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.
Make sure that the internal merge tools (internal:fail, internal:local,
internal:union and internal:other) are used when matched by a
merge-pattern in hgrc
Make sure HGMERGE doesn't interfere with the test:
$ unset HGMERGE
$ hg init repo
$ cd repo
Initial file contents:
$ echo "line 1" > f
$ echo "line 2" >> f
$ echo "line 3" >> f
$ hg ci -Am "revision 0"
adding f
$ cat f
line 1
line 2
line 3
Branch 1: editing line 1:
$ sed 's/line 1/first line/' f > f.new
$ mv f.new f
$ hg ci -Am "edited first line"
Branch 2: editing line 3:
$ hg update 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/line 3/third line/' f > f.new
$ mv f.new f
$ hg ci -Am "edited third line"
created new head
Merge using internal:fail tool:
$ echo "[merge-patterns]" > .hg/hgrc
$ echo "* = internal:fail" >> .hg/hgrc
$ hg merge
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
[1]
$ cat f
line 1
line 2
third line
$ hg stat
M f
Merge using internal:local tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/internal:fail/internal:local/' .hg/hgrc > .hg/hgrc.new
$ mv .hg/hgrc.new .hg/hgrc
$ hg merge
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
line 1
line 2
third line
$ hg stat
M f
Merge using internal:other tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ sed 's/internal:local/internal:other/' .hg/hgrc > .hg/hgrc.new
$ mv .hg/hgrc.new .hg/hgrc
$ hg merge
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
first line
line 2
line 3
$ hg stat
M f
Merge using default tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm .hg/hgrc
$ hg merge
merging f
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
first line
line 2
third line
$ hg stat
M f
Merge using internal:union tool:
$ hg update -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "line 4a" >>f
$ hg ci -Am "Adding fourth line (commit 4)"
$ hg update 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "line 4b" >>f
$ hg ci -Am "Adding fourth line v2 (commit 5)"
created new head
$ echo "[merge-patterns]" > .hg/hgrc
$ echo "* = internal:union" >> .hg/hgrc
$ hg merge 3
merging f
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
line 1
line 2
third line
line 4b
line 4a
Merge using internal:union-other-first tool:
$ hg update -C 4
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo "[merge-patterns]" > .hg/hgrc
$ echo "* = internal:union-other-first" >> .hg/hgrc
$ hg merge 3
merging f
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat f
line 1
line 2
third line
line 4a
line 4b