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.
test sparse
$ cat >> $HGRCPATH << EOF
> [ui]
> username = nobody <no.reply@fb.com>
> [extensions]
> sparse=
> purge=
> strip=
> rebase=
> EOF
$ hg init myrepo
$ cd myrepo
$ echo a > index.html
$ echo x > data.py
$ echo z > readme.txt
$ cat > webpage.sparse <<EOF
> [include]
> *.html
> EOF
$ cat > backend.sparse <<EOF
> [include]
> *.py
> EOF
$ hg ci -Aqm 'initial'
$ cd ..
Verify local clone with a sparse profile works
$ hg clone --enable-profile webpage.sparse myrepo clone1
updating to branch default
warning: sparse profile 'webpage.sparse' not found in rev 000000000000 - ignoring it
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd clone1
$ ls -A
.hg
index.html
$ cd ..
Verify local clone with include works
$ hg clone --include *.sparse myrepo clone2
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd clone2
$ ls -A
.hg
backend.sparse
webpage.sparse
$ cd ..
Verify local clone with exclude works
$ hg clone --exclude data.py myrepo clone3
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd clone3
$ ls -A
.hg
backend.sparse
index.html
readme.txt
webpage.sparse
$ cd ..
Verify sparse clone profile over ssh works
$ hg clone -q --enable-profile webpage.sparse ssh://user@dummy/myrepo clone4
warning: sparse profile 'webpage.sparse' not found in rev 000000000000 - ignoring it
$ cd clone4
$ ls -A
.hg
index.html
$ cd ..