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.
$ hg init repo
$ cd repo
$ echo foo > a
$ hg add a
$ hg commit -m "1"
$ echo bar > b
$ hg add b
$ hg remove a
Should show a removed and b added:
$ hg status
A b
R a
$ hg revert --all
forgetting b
undeleting a
Should show b unknown and a back to normal:
$ hg status
? b
$ rm b
$ hg co -C 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo foo-a > a
$ hg commit -m "2a"
$ hg co -C 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo foo-b > a
$ hg commit -m "2b"
created new head
$ HGMERGE=true hg merge 1
merging a
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
Should show foo-b:
$ cat a
foo-b
$ echo bar > b
$ hg add b
$ rm a
$ hg remove a
Should show a removed and b added:
$ hg status
A b
R a
Revert should fail:
$ hg revert
abort: uncommitted merge with no revision specified
(use 'hg update' or see 'hg help revert')
[10]
Revert should be ok now:
$ hg revert -r2 --all
forgetting b
undeleting a
Should show b unknown and a marked modified (merged):
$ hg status
M a
? b
Should show foo-b:
$ cat a
foo-b