push: rework the computation of fallbackheads to be correct
The previous computation tried to be smart but ended up being wrong. This was
caught by phase movement test while reworking the phase discovery logic to be
faster.
The previous logic was failing to catch case where the pushed set was not based
on a common heads (i.e. when the discovery seemed to have "over discovered"
content, outside the pushed set)
In the following graph, `e` is a common head and we `hg push -r f`. We need to
detect `c` as a fallback heads and we previous failed to do so::
e
|
d f
|/
c
|
b
|
a
The performance impact of the change seems minimal. On the most impacted
repository at hand (mozilla-try), the slowdown seems mostly mixed in the
overall noise `hg push` but seems to be in the hundred of milliseconds order of
magnitude. When using rust, we seems to be a bit faster, probably because we
leverage more accelaratd internals.
I added a couple of performance related common for further investigation later
on.
#require test-repo hg32
$ . "$TESTDIR/helpers-testrepo.sh"
$ import_checker="$TESTDIR"/../contrib/import-checker.py
$ cd "$TESTDIR"/..
There are a handful of cases here that require renaming a module so it
doesn't overlap with a stdlib module name. There are also some cycles
here that we should still endeavor to fix, and some cycles will be
hidden by deduplication algorithm in the cycle detector, so fixing
these may expose other cycles.
Known-bad files are excluded by -X as some of them would produce unstable
outputs, which should be fixed later.
NOTE: the `hg files` command here only works on files that are known to
Mercurial. If you add an import of a new file and haven't yet `hg add`ed it, you
will likely receive warnings about a direct import.
$ testrepohg files 'set:**.py or grep(r"^#!.*?python")' \
> 'glob:tests/**.t' \
> -X hgweb.cgi \
> -X setup.py \
> -X contrib/automation/ \
> -X contrib/debugshell.py \
> -X contrib/hgweb.fcgi \
> -X contrib/packaging/hg-docker \
> -X contrib/packaging/hgpackaging/ \
> -X contrib/packaging/inno/ \
> -X contrib/phab-clean.py \
> -X contrib/python-zstandard/ \
> -X contrib/win32/hgwebdir_wsgi.py \
> -X contrib/perf-utils/perf-revlog-write-plot.py \
> -X doc/gendoc.py \
> -X doc/hgmanpage.py \
> -X i18n/posplit \
> -X mercurial/thirdparty \
> -X tests/hypothesishelpers.py \
> -X tests/test-check-interfaces.py \
> -X tests/test-demandimport.py \
> -X tests/test-imports-checker.t \
> -X tests/test-verify-repo-operations.py \
> -X tests/test-extension.t \
> | sed 's-\\-/-g' | "$PYTHON" "$import_checker" -