1
# Copyright (C) 2006-2011 Canonical Ltd
3
# This program is free software; you can redistribute it and/or modify
4
# it under the terms of the GNU General Public License as published by
5
# the Free Software Foundation; either version 2 of the License, or
6
# (at your option) any later version.
8
# This program is distributed in the hope that it will be useful,
9
# but WITHOUT ANY WARRANTY; without even the implied warranty of
10
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11
# GNU General Public License for more details.
13
# You should have received a copy of the GNU General Public License
14
# along with this program; if not, write to the Free Software
15
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17
"""On-disk mutex protecting a resource
19
bzr on-disk objects are locked by the existence of a directory with a
20
particular name within the control directory. We use this rather than OS
21
internal locks (such as flock etc) because they can be seen across all
22
transports, including http.
24
Objects can be read if there is only physical read access; therefore
25
readers can never be required to create a lock, though they will
26
check whether a writer is using the lock. Writers can't detect
27
whether anyone else is reading from the resource as they write.
28
This works because of ordering constraints that make sure readers
29
see a consistent view of existing data.
31
Waiting for a lock must be done by polling; this can be aborted after
34
Locks must always be explicitly released, typically from a try/finally
35
block -- they are not released from a finalizer or when Python
38
Locks may fail to be released if the process is abruptly terminated
39
(machine stop, SIGKILL) or if a remote transport becomes permanently
40
disconnected. There is therefore a method to break an existing lock.
41
This should rarely be used, and generally only with user approval.
42
Locks contain some information on when the lock was taken and by who
43
which may guide in deciding whether it can safely be broken. (This is
44
similar to the messages displayed by emacs and vim.) Note that if the
45
lock holder is still alive they will get no notification that the lock
46
has been broken and will continue their work -- so it is important to be
47
sure they are actually dead.
49
A lock is represented on disk by a directory of a particular name,
50
containing an information file. Taking a lock is done by renaming a
51
temporary directory into place. We use temporary directories because
52
for all known transports and filesystems we believe that exactly one
53
attempt to claim the lock will succeed and the others will fail. (Files
54
won't do because some filesystems or transports only have
55
rename-and-overwrite, making it hard to tell who won.)
57
The desired characteristics are:
59
* Locks are not reentrant. (That is, a client that tries to take a
60
lock it already holds may deadlock or fail.)
61
* Stale locks can be guessed at by a heuristic
62
* Lost locks can be broken by any client
63
* Failed lock operations leave little or no mess
64
* Deadlocks are avoided by having a timeout always in use, clients
65
desiring indefinite waits can retry or set a silly big timeout.
67
Storage formats use the locks, and also need to consider concurrency
68
issues underneath the lock. A format may choose not to use a lock
69
at all for some operations.
71
LockDirs always operate over a Transport. The transport may be readonly, in
72
which case the lock can be queried but not acquired.
74
Locks are identified by a path name, relative to a base transport.
76
Calling code will typically want to make sure there is exactly one LockDir
77
object per actual lock on disk. This module does nothing to prevent aliasing
78
and deadlocks will likely occur if the locks are aliased.
80
In the future we may add a "freshen" method which can be called
81
by a lock holder to check that their lock has not been broken, and to
82
update the timestamp within it.
86
>>> from bzrlib.transport.memory import MemoryTransport
87
>>> # typically will be obtained from a BzrDir, Branch, etc
88
>>> t = MemoryTransport()
89
>>> l = LockDir(t, 'sample-lock')
91
>>> token = l.wait_lock()
92
>>> # do something here
95
Some classes of stale locks can be predicted by checking: the host name is the
96
same as the local host name; the user name is the same as the local user; the
97
process id no longer exists. The check on user name is not strictly necessary
98
but helps protect against colliding host names.
