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Viewing changes to bzrlib/lock.py

  • Committer: Vincent Ladeuil
  • Date: 2010-02-10 15:46:03 UTC
  • mfrom: (4985.3.21 update)
  • mto: This revision was merged to the branch mainline in revision 5021.
  • Revision ID: v.ladeuil+lp@free.fr-20100210154603-k4no1gvfuqpzrw7p
https://launchpad.net/bugs/113809
Update performs two merges in a more logical order but stop on conflicts

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bzrlib/lock.py
1
 
# Copyright (C) 2005, 2006, 2007, 2008 Canonical Ltd
 
1
# Copyright (C) 2005, 2006, 2007, 2008, 2009 Canonical Ltd
2
2
#
3
3
# This program is free software; you can redistribute it and/or modify
4
4
# it under the terms of the GNU General Public License as published by
12
12
#
13
13
# You should have received a copy of the GNU General Public License
14
14
# along with this program; if not, write to the Free Software
15
 
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
15
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
16
16
 
17
17
 
18
18
"""Locking using OS file locks or file existence.
35
35
"""
36
36
 
37
37
import errno
 
38
import os
38
39
import sys
 
40
import warnings
39
41
 
40
42
from bzrlib import (
 
43
    debug,
41
44
    errors,
42
45
    osutils,
43
46
    trace,
44
47
    )
45
 
from bzrlib.hooks import Hooks
 
48
from bzrlib.hooks import HookPoint, Hooks
46
49
 
47
50
 
48
51
class LockHooks(Hooks):
49
52
 
50
53
    def __init__(self):
51
54
        Hooks.__init__(self)
52
 
 
53
 
        # added in 1.8; called with a LockResult when a physical lock is
54
 
        # acquired
55
 
        self['lock_acquired'] = []
56
 
 
57
 
        # added in 1.8; called with a LockResult when a physical lock is
58
 
        # acquired
59
 
        self['lock_released'] = []
 
55
        self.create_hook(HookPoint('lock_acquired',
 
56
            "Called with a bzrlib.lock.LockResult when a physical lock is "
 
57
            "acquired.", (1, 8), None))
 
58
        self.create_hook(HookPoint('lock_released',
 
59
            "Called with a bzrlib.lock.LockResult when a physical lock is "
 
60
            "released.", (1, 8), None))
 
61
        self.create_hook(HookPoint('lock_broken',
 
62
            "Called with a bzrlib.lock.LockResult when a physical lock is "
 
63
            "broken.", (1, 15), None))
60
64
 
61
65
 
62
66
class Lock(object):
79
83
    def __eq__(self, other):
80
84
        return self.lock_url == other.lock_url and self.details == other.details
81
85
 
 
86
    def __repr__(self):
 
87
        return '%s(%s%s)' % (self.__class__.__name__,
 
88
                             self.lock_url, self.details)
 
89
 
 
90
 
 
91
def cant_unlock_not_held(locked_object):
 
92
    """An attempt to unlock failed because the object was not locked.
 
93
 
 
94
    This provides a policy point from which we can generate either a warning 
 
95
    or an exception.
 
96
    """
 
97
    # This is typically masking some other error and called from a finally
 
98
    # block, so it's useful to have the option not to generate a new error
 
99
    # here.  You can use -Werror to make it fatal.  It should possibly also
 
100
    # raise LockNotHeld.
 
101
    if 'unlock' in debug.debug_flags:
 
102
        warnings.warn("%r is already unlocked" % (locked_object,),
 
103
            stacklevel=3)
 
104
    else:
 
105
        raise errors.LockNotHeld(locked_object)
 
106
 
82
107
 
83
108
try:
84
109
    import fcntl
91
116
if sys.platform == 'win32':
92
117
    import msvcrt
93
118
    try:
94
 
        import win32con, win32file, pywintypes, winerror
 
119
        import win32file, pywintypes, winerror
95
120
        have_pywin32 = True
96
121
    except ImportError:
97
122
        pass
146
171
 
