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  • Committer: Canonical.com Patch Queue Manager
  • Date: 2010-09-29 22:03:03 UTC
  • mfrom: (5416.2.6 jam-integration)
  • Revision ID: pqm@pqm.ubuntu.com-20100929220303-cr95h8iwtggco721
(mbp) Add 'break-lock --force'

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bzrlib/lock.py
1
 
# Copyright (C) 2005, 2006, 2007, 2008, 2009 Canonical Ltd
 
1
# Copyright (C) 2005-2010 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
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,
81
84
        return self.lock_url == other.lock_url and self.details == other.details
82
85
 
83
86
    def __repr__(self):
84
 
        return '%s(%s%s)' % (self.__class__.__name__,
 
87
        return '%s(%s, %s)' % (self.__class__.__name__,
85
88
                             self.lock_url, self.details)
86
89
 
87
90
 
 
91
class LogicalLockResult(object):
 
92
    """The result of a lock_read/lock_write/lock_tree_write call on lockables.
 
93
 
 
94
    :ivar unlock: A callable which will unlock the lock.
 
95
    """
 
96
 
 
97
    def __init__(self, unlock):
 
98
        self.unlock = unlock
 
99
 
 
100
    def __repr__(self):
 
101
        return "LogicalLockResult(%s)" % (self.unlock)
 
102
 
 
103
 
 
104
 
 
105
def cant_unlock_not_held(locked_object):
 
106
    """An attempt to unlock failed because the object was not locked.
 
107
 
 
108
    This provides a policy point from which we can generate either a warning 
 
109
    or an exception.
 
110
    """
 
111
    # This is typically masking some other error and called from a finally
 
112
    # block, so it's useful to have the option not to generate a new error
 
113
    # here.  You can use -Werror to make it fatal.  It should possibly also
 
114
    # raise LockNotHeld.
 
115
    if 'unlock' in debug.debug_flags:
 
116
        warnings.warn("%r is already unlocked" % (locked_object,),
 
117
            stacklevel=3)
 
118
    else:
 
119
        raise errors.LockNotHeld(locked_object)
 
120
 
 
121
 
88
122
try:
89
123
    import fcntl
90
124
    have_fcntl = True
96
130
if sys.platform == 'win32':
97
131
    import msvcrt
98
132
    try:
99
 
        import win32con, win32file, pywintypes, winerror
 
133
        import win32file, pywintypes, winerror
100
134
        have_pywin32 = True
101
135
    except ImportError:
102
136
        pass
151
185
 
152
186
 
153
187
if have_fcntl:
154
 
    LOCK_SH = fcntl.LOCK_SH
155
 
    LOCK_NB = fcntl.LOCK_NB
156
 
    lock_EX = fcntl.LOCK_EX
157
 
 
158
188
 
159
189
    class _fcntl_FileLock(_OSLock):
160
190
 
174
204
            if self.filename in _fcntl_WriteLock._open_locks:
175
205
                self._clear_f()
176
206
                raise errors.LockContention(self.filename)
 
207
            if self.filename in _fcntl_ReadLock._open_locks:
 
208
                if 'strict_locks' in debug.debug_flags:
 
209
                    self._clear_f()
 
210
                    raise errors.LockContention(self.filename)
 
211
                else:
 
212
                    trace.mutter('Write lock taken w/ an open read lock on: %s'
 
213
                                 % (self.filename,))
177
214
 
178
215
            self._open(self.filename, 'rb+')
179
216
            # reserve a slot for this lock - even if the lockf call fails,
180
 
            # at thisi point unlock() will be called, because self.f is set.
 
217
            # at this point unlock() will be called, because self.f is set.
181
218
            # TODO: make this fully threadsafe, if we decide we care.
182
219
            _fcntl_WriteLock._open_locks.add(self.filename)
183
220
            try:
204
241
        def __init__(self, filename):
205
242
            super(_fcntl_ReadLock, self).__init__()
206
243
            self.filename = osutils.realpath(filename)
 
244
            if self.filename in _fcntl_WriteLock._open_locks:
 
