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  • Committer: Canonical.com Patch Queue Manager
  • Date: 2009-03-17 07:05:37 UTC
  • mfrom: (4152.1.2 branch.stacked.streams)
  • Revision ID: pqm@pqm.ubuntu.com-20090317070537-zaud24vjs2szna87
(robertc) Add client-side streaming from stacked branches (over
        bzr:// protocols) when the sort order is compatible with doing
        that. (Robert Collins, Andrew Bennetts)

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bzrlib/lock.py
1
 
# Copyright (C) 2005-2010 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 
15
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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
39
38
import sys
40
 
import warnings
41
39
 
42
40
from bzrlib import (
43
 
    debug,
44
41
    errors,
45
42
    osutils,
46
43
    trace,
58
55
        self.create_hook(HookPoint('lock_released',
59
56
            "Called with a bzrlib.lock.LockResult when a physical lock is "
60
57
            "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))
64
58
 
65
59
 
66
60
class Lock(object):
83
77
    def __eq__(self, other):
84
78
        return self.lock_url == other.lock_url and self.details == other.details
85
79
 
86
 
    def __repr__(self):
87
 
        return '%s(%s, %s)' % (self.__class__.__name__,
88
 
                             self.lock_url, self.details)
89
 
 
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
80
 
122
81
try:
123
82
    import fcntl
130
89
if sys.platform == 'win32':
131
90
    import msvcrt
132
91
    try:
133
 
        import win32file, pywintypes, winerror
 
92
        import win32con, win32file, pywintypes, winerror
134
93
        have_pywin32 = True
135
94
    except ImportError:
136
95
        pass
185
144
 
186
145
 
187
146
if have_fcntl:
 
147
    LOCK_SH = fcntl.LOCK_SH
 
148
    LOCK_NB = fcntl.LOCK_NB
 
149
    lock_EX = fcntl.LOCK_EX
 
150
 
188
151
 
189
152
    class _fcntl_FileLock(_OSLock):
190
153
 
204
167
            if self.filename in _fcntl_WriteLock._open_locks:
205
168
                self._clear_f()
206
169
                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,))
214
170
 
215
171
            self._open(self.filename, 'rb+')
216
172
            # reserve a slot for this lock - even if the lockf call fails,
217
 
            # at this point unlock() will be called, because self.f is set.
 
173
            # at thisi point unlock() will be called, because self.f is set.
218
174
            # TODO: make this fully threadsafe, if we decide we care.
219
175
            _fcntl_WriteLock._open_locks.add(self.filename)
220
176
            try:
241
197
        def __init__(self, filename):
242
198
            super(_fcntl_ReadLock, self).__init__()
243
199
            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,))
252
200
            _fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
253
201
            _fcntl_ReadLock._open_locks[self.filename] += 1
254
202
            self._open(filename, 'rb')
349
297
 
350
298
 
351
299
if have_pywin32 and sys.platform == 'win32':
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
 
300
    LOCK_SH = 0 # the default
 
301
    LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
 
302
    LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
 
303
 
358
304
 
359
305
    class _w32c_FileLock(_OSLock):
360
306
 
361
 
        def _open(self, filename, access, share, cflags, pymode):
362
 
            self.filename = osutils.realpath(filename)
 
307
        def _lock(self, filename, openmode, lockmode):
 
308
            self._open(filename, openmode)
 
309
 
 
310
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
 
311
            overlapped = pywintypes.OVERLAPPED()
363
312
            try:
364
 
                self._handle = win32file_CreateFile(filename, access, share,
365
 
                    None, win32file.OPEN_ALWAYS,
366
 
                    win32file.FILE_ATTRIBUTE_NORMAL, None)
 
313
                win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
 
314
                                     overlapped)
367
315
            except pywintypes.error, e:
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)
 
316
                self._clear_f()
 
317
                if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
 
318
                    raise errors.LockContention(filename)
 
319
                ## import pdb; pdb.set_trace()
372
320
                raise
373
 
            fd = win32file._open_osfhandle(self._handle, cflags)
374
 
            self.f = os.fdopen(fd, pymode)
375
 
            return self.f
 
321
            except Exception, e:
 
322
                self._clear_f()
 
323
                raise errors.LockContention(filename, e)
376
324
 
377
325
        def unlock(self):
378
 
            self._clear_f()
379
 
            self._handle = None
 
326
            overlapped = pywintypes.OVERLAPPED()
 
327
            try:
 
328
                win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
 
329
                self._clear_f()
 
330
            except Exception, e:
 
331
                raise errors.LockContention(self.filename, e)
380
332
 
381
333
 
382
334
    class _w32c_ReadLock(_w32c_FileLock):
383
335
        def __init__(self, filename):
384
336
            super(_w32c_ReadLock, self).__init__()
385
 
            self._open(filename, win32file.GENERIC_READ,
386
 
                win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
 
337
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
387
338
 
388
339
        def temporary_write_lock(self):
389
340
            """Try to grab a write lock on the file.
408
359
    class _w32c_WriteLock(_w32c_FileLock):
409
360
        def __init__(self, filename):
410
361
            super(_w32c_WriteLock, self).__init__()
411
 
            self._open(filename,
412
 
                win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
413
 
                os.O_RDWR, "rb+")
 
362
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
414
363
 
415
364
        def restore_read_lock(self):
416
365
            """Restore the original ReadLock."""
424
373
 
425
374
 
426
375
if have_ctypes_win32:
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
 
376
    # These constants were copied from the win32con.py module.
 
