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103
# the existing locking code and needs a new format of the containing object.
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104
# -- robertc, mbp 20070628
108
from cStringIO import StringIO
114
110
from bzrlib import (
123
from bzrlib.decorators import only_raises
124
115
from bzrlib.errors import (
125
116
DirectoryNotEmpty,
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118
LockBreakMismatch,
138
129
from bzrlib.trace import mutter, note
139
from bzrlib.osutils import format_delta, rand_chars, get_host_name
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from bzrlib.i18n import gettext
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from bzrlib.transport import Transport
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from bzrlib.osutils import rand_chars, format_delta, get_host_name
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from bzrlib.rio import read_stanza, Stanza
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from bzrlib.lazy_import import lazy_import
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lazy_import(globals(), """
144
from bzrlib import rio
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136
# XXX: At the moment there is no consideration of thread safety on LockDir
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137
# objects. This should perhaps be updated - e.g. if two threads try to take a
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148
# files/dirs created.
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_DEFAULT_TIMEOUT_SECONDS = 30
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_DEFAULT_TIMEOUT_SECONDS = 300
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152
_DEFAULT_POLL_SECONDS = 1.0
166
class LockDir(lock.Lock):
167
"""Write-lock guarding access to data.
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class LockDir(object):
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"""Write-lock guarding access to data."""
170
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__INFO_NAME = '/info'
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def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755,
173
extra_holder_info=None):
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def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755):
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"""Create a new LockDir object.
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The LockDir is initially unlocked - this just creates the object.
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:param transport: Transport which will contain the lock
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:param path: Path to the lock within the base directory of the
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:param path: Path to the lock within the base directory of the
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:param extra_holder_info: If passed, {str:str} dict of extra or
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updated information to insert into the info file when the lock is
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self.transport = transport
238
221
except (errors.TransportError, PathError), e:
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self._trace("... failed to create pending dir, %s", e)
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raise LockFailed(self, e)
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self.transport.rename(tmpname, self._held_dir)
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except (errors.TransportError, PathError, DirectoryNotEmpty,
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FileExists, ResourceBusy), e:
247
self._trace("... contention, %s", e)
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other_holder = self.peek()
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self._trace("other holder is %r" % other_holder)
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self._handle_lock_contention(other_holder)
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self._remove_pending_dir(tmpname)
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self._trace("... lock failed, %s", e)
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self._remove_pending_dir(tmpname)
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self.transport.rename(tmpname, self._held_dir)
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except (errors.TransportError, PathError, DirectoryNotEmpty,
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FileExists, ResourceBusy), e:
228
self._trace("... contention, %s", e)
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self._remove_pending_dir(tmpname)
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raise LockContention(self)
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self._trace("... lock failed, %s", e)
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self._remove_pending_dir(tmpname)
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# We must check we really got the lock, because Launchpad's sftp
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# server at one time had a bug were the rename would successfully
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# move the new directory into the existing directory, which was
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# incorrect. It's possible some other servers or filesystems will
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# have a similar bug allowing someone to think they got the lock
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# when it's already held.
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# See <https://bugs.launchpad.net/bzr/+bug/498378> for one case.
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# Strictly the check is unnecessary and a waste of time for most
269
# people, but probably worth trapping if something is wrong.
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241
info = self.peek()
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self._trace("after locking, info=%r", info)
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raise LockFailed(self, "lock was renamed into place, but "
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if info.get('nonce') != self.nonce:
243
if info['nonce'] != self.nonce:
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self._trace("rename succeeded, "
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245
"but lock is still held by someone else")
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raise LockContention(self)
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249
(time.time() - start_time) * 1000)
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250
return self.nonce
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def _handle_lock_contention(self, other_holder):
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"""A lock we want to take is held by someone else.
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This function can: tell the user about it; possibly detect that it's
288
safe or appropriate to steal the lock, or just raise an exception.