101
from __future__ import absolute_import
104
# TODO: We sometimes have the problem that our attempt to rename '1234' to
105
# 'held' fails because the transport server moves into an existing directory,
106
# rather than failing the rename. If we made the info file name the same as
107
# the locked directory name we would avoid this problem because moving into
108
# the held directory would implicitly clash. However this would not mesh with
109
# the existing locking code and needs a new format of the containing object.
110
# -- robertc, mbp 20070628
124
from bzrlib.decorators import only_raises
125
from bzrlib.errors import (
139
from bzrlib.trace import mutter, note
140
from bzrlib.osutils import format_delta, rand_chars, get_host_name
141
from bzrlib.i18n import gettext
143
from bzrlib.lazy_import import lazy_import
144
lazy_import(globals(), """
145
from bzrlib import rio
148
# XXX: At the moment there is no consideration of thread safety on LockDir
149
# objects. This should perhaps be updated - e.g. if two threads try to take a
150
# lock at the same time they should *both* get it. But then that's unlikely
153
# TODO: Perhaps store some kind of note like the bzr command line in the lock
156
# TODO: Some kind of callback run while polling a lock to show progress
159
# TODO: Make sure to pass the right file and directory mode bits to all
160
# files/dirs created.
163
_DEFAULT_TIMEOUT_SECONDS = 30
164
_DEFAULT_POLL_SECONDS = 1.0
167
class LockDir(lock.Lock):
168
"""Write-lock guarding access to data.
171
__INFO_NAME = '/info'
173
def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755,
174
extra_holder_info=None):
175
"""Create a new LockDir object.
177
The LockDir is initially unlocked - this just creates the object.
179
:param transport: Transport which will contain the lock
181
:param path: Path to the lock within the base directory of the
184
:param extra_holder_info: If passed, {str:str} dict of extra or
185
updated information to insert into the info file when the lock is
188
self.transport = transport
190
self._lock_held = False
191
self._locked_via_token = False
192
self._fake_read_lock = False
193
self._held_dir = path + '/held'
194
self._held_info_path = self._held_dir + self.__INFO_NAME
195
self._file_modebits = file_modebits
196
self._dir_modebits = dir_modebits
197
self._report_function = note
198
self.extra_holder_info = extra_holder_info
199
self._warned_about_lock_holder = None
202
return '%s(%s%s)' % (self.__class__.__name__,
206
is_held = property(lambda self: self._lock_held)
208
def create(self, mode=None):
209
"""Create the on-disk lock.
211
This is typically only called when the object/directory containing the
212
directory is first created. The lock is not held when it's created.
214
self._trace("create lock directory")
216
self.transport.mkdir(self.path, mode=mode)
217
except (TransportError, PathError), e:
218
raise LockFailed(self, e)
220
def _attempt_lock(self):
221
"""Make the pending directory and attempt to rename into place.
223
If the rename succeeds, we read back the info file to check that we
226
If we fail to acquire the lock, this method is responsible for
227
cleaning up the pending directory if possible. (But it doesn't do
230
:returns: The nonce of the lock, if it was successfully acquired.
232
:raises LockContention: If the lock is held by someone else. The
233
exception contains the info of the current holder of the lock.
235
self._trace("lock_write...")
236
start_time = time.time()
238
tmpname = self._create_pending_dir()
239
except (errors.TransportError, PathError), e:
240
self._trace("... failed to create pending dir, %s", e)
241
raise LockFailed(self, e)
244
self.transport.rename(tmpname, self._held_dir)
246
except (errors.TransportError, PathError, DirectoryNotEmpty,
247
FileExists, ResourceBusy), e:
248
self._trace("... contention, %s", e)
249
other_holder = self.peek()
250
self._trace("other holder is %r" % other_holder)
252
self._handle_lock_contention(other_holder)
254
self._remove_pending_dir(tmpname)
257
self._trace("... lock failed, %s", e)
258
self._remove_pending_dir(tmpname)
260
# We must check we really got the lock, because Launchpad's sftp
261
# server at one time had a bug were the rename would successfully
262
# move the new directory into the existing directory, which was
263
# incorrect. It's possible some other servers or filesystems will
264
# have a similar bug allowing someone to think they got the lock
265
# when it's already held.
267
# See <https://bugs.launchpad.net/bzr/+bug/498378> for one case.
269
# Strictly the check is unnecessary and a waste of time for most
270
# people, but probably worth trapping if something is wrong.
272
self._trace("after locking, info=%r", info)
274
raise LockFailed(self, "lock was renamed into place, but "
276
if info.get('nonce') != self.nonce:
277
self._trace("rename succeeded, "
278
"but lock is still held by someone else")
279
raise LockContention(self)
280
self._lock_held = True
281
self._trace("... lock succeeded after %dms",
282
(time.time() - start_time) * 1000)
285
def _handle_lock_contention(self, other_holder):
286
"""A lock we want to take is held by someone else.
288
This function can: tell the user about it; possibly detect that it's
289
safe or appropriate to steal the lock, or just raise an exception.