245
                if 'strict_locks' in debug.debug_flags:
 
246
                    # We raise before calling _open so we don't need to
 
247
                    # _clear_f
 
248
                    raise errors.LockContention(self.filename)
 
249
                else:
 
250
                    trace.mutter('Read lock taken w/ an open write lock on: %s'
 
251
                                 % (self.filename,))
207
252
            _fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
208
253
            _fcntl_ReadLock._open_locks[self.filename] += 1
209
254
            self._open(filename, 'rb')
304
349
 
305
350
 
306
351
if have_pywin32 and sys.platform == 'win32':
307
 
    LOCK_SH = 0 # the default
308
 
    LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
309
 
    LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
310
 
 
 
352
    if os.path.supports_unicode_filenames:
 
353
        # for Windows NT/2K/XP/etc
 
354
        win32file_CreateFile = win32file.CreateFileW
 
355
    else:
 
356
        # for Windows 98
 
357
        win32file_CreateFile = win32file.CreateFile
311
358
 
312
359
    class _w32c_FileLock(_OSLock):
313
360
 
314
 
        def _lock(self, filename, openmode, lockmode):
315
 
            self._open(filename, openmode)
316
 
 
317
 
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
318
 
            overlapped = pywintypes.OVERLAPPED()
 
361
        def _open(self, filename, access, share, cflags, pymode):
 
362
            self.filename = osutils.realpath(filename)
319
363
            try:
320
 
                win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
321
 
                                     overlapped)
 
364
                self._handle = win32file_CreateFile(filename, access, share,
 
365
                    None, win32file.OPEN_ALWAYS,
 
366
                    win32file.FILE_ATTRIBUTE_NORMAL, None)
322
367
            except pywintypes.error, e:
323
 
                self._clear_f()
324
 
                if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
325
 
                    raise errors.LockContention(filename)
326
 
                ## import pdb; pdb.set_trace()
 
368
                if e.args[0] == winerror.ERROR_ACCESS_DENIED:
 
369
                    raise errors.LockFailed(filename, e)
 
370
                if e.args[0] == winerror.ERROR_SHARING_VIOLATION:
 
371
                    raise errors.LockContention(filename, e)
327
372
                raise
328
 
            except Exception, e:
329
 
                self._clear_f()
330
 
                raise errors.LockContention(filename, e)
 
373
            fd = win32file._open_osfhandle(self._handle, cflags)
 
374
            self.f = os.fdopen(fd, pymode)
 
375
            return self.f
331
376
 
332
377
        def unlock(self):
333
 
            overlapped = pywintypes.OVERLAPPED()
334
 
            try:
335
 
                win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
336
 
                self._clear_f()
337
 
            except Exception, e:
338
 
                raise errors.LockContention(self.filename, e)
 
378
            self._clear_f()
 
379
            self._handle = None
339
380
 
340
381
 
341
382
    class _w32c_ReadLock(_w32c_FileLock):
342
383
        def __init__(self, filename):
343
384
            super(_w32c_ReadLock, self).__init__()
344
 
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
 
385
            self._open(filename, win32file.GENERIC_READ,
 
386
                win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
345
387
 
346
388
        def temporary_write_lock(self):
347
389
            """Try to grab a write lock on the file.
366
408
    class _w32c_WriteLock(_w32c_FileLock):
367
409
        def __init__(self, filename):
368
410
            super(_w32c_WriteLock, self).__init__()
369
 
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
 
411
            self._open(filename,
 
412
                win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
 
413
                os.O_RDWR, "rb+")
370
414
 
371
415
        def restore_read_lock(self):
372
416
            """Restore the original ReadLock."""
380
424
 
