Windows file locking with bzr 2.2.3

[W. Trevor King]

Bazaar folks,

We've been having some trouble with Bazaar v2.2.3 WriteLocks in Bugs
Everywhere on Windows [1], and have isolated the problem in the
attached script, basically wrapping:

    cmd = bzrlib.builtins.cmd_add()
    cmd.outf = sys.stdout
    cmd.run([new_file], file_ids_from='.')

On Linux I get [2]:

    $ python bzr-be-test.py
    working in /tmp/tmp-bbtMJijPe
    initialize Bazaar repo
    Created a standalone tree (format: 2a)
    create a dummy file a_file
    add the file via Python
    adding a_file
    success
    cleanup test directory

While on Windows Michael Chaffin gets [3]:

    C:\Temp>bzr-be-test.py
    working in c:\windows\temp\tmp-bbtuqtiq1
    initialize Bazaar repo
    Created a standalone tree (format: 2a)
    create a dummy file a_file
    add the file via Python
    cleanup test directory
    Traceback (most recent call last):
      File "C:\Temp\bzr-be-test.py", line 26, in <module>
        cmd.run([new_file], file_ids_from='.')
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\commands.py", line
    705, in run
        return self._operation.run_simple(*args, **kwargs)
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\cleanup.py", line 135,
    in run_simple
        self.cleanups, self.func, *args, **kwargs)
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\cleanup.py", line 165,
    in _do_with_cleanups
        result = func(*args, **kwargs)
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\builtins.py", line
    690, in run
        no_recurse, action=action, save=not dry_run)
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\mutabletree.py", line
    48, in tree_write_locked
        self.lock_tree_write()
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\workingtree_4.py",
    line 622, in lock_tree_write
        return self._lock_self_write()
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\workingtree_4.py",
    line 602, in _lock_self_write
        state.lock_write()
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\dirstate.py", line
    3065, in lock_write
        self._lock_token = lock.WriteLock(self._filename)
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\lock.py", line 413, in
    __init__
        os.O_RDWR, "rb+")
      File "C:\PROGRA~1\Python26\lib\site-packages\bzrlib\lock.py", line 371, in
    _open
        raise errors.LockContention(filename, e)
    bzrlib.errors.LockContention: Could not acquire lock
    "C:/windows/temp/tmp-bbtuqtiq1/.bzr/checkout/dirstate":
    (32, 'CreateFileW', 'The process cannot access the file because it is being
    used by another process.')

I see two possibilities:

1) I'm calling cmd_add wrong.  Certainly a possiblity, since the
calling conventions have changed a few times over the past two years.

2) This is a Bazaar bug (posibly fixed in more recent versions?).  I
couldn't find much searching through Bazaar's list archives or bug
tracker.  This is what I was able to find:

  * A message pointing out issues with fast lock creation/removal [4].
    The associated bug has been closed due to inability to reproduce
    [4], but it seems that the Windows-specificity was never layed out
    as clearly in the bug comments as it was in the original email.

  * A huge thread discussing a bzr lock overhaul [5], but that thread
    is too long for me to have read the whole thing.  A cursory
    inspection indicated that any bugs raised by the overhaul where
    solved before the patch went in.

Any thoughts?  Guidance?

Thanks,
Trevor

[1]: Two links into the broken thread:
  http://void.printf.net/pipermail/be-devel/2011-February/000700.html
  http://void.printf.net/pipermail/be-devel/2011-February/000702.html
[2]: http://void.printf.net/pipermail/be-devel/2011-February/000720.html
[3]: http://void.printf.net/pipermail/be-devel/2011-February/000723.html
[4]: http://article.gmane.org/gmane.comp.version-control.bazaar-ng.general/31718/
[5]: https://bugs.launchpad.net/bzr/+bug/140869
[6]: http://article.gmane.org/gmane.comp.version-control.bazaar-ng.general/59166

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