47
class _OSLock(object):
41
from bzrlib.errors import LockError
42
from bzrlib.osutils import realpath
43
from bzrlib.trace import mutter
46
class _base_Lock(object):
53
48
def _open(self, filename, filemode):
54
self.filename = osutils.realpath(filename)
56
self.f = open(self.filename, filemode)
50
self.f = open(filename, filemode)
59
if e.errno in (errno.EACCES, errno.EPERM):
60
raise errors.LockFailed(self.filename, str(e))
61
53
if e.errno != errno.ENOENT:
64
56
# maybe this is an old branch (before may 2005)
65
trace.mutter("trying to create missing lock %r", self.filename)
67
self.f = open(self.filename, 'wb+')
57
mutter("trying to create missing branch lock %r", filename)
59
self.f = open(filename, 'wb+')
71
"""Clear the self.f attribute cleanly."""
78
64
from warnings import warn
79
65
warn("lock on %r not released" % self.f)
83
69
raise NotImplementedError()
72
############################################################
92
import win32con, win32file, pywintypes, winerror, msvcrt
107
LOCK_SH = fcntl.LOCK_SH
108
LOCK_NB = fcntl.LOCK_NB
109
lock_EX = fcntl.LOCK_EX
112
class _fcntl_FileLock(_OSLock):
79
class _fcntl_FileLock(_base_Lock):
114
83
def _unlock(self):
115
84
fcntl.lockf(self.f, fcntl.LOCK_UN)
88
"""Clear the self.f attribute cleanly."""
119
93
class _fcntl_WriteLock(_fcntl_FileLock):
123
97
def __init__(self, filename):
124
super(_fcntl_WriteLock, self).__init__()
125
# Check we can grab a lock before we actually open the file.
126
self.filename = osutils.realpath(filename)
127
if self.filename in _fcntl_WriteLock._open_locks:
129
raise errors.LockContention(self.filename)
131
self._open(self.filename, 'rb+')
132
# reserve a slot for this lock - even if the lockf call fails,
133
# at thisi point unlock() will be called, because self.f is set.
134
# TODO: make this fully threadsafe, if we decide we care.
135
_fcntl_WriteLock._open_locks.add(self.filename)
98
# standard IO errors get exposed directly.
99
self._open(filename, 'wb')
137
# LOCK_NB will cause IOError to be raised if we can't grab a
139
fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
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)
140
110
except IOError, e:
141
if e.errno in (errno.EAGAIN, errno.EACCES):
142
# We couldn't grab the lock
144
111
# we should be more precise about whats a locking
145
112
# error and whats a random-other error
146
raise errors.LockContention(e)
148
115
def unlock(self):
149
_fcntl_WriteLock._open_locks.remove(self.filename)
116
del self.open_locks[self.filename]
153
120
class _fcntl_ReadLock(_fcntl_FileLock):
157
122
def __init__(self, filename):
158
super(_fcntl_ReadLock, self).__init__()
159
self.filename = osutils.realpath(filename)
160
_fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
161
_fcntl_ReadLock._open_locks[self.filename] += 1
123
# standard IO errors get exposed directly.
162
124
self._open(filename, 'rb')
164
# LOCK_NB will cause IOError to be raised if we can't grab a
166
fcntl.lockf(self.f, fcntl.LOCK_SH | fcntl.LOCK_NB)
126
fcntl.lockf(self.f, fcntl.LOCK_SH)
167
127
except IOError, e:
168
128
# we should be more precise about whats a locking
169
129
# error and whats a random-other error
170
raise errors.LockContention(e)
172
132
def unlock(self):
173
count = _fcntl_ReadLock._open_locks[self.filename]
175
del _fcntl_ReadLock._open_locks[self.filename]
177
_fcntl_ReadLock._open_locks[self.filename] = count - 1
180
def temporary_write_lock(self):
181
"""Try to grab a write lock on the file.
183
On platforms that support it, this will upgrade to a write lock
184
without unlocking the file.
