1
# Copyright (C) 2005, 2006, 2008, 2009 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
from bzrlib.lazy_import import lazy_import
18
lazy_import(globals(), """
32
from bzrlib.decorators import (
37
# XXX: The tracking here of lock counts and whether the lock is held is
38
# somewhat redundant with what's done in LockDir; the main difference is that
39
# LockableFiles permits reentrancy.
41
class _LockWarner(object):
42
"""Hold a counter for a lock and warn if GCed while the count is >= 1.
44
This is separate from LockableFiles because putting a __del__ on
45
LockableFiles can result in uncollectable cycles.
48
def __init__(self, repr):
53
if self.lock_count >= 1:
54
# There should have been a try/finally to unlock this.
55
warnings.warn("%r was gc'd while locked" % self.repr)
58
class LockableFiles(object):
59
"""Object representing a set of related files locked within the same scope.
61
This coordinates access to the lock along with providing a transaction.
63
LockableFiles manage a lock count and can be locked repeatedly by
64
a single caller. (The underlying lock implementation generally does not
67
Instances of this class are often called control_files.
69
This class is now deprecated; code should move to using the Transport
70
directly for file operations and using the lock or CountedLock for
73
:ivar _lock: The real underlying lock (e.g. a LockDir)
74
:ivar _counted_lock: A lock decorated with a semaphore, so that it
78
# _lock_mode: None, or 'r' or 'w'
80
# _lock_count: If _lock_mode is true, a positive count of the number of
81
# times the lock has been taken *by this process*.
83
def __init__(self, transport, lock_name, lock_class):
84
"""Create a LockableFiles group
86
:param transport: Transport pointing to the directory holding the
87
control files and lock.
88
:param lock_name: Name of the lock guarding these files.
89
:param lock_class: Class of lock strategy to use: typically
90
either LockDir or TransportLock.
92
self._transport = transport
93
self.lock_name = lock_name
94
self._transaction = None
95
self._lock_mode = None
96
self._lock_warner = _LockWarner(repr(self))
98
esc_name = self._escape(lock_name)
99
self._lock = lock_class(transport, esc_name,
100
file_modebits=self._file_mode,
101
dir_modebits=self._dir_mode)
102
self._counted_lock = counted_lock.CountedLock(self._lock)
104
def create_lock(self):
107
This should normally be called only when the LockableFiles directory
108
is first created on disk.
110
self._lock.create(mode=self._dir_mode)
113
return '%s(%r)' % (self.__class__.__name__,
116
return 'LockableFiles(%s, %s)' % (self.lock_name, self._transport.base)
118
def break_lock(self):
119
"""Break the lock of this lockable files group if it is held.
121
The current ui factory will be used to prompt for user conformation.
123
self._lock.break_lock()
125
def _escape(self, file_or_path):
126
"""DEPRECATED: Do not use outside this class"""
127
if not isinstance(file_or_path, basestring):
128
file_or_path = '/'.join(file_or_path)
129
if file_or_path == '':
131
return urlutils.escape(osutils.safe_unicode(file_or_path))
133
def _find_modes(self):
134
"""Determine the appropriate modes for files and directories.
136
:deprecated: Replaced by BzrDir._find_creation_modes.
138
# XXX: The properties created by this can be removed or deprecated
139
# once all the _get_text_store methods etc no longer use them.
142
st = self._transport.stat('.')
143
except errors.TransportNotPossible:
144
self._dir_mode = 0755
145
self._file_mode = 0644
147
# Check the directory mode, but also make sure the created
148
# directories and files are read-write for this user. This is
149
# mostly a workaround for filesystems which lie about being able to
150
# write to a directory (cygwin & win32)
151
self._dir_mode = (st.st_mode & 07777) | 00700
152
# Remove the sticky and execute bits for files
153
self._file_mode = self._dir_mode & ~07111
155
def leave_in_place(self):
156
"""Set this LockableFiles to not clear the physical lock on unlock."""
157
self._lock.leave_in_place()
159
def dont_leave_in_place(self):
160
"""Set this LockableFiles to clear the physical lock on unlock."""
161
self._lock.dont_leave_in_place()
163
def lock_write(self, token=None):
164
"""Lock this group of files for writing.
166
:param token: if this is already locked, then lock_write will fail
167
unless the token matches the existing lock.
168
:returns: a token if this instance supports tokens, otherwise None.
169
:raises TokenLockingNotSupported: when a token is given but this
170
instance doesn't support using token locks.