291
If this function returns (without raising an exception) the lock will
294
:param other_holder: A LockHeldInfo for the current holder; note that
295
it might be None if the lock can be seen to be held but the info
298
if (other_holder is not None):
299
if other_holder.is_lock_holder_known_dead():
300
if self.get_config().get('locks.steal_dead'):
301
ui.ui_factory.show_user_warning(
303
lock_url=urlutils.join(self.transport.base, self.path),
304
other_holder_info=unicode(other_holder))
305
self.force_break(other_holder)
306
self._trace("stole lock from dead holder")
308
raise LockContention(self)
310
def _remove_pending_dir(self, tmpname):
311
"""Remove the pending directory
313
This is called if we failed to rename into place, so that the pending
314
dirs don't clutter up the lockdir.
316
self._trace("remove %s", tmpname)
318
self.transport.delete(tmpname + self.__INFO_NAME)
319
self.transport.rmdir(tmpname)
321
note(gettext("error removing pending lock: %s"), e)
323
def _create_pending_dir(self):
324
tmpname = '%s/%s.tmp' % (self.path, rand_chars(10))
326
self.transport.mkdir(tmpname)
328
# This may raise a FileExists exception
329
# which is okay, it will be caught later and determined
330
# to be a LockContention.
331
self._trace("lock directory does not exist, creating it")
332
self.create(mode=self._dir_modebits)
333
# After creating the lock directory, try again
334
self.transport.mkdir(tmpname)
335
info = LockHeldInfo.for_this_process(self.extra_holder_info)
336
self.nonce = info.get('nonce')
337
# We use put_file_non_atomic because we just created a new unique
338
# directory so we don't have to worry about files existing there.
339
# We'll rename the whole directory into place to get atomic
341
self.transport.put_bytes_non_atomic(tmpname + self.__INFO_NAME,
345
@only_raises(LockNotHeld, LockBroken)
347
"""Release a held lock
349
if self._fake_read_lock:
350
self._fake_read_lock = False
352
if not self._lock_held:
353
return lock.cant_unlock_not_held(self)
354
if self._locked_via_token:
355
self._locked_via_token = False
356
self._lock_held = False
358
old_nonce = self.nonce
359
# rename before deleting, because we can't atomically remove the
361
start_time = time.time()
362
self._trace("unlocking")
363
tmpname = '%s/releasing.%s.tmp' % (self.path, rand_chars(20))
364
# gotta own it to unlock
366
self.transport.rename(self._held_dir, tmpname)
367
self._lock_held = False
368
self.transport.delete(tmpname + self.__INFO_NAME)
370
self.transport.rmdir(tmpname)
371
except DirectoryNotEmpty, e:
372
# There might have been junk left over by a rename that moved
373
# another locker within the 'held' directory. do a slower
374
# deletion where we list the directory and remove everything
377
# Maybe this should be broader to allow for ftp servers with
378
# non-specific error messages?
379
self._trace("doing recursive deletion of non-empty directory "
381
self.transport.delete_tree(tmpname)
382
self._trace("... unlock succeeded after %dms",
383
(time.time() - start_time) * 1000)
384
result = lock.LockResult(self.transport.abspath(self.path),
386
for hook in self.hooks['lock_released']:
389
def break_lock(self):
390
"""Break a lock not held by this instance of LockDir.
392
This is a UI centric function: it uses the ui.ui_factory to
393
prompt for input if a lock is detected and there is any doubt about
394
it possibly being still active. force_break is the non-interactive
397
:returns: LockResult for the broken lock.
399
self._check_not_locked()
401
holder_info = self.peek()
402
except LockCorrupt, e:
403
# The lock info is corrupt.
404
if ui.ui_factory.get_boolean(u"Break (corrupt %r)" % (self,)):
405
self.force_break_corrupt(e.file_data)
407
if holder_info is not None:
408
if ui.ui_factory.confirm_action(
409
u"Break %(lock_info)s",
410
'bzrlib.lockdir.break',
411
dict(lock_info=unicode(holder_info))):
412
result = self.force_break(holder_info)
413
ui.ui_factory.show_message(
414
"Broke lock %s" % result.lock_url)
416
def force_break(self, dead_holder_info):
417
"""Release a lock held by another process.
419
WARNING: This should only be used when the other process is dead; if
420
it still thinks it has the lock there will be two concurrent writers.
421
In general the user's approval should be sought for lock breaks.
423
After the lock is broken it will not be held by any process.
424
It is possible that another process may sneak in and take the
425
lock before the breaking process acquires it.
