branchmap-v3: filter topo heads using node for performance reason...
branchmap-v3: filter topo heads using node for performance reason
The branchmap currently contains heads as nodeid. If we build a set of revnum
with the topological heads, we need to turn the nodeid in the branchmap to revnum to
be able to check if they are topo-heads. That nodeid → revnum lookup is
"expensive" and adds up to something noticeable if you do it hundreds of thousand
of time.
Instead we turn all the topo-heads revnums into nodes and build a set. So we can
directly test membership of the nodeids stored in the branchmap. That is much
faster.
Ideally we would have revnum in the branchmap and could directly test revnum
against a revnum set and that would be even faster. However that's an adventure
for another time.
Without this change, the branchmap format "v3" was significantly slower than the
"v2" format. With this changes, some of that gap is recovered
With rust + persistent nodemap, this overhead was smaller because the extra
lookup did not had to to build the nodemap from scratch.
In addition the mozilla-unified repository is able to use the "pure_top" mode of
branchmap v3, so it was not really affected by this.
Future changeset will work of the remaining of the performance gap.
### 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: 0.380994 (+63.02%, +0.15)
branch-v3 after: 0.368769 (+57.79%, +0.14)
# bin-env-vars.hg.flavor = rust
branch-v2: 0.235230 ~~~~~
branch-v3 before: 0.385060 (+63.70%, +0.15)
branch-v3 after: 0.372460 (+58.34%, +0.14)
## data-env-vars.name = netbeans-2018-08-01-ds2-pnm
# bin-env-vars.hg.flavor = rust
branch-v2: 0.255586 ~~~~~
branch-v3 before: 0.317524 (+24.23%, +0.06)
branch-v3 after: 0.318907 (+24.78%, +0.06)
## 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: 0.410007 (+20.94%, +0.07)
branch-v3 after: 0.349752 (+3.17%, +0.01)
# bin-env-vars.hg.flavor = rust
branch-v2: 0.346525 ~~~~~
branch-v3 before: 0.410428 (+18.44%, +0.06)
branch-v3 after: 0.354300 (+2.24%, +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: 0.393871 (+3.60%, +0.01)
branch-v3 after: 0.396293 (+4.23%, +0.02)
## 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: 0.438105 (+6.29%, +0.03)
branch-v3 after: 0.424769 (+3.06%, +0.01)
# bin-env-vars.hg.flavor = rust
branch-v2: 0.412397 ~~~~~
branch-v3 before: 0.438405 (+6.31%, +0.03)
branch-v3 after: 0.421796 (+2.28%, +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: 0.452692 (+5.40%, +0.02)
branch-v3 after: 0.443849 (+3.34%, +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: 6.562345 (+92.83%, +3.16)
branch-v3 after: 6.234055 (+83.18%, +2.83)
# bin-env-vars.hg.flavor = rust
branch-v2: 3.454876 ~~~~~
branch-v3 before: 6.160248 (+78.31%, +2.71)
branch-v3 after: 6.307813 (+82.58%, +2.85)
## data-env-vars.name = mozilla-try-2024-03-26-ds2-pnm
# bin-env-vars.hg.flavor = rust
branch-v2: 3.465435 ~~~~~
branch-v3 before: 5.381648 (+55.30%, +1.92)
branch-v3 after: 5.176076 (+49.36%, +1.71)
