48
from bzrlib.hooks import Hooks
49
from bzrlib.i18n import gettext
51
class LockHooks(Hooks):
54
Hooks.__init__(self, "bzrlib.lock", "Lock.hooks")
55
self.add_hook('lock_acquired',
56
"Called with a bzrlib.lock.LockResult when a physical lock is "
58
self.add_hook('lock_released',
59
"Called with a bzrlib.lock.LockResult when a physical lock is "
61
self.add_hook('lock_broken',
62
"Called with a bzrlib.lock.LockResult when a physical lock is "
67
"""Base class for locks.
69
:cvar hooks: Hook dictionary for operations on locks.
75
class LockResult(object):
76
"""Result of an operation on a lock; passed to a hook"""
78
def __init__(self, lock_url, details=None):
79
"""Create a lock result for lock with optional details about the lock."""
80
self.lock_url = lock_url
81
self.details = details
83
def __eq__(self, other):
84
return self.lock_url == other.lock_url and self.details == other.details
87
return '%s(%s, %s)' % (self.__class__.__name__,
88
self.lock_url, self.details)
91
class LogicalLockResult(object):
92
"""The result of a lock_read/lock_write/lock_tree_write call on lockables.
94
:ivar unlock: A callable which will unlock the lock.
97
def __init__(self, unlock):
101
return "LogicalLockResult(%s)" % (self.unlock)
105
def cant_unlock_not_held(locked_object):
106
"""An attempt to unlock failed because the object was not locked.
108
This provides a policy point from which we can generate either a warning
111
# This is typically masking some other error and called from a finally
112
# block, so it's useful to have the option not to generate a new error
113
# here. You can use -Werror to make it fatal. It should possibly also
115
if 'unlock' in debug.debug_flags:
116
warnings.warn("%r is already unlocked" % (locked_object,),
119
raise errors.LockNotHeld(locked_object)
129
have_ctypes_win32 = False
130
if sys.platform == 'win32':
133
import win32file, pywintypes, winerror
140
have_ctypes_win32 = True
145
class _OSLock(object):
41
from bzrlib.trace import mutter, note, warning
42
from bzrlib.errors import LockError
44
class _base_Lock(object):
151
45
def _open(self, filename, filemode):
152
self.filename = osutils.realpath(filename)
154
self.f = open(self.filename, filemode)
47
self.f = open(filename, filemode)
156
49
except IOError, e:
157
if e.errno in (errno.EACCES, errno.EPERM):
158
raise errors.LockFailed(self.filename, str(e))
159
50
if e.errno != errno.ENOENT:
162
53
# maybe this is an old branch (before may 2005)
163
trace.mutter("trying to create missing lock %r", self.filename)
165
self.f = open(self.filename, 'wb+')
54
mutter("trying to create missing branch lock %r", filename)
56
self.f = open(filename, 'wb+')
169
"""Clear the self.f attribute cleanly."""
61
from warnings import warn
62
warn("lock on %r not released" % self.f)
175
66
raise NotImplementedError()
183
class _fcntl_FileLock(_OSLock):
73
############################################################
80
class _fcntl_FileLock(_base_Lock):
186
84
fcntl.lockf(self.f, fcntl.LOCK_UN)
190
88
class _fcntl_WriteLock(_fcntl_FileLock):
194
89
def __init__(self, filename):
195
super(_fcntl_WriteLock, self).__init__()
196
# Check we can grab a lock before we actually open the file.
197
self.filename = osutils.realpath(filename)
198
if self.filename in _fcntl_WriteLock._open_locks:
200
raise errors.LockContention(self.filename)
201
if self.filename in _fcntl_ReadLock._open_locks:
202
if 'strict_locks' in debug.debug_flags:
204
raise errors.LockContention(self.filename)
206
trace.mutter('Write lock taken w/ an open read lock on: %s'
209
self._open(self.filename, 'rb+')
210
# reserve a slot for this lock - even if the lockf call fails,
211
# at this point unlock() will be called, because self.f is set.
212
# TODO: make this fully threadsafe, if we decide we care.
213
_fcntl_WriteLock._open_locks.add(self.filename)