147
172
 
148
173
if have_fcntl:
149
 
    LOCK_SH = fcntl.LOCK_SH
150
 
    LOCK_NB = fcntl.LOCK_NB
151
 
    lock_EX = fcntl.LOCK_EX
152
 
 
153
174
 
154
175
    class _fcntl_FileLock(_OSLock):
155
176
 
169
190
            if self.filename in _fcntl_WriteLock._open_locks:
170
191
                self._clear_f()
171
192
                raise errors.LockContention(self.filename)
 
193
            if self.filename in _fcntl_ReadLock._open_locks:
 
194
                if 'strict_locks' in debug.debug_flags:
 
195
                    self._clear_f()
 
196
                    raise errors.LockContention(self.filename)
 
197
                else:
 
198
                    trace.mutter('Write lock taken w/ an open read lock on: %s'
 
199
                                 % (self.filename,))
172
200
 
173
201
            self._open(self.filename, 'rb+')
174
202
            # 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.
 
203
            # at this point unlock() will be called, because self.f is set.
176
204
            # TODO: make this fully threadsafe, if we decide we care.
177
205
            _fcntl_WriteLock._open_locks.add(self.filename)
178
206
            try:
185
213
                    self.unlock()
186
214
                # we should be more precise about whats a locking
187
215
                # error and whats a random-other error
188
 
                raise errors.LockContention(e)
 
216
                raise errors.LockContention(self.filename, e)
189
217
 
190
218
        def unlock(self):
191
219
            _fcntl_WriteLock._open_locks.remove(self.filename)
199
227
        def __init__(self, filename):
200
228
            super(_fcntl_ReadLock, self).__init__()
201
229
            self.filename = osutils.realpath(filename)
 
230
            if self.filename in _fcntl_WriteLock._open_locks:
 
231
                if 'strict_locks' in debug.debug_flags:
 
232
                    # We raise before calling _open so we don't need to
 
233
                    # _clear_f
 
234
                    raise errors.LockContention(self.filename)
 
235
                else:
 
236
                    trace.mutter('Read lock taken w/ an open write lock on: %s'
 
237
                                 % (self.filename,))
202
238
            _fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
203
239
            _fcntl_ReadLock._open_locks[self.filename] += 1
204
240
            self._open(filename, 'rb')
209
245
            except IOError, e:
210
246
                # we should be more precise about whats a locking
211
247
                # error and whats a random-other error
212
 
                raise errors.LockContention(e)
 
248
                raise errors.LockContention(self.filename, e)
213
249
 
214
250
        def unlock(self):
215
251
            count = _fcntl_ReadLock._open_locks[self.filename]
277
313
                fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
278
314
            except IOError, e:
279
315
                # TODO: Raise a more specific error based on the type of error
280
 
                raise errors.LockContention(e)
 
316
                raise errors.LockContention(self.filename, e)
281
317
            _fcntl_WriteLock._open_locks.add(self.filename)
282
318
 
283
319
            self.f = new_f
299
335
 
300
336
 
301
337
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
305
 
 
 
338
    if os.path.supports_unicode_filenames:
 
339
        # for Windows NT/2K/XP/etc
 
340
        win32file_CreateFile = win32file.CreateFileW
 
341
    else:
 
342
        # for Windows 98
 
343
        win32file_CreateFile = win32file.CreateFile
306
344
 
307
345
    class _w32c_FileLock(_OSLock):
308
346
 
309
 
        def _lock(self, filename, openmode, lockmode):
310
 
            self._open(filename, openmode)
311
 
 
312
 
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
313
 
            overlapped = pywintypes.OVERLAPPED()
 
347
        def _open(self, filename, access, share, cflags, pymode):
 
348
            self.filename = osutils.realpath(filename)
314
349
            try:
315
 
                win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
316
 
                                     overlapped)
 
350
                self._handle = win32file_CreateFile(filename, access, share,
 
351
                    None, win32file.OPEN_ALWAYS,
 
352
                    win32file.FILE_ATTRIBUTE_NORMAL, None)
317
353
            except pywintypes.error, e:
318
 
                self._clear_f()
319
 
                if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
320
 
                    raise errors.LockContention(filename)
321
 
                ## import pdb; pdb.set_trace()
 
354
                if e.args[0] == winerror.ERROR_ACCESS_DENIED:
 
