36
from __future__ import absolute_import
41
from bzrlib.errors import LockError
42
from bzrlib.osutils import realpath
43
from bzrlib.trace import mutter
46
class _base_Lock(object):
49
from bzrlib.hooks import Hooks
50
from bzrlib.i18n import gettext
52
class LockHooks(Hooks):
55
Hooks.__init__(self, "bzrlib.lock", "Lock.hooks")
56
self.add_hook('lock_acquired',
57
"Called with a bzrlib.lock.LockResult when a physical lock is "
59
self.add_hook('lock_released',
60
"Called with a bzrlib.lock.LockResult when a physical lock is "
62
self.add_hook('lock_broken',
63
"Called with a bzrlib.lock.LockResult when a physical lock is "
68
"""Base class for locks.
70
:cvar hooks: Hook dictionary for operations on locks.
76
class LockResult(object):
77
"""Result of an operation on a lock; passed to a hook"""
79
def __init__(self, lock_url, details=None):
80
"""Create a lock result for lock with optional details about the lock."""
81
self.lock_url = lock_url
82
self.details = details
84
def __eq__(self, other):
85
return self.lock_url == other.lock_url and self.details == other.details
88
return '%s(%s, %s)' % (self.__class__.__name__,
89
self.lock_url, self.details)
92
class LogicalLockResult(object):
93
"""The result of a lock_read/lock_write/lock_tree_write call on lockables.
95
:ivar unlock: A callable which will unlock the lock.
98
def __init__(self, unlock):
102
return "LogicalLockResult(%s)" % (self.unlock)
106
def cant_unlock_not_held(locked_object):
107
"""An attempt to unlock failed because the object was not locked.
109
This provides a policy point from which we can generate either a warning
112
# This is typically masking some other error and called from a finally
113
# block, so it's useful to have the option not to generate a new error
114
# here. You can use -Werror to make it fatal. It should possibly also
116
if 'unlock' in debug.debug_flags:
117
warnings.warn("%r is already unlocked" % (locked_object,),
120
raise errors.LockNotHeld(locked_object)
130
have_ctypes_win32 = False
131
if sys.platform == 'win32':
134
import win32file, pywintypes, winerror
141
have_ctypes_win32 = True
146
class _OSLock(object):
48
152
def _open(self, filename, filemode):
153
self.filename = osutils.realpath(filename)
50
self.f = open(filename, filemode)
155
self.f = open(self.filename, filemode)
52
157
except IOError, e:
158
if e.errno in (errno.EACCES, errno.EPERM):
159
raise errors.LockFailed(self.filename, str(e))
53
160
if e.errno != errno.ENOENT:
56
163
# maybe this is an old branch (before may 2005)
57
mutter("trying to create missing branch lock %r", filename)
59
self.f = open(filename, 'wb+')
164
trace.mutter("trying to create missing lock %r", self.filename)
166
self.f = open(self.filename, 'wb+')
170
"""Clear the self.f attribute cleanly."""
64
from warnings import warn
65
warn("lock on %r not released" % self.f)
69
176
raise NotImplementedError()
72
############################################################
79
class _fcntl_FileLock(_base_Lock):
184
class _fcntl_FileLock(_OSLock):
83
186
def _unlock(self):
84
187
fcntl.lockf(self.f, fcntl.LOCK_UN)
88
"""Clear the self.f attribute cleanly."""
93
191
class _fcntl_WriteLock(_fcntl_FileLock):
97
195
def __init__(self, filename):
98
# standard IO errors get exposed directly.
99
self._open(filename, 'wb')
196
super(_fcntl_WriteLock, self).__init__()
197
# Check we can grab a lock before we actually open the file.
198
self.filename = osutils.realpath(filename)
199
if self.filename in _fcntl_WriteLock._open_locks:
201
raise errors.LockContention(self.filename)
202
if self.filename in _fcntl_ReadLock._open_locks:
203
if 'strict_locks' in debug.debug_flags:
205
raise errors.LockContention(self.filename)
207
trace.mutter('Write lock taken w/ an open read lock on: %s'
210
self._open(self.filename, 'rb+')
211
# reserve a slot for this lock - even if the lockf call fails,
212
# at this point unlock() will be called, because self.f is set.
213
# TODO: make this fully threadsafe, if we decide we care.
214
_fcntl_WriteLock._open_locks.add(self.filename)
101
self.filename = realpath(filename)
102
if self.filename in self.open_locks:
104
raise LockError("Lock already held.")
