41
from bzrlib.errors import LockError, LockContention
42
from bzrlib.osutils import realpath
43
from bzrlib.trace import mutter
46
class _base_Lock(object):
45
from bzrlib.hooks import Hooks
48
class LockHooks(Hooks):
53
# added in 1.8; called with a LockResult when a physical lock is
55
self['lock_acquired'] = []
57
# added in 1.8; called with a LockResult when a physical lock is
59
self['lock_released'] = []
63
"""Base class for locks.
65
:cvar hooks: Hook dictionary for operations on locks.
71
class LockResult(object):
72
"""Result of an operation on a lock; passed to a hook"""
74
def __init__(self, lock_url, details=None):
75
"""Create a lock result for lock with optional details about the lock."""
76
self.lock_url = lock_url
77
self.details = details
79
def __eq__(self, other):
80
return self.lock_url == other.lock_url and self.details == other.details
90
have_ctypes_win32 = False
91
if sys.platform == 'win32':
94
import win32con, win32file, pywintypes, winerror
101
have_ctypes_win32 = True
106
class _OSLock(object):
48
112
def _open(self, filename, filemode):
113
self.filename = osutils.realpath(filename)
50
self.f = open(filename, filemode)
115
self.f = open(self.filename, filemode)
52
117
except IOError, e:
118
if e.errno in (errno.EACCES, errno.EPERM):
119
raise errors.LockFailed(self.filename, str(e))
53
120
if e.errno != errno.ENOENT:
56
123
# 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+')
124
trace.mutter("trying to create missing lock %r", self.filename)
126
self.f = open(self.filename, 'wb+')
130
"""Clear the self.f attribute cleanly."""
62
135
def __del__(self):
64
137
from warnings import warn
65
138
warn("lock on %r not released" % self.f)
69
142
raise NotImplementedError()
72
############################################################
79
class _fcntl_FileLock(_base_Lock):
149
LOCK_SH = fcntl.LOCK_SH
150
LOCK_NB = fcntl.LOCK_NB
151
lock_EX = fcntl.LOCK_EX
154
class _fcntl_FileLock(_OSLock):
83
156
def _unlock(self):
84
157
fcntl.lockf(self.f, fcntl.LOCK_UN)
88
"""Clear the self.f attribute cleanly."""
93
161
class _fcntl_WriteLock(_fcntl_FileLock):
97
165
def __init__(self, filename):
98
# standard IO errors get exposed directly.
99
self._open(filename, 'rb+')
166
super(_fcntl_WriteLock, self).__init__()
167
# Check we can grab a lock before we actually open the file.
168
self.filename = osutils.realpath(filename)
169
if self.filename in _fcntl_WriteLock._open_locks:
171
raise errors.LockContention(self.filename)
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self._open(self.filename, 'rb+')
174
# reserve a slot for this lock - even if the lockf call fails,
175
# at thisi point unlock() will be called, because self.f is set.
176
# TODO: make this fully threadsafe, if we decide we care.
177
_fcntl_WriteLock._open_locks.add(self.filename)
101
self.filename = realpath(filename)
102
if self.filename in self.open_locks:
104
raise LockContention("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)
179
# LOCK_NB will cause IOError to be raised if we can't grab a
181
fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
110
182
except IOError, e:
183
if e.errno in (errno.EAGAIN, errno.EACCES):
184
# We couldn't grab the lock
111
186
# we should be more precise about whats a locking
112
187
# error and whats a random-other error
188
raise errors.LockContention(e)
115
190
def unlock(self):
116
del self.open_locks[self.filename]
191
_fcntl_WriteLock._open_locks.remove(self.filename)
120
195
class _fcntl_ReadLock(_fcntl_FileLock):
122
199
def __init__(self, filename):
123
# standard IO errors get exposed directly.
200
super(_fcntl_ReadLock, self).__init__()
201
self.filename = osutils.realpath(filename)
202
_fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
203
_fcntl_ReadLock._open_locks[self.filename] += 1
124
204
self._open(filename, 'rb')
126
fcntl.lockf(self.f, fcntl.LOCK_SH)
206
# LOCK_NB will cause IOError to be raised if we can't grab a
208
fcntl.lockf(self.f, fcntl.LOCK_SH | fcntl.LOCK_NB)
127
209
except IOError, e:
128
210
# we should be more precise about whats a locking
129
211
# error and whats a random-other error
212
raise errors.LockContention(e)
132
214
def unlock(self):
215
count = _fcntl_ReadLock._open_locks[self.filename]
217
del _fcntl_ReadLock._open_locks[self.filename]
219
_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, 'rb+',
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, 'rb+'), 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)
222
def temporary_write_lock(self):
223
"""Try to grab a write lock on the file.
