annotate tests/test-mq-caches @ 11769:ca6cebd8734e stable

dirstate: ignore symlinks when fs cannot handle them (issue1888)

When the filesystem cannot handle the executable bit, we currently
ignore it completely when looking for modified files. Similarly, it is
impossible to set or clear the bit when the filesystem ignores it.

This patch makes Mercurial treat symbolic links the same way.

Symlinks are a little different since they manifest themselves as
small files containing a filename (the symlink target). On Windows,
these files show up as regular files, and on Linux and Mac they show
up as real symlinks.

Issue1888 presents a case where the symlink files are better ignored
from the Windows side. A Linux client creates symlinks in a working
copy which is shared over a network between Linux and Windows clients.

The Samba server is helpful and defererences the symlink when the
Windows client looks at it. This means that Mercurial on the Windows
side sees file content instead of a file name in the symlink, and
hence flags the link as modified. Ignoring the change would be much
more helpful, similarly to how Mercurial does not report any changes
when executable bits are ignored in a checkout on Windows.

An initial checkout of a symbolic link on a file system that cannot
handle symbolic links will still result in a regular file containing
the target file name as its content. Sharing such a checkout with a
Linux client will not turn the file into a symlink automatically, but
'hg revert' can fix that. After the revert, the Windows client will
see the correct file content (provided by the Samba server when it
follows the link on the Linux side) and otherwise ignore the change.

Running 'hg perfstatus' 10 times gives these results:

  Before:          After:
  min: 0.544703    min: 0.546549
  med: 0.547592    med: 0.548881
  avg: 0.549146    avg: 0.548549
  max: 0.564112    max: 0.551504

The median time is increased about 0.24%.

#!/bin/sh

branches=.hg/branchheads.cache
echo '[extensions]' >> $HGRCPATH
echo 'mq =' >> $HGRCPATH

show_branch_cache()
{
    # force cache (re)generation
    hg log -r does-not-exist 2> /dev/null
    hg log -r tip --template 'tip: {rev}\n'
    if [ -f $branches ]; then
	sort $branches
    else
	echo No branch cache
    fi
    if [ "$1" = 1 ]; then
	for b in foo bar; do
	    hg log -r $b --template "branch $b: "'{rev}\n'
	done
    fi
}

hg init a
cd a
hg qinit -c

echo '# mq patch on an empty repo'
hg qnew p1
show_branch_cache

echo > pfile
hg add pfile
hg qrefresh -m 'patch 1'
show_branch_cache

echo
echo '# some regular revisions'
hg qpop
echo foo > foo
hg add foo
echo foo > .hg/branch
hg ci -m 'branch foo' -d '1000000 0'

echo bar > bar
hg add bar
echo bar > .hg/branch
hg ci -m 'branch bar' -d '1000000 0'
show_branch_cache

echo
echo '# add some mq patches'
hg qpush
show_branch_cache

hg qnew p2
echo foo > .hg/branch
echo foo2 >> foo
hg qrefresh -m 'patch 2'
show_branch_cache 1

echo
echo '# removing the cache'
rm $branches
show_branch_cache 1

echo
echo '# importing rev 1 (the cache now ends in one of the patches)'
hg qimport -r 1 -n p0
show_branch_cache 1
hg log -r qbase --template 'qbase: {rev}\n'

echo
echo '# detect an invalid cache'
hg qpop -a
hg qpush -a
show_branch_cache