41
from bzrlib.errors import LockError
42
from bzrlib.osutils import realpath
43
from bzrlib.trace import mutter
46
class _base_Lock(object):
46
from bzrlib.hooks import HookPoint, Hooks
49
class LockHooks(Hooks):
53
self.create_hook(HookPoint('lock_acquired',
54
"Called with a bzrlib.lock.LockResult when a physical lock is "
55
"acquired.", (1, 8), None))
56
self.create_hook(HookPoint('lock_released',
57
"Called with a bzrlib.lock.LockResult when a physical lock is "
58
"released.", (1, 8), None))
59
self.create_hook(HookPoint('lock_broken',
60
"Called with a bzrlib.lock.LockResult when a physical lock is "
61
"broken.", (1, 15), None))
65
"""Base class for locks.
67
:cvar hooks: Hook dictionary for operations on locks.
73
class LockResult(object):
74
"""Result of an operation on a lock; passed to a hook"""
76
def __init__(self, lock_url, details=None):
77
"""Create a lock result for lock with optional details about the lock."""
78
self.lock_url = lock_url
79
self.details = details
81
def __eq__(self, other):
82
return self.lock_url == other.lock_url and self.details == other.details
85
return '%s(%s%s)' % (self.__class__.__name__,
86
self.lock_url, self.details)
96
have_ctypes_win32 = False
97
if sys.platform == 'win32':
100
import win32file, pywintypes, winerror
107
have_ctypes_win32 = True
112
class _OSLock(object):
48
118
def _open(self, filename, filemode):
119
self.filename = osutils.realpath(filename)
50
self.f = open(filename, filemode)
121
self.f = open(self.filename, filemode)
52
123
except IOError, e:
124
if e.errno in (errno.EACCES, errno.EPERM):
125
raise errors.LockFailed(self.filename, str(e))
53
126
if e.errno != errno.ENOENT:
56
129
# 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+')
130
trace.mutter("trying to create missing lock %r", self.filename)
132
self.f = open(self.filename, 'wb+')
136
"""Clear the self.f attribute cleanly."""
62
141
def __del__(self):
64
143
from warnings import warn
65
144
warn("lock on %r not released" % self.f)
69
148
raise NotImplementedError()
72
############################################################
79
class _fcntl_FileLock(_base_Lock):
156
class _fcntl_FileLock(_OSLock):
83
158
def _unlock(self):
84
159
fcntl.lockf(self.f, fcntl.LOCK_UN)
88
"""Clear the self.f attribute cleanly."""
93
163
class _fcntl_WriteLock(_fcntl_FileLock):
97
167
def __init__(self, filename):
98
# standard IO errors get exposed directly.
99
self._open(filename, 'wb')
168
super(_fcntl_WriteLock, self).__init__()
169
# Check we can grab a lock before we actually open the file.
170
self.filename = osutils.realpath(filename)
171
if self.filename in _fcntl_WriteLock._open_locks:
173
raise errors.LockContention(self.filename)
175
self._open(self.filename, 'rb+')
176
# reserve a slot for this lock - even if the lockf call fails,
177
# at thisi point unlock() will be called, because self.f is set.
178
# TODO: make this fully threadsafe, if we decide we care.
179
_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)
181
# LOCK_NB will cause IOError to be raised if we can't grab a
183
fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
110
184
except IOError, e:
185
if e.errno in (errno.EAGAIN, errno.EACCES):
186
# We couldn't grab the lock
111
188
# we should be more precise about whats a locking
112
189
# error and whats a random-other error
190
raise errors.LockContention(self.filename, e)
115
192
def unlock(self):
116
del self.open_locks[self.filename]
193
_fcntl_WriteLock._open_locks.remove(self.filename)
120
197
class _fcntl_ReadLock(_fcntl_FileLock):
122
201
def __init__(self, filename):
123
# standard IO errors get exposed directly.
202
super(_fcntl_ReadLock, self).__init__()
203
self.filename = osutils.realpath(filename)
204
_fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
205
_fcntl_ReadLock._open_locks[self.filename] += 1
124
206
self._open(filename, 'rb')
126
fcntl.lockf(self.f, fcntl.LOCK_SH)
208
# LOCK_NB will cause IOError to be raised if we can't grab a
210
fcntl.lockf(self.f, fcntl.LOCK_SH | fcntl.LOCK_NB)
127
211
except IOError, e:
128
212
# we should be more precise about whats a locking
129
213
# error and whats a random-other error
214
raise errors.LockContention(self.filename, e)
132
216
def unlock(self):
217
count = _fcntl_ReadLock._open_locks[self.filename]
219
del _fcntl_ReadLock._open_locks[self.filename]
221
_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)
224
def temporary_write_lock(self):
225
"""Try to grab a write lock on the file.