225
On platforms that support it, this will upgrade to a write lock
226
without unlocking the file.
227
Otherwise, this will release the read lock, and try to acquire a
230
:return: A token which can be used to switch back to a read lock.
232
if self.filename in _fcntl_WriteLock._open_locks:
233
raise AssertionError('file already locked: %r'
236
wlock = _fcntl_TemporaryWriteLock(self)
237
except errors.LockError:
238
# We didn't unlock, so we can just return 'self'
243
class _fcntl_TemporaryWriteLock(_OSLock):
244
"""A token used when grabbing a temporary_write_lock.
246
Call restore_read_lock() when you are done with the write lock.
249
def __init__(self, read_lock):
250
super(_fcntl_TemporaryWriteLock, self).__init__()
251
self._read_lock = read_lock
252
self.filename = read_lock.filename
254
count = _fcntl_ReadLock._open_locks[self.filename]
256
# Something else also has a read-lock, so we cannot grab a
258
raise errors.LockContention(self.filename)
260
if self.filename in _fcntl_WriteLock._open_locks:
261
raise AssertionError('file already locked: %r'
264
# See if we can open the file for writing. Another process might
265
# have a read lock. We don't use self._open() because we don't want
266
# to create the file if it exists. That would have already been
267
# done by _fcntl_ReadLock
269
new_f = open(self.filename, 'rb+')
271
if e.errno in (errno.EACCES, errno.EPERM):
272
raise errors.LockFailed(self.filename, str(e))
275
# LOCK_NB will cause IOError to be raised if we can't grab a
277
fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
279
# TODO: Raise a more specific error based on the type of error
280
raise errors.LockContention(e)
281
_fcntl_WriteLock._open_locks.add(self.filename)
285
def restore_read_lock(self):
286
"""Restore the original ReadLock."""
287
# For fcntl, since we never released the read lock, just release the
288
# write lock, and return the original lock.
289
fcntl.lockf(self.f, fcntl.LOCK_UN)
291
_fcntl_WriteLock._open_locks.remove(self.filename)
292
# Avoid reference cycles
293
read_lock = self._read_lock
294
self._read_lock = None
298
_lock_classes.append(('fcntl', _fcntl_WriteLock, _fcntl_ReadLock))
301
if have_pywin32 and sys.platform == 'win32':
302
LOCK_SH = 0 # the default
303
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
304
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
307
class _w32c_FileLock(_OSLock):
309
def _lock(self, filename, openmode, lockmode):
310
self._open(filename, openmode)
312
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
313
overlapped = pywintypes.OVERLAPPED()
315
win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
317
except pywintypes.error, e:
319
if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
320
raise errors.LockContention(filename)
321
## import pdb; pdb.set_trace()
325
raise errors.LockContention(e)
328
overlapped = pywintypes.OVERLAPPED()
330
win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
333
raise errors.LockContention(e)
336
class _w32c_ReadLock(_w32c_FileLock):
337
def __init__(self, filename):
338
super(_w32c_ReadLock, self).__init__()
339
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
341
def temporary_write_lock(self):
342
"""Try to grab a write lock on the file.
344
On platforms that support it, this will upgrade to a write lock
345
without unlocking the file.
346
Otherwise, this will release the read lock, and try to acquire a
349
:return: A token which can be used to switch back to a read lock.
351
# I can't find a way to upgrade a read lock to a write lock without
352
# unlocking first. So here, we do just that.
355
wlock = _w32c_WriteLock(self.filename)
356
except errors.LockError:
357
return False, _w32c_ReadLock(self.filename)
361
class _w32c_WriteLock(_w32c_FileLock):
362
def __init__(self, filename):
363
super(_w32c_WriteLock, self).__init__()
364
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
366
def restore_read_lock(self):
367
"""Restore the original ReadLock."""
