view tests/test-subrepo-deep-nested-change @ 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

echo % Preparing the subrepository 'sub2'
hg init sub2
echo sub2 > sub2/sub2
hg add -R sub2
hg commit -R sub2 -m "sub2 import"

echo % Preparing the 'sub1' repo which depends on the subrepo 'sub2'
hg init sub1
echo sub1 > sub1/sub1
echo "sub2 = ../sub2" > sub1/.hgsub
hg clone sub2 sub1/sub2 | sed 's/ .*sub/ ...sub/g'
hg add -R sub1
hg commit -R sub1 -m "sub1 import"

echo % Preparing the 'main' repo which depends on the subrepo 'sub1'
hg init main
echo main > main/main
echo "sub1 = ../sub1" > main/.hgsub
hg clone sub1 main/sub1  | sed 's/ .*sub/ ...sub/g'
hg add -R main
hg commit -R main -m "main import"

echo % Cleaning both repositories, just as a clone -U
hg up -C -R sub2 null
hg up -C -R sub1 null
hg up -C -R main null
rm -rf main/sub1
rm -rf sub1/sub2

echo % Clone main
hg clone main cloned | sed 's/ .*sub/ ...sub/g' 

echo % Checking cloned repo ids
printf "cloned " ; hg id -R cloned
printf "cloned/sub1 " ; hg id -R cloned/sub1
printf "cloned/sub1/sub2 " ; hg id -R cloned/sub1/sub2

echo % debugsub output for main and sub1
hg debugsub -R cloned
hg debugsub -R cloned/sub1

echo % Modifying deeply nested 'sub2'
echo modified > cloned/sub1/sub2/sub2
hg commit -m "deep nested modif should trigger a commit" -R cloned

echo % Checking modified node ids
printf "cloned " ; hg id -R cloned
printf "cloned/sub1 " ; hg id -R cloned/sub1
printf "cloned/sub1/sub2 " ; hg id -R cloned/sub1/sub2

echo % debugsub output for main and sub1
hg debugsub -R cloned
hg debugsub -R cloned/sub1

exit 0