90
# standard IO errors get exposed directly.
91
self._open(filename, 'wb')
215
# LOCK_NB will cause IOError to be raised if we can't grab a
217
fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
93
fcntl.lockf(self.f, fcntl.LOCK_EX)
218
94
except IOError, e:
219
if e.errno in (errno.EAGAIN, errno.EACCES):
220
# We couldn't grab the lock
222
95
# we should be more precise about whats a locking
223
96
# error and whats a random-other error
224
raise errors.LockContention(self.filename, e)
227
_fcntl_WriteLock._open_locks.remove(self.filename)
231
99
class _fcntl_ReadLock(_fcntl_FileLock):
235
101
def __init__(self, filename):
236
super(_fcntl_ReadLock, self).__init__()
237
self.filename = osutils.realpath(filename)
238
if self.filename in _fcntl_WriteLock._open_locks:
239
if 'strict_locks' in debug.debug_flags:
240
# We raise before calling _open so we don't need to
242
raise errors.LockContention(self.filename)
244
trace.mutter('Read lock taken w/ an open write lock on: %s'
246
_fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
247
_fcntl_ReadLock._open_locks[self.filename] += 1
102
# standard IO errors get exposed directly.
248
103
self._open(filename, 'rb')
250
# LOCK_NB will cause IOError to be raised if we can't grab a
252
fcntl.lockf(self.f, fcntl.LOCK_SH | fcntl.LOCK_NB)
105
fcntl.lockf(self.f, fcntl.LOCK_SH)
253
106
except IOError, e:
254
107
# we should be more precise about whats a locking
255
108
# error and whats a random-other error
256
raise errors.LockContention(self.filename, e)
259
count = _fcntl_ReadLock._open_locks[self.filename]
261
del _fcntl_ReadLock._open_locks[self.filename]
263
_fcntl_ReadLock._open_locks[self.filename] = count - 1
266
def temporary_write_lock(self):
267
"""Try to grab a write lock on the file.
269
On platforms that support it, this will upgrade to a write lock
270
without unlocking the file.
271
Otherwise, this will release the read lock, and try to acquire a
274
:return: A token which can be used to switch back to a read lock.
276
if self.filename in _fcntl_WriteLock._open_locks:
277
raise AssertionError('file already locked: %r'
280
wlock = _fcntl_TemporaryWriteLock(self)
281
except errors.LockError:
282
# We didn't unlock, so we can just return 'self'
287
class _fcntl_TemporaryWriteLock(_OSLock):
288
"""A token used when grabbing a temporary_write_lock.
290
Call restore_read_lock() when you are done with the write lock.
293
def __init__(self, read_lock):
294
super(_fcntl_TemporaryWriteLock, self).__init__()
295
self._read_lock = read_lock
296
self.filename = read_lock.filename
298
count = _fcntl_ReadLock._open_locks[self.filename]
300
# Something else also has a read-lock, so we cannot grab a
302
raise errors.LockContention(self.filename)
304
if self.filename in _fcntl_WriteLock._open_locks:
305
raise AssertionError('file already locked: %r'
308
# See if we can open the file for writing. Another process might
309
# have a read lock. We don't use self._open() because we don't want
310
# to create the file if it exists. That would have already been
311
# done by _fcntl_ReadLock
313
new_f = open(self.filename, 'rb+')
315
if e.errno in (errno.EACCES, errno.EPERM):
316
raise errors.LockFailed(self.filename, str(e))
319
# LOCK_NB will cause IOError to be raised if we can't grab a
321
fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
323
# TODO: Raise a more specific error based on the type of error
324
raise errors.LockContention(self.filename, e)
325
_fcntl_WriteLock._open_locks.add(self.filename)
329
def restore_read_lock(self):
330
"""Restore the original ReadLock."""
331
# For fcntl, since we never released the read lock, just release the
332
# write lock, and return the original lock.
333
fcntl.lockf(self.f, fcntl.LOCK_UN)
335
_fcntl_WriteLock._open_locks.remove(self.filename)
336
# Avoid reference cycles
337
read_lock = self._read_lock
338
self._read_lock = None
342
_lock_classes.append(('fcntl', _fcntl_WriteLock, _fcntl_ReadLock))
345
if have_pywin32 and sys.platform == 'win32':
346
if os.path.supports_unicode_filenames:
347
# for Windows NT/2K/XP/etc
348
win32file_CreateFile = win32file.CreateFileW
351
win32file_CreateFile = win32file.CreateFile
353
class _w32c_FileLock(_OSLock):
355
def _open(self, filename, access, share, cflags, pymode):
356
self.filename = osutils.realpath(filename)
358
self._handle = win32file_CreateFile(filename, access, share,
359
None, win32file.OPEN_ALWAYS,
360
win32file.FILE_ATTRIBUTE_NORMAL, None)
361
except pywintypes.error, e:
362
if e.args[0] == winerror.ERROR_ACCESS_DENIED:
363
raise errors.LockFailed(filename, e)
364
if e.args[0] == winerror.ERROR_SHARING_VIOLATION:
365
raise errors.LockContention(filename, e)
367
fd = win32file._open_osfhandle(self._handle, cflags)
368
self.f = os.fdopen(fd, pymode)
376
class _w32c_ReadLock(_w32c_FileLock):
377
def __init__(self, filename):
378
super(_w32c_ReadLock, self).__init__()
379
self._open(filename, win32file.GENERIC_READ,
380
win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
382
def temporary_write_lock(self):
383
"""Try to grab a write lock on the file.