105
# reserve a slot for this lock - even if the lockf call fails,
106
# at thisi point unlock() will be called, because self.f is set.
107
# TODO: make this fully threadsafe, if we decide we care.
108
self.open_locks[self.filename] = self.filename
109
fcntl.lockf(self.f, fcntl.LOCK_EX)
216
# LOCK_NB will cause IOError to be raised if we can't grab a
218
fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
110
219
except IOError, e:
220
if e.errno in (errno.EAGAIN, errno.EACCES):
221
# We couldn't grab the lock
111
223
# we should be more precise about whats a locking
112
224
# error and whats a random-other error
225
raise errors.LockContention(self.filename, e)
115
227
def unlock(self):
116
del self.open_locks[self.filename]
228
_fcntl_WriteLock._open_locks.remove(self.filename)
120
232
class _fcntl_ReadLock(_fcntl_FileLock):
122
236
def __init__(self, filename):
123
# standard IO errors get exposed directly.
237
super(_fcntl_ReadLock, self).__init__()
238
self.filename = osutils.realpath(filename)
239
if self.filename in _fcntl_WriteLock._open_locks:
240
if 'strict_locks' in debug.debug_flags:
241
# We raise before calling _open so we don't need to
243
raise errors.LockContention(self.filename)
245
trace.mutter('Read lock taken w/ an open write lock on: %s'
247
_fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
248
_fcntl_ReadLock._open_locks[self.filename] += 1
124
249
self._open(filename, 'rb')
126
fcntl.lockf(self.f, fcntl.LOCK_SH)
251
# LOCK_NB will cause IOError to be raised if we can't grab a
253
fcntl.lockf(self.f, fcntl.LOCK_SH | fcntl.LOCK_NB)
127
254
except IOError, e:
128
255
# we should be more precise about whats a locking
129
256
# error and whats a random-other error
257
raise errors.LockContention(self.filename, e)
132
259
def unlock(self):
260
count = _fcntl_ReadLock._open_locks[self.filename]
262
del _fcntl_ReadLock._open_locks[self.filename]
264
_fcntl_ReadLock._open_locks[self.filename] = count - 1
136
WriteLock = _fcntl_WriteLock
137
ReadLock = _fcntl_ReadLock
142
import win32con, win32file, pywintypes
145
LOCK_SH = 0 # the default
146
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
147
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
149
class _w32c_FileLock(_base_Lock):
150
def _lock(self, filename, openmode, lockmode):
152
self._open(filename, openmode)
153
self.hfile = win32file._get_osfhandle(self.f.fileno())
154
overlapped = pywintypes.OVERLAPPED()
155
win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000, overlapped)
164
overlapped = pywintypes.OVERLAPPED()
165
win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
172
class _w32c_ReadLock(_w32c_FileLock):
173
def __init__(self, filename):
174
_w32c_FileLock._lock(self, filename, 'rb',
177
class _w32c_WriteLock(_w32c_FileLock):
178
def __init__(self, filename):
179
_w32c_FileLock._lock(self, filename, 'wb',
183
WriteLock = _w32c_WriteLock
184
ReadLock = _w32c_ReadLock
191
# Unfortunately, msvcrt.locking() doesn't distinguish between
192
# read locks and write locks. Also, the way the combinations
193
# work to get non-blocking is not the same, so we
194
# have to write extra special functions here.
197
class _msvc_FileLock(_base_Lock):
207
class _msvc_ReadLock(_msvc_FileLock):
208
def __init__(self, filename):
209
_msvc_lock(self._open(filename, 'rb'), self.LOCK_SH)
212
class _msvc_WriteLock(_msvc_FileLock):
213
def __init__(self, filename):
214
_msvc_lock(self._open(filename, 'wb'), self.LOCK_EX)
217
def _msvc_lock(f, flags):
219
# Unfortunately, msvcrt.LK_RLCK is equivalent to msvcrt.LK_LOCK
220
# according to the comments, LK_RLCK is open the lock for writing.
222
# Unfortunately, msvcrt.locking() also has the side effect that it
223
# will only block for 10 seconds at most, and then it will throw an
224
# exception, this isn't terrible, though.
231
fpos = os.lseek(fn, 0,0)
234
if flags & _msvc_FileLock.LOCK_SH:
235
if flags & _msvc_FileLock.LOCK_NB:
236
lock_mode = msvcrt.LK_NBLCK
238
lock_mode = msvcrt.LK_LOCK
239
elif flags & _msvc_FileLock.LOCK_EX:
240
if flags & _msvc_FileLock.LOCK_NB:
241
lock_mode = msvcrt.LK_NBRLCK
243
lock_mode = msvcrt.LK_RLCK
245
raise ValueError('Invalid lock mode: %r' % flags)
247
msvcrt.locking(fn, lock_mode, -1)
249
os.lseek(fn, fpos, 0)
261
fpos = os.lseek(fn, 0,0)
265
msvcrt.locking(fn, msvcrt.LK_UNLCK, -1)
267
os.lseek(fn, fpos, 0)
272
WriteLock = _msvc_WriteLock
273
ReadLock = _msvc_ReadLock
275
raise NotImplementedError("please write a locking method "
276
"for platform %r" % sys.platform)
267
def temporary_write_lock(self):
268
"""Try to grab a write lock on the file.
