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107
# the existing locking code and needs a new format of the containing object.
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108
# -- robertc, mbp 20070628
108
from cStringIO import StringIO
110
114
from bzrlib import (
123
from bzrlib.decorators import only_raises
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124
from bzrlib.errors import (
116
125
DirectoryNotEmpty,
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127
LockBreakMismatch,
129
138
from bzrlib.trace import mutter, note
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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.osutils import format_delta, rand_chars, get_host_name
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from bzrlib.lazy_import import lazy_import
142
lazy_import(globals(), """
143
from bzrlib import rio
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146
# XXX: At the moment there is no consideration of thread safety on LockDir
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147
# objects. This should perhaps be updated - e.g. if two threads try to take a
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158
# files/dirs created.
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_DEFAULT_TIMEOUT_SECONDS = 300
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_DEFAULT_TIMEOUT_SECONDS = 30
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_DEFAULT_POLL_SECONDS = 1.0
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class LockDir(object):
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"""Write-lock guarding access to data."""
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class LockDir(lock.Lock):
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"""Write-lock guarding access to data.
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169
__INFO_NAME = '/info'
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def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755):
171
def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755,
172
extra_holder_info=None):
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"""Create a new LockDir object.
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175
The LockDir is initially unlocked - this just creates the object.
165
177
:param transport: Transport which will contain the lock
167
:param path: Path to the lock within the base directory of the
179
: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
183
updated information to insert into the info file when the lock is
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self.transport = transport
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237
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,
227
FileExists, ResourceBusy), e:
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self._trace("... contention, %s", e)
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self._remove_pending_dir(tmpname)
230
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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self.transport.rename(tmpname, self._held_dir)
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except (errors.TransportError, PathError, DirectoryNotEmpty,
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FileExists, ResourceBusy), e:
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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)
252
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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258
# We must check we really got the lock, because Launchpad's sftp
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259
# 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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261
# 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
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# people, but probably worth trapping if something is wrong.
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info = self.peek()
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self._trace("after locking, info=%r", info)
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if info['nonce'] != self.nonce:
272
raise LockFailed(self, "lock was renamed into place, but "
274
if info.get('nonce') != self.nonce:
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275
self._trace("rename succeeded, "
245
276
"but lock is still held by someone else")
246
277
raise LockContention(self)
249
280
(time.time() - start_time) * 1000)
250
281
return self.nonce
283
def _handle_lock_contention(self, other_holder):
284
"""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
287
safe or appropriate to steal the lock, or just raise an exception.
289
If this function returns (without raising an exception) the lock will
292
:param other_holder: A LockHeldInfo for the current holder; note that
293
it might be None if the lock can be seen to be held but the info
296
if (other_holder is not None):
297
if other_holder.is_lock_holder_known_dead():
298
if self.get_config().get_user_option_as_bool(
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)
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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']:
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389
def break_lock(self):
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"""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
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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.
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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)
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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):
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"""Release a lock held by another process.
343
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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.
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
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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)
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self._check_not_locked()
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current_info = self.peek()
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452
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)
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']:
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def _check_not_locked(self):
377
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"""If the lock is held by this instance, raise an error."""
502
618
start = 'Lock owner changed for'
503
619
last_info = new_info
504
formatted_info = self._format_lock_info(new_info)
620
msg = u'%s lock %s %s.' % (start, lock_url, new_info)
505
621
if deadline_str is None:
506
622
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',
623
time.localtime(deadline))
625
msg += ('\nWill continue to try until %s, unless '
628
msg += '\nSee "bzr help break-lock" for more.'
629
self._report_function(msg)
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630
if (max_attempts is not None) and (attempt_count >= max_attempts):
524
631
self._trace("exceeded %d attempts")
525
632
raise LockContention(self)
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675
def lock_read(self):
566
676
"""Compatibility-mode shared lock.
568
LockDir doesn't support shared read-only locks, so this
678
LockDir doesn't support shared read-only locks, so this
569
679
just pretends that the lock is taken but really does nothing.
571
# At the moment Branches are commonly locked for read, but
681
# At the moment Branches are commonly locked for read, but
572
682
# we can't rely on that remotely. Once this is cleaned up,
573
# reenable this warning to prevent it coming back in
683
# reenable this warning to prevent it coming back in
574
684
# -- mbp 20060303
575
685
## warn("LockDir.lock_read falls back to write lock")
576
686
if self._lock_held or self._fake_read_lock:
577
687
raise LockContention(self)
578
688
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
690
def validate_token(self, token):
591
691
if token is not None:
592
692
info = self.peek()
604
704
if 'lock' not in debug.debug_flags:
606
706
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
return config.GlobalConfig()
715
class LockHeldInfo(object):
716
"""The information recorded about a held lock.