427
:param dead_holder_info:
428
Must be the result of a previous LockDir.peek() call; this is used
429
to check that it's still held by the same process that the user
430
decided was dead. If this is not the current holder,
431
LockBreakMismatch is raised.
433
:returns: LockResult for the broken lock.
435
if not isinstance(dead_holder_info, LockHeldInfo):
436
raise ValueError("dead_holder_info: %r" % dead_holder_info)
437
self._check_not_locked()
438
current_info = self.peek()
439
if current_info is None:
440
# must have been recently released
442
if current_info != dead_holder_info:
443
raise LockBreakMismatch(self, current_info, dead_holder_info)
444
tmpname = '%s/broken.%s.tmp' % (self.path, rand_chars(20))
445
self.transport.rename(self._held_dir, tmpname)
446
# check that we actually broke the right lock, not someone else;
447
# there's a small race window between checking it and doing the
449
broken_info_path = tmpname + self.__INFO_NAME
450
broken_info = self._read_info_file(broken_info_path)
451
if broken_info != dead_holder_info:
452
raise LockBreakMismatch(self, broken_info, dead_holder_info)
453
self.transport.delete(broken_info_path)
454
self.transport.rmdir(tmpname)
455
result = lock.LockResult(self.transport.abspath(self.path),
456
current_info.get('nonce'))
457
for hook in self.hooks['lock_broken']:
461
def force_break_corrupt(self, corrupt_info_lines):
462
"""Release a lock that has been corrupted.
464
This is very similar to force_break, it except it doesn't assume that
465
self.peek() can work.
467
:param corrupt_info_lines: the lines of the corrupted info file, used
468
to check that the lock hasn't changed between reading the (corrupt)
469
info file and calling force_break_corrupt.
471
# XXX: this copes with unparseable info files, but what about missing
472
# info files? Or missing lock dirs?
473
self._check_not_locked()
474
tmpname = '%s/broken.%s.tmp' % (self.path, rand_chars(20))
475
self.transport.rename(self._held_dir, tmpname)
476
# check that we actually broke the right lock, not someone else;
477
# there's a small race window between checking it and doing the
479
broken_info_path = tmpname + self.__INFO_NAME
480
broken_content = self.transport.get_bytes(broken_info_path)
481
broken_lines = osutils.split_lines(broken_content)
482
if broken_lines != corrupt_info_lines:
483
raise LockBreakMismatch(self, broken_lines, corrupt_info_lines)
484
self.transport.delete(broken_info_path)
485
self.transport.rmdir(tmpname)
486
result = lock.LockResult(self.transport.abspath(self.path))
487
for hook in self.hooks['lock_broken']:
490
def _check_not_locked(self):
491
"""If the lock is held by this instance, raise an error."""
493
raise AssertionError("can't break own lock: %r" % self)
496
"""Make sure that the lock is still held by this locker.
498
This should only fail if the lock was broken by user intervention,
499
or if the lock has been affected by a bug.
501
If the lock is not thought to be held, raises LockNotHeld. If
502
the lock is thought to be held but has been broken, raises
505
if not self._lock_held:
506
raise LockNotHeld(self)
509
# no lock there anymore!
510
raise LockBroken(self)
511
if info.get('nonce') != self.nonce:
512
# there is a lock, but not ours
513
raise LockBroken(self)
515
def _read_info_file(self, path):
516
"""Read one given info file.
518
peek() reads the info file of the lock holder, if any.
520
return LockHeldInfo.from_info_file_bytes(
521
self.transport.get_bytes(path))
524
"""Check if the lock is held by anyone.
526
If it is held, this returns the lock info structure as a dict
527
which contains some information about the current lock holder.
528
Otherwise returns None.
531
info = self._read_info_file(self._held_info_path)
532
self._trace("peek -> held")
534
except NoSuchFile, e:
535
self._trace("peek -> not held")
537
def _prepare_info(self):
538
"""Write information about a pending lock to a temporary file.
541
def attempt_lock(self):
542
"""Take the lock; fail if it's already held.
544
If you wish to block until the lock can be obtained, call wait_lock()
547
:return: The lock token.
548
:raises LockContention: if the lock is held by someone else.
550
if self._fake_read_lock:
551
raise LockContention(self)
552
result = self._attempt_lock()
553
hook_result = lock.LockResult(self.transport.abspath(self.path),
555
for hook in self.hooks['lock_acquired']:
559
def lock_url_for_display(self):
560
"""Give a nicely-printable representation of the URL of this lock."""