355
                    raise errors.LockFailed(filename, e)
 
356
                if e.args[0] == winerror.ERROR_SHARING_VIOLATION:
 
357
                    raise errors.LockContention(filename, e)
322
358
                raise
323
 
            except Exception, e:
324
 
                self._clear_f()
325
 
                raise errors.LockContention(e)
 
359
            fd = win32file._open_osfhandle(self._handle, cflags)
 
360
            self.f = os.fdopen(fd, pymode)
 
361
            return self.f
326
362
 
327
363
        def unlock(self):
328
 
            overlapped = pywintypes.OVERLAPPED()
329
 
            try:
330
 
                win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
331
 
                self._clear_f()
332
 
            except Exception, e:
333
 
                raise errors.LockContention(e)
 
364
            self._clear_f()
 
365
            self._handle = None
334
366
 
335
367
 
336
368
    class _w32c_ReadLock(_w32c_FileLock):
337
369
        def __init__(self, filename):
338
370
            super(_w32c_ReadLock, self).__init__()
339
 
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
 
371
            self._open(filename, win32file.GENERIC_READ,
 
372
                win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
340
373
 
341
374
        def temporary_write_lock(self):
342
375
            """Try to grab a write lock on the file.
361
394
    class _w32c_WriteLock(_w32c_FileLock):
362
395
        def __init__(self, filename):
363
396
            super(_w32c_WriteLock, self).__init__()
364
 
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
 
397
            self._open(filename,
 
398
                win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
 
399
                os.O_RDWR, "rb+")
365
400
 
366
401
        def restore_read_lock(self):
367
402
            """Restore the original ReadLock."""
375
410
 
376
411
 
377
412
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
383
 
 
384
 
    LOCK_SH = 0
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
390
 
 
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;
396
 
    #   union {
397
 
    #     struct {
398
 
    #       DWORD Offset;
399
 
    #       DWORD OffsetHigh;
400
 
    #     };
401
 
    #     PVOID Pointer;
402
 
    #   };
403
 
    #   HANDLE hEvent;
404
 
    # } OVERLAPPED,
405
 
 
406
 
    class _inner_struct(ctypes.Structure):
407
 
        _fields_ = [('Offset', ctypes.c_uint), # DWORD
408
 
                    ('OffsetHigh', ctypes.c_uint), # DWORD
409
 
                   ]
410
 
 
411
 
    class _inner_union(ctypes.Union):
412
 
        _fields_  = [('anon_struct', _inner_struct), # struct
413
 
                     ('Pointer', ctypes.c_void_p), # PVOID
414
 
                    ]
415
 
 
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
421
 
                   ]
 
413
    from ctypes.wintypes import DWORD, LPCSTR, LPCWSTR
 
414
    LPSECURITY_ATTRIBUTES = ctypes.c_void_p # used as NULL no need to declare
 
415
    HANDLE = ctypes.c_int # rather than unsigned as in ctypes.wintypes
 
416
    if os.path.supports_unicode_filenames:
 
417
        _function_name = "CreateFileW"
 
418
        LPTSTR = LPCWSTR
 
419
    else:
 
420
        _function_name = "CreateFileA"
 
421
        class LPTSTR(LPCSTR):
 
422
            def __new__(cls, obj):
 
423
                return LPCSTR.__new__(cls, obj.encode("mbcs"))
 
424
 
 
425
    # CreateFile <http://msdn.microsoft.com/en-us/library/aa363858.aspx>
 
426
    _CreateFile = ctypes.WINFUNCTYPE(
 
427
            HANDLE,                # return value
 
428
            LPTSTR,                # lpFileName
 
429
            DWORD,                 # dwDesiredAccess
 
430
            DWORD,                 # dwShareMode
 
431
            LPSECURITY_ATTRIBUTES, # lpSecurityAttributes
 
432
            DWORD,                 # dwCreationDisposition
 
433
            DWORD,                 # dwFlagsAndAttributes
 
434
            HANDLE                 # hTemplateFile
 
435
        )((_function_name, ctypes.windll.kernel32))
 