270
On platforms that support it, this will upgrade to a write lock
271
without unlocking the file.
272
Otherwise, this will release the read lock, and try to acquire a
275
:return: A token which can be used to switch back to a read lock.
277
if self.filename in _fcntl_WriteLock._open_locks:
278
raise AssertionError('file already locked: %r'
281
wlock = _fcntl_TemporaryWriteLock(self)
282
except errors.LockError:
283
# We didn't unlock, so we can just return 'self'
288
class _fcntl_TemporaryWriteLock(_OSLock):
289
"""A token used when grabbing a temporary_write_lock.
291
Call restore_read_lock() when you are done with the write lock.
294
def __init__(self, read_lock):
295
super(_fcntl_TemporaryWriteLock, self).__init__()
296
self._read_lock = read_lock
297
self.filename = read_lock.filename
299
count = _fcntl_ReadLock._open_locks[self.filename]
301
# Something else also has a read-lock, so we cannot grab a
303
raise errors.LockContention(self.filename)
305
if self.filename in _fcntl_WriteLock._open_locks:
306
raise AssertionError('file already locked: %r'
309
# See if we can open the file for writing. Another process might
310
# have a read lock. We don't use self._open() because we don't want
311
# to create the file if it exists. That would have already been
312
# done by _fcntl_ReadLock
314
new_f = open(self.filename, 'rb+')
316
if e.errno in (errno.EACCES, errno.EPERM):
317
raise errors.LockFailed(self.filename, str(e))
320
# LOCK_NB will cause IOError to be raised if we can't grab a
322
fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
324
# TODO: Raise a more specific error based on the type of error
325
raise errors.LockContention(self.filename, e)
326
_fcntl_WriteLock._open_locks.add(self.filename)
330
def restore_read_lock(self):
331
"""Restore the original ReadLock."""
332
# For fcntl, since we never released the read lock, just release the
333
# write lock, and return the original lock.
334
fcntl.lockf(self.f, fcntl.LOCK_UN)
336
_fcntl_WriteLock._open_locks.remove(self.filename)
337
# Avoid reference cycles
338
read_lock = self._read_lock
339
self._read_lock = None
343
_lock_classes.append(('fcntl', _fcntl_WriteLock, _fcntl_ReadLock))
346
if have_pywin32 and sys.platform == 'win32':
347
if os.path.supports_unicode_filenames:
348
# for Windows NT/2K/XP/etc
349
win32file_CreateFile = win32file.CreateFileW
352
win32file_CreateFile = win32file.CreateFile
354
class _w32c_FileLock(_OSLock):
356
def _open(self, filename, access, share, cflags, pymode):
357
self.filename = osutils.realpath(filename)
359
self._handle = win32file_CreateFile(filename, access, share,
360
None, win32file.OPEN_ALWAYS,
361
win32file.FILE_ATTRIBUTE_NORMAL, None)
362
except pywintypes.error, e:
363
if e.args[0] == winerror.ERROR_ACCESS_DENIED:
364
raise errors.LockFailed(filename, e)
365
if e.args[0] == winerror.ERROR_SHARING_VIOLATION:
366
raise errors.LockContention(filename, e)
368
fd = win32file._open_osfhandle(self._handle, cflags)
369
self.f = os.fdopen(fd, pymode)
377
class _w32c_ReadLock(_w32c_FileLock):
378
def __init__(self, filename):
379
super(_w32c_ReadLock, self).__init__()
380
self._open(filename, win32file.GENERIC_READ,
381
win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
383
def temporary_write_lock(self):
384
"""Try to grab a write lock on the file.
386
On platforms that support it, this will upgrade to a write lock
387
without unlocking the file.
388
Otherwise, this will release the read lock, and try to acquire a
391
:return: A token which can be used to switch back to a read lock.
393
# I can't find a way to upgrade a read lock to a write lock without
394
# unlocking first. So here, we do just that.
397
wlock = _w32c_WriteLock(self.filename)
398
except errors.LockError:
399
return False, _w32c_ReadLock(self.filename)
403
class _w32c_WriteLock(_w32c_FileLock):
404
def __init__(self, filename):
405
super(_w32c_WriteLock, self).__init__()
407
win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
410
def restore_read_lock(self):
411
"""Restore the original ReadLock."""
