branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
#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(-)