290
If this function returns (without raising an exception) the lock will
293
:param other_holder: A LockHeldInfo for the current holder; note that
294
it might be None if the lock can be seen to be held but the info
297
if (other_holder is not None):
298
if other_holder.is_lock_holder_known_dead():
299
if self.get_config().get('locks.steal_dead'):
300
ui.ui_factory.show_user_warning(
302
lock_url=urlutils.join(self.transport.base, self.path),
303
other_holder_info=unicode(other_holder))
304
self.force_break(other_holder)
305
self._trace("stole lock from dead holder")
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raise LockContention(self)
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252
def _remove_pending_dir(self, tmpname):
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"""Remove the pending directory
312
This is called if we failed to rename into place, so that the pending
255
This is called if we failed to rename into place, so that the pending
313
256
dirs don't clutter up the lockdir.
315
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self._trace("remove %s", tmpname)
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321
self.transport.delete_tree(tmpname)
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self._trace("... unlock succeeded after %dms",
382
323
(time.time() - start_time) * 1000)
383
result = lock.LockResult(self.transport.abspath(self.path),
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for hook in self.hooks['lock_released']:
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325
def break_lock(self):
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"""Break a lock not held by this instance of LockDir.
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This is a UI centric function: it uses the ui.ui_factory to
328
This is a UI centric function: it uses the bzrlib.ui.ui_factory to
392
329
prompt for input if a lock is detected and there is any doubt about
393
it possibly being still active. force_break is the non-interactive
396
:returns: LockResult for the broken lock.
330
it possibly being still active.
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self._check_not_locked()
400
holder_info = self.peek()
401
except LockCorrupt, e:
402
# The lock info is corrupt.
403
if ui.ui_factory.get_boolean(u"Break (corrupt %r)" % (self,)):
404
self.force_break_corrupt(e.file_data)
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holder_info = self.peek()
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if holder_info is not None:
407
if ui.ui_factory.confirm_action(
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u"Break %(lock_info)s",
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'bzrlib.lockdir.break',
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dict(lock_info=unicode(holder_info))):
411
result = self.force_break(holder_info)
412
ui.ui_factory.show_message(
413
"Broke lock %s" % result.lock_url)
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lock_info = '\n'.join(self._format_lock_info(holder_info))
336
if bzrlib.ui.ui_factory.get_boolean("Break %s" % lock_info):
337
self.force_break(holder_info)
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339
def force_break(self, dead_holder_info):
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"""Release a lock held by another process.
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it still thinks it has the lock there will be two concurrent writers.
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In general the user's approval should be sought for lock breaks.
346
dead_holder_info must be the result of a previous LockDir.peek() call;
347
this is used to check that it's still held by the same process that
348
the user decided was dead. If this is not the current holder,
349
LockBreakMismatch is raised.
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After the lock is broken it will not be held by any process.
423
It is possible that another process may sneak in and take the
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It is possible that another process may sneak in and take the
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lock before the breaking process acquires it.
426
:param dead_holder_info:
427
Must be the result of a previous LockDir.peek() call; this is used
428
to check that it's still held by the same process that the user
429
decided was dead. If this is not the current holder,
430
LockBreakMismatch is raised.
432
:returns: LockResult for the broken lock.
434
if not isinstance(dead_holder_info, LockHeldInfo):
355
if not isinstance(dead_holder_info, dict):
435
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raise ValueError("dead_holder_info: %r" % dead_holder_info)
436
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self._check_not_locked()
437
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current_info = self.peek()
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raise LockBreakMismatch(self, broken_info, dead_holder_info)
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self.transport.delete(broken_info_path)
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self.transport.rmdir(tmpname)
454
result = lock.LockResult(self.transport.abspath(self.path),
455
current_info.get('nonce'))
456
for hook in self.hooks['lock_broken']:
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def force_break_corrupt(self, corrupt_info_lines):
461
"""Release a lock that has been corrupted.
463
This is very similar to force_break, it except it doesn't assume that
464
self.peek() can work.
466
:param corrupt_info_lines: the lines of the corrupted info file, used
467
to check that the lock hasn't changed between reading the (corrupt)
468
info file and calling force_break_corrupt.
