160
148
# files/dirs created.
163
_DEFAULT_TIMEOUT_SECONDS = 30
151
_DEFAULT_TIMEOUT_SECONDS = 300
164
152
_DEFAULT_POLL_SECONDS = 1.0
167
class LockDir(lock.Lock):
168
"""Write-lock guarding access to data.
155
class LockDir(object):
156
"""Write-lock guarding access to data."""
171
158
__INFO_NAME = '/info'
173
def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755,
174
extra_holder_info=None):
160
def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755):
175
161
"""Create a new LockDir object.
177
163
The LockDir is initially unlocked - this just creates the object.
179
165
:param transport: Transport which will contain the lock
181
:param path: Path to the lock within the base directory of the
167
: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
assert isinstance(transport, Transport), \
171
("not a transport: %r" % transport)
188
172
self.transport = transport
190
174
self._lock_held = False
239
223
except (errors.TransportError, PathError), e:
240
224
self._trace("... failed to create pending dir, %s", e)
241
225
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)
227
self.transport.rename(tmpname, self._held_dir)
228
except (errors.TransportError, PathError, DirectoryNotEmpty,
229
FileExists, ResourceBusy), e:
230
self._trace("... contention, %s", e)
231
self._remove_pending_dir(tmpname)
232
raise LockContention(self)
234
self._trace("... lock failed, %s", e)
235
self._remove_pending_dir(tmpname)
260
237
# We must check we really got the lock, because Launchpad's sftp
261
238
# server at one time had a bug were the rename would successfully
262
239
# move the new directory into the existing directory, which was
263
240
# incorrect. It's possible some other servers or filesystems will
264
241
# have a similar bug allowing someone to think they got the lock
265
242
# 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.
271
243
info = self.peek()
272
244
self._trace("after locking, info=%r", info)
274
raise LockFailed(self, "lock was renamed into place, but "
276
if info.get('nonce') != self.nonce:
245
if info['nonce'] != self.nonce:
277
246
self._trace("rename succeeded, "
278
247
"but lock is still held by someone else")
279
248
raise LockContention(self)
282
251
(time.time() - start_time) * 1000)
283
252
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)
310
254
def _remove_pending_dir(self, tmpname):
311
255
"""Remove the pending directory
313
This is called if we failed to rename into place, so that the pending
257
This is called if we failed to rename into place, so that the pending
314
258
dirs don't clutter up the lockdir.
316
260
self._trace("remove %s", tmpname)
381
323
self.transport.delete_tree(tmpname)
382
324
self._trace("... unlock succeeded after %dms",
383
325
(time.time() - start_time) * 1000)
384
result = lock.LockResult(self.transport.abspath(self.path),
386
for hook in self.hooks['lock_released']:
389
327
def break_lock(self):
390
328
"""Break a lock not held by this instance of LockDir.
392
This is a UI centric function: it uses the ui.ui_factory to
330
This is a UI centric function: it uses the bzrlib.ui.ui_factory to
393
331
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.
332
it possibly being still active.
399
334
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)
335
holder_info = self.peek()
407
336
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)
337
lock_info = '\n'.join(self._format_lock_info(holder_info))
338
if bzrlib.ui.ui_factory.get_boolean("Break %s" % lock_info):
339
self.force_break(holder_info)
416
341
def force_break(self, dead_holder_info):
417
342
"""Release a lock held by another process.
420
345
it still thinks it has the lock there will be two concurrent writers.
421
346
In general the user's approval should be sought for lock breaks.
348
dead_holder_info must be the result of a previous LockDir.peek() call;
349
this is used to check that it's still held by the same process that
350
the user decided was dead. If this is not the current holder,
351
LockBreakMismatch is raised.
423
353
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
354
It is possible that another process may sneak in and take the
425
355
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):
357
if not isinstance(dead_holder_info, dict):
436
358
raise ValueError("dead_holder_info: %r" % dead_holder_info)
437
359
self._check_not_locked()
438
360
current_info = self.peek()
452
374
raise LockBreakMismatch(self, broken_info, dead_holder_info)
453
375
self.transport.delete(broken_info_path)
454
376
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
378
def _check_not_locked(self):
491
379
"""If the lock is held by this instance, raise an error."""
511
399
if info.get('nonce') != self.nonce:
512
400
# there is a lock, but not ours
513
401
raise LockBroken(self)
515
403
def _read_info_file(self, path):
516
404
"""Read one given info file.
518
406
peek() reads the info file of the lock holder, if any.
520
return LockHeldInfo.from_info_file_bytes(
521
self.transport.get_bytes(path))
408
return self._parse_info(self.transport.get(path))
524
411
"""Check if the lock is held by anyone.
526
If it is held, this returns the lock info structure as a dict
413
If it is held, this returns the lock info structure as a rio Stanza,
527
414
which contains some information about the current lock holder.
528
415
Otherwise returns None.
531
418
info = self._read_info_file(self._held_info_path)
532
419
self._trace("peek -> held")
420
assert isinstance(info, dict), \
421
"bad parse result %r" % info
534
423
except NoSuchFile, e:
535
424
self._trace("peek -> not held")
613
502
new_info = self.peek()
614
503
if new_info is not None and new_info != last_info:
615
504
if last_info is None:
616
start = gettext('Unable to obtain')
505
start = 'Unable to obtain'
618
start = gettext('Lock owner changed for')
507
start = 'Lock owner changed for'
619
508
last_info = new_info
620
msg = gettext('{0} lock {1} {2}.').format(start, lock_url,
509
formatted_info = self._format_lock_info(new_info)
622
510
if deadline_str is None:
623
511
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)
512
time.localtime(deadline))
513
self._report_function('%s %s\n'
515
'%s\n' # locked ... ago
516
'Will continue to try until %s\n',
631
523
if (max_attempts is not None) and (attempt_count >= max_attempts):
632
524
self._trace("exceeded %d attempts")
633
525
raise LockContention(self)
676
565
def lock_read(self):
677
566
"""Compatibility-mode shared lock.
679
LockDir doesn't support shared read-only locks, so this
568
LockDir doesn't support shared read-only locks, so this
680
569
just pretends that the lock is taken but really does nothing.
682
# At the moment Branches are commonly locked for read, but
571
# At the moment Branches are commonly locked for read, but
683
572
# we can't rely on that remotely. Once this is cleaned up,
684
# reenable this warning to prevent it coming back in
573
# reenable this warning to prevent it coming back in
685
574
# -- mbp 20060303
686
575
## warn("LockDir.lock_read falls back to write lock")
687
576
if self._lock_held or self._fake_read_lock:
688
577
raise LockContention(self)
689
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),),
691
590
def validate_token(self, token):
692
591
if token is not None:
693
592
info = self.peek()
705
604
if 'lock' not in debug.debug_flags:
707
606
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