185
Otherwise, this will release the read lock, and try to acquire a
188
:return: A token which can be used to switch back to a read lock.
190
if self.filename in _fcntl_WriteLock._open_locks:
191
raise AssertionError('file already locked: %r'
194
wlock = _fcntl_TemporaryWriteLock(self)
195
except errors.LockError:
196
# We didn't unlock, so we can just return 'self'
201
class _fcntl_TemporaryWriteLock(_OSLock):
202
"""A token used when grabbing a temporary_write_lock.
204
Call restore_read_lock() when you are done with the write lock.
207
def __init__(self, read_lock):
208
super(_fcntl_TemporaryWriteLock, self).__init__()
209
self._read_lock = read_lock
210
self.filename = read_lock.filename
212
count = _fcntl_ReadLock._open_locks[self.filename]
214
# Something else also has a read-lock, so we cannot grab a
216
raise errors.LockContention(self.filename)
218
if self.filename in _fcntl_WriteLock._open_locks:
219
raise AssertionError('file already locked: %r'
222
# See if we can open the file for writing. Another process might
223
# have a read lock. We don't use self._open() because we don't want
224
# to create the file if it exists. That would have already been
225
# done by _fcntl_ReadLock
227
new_f = open(self.filename, 'rb+')
229
if e.errno in (errno.EACCES, errno.EPERM):
230
raise errors.LockFailed(self.filename, str(e))
233
# LOCK_NB will cause IOError to be raised if we can't grab a
235
fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
237
# TODO: Raise a more specific error based on the type of error
238
raise errors.LockContention(e)
239
_fcntl_WriteLock._open_locks.add(self.filename)
243
def restore_read_lock(self):
244
"""Restore the original ReadLock."""
245
# For fcntl, since we never released the read lock, just release the
246
# write lock, and return the original lock.
247
fcntl.lockf(self.f, fcntl.LOCK_UN)
249
_fcntl_WriteLock._open_locks.remove(self.filename)
250
# Avoid reference cycles
251
read_lock = self._read_lock
252
self._read_lock = None
256
_lock_classes.append(('fcntl', _fcntl_WriteLock, _fcntl_ReadLock))
259
if have_pywin32 and sys.platform == 'win32':
260
LOCK_SH = 0 # the default
261
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
262
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
265
class _w32c_FileLock(_OSLock):
267
def _lock(self, filename, openmode, lockmode):
268
self._open(filename, openmode)
270
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
271
overlapped = pywintypes.OVERLAPPED()
273
win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
275
except pywintypes.error, e:
277
if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
278
raise errors.LockContention(filename)
279
## import pdb; pdb.set_trace()
283
raise errors.LockContention(e)
286
overlapped = pywintypes.OVERLAPPED()
288
win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
291
raise errors.LockContention(e)
294
class _w32c_ReadLock(_w32c_FileLock):
295
def __init__(self, filename):
296
super(_w32c_ReadLock, self).__init__()
297
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
299
def temporary_write_lock(self):
300
"""Try to grab a write lock on the file.
302
On platforms that support it, this will upgrade to a write lock
303
without unlocking the file.
304
Otherwise, this will release the read lock, and try to acquire a
307
:return: A token which can be used to switch back to a read lock.
309
# I can't find a way to upgrade a read lock to a write lock without
310
# unlocking first. So here, we do just that.
313
wlock = _w32c_WriteLock(self.filename)
314
except errors.LockError:
315
return False, _w32c_ReadLock(self.filename)
319
class _w32c_WriteLock(_w32c_FileLock):
320
def __init__(self, filename):
321
super(_w32c_WriteLock, self).__init__()
322
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
324
def restore_read_lock(self):
325
"""Restore the original ReadLock."""
