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  • Committer: Canonical.com Patch Queue Manager
  • Date: 2009-04-09 20:23:07 UTC
  • mfrom: (4265.1.4 bbc-merge)
  • Revision ID: pqm@pqm.ubuntu.com-20090409202307-n0depb16qepoe21o
(jam) Change _fetch_uses_deltas = False for CHK repos until we can
        write a better fix.

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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
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
 
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
 
 
107
80
 
108
81
try:
109
82
    import fcntl
116
89
if sys.platform == 'win32':
117
90
    import msvcrt
118
91
    try:
119
 
        import win32file, pywintypes, winerror
 
92
        import win32con, win32file, pywintypes, winerror
120
93
        have_pywin32 = True
121
94
    except ImportError:
122
95
        pass
171
144
 
172
145
 
173
146
if have_fcntl:
 
147
    LOCK_SH = fcntl.LOCK_SH
 
148
    LOCK_NB = fcntl.LOCK_NB
 
149
    lock_EX = fcntl.LOCK_EX
 
150
 
174
151
 
175
152
    class _fcntl_FileLock(_OSLock):
176
153
 
190
167
            if self.filename in _fcntl_WriteLock._open_locks:
191
168
                self._clear_f()
192
169
                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,))
200
170
 
201
171
            self._open(self.filename, 'rb+')
202
172
            # reserve a slot for this lock - even if the lockf call fails,
203
 
            # 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.
204
174
            # TODO: make this fully threadsafe, if we decide we care.
205
175
            _fcntl_WriteLock._open_locks.add(self.filename)
206
176
            try:
227
197
        def __init__(self, filename):
228
198
            super(_fcntl_ReadLock, self).__init__()
229
199
            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,))
238
200
            _fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
239
201
            _fcntl_ReadLock._open_locks[self.filename] += 1
240
202
            self._open(filename, 'rb')
335
297
 
336
298
 
337
299
if have_pywin32 and sys.platform == 'win32':
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
 
300
    LOCK_SH = 0 # the default
 
301
    LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
 
302
    LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
 
303
 
344
304
 
345
305
    class _w32c_FileLock(_OSLock):
346
306
 
347
 
        def _open(self, filename, access, share, cflags, pymode):
348
 
            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()
349
312
            try:
350
 
                self._handle = win32file_CreateFile(filename, access, share,
351
 
                    None, win32file.OPEN_ALWAYS,
352
 
                    win32file.FILE_ATTRIBUTE_NORMAL, None)
 
313
                win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
 
314
                                     overlapped)
353
315
            except pywintypes.error, e:
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)
 
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()
358
320
                raise
359
 
            fd = win32file._open_osfhandle(self._handle, cflags)
360
 
            self.f = os.fdopen(fd, pymode)
361
 
            return self.f
 
321
            except Exception, e:
 
322
                self._clear_f()
 
323
                raise errors.LockContention(filename, e)
362
324
 
363
325
        def unlock(self):
364
 
            self._clear_f()
365
 
            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)
366
332
 
367
333
 
368
334
    class _w32c_ReadLock(_w32c_FileLock):
369
335
        def __init__(self, filename):
370
336
            super(_w32c_ReadLock, self).__init__()
371
 
            self._open(filename, win32file.GENERIC_READ,
372
 
                win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
 
337
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
373
338
 
374
339
        def temporary_write_lock(self):
375
340
            """Try to grab a write lock on the file.
394
359
    class _w32c_WriteLock(_w32c_FileLock):
395
360
        def __init__(self, filename):
396
361
            super(_w32c_WriteLock, self).__init__()
397
 
            self._open(filename,
398
 
                win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
399
 
                os.O_RDWR, "rb+")
 
362
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
400
363
 
401
364
        def restore_read_lock(self):
402
365
            """Restore the original ReadLock."""
410
373
 
411
374
 
412
375
if have_ctypes_win32:
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
 
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
                   ]
447
420
 
448
421
    class _ctypes_FileLock(_OSLock):
449
422
 
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
 
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,))
464
442
 
465
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
                                  )
466
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,))
467
457
 
468
458
 
469
459
    class _ctypes_ReadLock(_ctypes_FileLock):
470
460
        def __init__(self, filename):
471
461
            super(_ctypes_ReadLock, self).__init__()
472
 
            self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
473
 
                "rb")
 
462
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
474
463
 
475
464
        def temporary_write_lock(self):
476
465
            """Try to grab a write lock on the file.
494
483
    class _ctypes_WriteLock(_ctypes_FileLock):
495
484
        def __init__(self, filename):
496
485
            super(_ctypes_WriteLock, self).__init__()
497
 
            self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
498
 
                "rb+")
 
486
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
499
487
 
500
488
        def restore_read_lock(self):
501
489
            """Restore the original ReadLock."""
518
506
# We default to using the first available lock class.
519
507
_lock_type, WriteLock, ReadLock = _lock_classes[0]
520
508
 
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