view contrib/discovery-helper.sh @ 41247:a89b20a49c13

rust-cpython: using MissingAncestors from Python code

As precedently done with LazyAncestors on cpython.rs, we test for the
presence of the 'rustext' module.

incrementalmissingrevs() has two callers within the Mercurial core:
`setdiscovery.partialdiscovery` and the `only()` revset.

This move shows a significant discovery performance improvement
in cases where the baseline is slow: using perfdiscovery on the PyPy
repos, prepared with `contrib/discovery-helper <repo> 50 100`, we
get averaged medians of 403ms with the Rust version vs 742ms without
(about 45% better).

But there are still indications that performance can be worse in cases
the baseline is fast, possibly due to the conversion from Python to
Rust and back becoming the bottleneck. We could measure this on
mozilla-central in cases were the delta is just a few changesets.
This requires confirmation, but if that's the reason, then an
upcoming `partialdiscovery` fully in Rust should solve the problem.

Differential Revision: https://phab.mercurial-scm.org/D5551

#!/bin/bash
#
# produces two repositories with different common and missing subsets
#
#   $ discovery-helper.sh REPO NBHEADS DEPT
#
# The Goal is to produce two repositories with some common part and some
# exclusive part on each side. Provide a source repository REPO, it will
# produce two repositories REPO-left and REPO-right.
#
# Each repository will be missing some revisions exclusive to NBHEADS of the
# repo topological heads. These heads and revisions exclusive to them (up to
# DEPTH depth) are stripped.
#
# The "left" repository will use the NBHEADS first heads (sorted by
# description). The "right" use the last NBHEADS one.
#
# To find out how many topological heads a repo has, use:
#
#   $ hg heads -t -T '{rev}\n' | wc -l
#
# Example:
#
#  The `pypy-2018-09-01` repository has 192 heads. To produce two repositories
#  with 92 common heads and ~50 exclusive heads on each side.
#
#    $ ./discovery-helper.sh pypy-2018-08-01 50 10

set -euo pipefail

if [ $# -lt 3 ]; then
     echo "usage: `basename $0` REPO NBHEADS DEPTH"
     exit 64
fi

repo="$1"
shift

nbheads="$1"
shift

depth="$1"
shift

leftrepo="${repo}-left"
rightrepo="${repo}-right"

left="first(sort(heads(all()), 'desc'), $nbheads)"
right="last(sort(heads(all()), 'desc'), $nbheads)"

leftsubset="ancestors($left, $depth) and only($left, heads(all() - $left))"
rightsubset="ancestors($right, $depth) and only($right, heads(all() - $right))"

echo '### building left repository:' $left-repo
echo '# cloning'
hg clone --noupdate "${repo}" "${leftrepo}"
echo '# stripping' '"'${leftsubset}'"'
hg -R "${leftrepo}" --config extensions.strip= strip --rev "$leftsubset" --no-backup

echo '### building right repository:' $right-repo
echo '# cloning'
hg clone --noupdate "${repo}" "${rightrepo}"
echo '# stripping:' '"'${rightsubset}'"'
hg -R "${rightrepo}" --config extensions.strip= strip --rev "$rightsubset" --no-backup