148
160
# files/dirs created.
151
_DEFAULT_TIMEOUT_SECONDS = 300
163
_DEFAULT_TIMEOUT_SECONDS = 30
152
164
_DEFAULT_POLL_SECONDS = 1.0
155
class LockDir(object):
156
"""Write-lock guarding access to data."""
167
class LockDir(lock.Lock):
168
"""Write-lock guarding access to data.
158
171
__INFO_NAME = '/info'
160
def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755):
173
def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755,
174
extra_holder_info=None):
161
175
"""Create a new LockDir object.
163
177
The LockDir is initially unlocked - this just creates the object.
165
179
:param transport: Transport which will contain the lock
167
:param path: Path to the lock within the base directory of the
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
170
188
self.transport = transport
221
239
except (errors.TransportError, PathError), e:
222
240
self._trace("... failed to create pending dir, %s", e)
223
241
raise LockFailed(self, e)
225
self.transport.rename(tmpname, self._held_dir)
226
except (errors.TransportError, PathError, DirectoryNotEmpty,
227
FileExists, ResourceBusy), e:
228
self._trace("... contention, %s", e)
229
self._remove_pending_dir(tmpname)
230
raise LockContention(self)
232
self._trace("... lock failed, %s", e)
233
self._remove_pending_dir(tmpname)
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)
235
260
# We must check we really got the lock, because Launchpad's sftp
236
261
# server at one time had a bug were the rename would successfully
237
262
# move the new directory into the existing directory, which was
238
263
# incorrect. It's possible some other servers or filesystems will
239
264
# have a similar bug allowing someone to think they got the lock
240
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.
241
271
info = self.peek()
242
272
self._trace("after locking, info=%r", info)
243
if info['nonce'] != self.nonce:
274
raise LockFailed(self, "lock was renamed into place, but "
276
if info.get('nonce') != self.nonce:
244
277
self._trace("rename succeeded, "
245
278
"but lock is still held by someone else")
246
279
raise LockContention(self)
249
282
(time.time() - start_time) * 1000)
250
283
return self.nonce
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)
252
310
def _remove_pending_dir(self, tmpname):
253
311
"""Remove the pending directory
255
This is called if we failed to rename into place, so that the pending
313
This is called if we failed to rename into place, so that the pending
256
314
dirs don't clutter up the lockdir.
258
316
self._trace("remove %s", tmpname)
321
381
self.transport.delete_tree(tmpname)
322
382
self._trace("... unlock succeeded after %dms",
323
383
(time.time() - start_time) * 1000)
384
result = lock.LockResult(self.transport.abspath(self.path),
386
for hook in self.hooks['lock_released']:
325
389
def break_lock(self):
326
390
"""Break a lock not held by this instance of LockDir.
328
This is a UI centric function: it uses the bzrlib.ui.ui_factory to
392
This is a UI centric function: it uses the ui.ui_factory to
329
393
prompt for input if a lock is detected and there is any doubt about
330
it possibly being still active.
394
it possibly being still active. force_break is the non-interactive
397
:returns: LockResult for the broken lock.
332
399
self._check_not_locked()
333
holder_info = self.peek()
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)
334
407
if holder_info is not None:
335
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)
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)
339
416
def force_break(self, dead_holder_info):
340
417
"""Release a lock held by another process.
343
420
it still thinks it has the lock there will be two concurrent writers.
344
421
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.
351
423
After the lock is broken it will not be held by any process.
352
It is possible that another process may sneak in and take the
424
It is possible that another process may sneak in and take the
353
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.
355
if not isinstance(dead_holder_info, dict):
435
if not isinstance(dead_holder_info, LockHeldInfo):
356
436
raise ValueError("dead_holder_info: %r" % dead_holder_info)
357
437
self._check_not_locked()
358
438
current_info = self.peek()
372
452
raise LockBreakMismatch(self, broken_info, dead_holder_info)
373
453
self.transport.delete(broken_info_path)
374
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']:
376
490
def _check_not_locked(self):
377
491
"""If the lock is held by this instance, raise an error."""
497
613
new_info = self.peek()
498
614
if new_info is not None and new_info != last_info:
499
615
if last_info is None:
500
start = 'Unable to obtain'
616
start = gettext('Unable to obtain')
502
start = 'Lock owner changed for'
618
start = gettext('Lock owner changed for')
503
619
last_info = new_info
504
formatted_info = self._format_lock_info(new_info)
620
msg = gettext('{0} lock {1} {2}.').format(start, lock_url,
505
622
if deadline_str is None:
506
623
deadline_str = time.strftime('%H:%M:%S',
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',
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)
523
631
if (max_attempts is not None) and (attempt_count >= max_attempts):
524
632
self._trace("exceeded %d attempts")
525
633
raise LockContention(self)
565
676
def lock_read(self):
566
677
"""Compatibility-mode shared lock.
568
LockDir doesn't support shared read-only locks, so this
679
LockDir doesn't support shared read-only locks, so this
569
680
just pretends that the lock is taken but really does nothing.
571
# At the moment Branches are commonly locked for read, but
682
# At the moment Branches are commonly locked for read, but
572
683
# we can't rely on that remotely. Once this is cleaned up,
573
# reenable this warning to prevent it coming back in
684
# reenable this warning to prevent it coming back in
574
685
# -- mbp 20060303
575
686
## warn("LockDir.lock_read falls back to write lock")
576
687
if self._lock_held or self._fake_read_lock:
577
688
raise LockContention(self)
578
689
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),),
590
691
def validate_token(self, token):
591
692
if token is not None:
592
693
info = self.peek()
604
705
if 'lock' not in debug.debug_flags:
606
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
