view tests/test-convert-cvs-detectmerge.out @ 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%.

% create cvs repository with one project
cvs -f -q -d *REPO* init
% populate cvs repository
cvs -f -Q co proj
cvs -f -Q add file1
cvs -f ci -madd file1 on trunk
% create two release branches
cvs -f -q tag -b v1_0
T file1
cvs -f -q tag -b v1_1
T file1
% modify file1 on branch v1_0
cvs -f -Q update -rv1_0
cvs -f ci -madd text
% make unrelated change on v1_1
cvs -f -Q update -rv1_1
cvs -f -Q add unrelated
cvs -f ci -munrelated change
% merge file1 to v1_1
cvs -f -Q update -jv1_0
RCS file: *REPO*/proj/file1,v
retrieving revision 1.1
retrieving revision 1.1.2.1
Merging differences between 1.1 and 1.1.2.1 into file1
cvs -f ci -madd text [MERGE from v1_0]
% merge change to trunk
cvs -f -Q update -A
cvs -f -Q update -jv1_1
RCS file: *REPO*/proj/file1,v
retrieving revision 1.1
retrieving revision 1.1.4.1
Merging differences between 1.1 and 1.1.4.1 into file1
cvs -f ci -madd text [MERGE from v1_1]
% non-merged change on trunk
cvs -f -Q add file2
cvs -f ci -madd file2 on trunk file2
% change on trunk to backport
cvs -f ci -madd other text file1
revision 1.3
add other text
----------------------------
revision 1.2
add text [MERGE from v1_1]
----------------------------
revision 1.1
branches:  1.1.2;  1.1.4;
add file1 on trunk
----------------------------
revision 1.1.4.1
add text [MERGE from v1_0]
----------------------------
revision 1.1.2.1
add text
=============================================================================
% backport trunk change to v1_1
cvs -f -Q update -rv1_1
cvs -f -Q update -j1.2 -j1.3 file1
RCS file: *REPO*/proj/file1,v
retrieving revision 1.2
retrieving revision 1.3
Merging differences between 1.2 and 1.3 into file1
cvs -f ci -madd other text [MERGE from HEAD] file1
% fix bug on v1_1, merge to trunk with error
cvs -f -Q update -rv1_1
cvs -f -Q tag unmerged
cvs -f ci -mfix file1
cvs -f -Q update -A
cvs -f -Q update -junmerged -jv1_1
RCS file: *REPO*/proj/file1,v
retrieving revision 1.1.4.2
retrieving revision 1.1.4.3
Merging differences between 1.1.4.2 and 1.1.4.3 into file1
cvs -f ci -mfix file1 [MERGE from v1-1]
% convert to hg
warning: CVS commit message references non-existent branch 'v1-1':
fix file1 [MERGE from v1-1]
initializing destination proj.hg repository
connecting to *REPO*
scanning source...
collecting CVS rlog
12 log entries
creating changesets
10 changeset entries
sorting...
converting...
9 add file1 on trunk
8 add text
7 unrelated change
6 add text [MERGE from v1_0]
5 add text [MERGE from v1_1]
4 add file2 on trunk
3 add other text
2 add other text [MERGE from HEAD]
1 fix file1
0 fix file1 [MERGE from v1-1]
% complete log
9: '' fix file1 [MERGE from v1-1]
8: 'v1_1' fix file1
7: 'v1_1' add other text [MERGE from HEAD]
6: '' add other text
5: '' add file2 on trunk
4: '' add text [MERGE from v1_1]
3: 'v1_1' add text [MERGE from v1_0]
2: 'v1_1' unrelated change
1: 'v1_0' add text
0: '' add file1 on trunk
% graphical log
o  9: '' fix file1 [MERGE from v1-1]
|
| o  8: 'v1_1' fix file1
| |
| o  7: 'v1_1' add other text [MERGE from HEAD]
|/|
o |  6: '' add other text
| |
o |  5: '' add file2 on trunk
| |
o |  4: '' add text [MERGE from v1_1]
|\|
| o    3: 'v1_1' add text [MERGE from v1_0]
| |\
+---o  2: 'v1_1' unrelated change
| |
| o  1: 'v1_0' add text
|/
o  0: '' add file1 on trunk