385
On platforms that support it, this will upgrade to a write lock
386
without unlocking the file.
387
Otherwise, this will release the read lock, and try to acquire a
390
:return: A token which can be used to switch back to a read lock.
392
# I can't find a way to upgrade a read lock to a write lock without
393
# unlocking first. So here, we do just that.
396
wlock = _w32c_WriteLock(self.filename)
397
except errors.LockError:
398
return False, _w32c_ReadLock(self.filename)
402
class _w32c_WriteLock(_w32c_FileLock):
403
def __init__(self, filename):
404
super(_w32c_WriteLock, self).__init__()
406
win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
409
def restore_read_lock(self):
410
"""Restore the original ReadLock."""
411
# For win32 we had to completely let go of the original lock, so we
412
# just unlock and create a new read lock.
414
return _w32c_ReadLock(self.filename)
417
_lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
420
if have_ctypes_win32:
421
from ctypes.wintypes import DWORD, LPCSTR, LPCWSTR
422
LPSECURITY_ATTRIBUTES = ctypes.c_void_p # used as NULL no need to declare
423
HANDLE = ctypes.c_int # rather than unsigned as in ctypes.wintypes
424
if os.path.supports_unicode_filenames:
425
_function_name = "CreateFileW"
428
_function_name = "CreateFileA"
429
class LPTSTR(LPCSTR):
430
def __new__(cls, obj):
431
return LPCSTR.__new__(cls, obj.encode("mbcs"))
433
# CreateFile <http://msdn.microsoft.com/en-us/library/aa363858.aspx>
434
_CreateFile = ctypes.WINFUNCTYPE(
435
HANDLE, # return value
437
DWORD, # dwDesiredAccess
439
LPSECURITY_ATTRIBUTES, # lpSecurityAttributes
440
DWORD, # dwCreationDisposition
441
DWORD, # dwFlagsAndAttributes
442
HANDLE # hTemplateFile
443
)((_function_name, ctypes.windll.kernel32))
445
INVALID_HANDLE_VALUE = -1
447
GENERIC_READ = 0x80000000
448
GENERIC_WRITE = 0x40000000
451
FILE_ATTRIBUTE_NORMAL = 128
453
ERROR_ACCESS_DENIED = 5
454
ERROR_SHARING_VIOLATION = 32
456
class _ctypes_FileLock(_OSLock):
458
def _open(self, filename, access, share, cflags, pymode):
459
self.filename = osutils.realpath(filename)
460
handle = _CreateFile(filename, access, share, None, OPEN_ALWAYS,
461
FILE_ATTRIBUTE_NORMAL, 0)
462
if handle in (INVALID_HANDLE_VALUE, 0):
463
e = ctypes.WinError()
464
if e.args[0] == ERROR_ACCESS_DENIED:
465
raise errors.LockFailed(filename, e)
466
if e.args[0] == ERROR_SHARING_VIOLATION:
467
raise errors.LockContention(filename, e)
469
fd = msvcrt.open_osfhandle(handle, cflags)
470
self.f = os.fdopen(fd, pymode)
477
class _ctypes_ReadLock(_ctypes_FileLock):
478
def __init__(self, filename):
479
super(_ctypes_ReadLock, self).__init__()
480
self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
483
def temporary_write_lock(self):
484
"""Try to grab a write lock on the file.
486
On platforms that support it, this will upgrade to a write lock
487
without unlocking the file.
488
Otherwise, this will release the read lock, and try to acquire a
491
:return: A token which can be used to switch back to a read lock.