381
425
 
382
426
if have_ctypes_win32:
383
 
    # These constants were copied from the win32con.py module.
384
 
    LOCKFILE_FAIL_IMMEDIATELY = 1
385
 
    LOCKFILE_EXCLUSIVE_LOCK = 2
386
 
    # Constant taken from winerror.py module
387
 
    ERROR_LOCK_VIOLATION = 33
388
 
 
389
 
    LOCK_SH = 0
390
 
    LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
391
 
    LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
392
 
    _LockFileEx = ctypes.windll.kernel32.LockFileEx
393
 
    _UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
394
 
 
395
 
    ### Define the OVERLAPPED structure.
396
 
    #   http://msdn2.microsoft.com/en-us/library/ms684342.aspx
397
 
    # typedef struct _OVERLAPPED {
398
 
    #   ULONG_PTR Internal;
399
 
    #   ULONG_PTR InternalHigh;
400
 
    #   union {
401
 
    #     struct {
402
 
    #       DWORD Offset;
403
 
    #       DWORD OffsetHigh;
404
 
    #     };
405
 
    #     PVOID Pointer;
406
 
    #   };
407
 
    #   HANDLE hEvent;
408
 
    # } OVERLAPPED,
409
 
 
410
 
    class _inner_struct(ctypes.Structure):
411
 
        _fields_ = [('Offset', ctypes.c_uint), # DWORD
412
 
                    ('OffsetHigh', ctypes.c_uint), # DWORD
413
 
                   ]
414
 
 
415
 
    class _inner_union(ctypes.Union):
416
 
        _fields_  = [('anon_struct', _inner_struct), # struct
417
 
                     ('Pointer', ctypes.c_void_p), # PVOID
418
 
                    ]
419
 
 
420
 
    class OVERLAPPED(ctypes.Structure):
421
 
        _fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
422
 
                    ('InternalHigh', ctypes.c_void_p), # ULONG_PTR
423
 
                    ('_inner_union', _inner_union),
424
 
                    ('hEvent', ctypes.c_void_p), # HANDLE
425
 
                   ]
 
427
    from ctypes.wintypes import DWORD, LPCSTR, LPCWSTR
 
428
    LPSECURITY_ATTRIBUTES = ctypes.c_void_p # used as NULL no need to declare
 
429
    HANDLE = ctypes.c_int # rather than unsigned as in ctypes.wintypes
 
430
    if os.path.supports_unicode_filenames:
 
431
        _function_name = "CreateFileW"
 
432
        LPTSTR = LPCWSTR
 
433
    else:
 
434
        _function_name = "CreateFileA"
 
435
        class LPTSTR(LPCSTR):
 
436
            def __new__(cls, obj):
 
437
                return LPCSTR.__new__(cls, obj.encode("mbcs"))
 
438
 
 
439
    # CreateFile <http://msdn.microsoft.com/en-us/library/aa363858.aspx>
 
440
    _CreateFile = ctypes.WINFUNCTYPE(
 
441
            HANDLE,                # return value
 
442
            LPTSTR,                # lpFileName
 
443
            DWORD,                 # dwDesiredAccess
 
444
            DWORD,                 # dwShareMode
 
445
            LPSECURITY_ATTRIBUTES, # lpSecurityAttributes
 
446
            DWORD,                 # dwCreationDisposition
 
447
            DWORD,                 # dwFlagsAndAttributes
 
448
            HANDLE                 # hTemplateFile
 
449
        )((_function_name, ctypes.windll.kernel32))
 
