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# 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
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115
from bzrlib.errors import (
125
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DirectoryNotEmpty,
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LockBreakMismatch,
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129
from bzrlib.trace import mutter, note
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from bzrlib.osutils import format_delta, rand_chars, get_host_name
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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(), """
143
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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# files/dirs created.
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_DEFAULT_TIMEOUT_SECONDS = 30
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_DEFAULT_TIMEOUT_SECONDS = 300
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_DEFAULT_POLL_SECONDS = 1.0
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class LockDir(lock.Lock):
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"""Write-lock guarding access to data.
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class LockDir(object):
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"""Write-lock guarding access to data."""
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__INFO_NAME = '/info'
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def __init__(self, transport, path, file_modebits=0644, dir_modebits=0755,
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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
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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:
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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)
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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:
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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
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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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raise LockFailed(self, "lock was renamed into place, but "
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if info.get('nonce') != self.nonce:
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if info['nonce'] != self.nonce:
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self._trace("rename succeeded, "
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"but lock is still held by someone else")
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raise LockContention(self)
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(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
287
safe or appropriate to steal the lock, or just raise an exception.
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If this function returns (without raising an exception) the lock will
292
:param other_holder: A LockHeldInfo for the current holder; note that
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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('locks.steal_dead'):
299
ui.ui_factory.show_user_warning(
301
lock_url=urlutils.join(self.transport.base, self.path),
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other_holder_info=unicode(other_holder))
303
self.force_break(other_holder)
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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
311
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
312
256
dirs don't clutter up the lockdir.
314
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self._trace("remove %s", tmpname)
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self.transport.delete_tree(tmpname)
380
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self._trace("... unlock succeeded after %dms",
381
323
(time.time() - start_time) * 1000)
382
result = lock.LockResult(self.transport.abspath(self.path),
384
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
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This is a UI centric function: it uses the bzrlib.ui.ui_factory to
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prompt for input if a lock is detected and there is any doubt about
392
it possibly being still active. force_break is the non-interactive
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:returns: LockResult for the broken lock.
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it possibly being still active.
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self._check_not_locked()
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holder_info = self.peek()
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except LockCorrupt, e:
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# The lock info is corrupt.
402
if ui.ui_factory.get_boolean(u"Break (corrupt %r)" % (self,)):
403
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:
406
if ui.ui_factory.confirm_action(
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u"Break %(lock_info)s",
408
'bzrlib.lockdir.break',
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dict(lock_info=unicode(holder_info))):
410
result = self.force_break(holder_info)
411
ui.ui_factory.show_message(
412
"Broke lock %s" % result.lock_url)
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lock_info = '\n'.join(self._format_lock_info(holder_info))
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if bzrlib.ui.ui_factory.get_boolean("Break %s" % lock_info):
337
self.force_break(holder_info)
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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.
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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,
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LockBreakMismatch is raised.
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After the lock is broken it will not be held by any process.
422
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.
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:param dead_holder_info:
426
Must be the result of a previous LockDir.peek() call; this is used
427
to check that it's still held by the same process that the user
428
decided was dead. If this is not the current holder,
429
LockBreakMismatch is raised.
431
:returns: LockResult for the broken lock.
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if not isinstance(dead_holder_info, LockHeldInfo):
355
if not isinstance(dead_holder_info, dict):
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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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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)
453
result = lock.LockResult(self.transport.abspath(self.path),
454
current_info.get('nonce'))
455
for hook in self.hooks['lock_broken']:
459
def force_break_corrupt(self, corrupt_info_lines):
460
"""Release a lock that has been corrupted.
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This is very similar to force_break, it except it doesn't assume that
463
self.peek() can work.
465
:param corrupt_info_lines: the lines of the corrupted info file, used
466
to check that the lock hasn't changed between reading the (corrupt)
467
info file and calling force_break_corrupt.
469
# XXX: this copes with unparseable info files, but what about missing
470
# info files? Or missing lock dirs?
471
self._check_not_locked()
472
tmpname = '%s/broken.%s.tmp' % (self.path, rand_chars(20))
473
self.transport.rename(self._held_dir, tmpname)
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# check that we actually broke the right lock, not someone else;
475
# there's a small race window between checking it and doing the
477
broken_info_path = tmpname + self.__INFO_NAME
478
broken_content = self.transport.get_bytes(broken_info_path)
479
broken_lines = osutils.split_lines(broken_content)
480
if broken_lines != corrupt_info_lines:
481
raise LockBreakMismatch(self, broken_lines, corrupt_info_lines)
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self.transport.delete(broken_info_path)
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self.transport.rmdir(tmpname)
484
result = lock.LockResult(self.transport.abspath(self.path))
485
for hook in self.hooks['lock_broken']:
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def _check_not_locked(self):
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"""If the lock is held by this instance, raise an error."""
616
502
start = 'Lock owner changed for'
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last_info = new_info
618
msg = u'%s lock %s %s.' % (start, lock_url, new_info)
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formatted_info = self._format_lock_info(new_info)
619
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if deadline_str is None:
620
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deadline_str = time.strftime('%H:%M:%S',
621
time.localtime(deadline))
623
msg += ('\nWill continue to try until %s, unless '
626
msg += '\nSee "bzr help break-lock" for more.'
627
self._report_function(msg)
507
time.localtime(deadline))
508
lock_url = self.transport.abspath(self.path)
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self._report_function('%s %s\n'
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'%s\n' # locked ... ago
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'Will continue to try until %s, unless '
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'If you\'re sure that it\'s not being '
515
'modified, use bzr break-lock %s',
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if (max_attempts is not None) and (attempt_count >= max_attempts):
629
524
self._trace("exceeded %d attempts")
630
525
raise LockContention(self)
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565
def lock_read(self):
674
566
"""Compatibility-mode shared lock.