326
# For win32 we had to completely let go of the original lock, so we
327
# just unlock and create a new read lock.
329
return _w32c_ReadLock(self.filename)
332
_lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
335
if have_ctypes and sys.platform == 'win32':
336
# These constants were copied from the win32con.py module.
337
LOCKFILE_FAIL_IMMEDIATELY = 1
338
LOCKFILE_EXCLUSIVE_LOCK = 2
339
# Constant taken from winerror.py module
340
ERROR_LOCK_VIOLATION = 33
343
LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
344
LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
345
_LockFileEx = ctypes.windll.kernel32.LockFileEx
346
_UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
347
_GetLastError = ctypes.windll.kernel32.GetLastError
349
### Define the OVERLAPPED structure.
350
# http://msdn2.microsoft.com/en-us/library/ms684342.aspx
351
# typedef struct _OVERLAPPED {
352
# ULONG_PTR Internal;
353
# ULONG_PTR InternalHigh;
364
class _inner_struct(ctypes.Structure):
365
_fields_ = [('Offset', ctypes.c_uint), # DWORD
366
('OffsetHigh', ctypes.c_uint), # DWORD
369
class _inner_union(ctypes.Union):
370
_fields_ = [('anon_struct', _inner_struct), # struct
371
('Pointer', ctypes.c_void_p), # PVOID
374
class OVERLAPPED(ctypes.Structure):
375
_fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
376
('InternalHigh', ctypes.c_void_p), # ULONG_PTR
377
('_inner_union', _inner_union),
378
('hEvent', ctypes.c_void_p), # HANDLE
381
class _ctypes_FileLock(_OSLock):
383
def _lock(self, filename, openmode, lockmode):
384
self._open(filename, openmode)
386
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
387
overlapped = OVERLAPPED()
388
result = _LockFileEx(self.hfile, # HANDLE hFile
389
lockmode, # DWORD dwFlags
390
0, # DWORD dwReserved
391
0x7fffffff, # DWORD nNumberOfBytesToLockLow
392
0x00000000, # DWORD nNumberOfBytesToLockHigh
393
ctypes.byref(overlapped), # lpOverlapped
397
last_err = _GetLastError()
398
if last_err in (ERROR_LOCK_VIOLATION,):
399
raise errors.LockContention(filename)
400
raise errors.LockContention('Unknown locking error: %s'
404
overlapped = OVERLAPPED()
405
result = _UnlockFileEx(self.hfile, # HANDLE hFile
406
0, # DWORD dwReserved
407
0x7fffffff, # DWORD nNumberOfBytesToLockLow
408
0x00000000, # DWORD nNumberOfBytesToLockHigh
409
ctypes.byref(overlapped), # lpOverlapped
414
last_err = _GetLastError()
415
raise errors.LockContention('Unknown unlocking error: %s'
419
class _ctypes_ReadLock(_ctypes_FileLock):
420
def __init__(self, filename):
421
super(_ctypes_ReadLock, self).__init__()
422
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
424
def temporary_write_lock(self):
425
"""Try to grab a write lock on the file.
427
On platforms that support it, this will upgrade to a write lock
428
without unlocking the file.
429
Otherwise, this will release the read lock, and try to acquire a
432
:return: A token which can be used to switch back to a read lock.
434
# I can't find a way to upgrade a read lock to a write lock without
435
# unlocking first. So here, we do just that.
438
wlock = _ctypes_WriteLock(self.filename)
439
except errors.LockError:
440
return False, _ctypes_ReadLock(self.filename)
443
class _ctypes_WriteLock(_ctypes_FileLock):
444
def __init__(self, filename):
445
super(_ctypes_WriteLock, self).__init__()
446
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
448
def restore_read_lock(self):
449
"""Restore the original ReadLock."""
450
# For win32 we had to completely let go of the original lock, so we
451
# just unlock and create a new read lock.
453
return _ctypes_ReadLock(self.filename)
456
_lock_classes.append(('ctypes', _ctypes_WriteLock, _ctypes_ReadLock))
459
if len(_lock_classes) == 0:
460
raise NotImplementedError(
461
"We must have one of fcntl, pywin32, or ctypes available"
462
" to support OS locking."
466
# We default to using the first available lock class.
467
_lock_type, WriteLock, ReadLock = _lock_classes[0]
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)
added
removed
bzrlib/lock.py