227
On platforms that support it, this will upgrade to a write lock
228
without unlocking the file.
229
Otherwise, this will release the read lock, and try to acquire a
232
:return: A token which can be used to switch back to a read lock.
234
if self.filename in _fcntl_WriteLock._open_locks:
235
raise AssertionError('file already locked: %r'
238
wlock = _fcntl_TemporaryWriteLock(self)
239
except errors.LockError:
240
# We didn't unlock, so we can just return 'self'
245
class _fcntl_TemporaryWriteLock(_OSLock):
246
"""A token used when grabbing a temporary_write_lock.
248
Call restore_read_lock() when you are done with the write lock.
251
def __init__(self, read_lock):
252
super(_fcntl_TemporaryWriteLock, self).__init__()
253
self._read_lock = read_lock
254
self.filename = read_lock.filename
256
count = _fcntl_ReadLock._open_locks[self.filename]
258
# Something else also has a read-lock, so we cannot grab a
260
raise errors.LockContention(self.filename)
262
if self.filename in _fcntl_WriteLock._open_locks:
263
raise AssertionError('file already locked: %r'
266
# See if we can open the file for writing. Another process might
267
# have a read lock. We don't use self._open() because we don't want
268
# to create the file if it exists. That would have already been
269
# done by _fcntl_ReadLock
271
new_f = open(self.filename, 'rb+')
273
if e.errno in (errno.EACCES, errno.EPERM):
274
raise errors.LockFailed(self.filename, str(e))
277
# LOCK_NB will cause IOError to be raised if we can't grab a
279
fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
281
# TODO: Raise a more specific error based on the type of error
282
raise errors.LockContention(self.filename, e)
283
_fcntl_WriteLock._open_locks.add(self.filename)
287
def restore_read_lock(self):
288
"""Restore the original ReadLock."""
289
# For fcntl, since we never released the read lock, just release the
290
# write lock, and return the original lock.
291
fcntl.lockf(self.f, fcntl.LOCK_UN)
293
_fcntl_WriteLock._open_locks.remove(self.filename)
294
# Avoid reference cycles
295
read_lock = self._read_lock
296
self._read_lock = None
300
_lock_classes.append(('fcntl', _fcntl_WriteLock, _fcntl_ReadLock))
303
if have_pywin32 and sys.platform == 'win32':
305
class _w32c_FileLock(_OSLock):
307
def _open(self, filename, access, share, cflags, pymode):
308
self.filename = osutils.realpath(filename)
310
self._handle = win32file.CreateFile(filename, access, share,
311
None, win32file.OPEN_ALWAYS,
312
win32file.FILE_ATTRIBUTE_NORMAL, None)
313
except pywintypes.error, e:
314
if e.args[0] == winerror.ERROR_ACCESS_DENIED:
315
raise errors.LockFailed(filename, e)
316
if e.args[0] == winerror.ERROR_SHARING_VIOLATION:
317
raise errors.LockContention(filename, e)
319
fd = win32file._open_osfhandle(self._handle, cflags)
320
self.f = os.fdopen(fd, pymode)
328
class _w32c_ReadLock(_w32c_FileLock):
329
def __init__(self, filename):
330
super(_w32c_ReadLock, self).__init__()
331
self._open(filename, win32file.GENERIC_READ,
332
win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
334
def temporary_write_lock(self):
335
"""Try to grab a write lock on the file.
337
On platforms that support it, this will upgrade to a write lock
338
without unlocking the file.
339
Otherwise, this will release the read lock, and try to acquire a
342
:return: A token which can be used to switch back to a read lock.