171
:raises MismatchedToken: if the specified token doesn't match the token
172
of the existing lock.
174
A token should be passed in if you know that you have locked the object
175
some other way, and need to synchronise this object's state with that
178
# TODO: Upgrade locking to support using a Transport,
179
# and potentially a remote locking protocol
181
if self._lock_mode != 'w' or not self.get_transaction().writeable():
182
raise errors.ReadOnlyError(self)
183
self._lock.validate_token(token)
184
self._lock_warner.lock_count += 1
185
return self._token_from_lock
187
token_from_lock = self._lock.lock_write(token=token)
188
#traceback.print_stack()
189
self._lock_mode = 'w'
190
self._lock_warner.lock_count = 1
191
self._set_write_transaction()
192
self._token_from_lock = token_from_lock
193
return token_from_lock
197
if self._lock_mode not in ('r', 'w'):
198
raise ValueError("invalid lock mode %r" % (self._lock_mode,))
199
self._lock_warner.lock_count += 1
201
self._lock.lock_read()
202
#traceback.print_stack()
203
self._lock_mode = 'r'
204
self._lock_warner.lock_count = 1
205
self._set_read_transaction()
207
def _set_read_transaction(self):
208
"""Setup a read transaction."""
209
self._set_transaction(transactions.ReadOnlyTransaction())
210
# 5K may be excessive, but hey, its a knob.
211
self.get_transaction().set_cache_size(5000)
213
def _set_write_transaction(self):
214
"""Setup a write transaction."""
215
self._set_transaction(transactions.WriteTransaction())
217
@only_raises(errors.LockNotHeld, errors.LockBroken)
219
if not self._lock_mode:
220
return lock.cant_unlock_not_held(self)
221
if self._lock_warner.lock_count > 1:
222
self._lock_warner.lock_count -= 1
224
#traceback.print_stack()
225
self._finish_transaction()
229
self._lock_mode = self._lock_warner.lock_count = None
232
def _lock_count(self):
233
return self._lock_warner.lock_count
236
"""Return true if this LockableFiles group is locked"""
237
return self._lock_warner.lock_count >= 1
239
def get_physical_lock_status(self):
240
"""Return physical lock status.
242
Returns true if a lock is held on the transport. If no lock is held, or
243
the underlying locking mechanism does not support querying lock
244
status, false is returned.
247
return self._lock.peek() is not None
248
except NotImplementedError:
251
def get_transaction(self):
252
"""Return the current active transaction.
254
If no transaction is active, this returns a passthrough object
255
for which all data is immediately flushed and no caching happens.
257
if self._transaction is None:
258
return transactions.PassThroughTransaction()
260
return self._transaction
262
def _set_transaction(self, new_transaction):
263
"""Set a new active transaction."""
264
if self._transaction is not None:
265
raise errors.LockError('Branch %s is in a transaction already.' %
267
self._transaction = new_transaction
269
def _finish_transaction(self):
270
"""Exit the current transaction."""
271
if self._transaction is None:
272
raise errors.LockError('Branch %s is not in a transaction' %
274
transaction = self._transaction
275
self._transaction = None
279
class TransportLock(object):
280
"""Locking method which uses transport-dependent locks.
282
On the local filesystem these transform into OS-managed locks.
284
These do not guard against concurrent access via different
287
This is suitable for use only in WorkingTrees (which are at present
290
def __init__(self, transport, escaped_name, file_modebits, dir_modebits):
291
self._transport = transport
292
self._escaped_name = escaped_name
293
self._file_modebits = file_modebits
294
self._dir_modebits = dir_modebits
296
def break_lock(self):
297
raise NotImplementedError(self.break_lock)
299
def leave_in_place(self):
300
raise NotImplementedError(self.leave_in_place)
302
def dont_leave_in_place(self):
303
raise NotImplementedError(self.dont_leave_in_place)
305
def lock_write(self, token=None):
306
if token is not None:
307
raise errors.TokenLockingNotSupported(self)
308
self._lock = self._transport.lock_write(self._escaped_name)
311
self._lock = self._transport.lock_read(self._escaped_name)
318
raise NotImplementedError()
320
def create(self, mode=None):
321
"""Create lock mechanism"""
322
# for old-style locks, create the file now
323
self._transport.put_bytes(self._escaped_name, '',
324
mode=self._file_modebits)
326
def validate_token(self, token):
327
if token is not None:
328
raise errors.TokenLockingNotSupported(self)
added
removed
bzrlib/lockable_files.py