561
# As local lock urls are correct we display them.
562
# We avoid displaying remote lock urls.
563
lock_url = self.transport.abspath(self.path)
564
if lock_url.startswith('file://'):
565
lock_url = lock_url.split('.bzr/')[0]
570
def wait_lock(self, timeout=None, poll=None, max_attempts=None):
571
"""Wait a certain period for a lock.
573
If the lock can be acquired within the bounded time, it
574
is taken and this returns. Otherwise, LockContention
575
is raised. Either way, this function should return within
576
approximately `timeout` seconds. (It may be a bit more if
577
a transport operation takes a long time to complete.)
579
:param timeout: Approximate maximum amount of time to wait for the
582
:param poll: Delay in seconds between retrying the lock.
584
:param max_attempts: Maximum number of times to try to lock.
586
:return: The lock token.
589
timeout = _DEFAULT_TIMEOUT_SECONDS
591
poll = _DEFAULT_POLL_SECONDS
592
# XXX: the transport interface doesn't let us guard against operations
593
# there taking a long time, so the total elapsed time or poll interval
594
# may be more than was requested.
595
deadline = time.time() + timeout
599
lock_url = self.lock_url_for_display()
603
return self.attempt_lock()
604
except LockContention:
605
# possibly report the blockage, then try again
607
# TODO: In a few cases, we find out that there's contention by
608
# reading the held info and observing that it's not ours. In
609
# those cases it's a bit redundant to read it again. However,
610
# the normal case (??) is that the rename fails and so we
611
# don't know who holds the lock. For simplicity we peek
613
new_info = self.peek()
614
if new_info is not None and new_info != last_info:
615
if last_info is None:
616
start = gettext('Unable to obtain')
618
start = gettext('Lock owner changed for')
620
msg = gettext('{0} lock {1} {2}.').format(start, lock_url,
622
if deadline_str is None:
623
deadline_str = time.strftime('%H:%M:%S',
624
time.localtime(deadline))
626
msg += '\n' + gettext(
627
'Will continue to try until %s, unless '
628
'you press Ctrl-C.') % deadline_str
629
msg += '\n' + gettext('See "bzr help break-lock" for more.')
630
self._report_function(msg)
631
if (max_attempts is not None) and (attempt_count >= max_attempts):
632
self._trace("exceeded %d attempts")
633
raise LockContention(self)
634
if time.time() + poll < deadline:
635
self._trace("waiting %ss", poll)
638
# As timeout is always 0 for remote locks
639
# this block is applicable only for local
641
self._trace("timeout after waiting %ss", timeout)
642
raise LockContention('(local)', lock_url)
644
def leave_in_place(self):
645
self._locked_via_token = True
647
def dont_leave_in_place(self):
648
self._locked_via_token = False
650
def lock_write(self, token=None):
651
"""Wait for and acquire the lock.
653
:param token: if this is already locked, then lock_write will fail
654
unless the token matches the existing lock.
655
:returns: a token if this instance supports tokens, otherwise None.
656
:raises TokenLockingNotSupported: when a token is given but this
657
instance doesn't support using token locks.
658
:raises MismatchedToken: if the specified token doesn't match the token
659
of the existing lock.
661
A token should be passed in if you know that you have locked the object
662
some other way, and need to synchronise this object's state with that
665
XXX: docstring duplicated from LockableFiles.lock_write.
667
if token is not None:
668
self.validate_token(token)
670
self._lock_held = True
671
self._locked_via_token = True
674
return self.wait_lock()
677
"""Compatibility-mode shared lock.
679
LockDir doesn't support shared read-only locks, so this
680
just pretends that the lock is taken but really does nothing.
682
# At the moment Branches are commonly locked for read, but
683
# we can't rely on that remotely. Once this is cleaned up,
684
# reenable this warning to prevent it coming back in
686
## warn("LockDir.lock_read falls back to write lock")
687
if self._lock_held or self._fake_read_lock:
688
raise LockContention(self)
689
self._fake_read_lock = True
691
def validate_token(self, token):
692
if token is not None:
698
lock_token = info.get('nonce')
699
if token != lock_token:
700
raise errors.TokenMismatch(token, lock_token)
702
self._trace("revalidated by token %r", token)
704
def _trace(self, format, *args):
705
if 'lock' not in debug.debug_flags:
707
mutter(str(self) + ": " + (format % args))
709
def get_config(self):
710
"""Get the configuration that governs this lockdir."""