493
# I can't find a way to upgrade a read lock to a write lock without
494
# unlocking first. So here, we do just that.
497
wlock = _ctypes_WriteLock(self.filename)
498
except errors.LockError:
499
return False, _ctypes_ReadLock(self.filename)
502
class _ctypes_WriteLock(_ctypes_FileLock):
503
def __init__(self, filename):
504
super(_ctypes_WriteLock, self).__init__()
505
self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
508
def restore_read_lock(self):
509
"""Restore the original ReadLock."""
510
# For win32 we had to completely let go of the original lock, so we
511
# just unlock and create a new read lock.
513
return _ctypes_ReadLock(self.filename)
516
_lock_classes.append(('ctypes', _ctypes_WriteLock, _ctypes_ReadLock))
519
if len(_lock_classes) == 0:
520
raise NotImplementedError(
521
"We must have one of fcntl, pywin32, or ctypes available"
522
" to support OS locking."
526
# We default to using the first available lock class.
527
_lock_type, WriteLock, ReadLock = _lock_classes[0]
530
class _RelockDebugMixin(object):
531
"""Mixin support for -Drelock flag.
533
Add this as a base class then call self._note_lock with 'r' or 'w' when
534
acquiring a read- or write-lock. If this object was previously locked (and
535
locked the same way), and -Drelock is set, then this will trace.note a
541
def _note_lock(self, lock_type):
542
if 'relock' in debug.debug_flags and self._prev_lock == lock_type:
547
trace.note(gettext('{0!r} was {1} locked again'), self, type_name)
548
self._prev_lock = lock_type
111
WriteLock = _fcntl_WriteLock
112
ReadLock = _fcntl_ReadLock
117
import win32con, win32file, pywintypes
120
LOCK_SH = 0 # the default
121
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
122
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
124
class _w32c_FileLock(_base_Lock):
125
def _lock(self, filename, openmode, lockmode):
127
self._open(filename, openmode)
128
self.hfile = win32file._get_osfhandle(self.f.fileno())
129
overlapped = pywintypes.OVERLAPPED()
130
win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000, overlapped)
136
overlapped = pywintypes.OVERLAPPED()
137
win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
145
class _w32c_ReadLock(_w32c_FileLock):
146
def __init__(self, filename):
147
_w32c_FileLock._lock(self, filename, 'rb',
150
class _w32c_WriteLock(_w32c_FileLock):
151
def __init__(self, filename):
152
_w32c_FileLock._lock(self, filename, 'wb',
157
WriteLock = _w32c_WriteLock
158
ReadLock = _w32c_ReadLock
165
# Unfortunately, msvcrt.locking() doesn't distinguish between
166
# read locks and write locks. Also, the way the combinations
167
# work to get non-blocking is not the same, so we
168
# have to write extra special functions here.
171
class _msvc_FileLock(_base_Lock):
181
class _msvc_ReadLock(_msvc_FileLock):
182
def __init__(self, filename):
183
_msvc_lock(self._open(filename, 'rb'), self.LOCK_SH)
186
class _msvc_WriteLock(_msvc_FileLock):
187
def __init__(self, filename):
188
_msvc_lock(self._open(filename, 'wb'), self.LOCK_EX)
192
def _msvc_lock(f, flags):
194
# Unfortunately, msvcrt.LK_RLCK is equivalent to msvcrt.LK_LOCK
195
# according to the comments, LK_RLCK is open the lock for writing.
197
# Unfortunately, msvcrt.locking() also has the side effect that it
198
# will only block for 10 seconds at most, and then it will throw an
199
# exception, this isn't terrible, though.
206
fpos = os.lseek(fn, 0,0)
209
if flags & _msvc_FileLock.LOCK_SH:
210
if flags & _msvc_FileLock.LOCK_NB:
211
lock_mode = msvcrt.LK_NBLCK
213
lock_mode = msvcrt.LK_LOCK
214
elif flags & _msvc_FileLock.LOCK_EX:
215
if flags & _msvc_FileLock.LOCK_NB:
216
lock_mode = msvcrt.LK_NBRLCK
218
lock_mode = msvcrt.LK_RLCK
220
raise ValueError('Invalid lock mode: %r' % flags)
222
msvcrt.locking(fn, lock_mode, -1)
224
os.lseek(fn, fpos, 0)
236
fpos = os.lseek(fn, 0,0)
240
msvcrt.locking(fn, msvcrt.LK_UNLCK, -1)
242
os.lseek(fn, fpos, 0)
248
WriteLock = _msvc_WriteLock
249
ReadLock = _msvc_ReadLock
251
raise NotImplementedError("please write a locking method "
252
"for platform %r" % sys.platform)
added
removed
bzrlib/lock.py
