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.
#testcases dirstate-v1 dirstate-v2
#if dirstate-v2
$ cat >> $HGRCPATH << EOF
> [format]
> use-dirstate-v2=1
> [storage]
> dirstate-v2.slow-path=allow
> EOF
#endif
Checking the size/permissions/file-type of files stored in the
dirstate after an update where the files are changed concurrently
outside of hg's control.
$ hg init repo
$ cd repo
$ echo a > a
$ hg commit -qAm _
$ echo aa > a
$ hg commit -m _
# this sleep is there to ensure current time has -at-least- one second away
# from the current time. It ensure the mtime is not ambiguous. If the test
# "sleep" longer this will be fine.
# It is not used to synchronise parallele operation so it is "fine" to use it.
$ sleep 1
$ hg status
$ hg debugdirstate --no-dates
n 644 3 (set |unset) a (re)
$ cat >> $TESTTMP/dirstaterace.py << EOF
> import time
> from mercurial import (
> commit,
> extensions,
> merge,
> )
> def extsetup(ui):
> extensions.wrapfunction(merge, 'applyupdates', wrap(0))
> extensions.wrapfunction(commit, 'commitctx', wrap(1))
> def wrap(duration):
> def new(orig, *args, **kwargs):
> res = orig(*args, **kwargs)
> with open("a", "w"):
> pass # just truncate the file
> time.sleep(duration)
> return res
> return new
> EOF
Do an update where file 'a' is changed between hg writing it to disk
and hg writing the dirstate. The dirstate is correct nonetheless, and
so hg status correctly shows a as clean.
$ hg up -r 0 --config extensions.race=$TESTTMP/dirstaterace.py
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg debugdirstate --no-dates
n 644 2 (set |unset) a (re)
$ echo a > a; hg status; hg diff
Do a commit where file 'a' is changed between hg committing its new
revision into the repository, and the writing of the dirstate.
This used to results in a corrupted dirstate (size did not match committed size).
$ echo aaa > a; hg commit -qm _
$ hg merge -qr 1; hg resolve -m; rm a.orig
warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
(no more unresolved files)
$ cat a
<<<<<<< working copy: be46f74ce38d - test: _
aaa
=======
aa
>>>>>>> merge rev: eb3fc6c17aa3 - test: _
$ hg debugdirstate --no-dates
m 0 -2 (set |unset) a (re)
$ hg commit -m _ --config extensions.race=$TESTTMP/dirstaterace.py
$ hg debugdirstate --no-dates
n 0 -1 unset a
$ cat a | wc -c
*0 (re)
$ hg cat -r . a | wc -c
*105 (re)
$ hg status; hg diff --stat
M a
a | 5 -----
1 files changed, 0 insertions(+), 5 deletions(-)