718
This information is recorded into the lock when it's taken, and it can be
719
read back by any process with access to the lockdir. It can be used, for
720
example, to tell the user who holds the lock, or to try to detect whether
721
the lock holder is still alive.
723
Prior to bzr 2.4 a simple dict was used instead of an object.
726
def __init__(self, info_dict):
727
self.info_dict = info_dict
730
"""Return a debugging representation of this object."""
731
return "%s(%r)" % (self.__class__.__name__, self.info_dict)
733
def __unicode__(self):
734
"""Return a user-oriented description of this object."""
735
d = self.to_readable_dict()
737
u'held by %(user)s on %(hostname)s (process #%(pid)s), '
738
u'acquired %(time_ago)s' % d)
740
def to_readable_dict(self):
741
"""Turn the holder info into a dict of human-readable attributes.
743
For example, the start time is presented relative to the current time,
744
rather than as seconds since the epoch.
746
Returns a list of [user, hostname, pid, time_ago] all as readable
749
start_time = self.info_dict.get('start_time')
750
if start_time is None:
751
time_ago = '(unknown)'
753
time_ago = format_delta(
754
time.time() - int(self.info_dict['start_time']))
755
user = self.info_dict.get('user', '<unknown>')
756
hostname = self.info_dict.get('hostname', '<unknown>')
757
pid = self.info_dict.get('pid', '<unknown>')
764
def get(self, field_name):
765
"""Return the contents of a field from the lock info, or None."""
766
return self.info_dict.get(field_name)
769
def for_this_process(cls, extra_holder_info):
770
"""Return a new LockHeldInfo for a lock taken by this process.
773
hostname=get_host_name(),
774
pid=str(os.getpid()),
775
nonce=rand_chars(20),
776
start_time=str(int(time.time())),
777
user=get_username_for_lock_info(),
779
if extra_holder_info is not None:
780
info.update(extra_holder_info)
784
s = rio.Stanza(**self.info_dict)
788
def from_info_file_bytes(cls, info_file_bytes):
789
"""Construct from the contents of the held file."""
790
lines = osutils.split_lines(info_file_bytes)
792
stanza = rio.read_stanza(lines)
793
except ValueError, e:
794
mutter('Corrupt lock info file: %r', lines)
795
raise LockCorrupt("could not parse lock info file: " + str(e),
798
# see bug 185013; we fairly often end up with the info file being
799
# empty after an interruption; we could log a message here but
800
# there may not be much we can say
803
return cls(stanza.as_dict())
805
def __cmp__(self, other):
806
"""Value comparison of lock holders."""
808
cmp(type(self), type(other))
809
or cmp(self.info_dict, other.info_dict))
811
def is_locked_by_this_process(self):
812
"""True if this process seems to be the current lock holder."""
814
self.get('hostname') == get_host_name()
815
and self.get('pid') == str(os.getpid())
816
and self.get('user') == get_username_for_lock_info())
818
def is_lock_holder_known_dead(self):
819
"""True if the lock holder process is known to be dead.
821
False if it's either known to be still alive, or if we just can't tell.
823
We can be fairly sure the lock holder is dead if it declared the same
824
hostname and there is no process with the given pid alive. If people
825
have multiple machines with the same hostname this may cause trouble.
827
This doesn't check whether the lock holder is in fact the same process
828
calling this method. (In that case it will return true.)
830
if self.get('hostname') != get_host_name():
832
if self.get('hostname') == 'localhost':
835
if self.get('user') != get_username_for_lock_info():
836
# Could well be another local process by a different user, but
837
# just to be safe we won't conclude about this either.
839
pid_str = self.info_dict.get('pid', None)
841
mutter("no pid recorded in %r" % (self, ))
846
mutter("can't parse pid %r from %r"
849
return osutils.is_local_pid_dead(pid)
852
def get_username_for_lock_info():
853
"""Get a username suitable for putting into a lock.
855
It's ok if what's written here is not a proper email address as long
856
as it gives some clue who the user is.
859
return config.GlobalConfig().username()
860
except errors.NoWhoami:
861
return osutils.getuser_unicode()
added
removed
bzrlib/lockdir.py