368
# For win32 we had to completely let go of the original lock, so we
369
# just unlock and create a new read lock.
371
return _w32c_ReadLock(self.filename)
374
_lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
377
if have_ctypes_win32:
378
# These constants were copied from the win32con.py module.
379
LOCKFILE_FAIL_IMMEDIATELY = 1
380
LOCKFILE_EXCLUSIVE_LOCK = 2
381
# Constant taken from winerror.py module
382
ERROR_LOCK_VIOLATION = 33
385
LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
386
LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
387
_LockFileEx = ctypes.windll.kernel32.LockFileEx
388
_UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
389
_GetLastError = ctypes.windll.kernel32.GetLastError
391
### Define the OVERLAPPED structure.
392
# http://msdn2.microsoft.com/en-us/library/ms684342.aspx
393
# typedef struct _OVERLAPPED {
394
# ULONG_PTR Internal;
395
# ULONG_PTR InternalHigh;
406
class _inner_struct(ctypes.Structure):
407
_fields_ = [('Offset', ctypes.c_uint), # DWORD
408
('OffsetHigh', ctypes.c_uint), # DWORD
411
class _inner_union(ctypes.Union):
412
_fields_ = [('anon_struct', _inner_struct), # struct
413
('Pointer', ctypes.c_void_p), # PVOID
416
class OVERLAPPED(ctypes.Structure):
417
_fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
418
('InternalHigh', ctypes.c_void_p), # ULONG_PTR
419
('_inner_union', _inner_union),
420
('hEvent', ctypes.c_void_p), # HANDLE
423
class _ctypes_FileLock(_OSLock):
425
def _lock(self, filename, openmode, lockmode):
426
self._open(filename, openmode)
428
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
429
overlapped = OVERLAPPED()
430
result = _LockFileEx(self.hfile, # HANDLE hFile
431
lockmode, # DWORD dwFlags
432
0, # DWORD dwReserved
433
0x7fffffff, # DWORD nNumberOfBytesToLockLow
434
0x00000000, # DWORD nNumberOfBytesToLockHigh
435
ctypes.byref(overlapped), # lpOverlapped
439
last_err = _GetLastError()
440
if last_err in (ERROR_LOCK_VIOLATION,):
441
raise errors.LockContention(filename)
442
raise errors.LockContention('Unknown locking error: %s'
446
overlapped = OVERLAPPED()
447
result = _UnlockFileEx(self.hfile, # HANDLE hFile
448
0, # DWORD dwReserved
449
0x7fffffff, # DWORD nNumberOfBytesToLockLow
450
0x00000000, # DWORD nNumberOfBytesToLockHigh
451
ctypes.byref(overlapped), # lpOverlapped
456
last_err = _GetLastError()
457
raise errors.LockContention('Unknown unlocking error: %s'
461
class _ctypes_ReadLock(_ctypes_FileLock):
462
def __init__(self, filename):
463
super(_ctypes_ReadLock, self).__init__()
464
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
466
def temporary_write_lock(self):
467
"""Try to grab a write lock on the file.
469
On platforms that support it, this will upgrade to a write lock
470
without unlocking the file.
471
Otherwise, this will release the read lock, and try to acquire a
474
:return: A token which can be used to switch back to a read lock.
476
# I can't find a way to upgrade a read lock to a write lock without
477
# unlocking first. So here, we do just that.
480
wlock = _ctypes_WriteLock(self.filename)
481
except errors.LockError:
482
return False, _ctypes_ReadLock(self.filename)
485
class _ctypes_WriteLock(_ctypes_FileLock):
486
def __init__(self, filename):
487
super(_ctypes_WriteLock, self).__init__()
488
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
490
def restore_read_lock(self):
491
"""Restore the original ReadLock."""
492
# For win32 we had to completely let go of the original lock, so we
493
# just unlock and create a new read lock.
495
return _ctypes_ReadLock(self.filename)
498
_lock_classes.append(('ctypes', _ctypes_WriteLock, _ctypes_ReadLock))
501
if len(_lock_classes) == 0:
502
raise NotImplementedError(
503
"We must have one of fcntl, pywin32, or ctypes available"
504
" to support OS locking."
508
# We default to using the first available lock class.
509
_lock_type, WriteLock, ReadLock = _lock_classes[0]
added
removed
bzrlib/lock.py