344
# I can't find a way to upgrade a read lock to a write lock without
345
# unlocking first. So here, we do just that.
348
wlock = _w32c_WriteLock(self.filename)
349
except errors.LockError:
350
return False, _w32c_ReadLock(self.filename)
354
class _w32c_WriteLock(_w32c_FileLock):
355
def __init__(self, filename):
356
super(_w32c_WriteLock, self).__init__()
358
win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
361
def restore_read_lock(self):
362
"""Restore the original ReadLock."""
363
# For win32 we had to completely let go of the original lock, so we
364
# just unlock and create a new read lock.
366
return _w32c_ReadLock(self.filename)
369
_lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
372
if have_ctypes_win32:
373
from ctypes.wintypes import DWORD, LPCSTR, LPCWSTR
374
LPSECURITY_ATTRIBUTES = ctypes.c_void_p # used as NULL no need to declare
375
HANDLE = ctypes.c_int # rather than unsigned as in ctypes.wintypes
376
if os.path.supports_unicode_filenames:
377
_function_name = "CreateFileW"
380
_function_name = "CreateFileA"
381
class LPTSTR(LPCSTR):
382
def __new__(cls, obj):
383
return LPCSTR.__new__(cls, obj.encode("mbcs"))
385
# CreateFile <http://msdn.microsoft.com/en-us/library/aa363858.aspx>
386
_CreateFile = ctypes.WINFUNCTYPE(
387
HANDLE, # return value
389
DWORD, # dwDesiredAccess
391
LPSECURITY_ATTRIBUTES, # lpSecurityAttributes
392
DWORD, # dwCreationDisposition
393
DWORD, # dwFlagsAndAttributes
394
HANDLE # hTemplateFile
395
)((_function_name, ctypes.windll.kernel32))
397
INVALID_HANDLE_VALUE = -1
399
GENERIC_READ = 0x80000000
400
GENERIC_WRITE = 0x40000000
403
FILE_ATTRIBUTE_NORMAL = 128
405
ERROR_ACCESS_DENIED = 5
406
ERROR_SHARING_VIOLATION = 32
408
class _ctypes_FileLock(_OSLock):
410
def _open(self, filename, access, share, cflags, pymode):
411
self.filename = osutils.realpath(filename)
412
handle = _CreateFile(filename, access, share, None, OPEN_ALWAYS,
413
FILE_ATTRIBUTE_NORMAL, 0)
414
if handle in (INVALID_HANDLE_VALUE, 0):
415
e = ctypes.WinError()
416
if e.args[0] == ERROR_ACCESS_DENIED:
417
raise errors.LockFailed(filename, e)
418
if e.args[0] == ERROR_SHARING_VIOLATION:
419
raise errors.LockContention(filename, e)
421
fd = msvcrt.open_osfhandle(handle, cflags)
422
self.f = os.fdopen(fd, pymode)
429
class _ctypes_ReadLock(_ctypes_FileLock):
430
def __init__(self, filename):
431
super(_ctypes_ReadLock, self).__init__()
432
self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
435
def temporary_write_lock(self):
436
"""Try to grab a write lock on the file.
438
On platforms that support it, this will upgrade to a write lock
439
without unlocking the file.
440
Otherwise, this will release the read lock, and try to acquire a
443
:return: A token which can be used to switch back to a read lock.
445
# I can't find a way to upgrade a read lock to a write lock without
446
# unlocking first. So here, we do just that.
449
wlock = _ctypes_WriteLock(self.filename)
450
except errors.LockError:
451
return False, _ctypes_ReadLock(self.filename)
454
class _ctypes_WriteLock(_ctypes_FileLock):
455
def __init__(self, filename):
456
super(_ctypes_WriteLock, self).__init__()
457
self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
460
def restore_read_lock(self):
461
"""Restore the original ReadLock."""
462
# For win32 we had to completely let go of the original lock, so we
463
# just unlock and create a new read lock.
465
return _ctypes_ReadLock(self.filename)
468
_lock_classes.append(('ctypes', _ctypes_WriteLock, _ctypes_ReadLock))
471
if len(_lock_classes) == 0:
472
raise NotImplementedError(
473
"We must have one of fcntl, pywin32, or ctypes available"
474
" to support OS locking."
478
# We default to using the first available lock class.
479
_lock_type, WriteLock, ReadLock = _lock_classes[0]
added
removed
bzrlib/lock.py