676
LockDir doesn't support shared read-only locks, so this
568
LockDir doesn't support shared read-only locks, so this
677
569
just pretends that the lock is taken but really does nothing.
679
# At the moment Branches are commonly locked for read, but
571
# At the moment Branches are commonly locked for read, but
680
572
# we can't rely on that remotely. Once this is cleaned up,
681
# reenable this warning to prevent it coming back in
573
# reenable this warning to prevent it coming back in
682
574
# -- mbp 20060303
683
575
## warn("LockDir.lock_read falls back to write lock")
684
576
if self._lock_held or self._fake_read_lock:
685
577
raise LockContention(self)
686
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),),
688
590
def validate_token(self, token):
689
591
if token is not None:
690
592
info = self.peek()
702
604
if 'lock' not in debug.debug_flags:
704
606
mutter(str(self) + ": " + (format % args))
706
def get_config(self):
707
"""Get the configuration that governs this lockdir."""
708
# XXX: This really should also use the locationconfig at least, but
709
# that seems a bit hard to hook up at the moment. -- mbp 20110329
710
# FIXME: The above is still true ;) -- vila 20110811
711
return config.GlobalStack()
714
class LockHeldInfo(object):
715
"""The information recorded about a held lock.
717
This information is recorded into the lock when it's taken, and it can be
718
read back by any process with access to the lockdir. It can be used, for
719
example, to tell the user who holds the lock, or to try to detect whether
720
the lock holder is still alive.
722
Prior to bzr 2.4 a simple dict was used instead of an object.
725
def __init__(self, info_dict):
726
self.info_dict = info_dict
729
"""Return a debugging representation of this object."""
730
return "%s(%r)" % (self.__class__.__name__, self.info_dict)
732
def __unicode__(self):
733
"""Return a user-oriented description of this object."""
734
d = self.to_readable_dict()
736
u'held by %(user)s on %(hostname)s (process #%(pid)s), '
737
u'acquired %(time_ago)s' % d)
739
def to_readable_dict(self):
740
"""Turn the holder info into a dict of human-readable attributes.
742
For example, the start time is presented relative to the current time,
743
rather than as seconds since the epoch.
745
Returns a list of [user, hostname, pid, time_ago] all as readable
748
start_time = self.info_dict.get('start_time')
749
if start_time is None:
750
time_ago = '(unknown)'
752
time_ago = format_delta(
753
time.time() - int(self.info_dict['start_time']))
754
user = self.info_dict.get('user', '<unknown>')
755
hostname = self.info_dict.get('hostname', '<unknown>')
756
pid = self.info_dict.get('pid', '<unknown>')
763
def get(self, field_name):
764
"""Return the contents of a field from the lock info, or None."""
765
return self.info_dict.get(field_name)
768
def for_this_process(cls, extra_holder_info):
769
"""Return a new LockHeldInfo for a lock taken by this process.
772
hostname=get_host_name(),
773
pid=str(os.getpid()),
774
nonce=rand_chars(20),
775
start_time=str(int(time.time())),
776
user=get_username_for_lock_info(),
778
if extra_holder_info is not None:
779
info.update(extra_holder_info)
783
s = rio.Stanza(**self.info_dict)
787
def from_info_file_bytes(cls, info_file_bytes):
788
"""Construct from the contents of the held file."""
789
lines = osutils.split_lines(info_file_bytes)
791
stanza = rio.read_stanza(lines)
792
except ValueError, e:
793
mutter('Corrupt lock info file: %r', lines)
794
raise LockCorrupt("could not parse lock info file: " + str(e),
797
# see bug 185013; we fairly often end up with the info file being
798
# empty after an interruption; we could log a message here but
799
# there may not be much we can say
802
return cls(stanza.as_dict())
804
def __cmp__(self, other):
805
"""Value comparison of lock holders."""
807
cmp(type(self), type(other))
808
or cmp(self.info_dict, other.info_dict))
810
def is_locked_by_this_process(self):
811
"""True if this process seems to be the current lock holder."""
813
self.get('hostname') == get_host_name()
814
and self.get('pid') == str(os.getpid())
815
and self.get('user') == get_username_for_lock_info())
817
def is_lock_holder_known_dead(self):
818
"""True if the lock holder process is known to be dead.
820
False if it's either known to be still alive, or if we just can't tell.
822
We can be fairly sure the lock holder is dead if it declared the same
823
hostname and there is no process with the given pid alive. If people
824
have multiple machines with the same hostname this may cause trouble.
826
This doesn't check whether the lock holder is in fact the same process
827
calling this method. (In that case it will return true.)
829
if self.get('hostname') != get_host_name():
831
if self.get('hostname') == 'localhost':
834
if self.get('user') != get_username_for_lock_info():
835
# Could well be another local process by a different user, but
836
# just to be safe we won't conclude about this either.
838
pid_str = self.info_dict.get('pid', None)
840
mutter("no pid recorded in %r" % (self, ))
845
mutter("can't parse pid %r from %r"
848
return osutils.is_local_pid_dead(pid)
851
def get_username_for_lock_info():
852
"""Get a username suitable for putting into a lock.
854
It's ok if what's written here is not a proper email address as long
855
as it gives some clue who the user is.
858
return config.GlobalConfig().username()
859
except errors.NoWhoami:
860
return osutils.getuser_unicode()
added
removed
bzrlib/lockdir.py
