41
from bzrlib.trace import mutter, note, warning
42
from bzrlib.errors import LockError
44
class _base_Lock(object):
47
class _OSLock(object):
45
53
def _open(self, filename, filemode):
54
self.filename = osutils.realpath(filename)
47
self.f = open(filename, filemode)
56
self.f = open(self.filename, filemode)
59
if e.errno in (errno.EACCES, errno.EPERM):
60
raise errors.LockFailed(self.filename, str(e))
50
61
if e.errno != errno.ENOENT:
53
64
# maybe this is an old branch (before may 2005)
54
mutter("trying to create missing branch lock %r", filename)
56
self.f = open(filename, 'wb+')
65
trace.mutter("trying to create missing lock %r", self.filename)
67
self.f = open(self.filename, 'wb+')
71
"""Clear the self.f attribute cleanly."""
61
78
from warnings import warn
62
79
warn("lock on %r not released" % self.f)
66
83
raise NotImplementedError()
73
############################################################
80
class _fcntl_FileLock(_base_Lock):
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):
84
115
fcntl.lockf(self.f, fcntl.LOCK_UN)
88
119
class _fcntl_WriteLock(_fcntl_FileLock):
89
123
def __init__(self, filename):
90
# standard IO errors get exposed directly.
91
self._open(filename, 'wb')
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)
93
fcntl.lockf(self.f, fcntl.LOCK_EX)
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)
94
140
except IOError, e:
141
if e.errno in (errno.EAGAIN, errno.EACCES):
142
# We couldn't grab the lock
95
144
# we should be more precise about whats a locking
96
145
# error and whats a random-other error
146
raise errors.LockContention(e)
149
_fcntl_WriteLock._open_locks.remove(self.filename)
99
153
class _fcntl_ReadLock(_fcntl_FileLock):
101
157
def __init__(self, filename):
102
# standard IO errors get exposed directly.
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
103
162
self._open(filename, 'rb')
105
fcntl.lockf(self.f, fcntl.LOCK_SH)
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)
106
167
except IOError, e:
107
168
# we should be more precise about whats a locking
108
169
# error and whats a random-other error
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)
170
raise errors.LockContention(e)
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]
added
removed
bzrlib/lock.py