436
 
 
437
    INVALID_HANDLE_VALUE = -1
 
438
 
 
439
    GENERIC_READ = 0x80000000
 
440
    GENERIC_WRITE = 0x40000000
 
441
    FILE_SHARE_READ = 1
 
442
    OPEN_ALWAYS = 4
 
443
    FILE_ATTRIBUTE_NORMAL = 128
 
444
 
 
445
    ERROR_ACCESS_DENIED = 5
 
446
    ERROR_SHARING_VIOLATION = 32
422
447
 
423
448
    class _ctypes_FileLock(_OSLock):
424
449
 
425
 
        def _lock(self, filename, openmode, lockmode):
426
 
            self._open(filename, openmode)
427
 
 
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
436
 
                                )
437
 
            if result == 0:
438
 
                self._clear_f()
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'
443
 
                                            % (last_err,))
 
450
        def _open(self, filename, access, share, cflags, pymode):
 
451
            self.filename = osutils.realpath(filename)
 
452
            handle = _CreateFile(filename, access, share, None, OPEN_ALWAYS,
 
453
                FILE_ATTRIBUTE_NORMAL, 0)
 
454
            if handle in (INVALID_HANDLE_VALUE, 0):
 
455
                e = ctypes.WinError()
 
456
                if e.args[0] == ERROR_ACCESS_DENIED:
 
457
                    raise errors.LockFailed(filename, e)
 
458
                if e.args[0] == ERROR_SHARING_VIOLATION:
 
459
                    raise errors.LockContention(filename, e)
 
460
                raise e
 
461
            fd = msvcrt.open_osfhandle(handle, cflags)
 
462
            self.f = os.fdopen(fd, pymode)
 
463
            return self.f
444
464
 
445
465
        def unlock(self):
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
452
 
                                  )
453
466
            self._clear_f()
454
 
            if result == 0:
455
 
                self._clear_f()
456
 
                last_err = _GetLastError()
457
 
                raise errors.LockContention('Unknown unlocking error: %s'
458
 
                                            % (last_err,))
459
467
 
460
468
 
461
469
    class _ctypes_ReadLock(_ctypes_FileLock):
462
470
        def __init__(self, filename):
463
471
            super(_ctypes_ReadLock, self).__init__()
464
 
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
 
472
            self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
 
473
                "rb")
465
474
 
466
475
        def temporary_write_lock(self):
467
476
            """Try to grab a write lock on the file.
485
494
    class _ctypes_WriteLock(_ctypes_FileLock):
486
495
        def __init__(self, filename):
487
496
            super(_ctypes_WriteLock, self).__init__()
488
 
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
 
497
            self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
 
498
                "rb+")
489
499
 
490
500
        def restore_read_lock(self):
491
501
            """Restore the original ReadLock."""
508
518
# We default to using the first available lock class.
509
519
_lock_type, WriteLock, ReadLock = _lock_classes[0]
510
520
 
 
521
 
 
522
class _RelockDebugMixin(object):
 
523
    """Mixin support for -Drelock flag.
 
524
 
 
525
    Add this as a base class then call self._note_lock with 'r' or 'w' when
 
526
    acquiring a read- or write-lock.  If this object was previously locked (and
 
527
    locked the same way), and -Drelock is set, then this will trace.note a
 
528
    message about it.
 
529
    """
 
530
    
 
531
    _prev_lock = None
 
532
 
 
533
    def _note_lock(self, lock_type):
 
534
        if 'relock' in debug.debug_flags and self._prev_lock == lock_type:
 
535
            if lock_type == 'r':
 
536
                type_name = 'read'
 
537
            else:
 
538
                type_name = 'write'
 
539
            trace.note('%r was %s locked again', self, type_name)
 
540
        self._prev_lock = lock_type
 
541