450
 
 
451
    INVALID_HANDLE_VALUE = -1
 
452
 
 
453
    GENERIC_READ = 0x80000000
 
454
    GENERIC_WRITE = 0x40000000
 
455
    FILE_SHARE_READ = 1
 
456
    OPEN_ALWAYS = 4
 
457
    FILE_ATTRIBUTE_NORMAL = 128
 
458
 
 
459
    ERROR_ACCESS_DENIED = 5
 
460
    ERROR_SHARING_VIOLATION = 32
426
461
 
427
462
    class _ctypes_FileLock(_OSLock):
428
463
 
429
 
        def _lock(self, filename, openmode, lockmode):
430
 
            self._open(filename, openmode)
431
 
 
432
 
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
433
 
            overlapped = OVERLAPPED()
434
 
            result = _LockFileEx(self.hfile, # HANDLE hFile
435
 
                                 lockmode,   # DWORD dwFlags
436
 
                                 0,          # DWORD dwReserved
437
 
                                 0x7fffffff, # DWORD nNumberOfBytesToLockLow
438
 
                                 0x00000000, # DWORD nNumberOfBytesToLockHigh
439
 
                                 ctypes.byref(overlapped), # lpOverlapped
440
 
                                )
441
 
            if result == 0:
442
 
                last_err = ctypes.GetLastError()
443
 
                self._clear_f()
444
 
                if last_err in (ERROR_LOCK_VIOLATION,):
445
 
                    raise errors.LockContention(filename)
446
 
                raise errors.LockContention(filename,
447
 
                    'Unknown locking error: %s' % (last_err,))
 
464
        def _open(self, filename, access, share, cflags, pymode):
 
465
            self.filename = osutils.realpath(filename)
 
466
            handle = _CreateFile(filename, access, share, None, OPEN_ALWAYS,
 
467
                FILE_ATTRIBUTE_NORMAL, 0)
 
468
            if handle in (INVALID_HANDLE_VALUE, 0):
 
469
                e = ctypes.WinError()
 
470
                if e.args[0] == ERROR_ACCESS_DENIED:
 
471
                    raise errors.LockFailed(filename, e)
 
472
                if e.args[0] == ERROR_SHARING_VIOLATION:
 
473
                    raise errors.LockContention(filename, e)
 
474
                raise e
 
475
            fd = msvcrt.open_osfhandle(handle, cflags)
 
476
            self.f = os.fdopen(fd, pymode)
 
477
            return self.f
448
478
 
449
479
        def unlock(self):
450
 
            overlapped = OVERLAPPED()
451
 
            result = _UnlockFileEx(self.hfile, # HANDLE hFile
452
 
                                   0,          # DWORD dwReserved
453
 
                                   0x7fffffff, # DWORD nNumberOfBytesToLockLow
454
 
                                   0x00000000, # DWORD nNumberOfBytesToLockHigh
455
 
                                   ctypes.byref(overlapped), # lpOverlapped
456
 
                                  )
457
 
            if result == 0:
458
 
                last_err = ctypes.GetLastError()
459
 
                self._clear_f()
460
 
                raise errors.LockContention(self.filename,
461
 
                    'Unknown unlocking error: %s' % (last_err,))
462
480
            self._clear_f()
463
481
 
464
482
 
465
483
    class _ctypes_ReadLock(_ctypes_FileLock):
466
484
        def __init__(self, filename):
467
485
            super(_ctypes_ReadLock, self).__init__()
468
 
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
 
486
            self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
 
487
                "rb")
469
488
 
470
489
        def temporary_write_lock(self):
471
490
            """Try to grab a write lock on the file.
489
508
    class _ctypes_WriteLock(_ctypes_FileLock):
490
509
        def __init__(self, filename):
491
510
            super(_ctypes_WriteLock, self).__init__()
492
 
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
 
511
            self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
 
512
                "rb+")
493
513
 
494
514
        def restore_read_lock(self):
495
515
            """Restore the original ReadLock."""
512
532
# We default to using the first available lock class.
513
533
_lock_type, WriteLock, ReadLock = _lock_classes[0]
514
534
 
 
535
 
 
536
class _RelockDebugMixin(object):
 
537
    """Mixin support for -Drelock flag.
 
538
 
 
539
    Add this as a base class then call self._note_lock with 'r' or 'w' when
 
540
    acquiring a read- or write-lock.  If this object was previously locked (and
 
541
    locked the same way), and -Drelock is set, then this will trace.note a
 
542
    message about it.
 
543
    """
 
544
    
 
545
    _prev_lock = None
 
546
 
 
547
    def _note_lock(self, lock_type):
 
548
        if 'relock' in debug.debug_flags and self._prev_lock == lock_type:
 
549
            if lock_type == 'r':
 
550
                type_name = 'read'
 
551
            else:
 
552
                type_name = 'write'
 
553
            trace.note('%r was %s locked again', self, type_name)
 
554
        self._prev_lock = lock_type
 
555