470
# XXX: this copes with unparseable info files, but what about missing
471
# info files? Or missing lock dirs?
472
self._check_not_locked()
473
tmpname = '%s/broken.%s.tmp' % (self.path, rand_chars(20))
474
self.transport.rename(self._held_dir, tmpname)
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# check that we actually broke the right lock, not someone else;
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# there's a small race window between checking it and doing the
478
broken_info_path = tmpname + self.__INFO_NAME
479
broken_content = self.transport.get_bytes(broken_info_path)
480
broken_lines = osutils.split_lines(broken_content)
481
if broken_lines != corrupt_info_lines:
482
raise LockBreakMismatch(self, broken_lines, corrupt_info_lines)
483
self.transport.delete(broken_info_path)
484
self.transport.rmdir(tmpname)
485
result = lock.LockResult(self.transport.abspath(self.path))
486
for hook in self.hooks['lock_broken']:
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376
def _check_not_locked(self):
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"""If the lock is held by this instance, raise an error."""
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new_info = self.peek()
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498
if new_info is not None and new_info != last_info:
614
499
if last_info is None:
615
start = gettext('Unable to obtain')
500
start = 'Unable to obtain'
617
start = gettext('Lock owner changed for')
502
start = 'Lock owner changed for'
618
503
last_info = new_info
619
msg = gettext('{0} lock {1} {2}.').format(start, lock_url,
504
formatted_info = self._format_lock_info(new_info)
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if deadline_str is None:
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deadline_str = time.strftime('%H:%M:%S',
623
time.localtime(deadline))
625
msg += '\n' + gettext(
626
'Will continue to try until %s, unless '
627
'you press Ctrl-C.') % deadline_str
628
msg += '\n' + gettext('See "bzr help break-lock" for more.')
629
self._report_function(msg)
507
time.localtime(deadline))
508
lock_url = self.transport.abspath(self.path)
509
self._report_function('%s %s\n'
511
'%s\n' # locked ... ago
512
'Will continue to try until %s, unless '
514
'If you\'re sure that it\'s not being '
515
'modified, use bzr break-lock %s',
630
523
if (max_attempts is not None) and (attempt_count >= max_attempts):
631
524
self._trace("exceeded %d attempts")
632
525
raise LockContention(self)
675
565
def lock_read(self):
676
566
"""Compatibility-mode shared lock.
678
LockDir doesn't support shared read-only locks, so this
568
LockDir doesn't support shared read-only locks, so this
679
569
just pretends that the lock is taken but really does nothing.
681
# At the moment Branches are commonly locked for read, but
571
# At the moment Branches are commonly locked for read, but
682
572
# we can't rely on that remotely. Once this is cleaned up,
683
# reenable this warning to prevent it coming back in
573
# reenable this warning to prevent it coming back in
684
574
# -- mbp 20060303
685
575
## warn("LockDir.lock_read falls back to write lock")
686
576
if self._lock_held or self._fake_read_lock:
687
577
raise LockContention(self)
688
578
self._fake_read_lock = True
580
def _format_lock_info(self, info):
581
"""Turn the contents of peek() into something for the user"""
582
lock_url = self.transport.abspath(self.path)
583
delta = time.time() - int(info['start_time'])
585
'lock %s' % (lock_url,),
586
'held by %(user)s on host %(hostname)s [process #%(pid)s]' % info,
587
'locked %s' % (format_delta(delta),),
690
590
def validate_token(self, token):
691
591
if token is not None:
692
592
info = self.peek()
704
604
if 'lock' not in debug.debug_flags:
706
606
mutter(str(self) + ": " + (format % args))
708
def get_config(self):
709
"""Get the configuration that governs this lockdir."""
710
# XXX: This really should also use the locationconfig at least, but
711
# that seems a bit hard to hook up at the moment. -- mbp 20110329
712
# FIXME: The above is still true ;) -- vila 20110811
713
return config.GlobalStack()
716
class LockHeldInfo(object):
717
"""The information recorded about a held lock.
