460 (+58.34%, +0.14)
branch-v3 after: 0.240972 (+2.44%, +0.01)
## data-env-vars.name = netbeans-2018-08-01-ds2-pnm
# bin-env-vars.hg.flavor = rust
branch-v2: 0.255586 ~~~~~
branch-v3 before: 0.318907 (+24.78%, +0.06)
branch-v3 after: 0.268560 (+5.08%, +0.01)
## data-env-vars.name = mozilla-central-2024-03-22-zstd-sparse-revlog
# bin-env-vars.hg.flavor = default
branch-v2: 0.339010 ~~~~~
branch-v3 before: 0.349752 (+3.17%, +0.01)
branch-v3 after: 0.349389 (+3.06%, +0.01)
# bin-env-vars.hg.flavor = rust
branch-v2: 0.346525 ~~~~~
branch-v3 before: 0.354300 (+2.24%, +0.01)
branch-v3 after: 0.355661 (+2.64%, +0.01)
## data-env-vars.name = mozilla-central-2024-03-22-ds2-pnm
# bin-env-vars.hg.flavor = rust
branch-v2: 0.380202 ~~~~~
branch-v3 before: 0.396293 (+4.23%, +0.02)
branch-v3 after: 0.408851 (+7.54%, +0.03)
## data-env-vars.name = mozilla-unified-2024-03-22-zstd-sparse-revlog
# bin-env-vars.hg.flavor = default
branch-v2: 0.412165 ~~~~~
branch-v3 before: 0.424769 (+3.06%, +0.01)
branch-v3 after: 0.427782 (+3.79%, +0.02)
# bin-env-vars.hg.flavor = rust
branch-v2: 0.412397 ~~~~~
branch-v3 before: 0.421796 (+2.28%, +0.01)
branch-v3 after: 0.422354 (+2.41%, +0.01)
## data-env-vars.name = mozilla-unified-2024-03-22-ds2-pnm
# bin-env-vars.hg.flavor = rust
branch-v2: 0.429501 ~~~~~
branch-v3 before: 0.443849 (+3.34%, +0.01)
branch-v3 after: 0.443197 (+3.19%, +0.01)
## data-env-vars.name = mozilla-try-2024-03-26-zstd-sparse-revlog
# bin-env-vars.hg.flavor = default
branch-v2: 3.403171 ~~~~~
branch-v3 before: 6.234055 (+83.18%, +2.83)
branch-v3 after: 3.819477 (+12.23%, +0.42)
# bin-env-vars.hg.flavor = rust
branch-v2: 3.454876 ~~~~~
branch-v3 before: 6.307813 (+82.58%, +2.85)
branch-v3 after: 3.590284 (+3.92%, +0.14)
## data-env-vars.name = mozilla-try-2024-03-26-ds2-pnm
# bin-env-vars.hg.flavor = rust
branch-v2: 3.465435 ~~~~~
branch-v3 before: 5.176076 (+49.36%, +1.71)
branch-v3 after: 3.633278 (+4.84%, +0.17)
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).