412
# For win32 we had to completely let go of the original lock, so we
413
# just unlock and create a new read lock.
415
return _w32c_ReadLock(self.filename)
418
_lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
421
if have_ctypes_win32:
422
from ctypes.wintypes import DWORD, LPCSTR, LPCWSTR
423
LPSECURITY_ATTRIBUTES = ctypes.c_void_p # used as NULL no need to declare
424
HANDLE = ctypes.c_int # rather than unsigned as in ctypes.wintypes
425
if os.path.supports_unicode_filenames:
426
_function_name = "CreateFileW"
429
_function_name = "CreateFileA"
430
class LPTSTR(LPCSTR):
431
def __new__(cls, obj):
432
return LPCSTR.__new__(cls, obj.encode("mbcs"))
434
# CreateFile <http://msdn.microsoft.com/en-us/library/aa363858.aspx>
435
_CreateFile = ctypes.WINFUNCTYPE(
436
HANDLE, # return value
438
DWORD, # dwDesiredAccess
440
LPSECURITY_ATTRIBUTES, # lpSecurityAttributes
441
DWORD, # dwCreationDisposition
442
DWORD, # dwFlagsAndAttributes
443
HANDLE # hTemplateFile
444
)((_function_name, ctypes.windll.kernel32))
446
INVALID_HANDLE_VALUE = -1
448
GENERIC_READ = 0x80000000
449
GENERIC_WRITE = 0x40000000
452
FILE_ATTRIBUTE_NORMAL = 128
454
ERROR_ACCESS_DENIED = 5
455
ERROR_SHARING_VIOLATION = 32
457
class _ctypes_FileLock(_OSLock):
459
def _open(self, filename, access, share, cflags, pymode):
460
self.filename = osutils.realpath(filename)
461
handle = _CreateFile(filename, access, share, None, OPEN_ALWAYS,
462
FILE_ATTRIBUTE_NORMAL, 0)
463
if handle in (INVALID_HANDLE_VALUE, 0):
464
e = ctypes.WinError()
465
if e.args[0] == ERROR_ACCESS_DENIED:
466
raise errors.LockFailed(filename, e)
467
if e.args[0] == ERROR_SHARING_VIOLATION:
468
raise errors.LockContention(filename, e)
470
fd = msvcrt.open_osfhandle(handle, cflags)
471
self.f = os.fdopen(fd, pymode)
478
class _ctypes_ReadLock(_ctypes_FileLock):
479
def __init__(self, filename):
480
super(_ctypes_ReadLock, self).__init__()
481
self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
484
def temporary_write_lock(self):
485
"""Try to grab a write lock on the file.
487
On platforms that support it, this will upgrade to a write lock
488
without unlocking the file.
489
Otherwise, this will release the read lock, and try to acquire a
492
:return: A token which can be used to switch back to a read lock.
494
# I can't find a way to upgrade a read lock to a write lock without
495
# unlocking first. So here, we do just that.
498
wlock = _ctypes_WriteLock(self.filename)
499
except errors.LockError:
500
return False, _ctypes_ReadLock(self.filename)
503
class _ctypes_WriteLock(_ctypes_FileLock):
504
def __init__(self, filename):
505
super(_ctypes_WriteLock, self).__init__()
506
self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
509
def restore_read_lock(self):
510
"""Restore the original ReadLock."""
511
# For win32 we had to completely let go of the original lock, so we
512
# just unlock and create a new read lock.
514
return _ctypes_ReadLock(self.filename)
517
_lock_classes.append(('ctypes', _ctypes_WriteLock, _ctypes_ReadLock))
520
if len(_lock_classes) == 0:
521
raise NotImplementedError(
522
"We must have one of fcntl, pywin32, or ctypes available"
523
" to support OS locking."
527
# We default to using the first available lock class.
528
_lock_type, WriteLock, ReadLock = _lock_classes[0]
531
class _RelockDebugMixin(object):
532
"""Mixin support for -Drelock flag.
534
Add this as a base class then call self._note_lock with 'r' or 'w' when
535
acquiring a read- or write-lock. If this object was previously locked (and
536
locked the same way), and -Drelock is set, then this will trace.note a
542
def _note_lock(self, lock_type):
543
if 'relock' in debug.debug_flags and self._prev_lock == lock_type:
548
trace.note(gettext('{0!r} was {1} locked again'), self, type_name)
549
self._prev_lock = lock_type
added
removed
bzrlib/lock.py
