branchcache: skip entries that are topological heads in the on disk file
In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.
So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.
#require execbit unix-permissions no-chg
Checking that experimental.atomic-file works.
$ cat > $TESTTMP/show_mode.py <<EOF
> import os
> import stat
> import sys
> ST_MODE = stat.ST_MODE
>
> for file_path in sys.argv[1:]:
> file_stat = os.stat(file_path)
> octal_mode = oct(file_stat[ST_MODE] & 0o777).replace('o', '')
> print("%s:%s" % (file_path, octal_mode))
>
> EOF
$ hg init repo
$ cd repo
$ cat > .hg/showwrites.py <<EOF
> from mercurial import pycompat
> from mercurial.utils import stringutil
> def uisetup(ui):
> from mercurial import vfs
> class newvfs(vfs.vfs):
> def __call__(self, *args, **kwargs):
> print(pycompat.sysstr(stringutil.pprint(
> ('vfs open', args, sorted(list(kwargs.items()))))))
> return super(newvfs, self).__call__(*args, **kwargs)
> vfs.vfs = newvfs
> EOF
$ for v in a1 a2 b1 b2 c ro; do echo $v > $v; done
$ chmod +x b*
$ hg commit -Aqm _
# We check that
# - the changes are actually atomic
# - that permissions are correct (all 4 cases of (executable before) * (executable after))
# - that renames work, though they should be atomic anyway
# - that it works when source files are read-only (but directories are read-write still)
$ for v in a1 a2 b1 b2 ro; do echo changed-$v > $v; done
$ chmod -x *1; chmod +x *2
$ hg rename c d
$ hg commit -qm _
Check behavior without update.atomic-file
$ hg update -r 0 -q
$ hg update -r 1 --config extensions.showwrites=.hg/showwrites.py 2>&1 | grep "a1'.*wb"
('vfs open', ('a1', 'wb'), [('atomictemp', False), ('backgroundclose', True)])
$ "$PYTHON" $TESTTMP/show_mode.py *
a1:0644
a2:0755
b1:0644
b2:0755
d:0644
ro:0644
Add a second revision for the ro file so we can test update when the file is
present or not
$ echo "ro" > ro
$ hg commit -qm _
Check behavior without update.atomic-file first
$ hg update -C -r 0 -q
$ hg update -r 1
6 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ "$PYTHON" $TESTTMP/show_mode.py *
a1:0644
a2:0755
b1:0644
b2:0755
d:0644
ro:0644
Manually reset the mode of the read-only file
$ chmod a-w ro
$ "$PYTHON" $TESTTMP/show_mode.py ro
ro:0444
Now the file is present, try to update and check the permissions of the file
$ hg up -r 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ "$PYTHON" $TESTTMP/show_mode.py ro
ro:0644
# The file which was read-only is now writable in the default behavior
Check behavior with update.atomic-files
$ cat >> .hg/hgrc <<EOF
> [experimental]
> update.atomic-file = true
> EOF
$ hg update -C -r 0 -q
$ hg update -r 1 --config extensions.showwrites=.hg/showwrites.py 2>&1 | grep "a1'.*wb"
('vfs open', ('a1', 'wb'), [('atomictemp', True), ('backgroundclose', True)])
$ hg st -A --rev 1
C a1
C a2
C b1
C b2
C d
C ro
Check the file permission after update
$ "$PYTHON" $TESTTMP/show_mode.py *
a1:0644
a2:0755
b1:0644
b2:0755
d:0644
ro:0644
Manually reset the mode of the read-only file
$ chmod a-w ro
$ "$PYTHON" $TESTTMP/show_mode.py ro
ro:0444
Now the file is present, try to update and check the permissions of the file
$ hg update -r 2 --traceback
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ "$PYTHON" $TESTTMP/show_mode.py ro
ro:0644
# The behavior is the same as without atomic update