377
    LOCKFILE_FAIL_IMMEDIATELY = 1
 
378
    LOCKFILE_EXCLUSIVE_LOCK = 2
 
379
    # Constant taken from winerror.py module
 
380
    ERROR_LOCK_VIOLATION = 33
 
381
 
 
382
    LOCK_SH = 0
 
383
    LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
 
384
    LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
 
385
    _LockFileEx = ctypes.windll.kernel32.LockFileEx
 
386
    _UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
 
387
    _GetLastError = ctypes.windll.kernel32.GetLastError
 
388
 
 
389
    ### Define the OVERLAPPED structure.
 
390
    #   http://msdn2.microsoft.com/en-us/library/ms684342.aspx
 
391
    # typedef struct _OVERLAPPED {
 
392
    #   ULONG_PTR Internal;
 
393
    #   ULONG_PTR InternalHigh;
 
394
    #   union {
 
395
    #     struct {
 
396
    #       DWORD Offset;
 
397
    #       DWORD OffsetHigh;
 
398
    #     };
 
399
    #     PVOID Pointer;
 
400
    #   };
 
401
    #   HANDLE hEvent;
 
402
    # } OVERLAPPED,
 
403
 
 
404
    class _inner_struct(ctypes.Structure):
 
405
        _fields_ = [('Offset', ctypes.c_uint), # DWORD
 
406
                    ('OffsetHigh', ctypes.c_uint), # DWORD
 
407
                   ]
 
408
 
 
409
    class _inner_union(ctypes.Union):
 
410
        _fields_  = [('anon_struct', _inner_struct), # struct
 
411
                     ('Pointer', ctypes.c_void_p), # PVOID
 
412
                    ]
 
413
 
 
414
    class OVERLAPPED(ctypes.Structure):
 
415
        _fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
 
416
                    ('InternalHigh', ctypes.c_void_p), # ULONG_PTR
 
417
                    ('_inner_union', _inner_union),
 
418
                    ('hEvent', ctypes.c_void_p), # HANDLE
 
419
                   ]
461
420
 
462
421
    class _ctypes_FileLock(_OSLock):
463
422
 
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
 
423
        def _lock(self, filename, openmode, lockmode):
 
424
            self._open(filename, openmode)
 
425
 
 
426
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
 
427
            overlapped = OVERLAPPED()
 
428
            result = _LockFileEx(self.hfile, # HANDLE hFile
 
429
                                 lockmode,   # DWORD dwFlags
 
430
                                 0,          # DWORD dwReserved
 
431
                                 0x7fffffff, # DWORD nNumberOfBytesToLockLow
 
432
                                 0x00000000, # DWORD nNumberOfBytesToLockHigh
 
433
                                 ctypes.byref(overlapped), # lpOverlapped
 
434
                                )
 
435
            if result == 0:
 
436
                self._clear_f()
 
437
                last_err = _GetLastError()
 
438
                if last_err in (ERROR_LOCK_VIOLATION,):
 
439
                    raise errors.LockContention(filename)
 
440
                raise errors.LockContention(filename,
 
441
                    'Unknown locking error: %s' % (last_err,))
478
442
 
479
443
        def unlock(self):
 
444
            overlapped = OVERLAPPED()
 
445
            result = _UnlockFileEx(self.hfile, # HANDLE hFile
 
446
                                   0,          # DWORD dwReserved
 
447
                                   0x7fffffff, # DWORD nNumberOfBytesToLockLow
 
448
                                   0x00000000, # DWORD nNumberOfBytesToLockHigh
 
449
                                   ctypes.byref(overlapped), # lpOverlapped
 
450
                                  )
480
451
            self._clear_f()
 
452
            if result == 0:
 
453
                self._clear_f()
 
454
                last_err = _GetLastError()
 
455
                raise errors.LockContention(self.filename,
 
456
                    'Unknown unlocking error: %s' % (last_err,))
481
457
 
482
458
 
483
459
    class _ctypes_ReadLock(_ctypes_FileLock):
484
460
        def __init__(self, filename):
485
461
            super(_ctypes_ReadLock, self).__init__()
486
 
            self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
487
 
                "rb")
 
462
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
488
463
 
489
464
        def temporary_write_lock(self):
490
465
            """Try to grab a write lock on the file.
508
483
    class _ctypes_WriteLock(_ctypes_FileLock):
509
484
        def __init__(self, filename):
510
485
            super(_ctypes_WriteLock, self).__init__()
511
 
            self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
512
 
                "rb+")
 
486
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
513
487
 
514
488
        def restore_read_lock(self):
515
489
            """Restore the original ReadLock."""
532
506
# We default to using the first available lock class.
533
507
_lock_type, WriteLock, ReadLock = _lock_classes[0]
534
508
 
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