719
This information is recorded into the lock when it's taken, and it can be
720
read back by any process with access to the lockdir. It can be used, for
721
example, to tell the user who holds the lock, or to try to detect whether
722
the lock holder is still alive.
724
Prior to bzr 2.4 a simple dict was used instead of an object.
727
def __init__(self, info_dict):
728
self.info_dict = info_dict
731
"""Return a debugging representation of this object."""
732
return "%s(%r)" % (self.__class__.__name__, self.info_dict)
734
def __unicode__(self):
735
"""Return a user-oriented description of this object."""
736
d = self.to_readable_dict()
738
u'held by %(user)s on %(hostname)s (process #%(pid)s), '
739
u'acquired %(time_ago)s') % d)
741
def to_readable_dict(self):
742
"""Turn the holder info into a dict of human-readable attributes.
744
For example, the start time is presented relative to the current time,
745
rather than as seconds since the epoch.
747
Returns a list of [user, hostname, pid, time_ago] all as readable
750
start_time = self.info_dict.get('start_time')
751
if start_time is None:
752
time_ago = '(unknown)'
754
time_ago = format_delta(
755
time.time() - int(self.info_dict['start_time']))
756
user = self.info_dict.get('user', '<unknown>')
757
hostname = self.info_dict.get('hostname', '<unknown>')
758
pid = self.info_dict.get('pid', '<unknown>')
765
def get(self, field_name):
766
"""Return the contents of a field from the lock info, or None."""
767
return self.info_dict.get(field_name)
770
def for_this_process(cls, extra_holder_info):
771
"""Return a new LockHeldInfo for a lock taken by this process.
774
hostname=get_host_name(),
775
pid=str(os.getpid()),
776
nonce=rand_chars(20),
777
start_time=str(int(time.time())),
778
user=get_username_for_lock_info(),
780
if extra_holder_info is not None:
781
info.update(extra_holder_info)
785
s = rio.Stanza(**self.info_dict)
789
def from_info_file_bytes(cls, info_file_bytes):
790
"""Construct from the contents of the held file."""
791
lines = osutils.split_lines(info_file_bytes)
793
stanza = rio.read_stanza(lines)
794
except ValueError, e:
795
mutter('Corrupt lock info file: %r', lines)
796
raise LockCorrupt("could not parse lock info file: " + str(e),
799
# see bug 185013; we fairly often end up with the info file being
800
# empty after an interruption; we could log a message here but
801
# there may not be much we can say
804
return cls(stanza.as_dict())
806
def __cmp__(self, other):
807
"""Value comparison of lock holders."""
809
cmp(type(self), type(other))
810
or cmp(self.info_dict, other.info_dict))
812
def is_locked_by_this_process(self):
813
"""True if this process seems to be the current lock holder."""
815
self.get('hostname') == get_host_name()
816
and self.get('pid') == str(os.getpid())
817
and self.get('user') == get_username_for_lock_info())
819
def is_lock_holder_known_dead(self):
820
"""True if the lock holder process is known to be dead.
822
False if it's either known to be still alive, or if we just can't tell.
824
We can be fairly sure the lock holder is dead if it declared the same
825
hostname and there is no process with the given pid alive. If people
826
have multiple machines with the same hostname this may cause trouble.
828
This doesn't check whether the lock holder is in fact the same process
829
calling this method. (In that case it will return true.)
831
if self.get('hostname') != get_host_name():
833
if self.get('hostname') == 'localhost':
836
if self.get('user') != get_username_for_lock_info():
837
# Could well be another local process by a different user, but
838
# just to be safe we won't conclude about this either.
840
pid_str = self.info_dict.get('pid', None)
842
mutter("no pid recorded in %r" % (self, ))
847
mutter("can't parse pid %r from %r"
850
return osutils.is_local_pid_dead(pid)
853
def get_username_for_lock_info():
854
"""Get a username suitable for putting into a lock.
856
It's ok if what's written here is not a proper email address as long
857
as it gives some clue who the user is.
860
return config.GlobalConfig().username()
861
except errors.NoWhoami:
862
return osutils.getuser_unicode()
added
removed
bzrlib/lockdir.py