711
# XXX: This really should also use the locationconfig at least, but
712
# that seems a bit hard to hook up at the moment. -- mbp 20110329
713
# FIXME: The above is still true ;) -- vila 20110811
714
return config.GlobalStack()
717
class LockHeldInfo(object):
718
"""The information recorded about a held lock.
720
This information is recorded into the lock when it's taken, and it can be
721
read back by any process with access to the lockdir. It can be used, for
722
example, to tell the user who holds the lock, or to try to detect whether
723
the lock holder is still alive.
725
Prior to bzr 2.4 a simple dict was used instead of an object.
728
def __init__(self, info_dict):
729
self.info_dict = info_dict
732
"""Return a debugging representation of this object."""
733
return "%s(%r)" % (self.__class__.__name__, self.info_dict)
735
def __unicode__(self):
736
"""Return a user-oriented description of this object."""
737
d = self.to_readable_dict()
739
u'held by %(user)s on %(hostname)s (process #%(pid)s), '
740
u'acquired %(time_ago)s') % d)
742
def to_readable_dict(self):
743
"""Turn the holder info into a dict of human-readable attributes.
745
For example, the start time is presented relative to the current time,
746
rather than as seconds since the epoch.
748
Returns a list of [user, hostname, pid, time_ago] all as readable
751
start_time = self.info_dict.get('start_time')
752
if start_time is None:
753
time_ago = '(unknown)'
755
time_ago = format_delta(
756
time.time() - int(self.info_dict['start_time']))
757
user = self.info_dict.get('user', '<unknown>')
758
hostname = self.info_dict.get('hostname', '<unknown>')
759
pid = self.info_dict.get('pid', '<unknown>')
766
def get(self, field_name):
767
"""Return the contents of a field from the lock info, or None."""
768
return self.info_dict.get(field_name)
771
def for_this_process(cls, extra_holder_info):
772
"""Return a new LockHeldInfo for a lock taken by this process.
775
hostname=get_host_name(),
776
pid=str(os.getpid()),
777
nonce=rand_chars(20),
778
start_time=str(int(time.time())),
779
user=get_username_for_lock_info(),
781
if extra_holder_info is not None:
782
info.update(extra_holder_info)
786
s = rio.Stanza(**self.info_dict)
790
def from_info_file_bytes(cls, info_file_bytes):
791
"""Construct from the contents of the held file."""
792
lines = osutils.split_lines(info_file_bytes)
794
stanza = rio.read_stanza(lines)
795
except ValueError, e:
796
mutter('Corrupt lock info file: %r', lines)
797
raise LockCorrupt("could not parse lock info file: " + str(e),
800
# see bug 185013; we fairly often end up with the info file being
801
# empty after an interruption; we could log a message here but
802
# there may not be much we can say
805
return cls(stanza.as_dict())
807
def __cmp__(self, other):
808
"""Value comparison of lock holders."""
810
cmp(type(self), type(other))
811
or cmp(self.info_dict, other.info_dict))
813
def is_locked_by_this_process(self):
814
"""True if this process seems to be the current lock holder."""
816
self.get('hostname') == get_host_name()
817
and self.get('pid') == str(os.getpid())
818
and self.get('user') == get_username_for_lock_info())
820
def is_lock_holder_known_dead(self):
821
"""True if the lock holder process is known to be dead.
823
False if it's either known to be still alive, or if we just can't tell.
825
We can be fairly sure the lock holder is dead if it declared the same
826
hostname and there is no process with the given pid alive. If people
827
have multiple machines with the same hostname this may cause trouble.
829
This doesn't check whether the lock holder is in fact the same process
830
calling this method. (In that case it will return true.)
832
if self.get('hostname') != get_host_name():
834
if self.get('hostname') == 'localhost':
837
if self.get('user') != get_username_for_lock_info():
838
# Could well be another local process by a different user, but
839
# just to be safe we won't conclude about this either.
841
pid_str = self.info_dict.get('pid', None)
843
mutter("no pid recorded in %r" % (self, ))
848
mutter("can't parse pid %r from %r"
851
return osutils.is_local_pid_dead(pid)
854
def get_username_for_lock_info():
855
"""Get a username suitable for putting into a lock.
857
It's ok if what's written here is not a proper email address as long
858
as it gives some clue who the user is.
861
return config.GlobalStack().get('email')
862
except errors.NoWhoami:
863
return osutils.getuser_unicode()
added
removed
bzrlib/lockdir.py
