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.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
>
> [phases]
> publish=False
>
> [alias]
> tglog = log -G --template "{rev}: {node|short} '{desc}' {branches}\n"
> EOF
$ hg init a
$ cd a
$ echo c1 > c1
$ hg ci -Am c1
adding c1
$ echo c2 > c2
$ hg ci -Am c2
adding c2
$ echo l1 > l1
$ hg ci -Am l1
adding l1
$ hg up -q -C 1
$ echo r1 > r1
$ hg ci -Am r1
adding r1
created new head
$ echo r2 > r2
$ hg ci -Am r2
adding r2
$ hg tglog
@ 4: 225af64d03e6 'r2'
|
o 3: 8d0a8c99b309 'r1'
|
| o 2: 87c180a611f2 'l1'
|/
o 1: 56daeba07f4b 'c2'
|
o 0: e8faad3d03ff 'c1'
Rebase with no arguments - single revision in source branch:
$ hg up -q -C 2
$ hg rebase
rebasing 2:87c180a611f2 "l1"
saved backup bundle to $TESTTMP/a/.hg/strip-backup/87c180a611f2-a5be192d-rebase.hg
$ hg tglog
@ 4: b1152cc99655 'l1'
|
o 3: 225af64d03e6 'r2'
|
o 2: 8d0a8c99b309 'r1'
|
o 1: 56daeba07f4b 'c2'
|
o 0: e8faad3d03ff 'c1'
$ cd ..
$ hg init b
$ cd b
$ echo c1 > c1
$ hg ci -Am c1
adding c1
$ echo c2 > c2
$ hg ci -Am c2
adding c2
$ echo l1 > l1
$ hg ci -Am l1
adding l1
$ echo l2 > l2
$ hg ci -Am l2
adding l2
$ hg up -q -C 1
$ echo r1 > r1
$ hg ci -Am r1
adding r1
created new head
$ hg tglog
@ 4: 8d0a8c99b309 'r1'
|
| o 3: 1ac923b736ef 'l2'
| |
| o 2: 87c180a611f2 'l1'
|/
o 1: 56daeba07f4b 'c2'
|
o 0: e8faad3d03ff 'c1'
Rebase with no arguments - single revision in target branch:
$ hg up -q -C 3
$ hg rebase
rebasing 2:87c180a611f2 "l1"
rebasing 3:1ac923b736ef "l2"
saved backup bundle to $TESTTMP/b/.hg/strip-backup/87c180a611f2-b980535c-rebase.hg
$ hg tglog
@ 4: 023181307ed0 'l2'
|
o 3: 913ab52b43b4 'l1'
|
o 2: 8d0a8c99b309 'r1'
|
o 1: 56daeba07f4b 'c2'
|
o 0: e8faad3d03ff 'c1'
$ cd ..