/brz/remove-bazaar

To get this branch, use:
bzr branch http://gegoxaren.bato24.eu/bzr/brz/remove-bazaar

« back to all changes in this revision

Viewing changes to bzrlib/lock.py

  • Committer: Martin Pool
  • Date: 2008-05-27 03:12:19 UTC
  • mto: (3724.1.1 lock-hooks)
  • mto: This revision was merged to the branch mainline in revision 3730.
  • Revision ID: mbp@sourcefrog.net-20080527031219-whr998jr17x233qh
Update test_help for hooks doc

Show diffs side-by-side

added added

removed removed

Lines of Context:
bzrlib/lock.py
1
 
# Copyright (C) 2005-2010 Canonical Ltd
 
1
# Copyright (C) 2005, 2006, 2007 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,
47
44
    )
48
 
from bzrlib.hooks import HookPoint, Hooks
49
 
 
50
 
 
51
 
class LockHooks(Hooks):
52
 
 
53
 
    def __init__(self):
54
 
        Hooks.__init__(self)
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))
64
 
 
65
 
 
66
 
class Lock(object):
67
 
    """Base class for locks.
 
45
from bzrlib.hooks import Hooks
 
46
 
 
47
 
 
48
class PhysicalLock(object):
 
49
    """Base class for external on-disk physical locks.
 
50
 
 
51
    At present only LockDir descends from this, but all locks should.
68
52
 
69
53
    :cvar hooks: Hook dictionary for operations on locks.
70
54
    """
71
55
 
72
 
    hooks = LockHooks()
 
56
    hooks = Hooks()
 
57
    hooks['lock_acquired'] = []
 
58
    hooks['lock_released'] = []
73
59
 
74
60
 
75
61
class LockResult(object):
83
69
    def __eq__(self, other):
84
70
        return self.lock_url == other.lock_url and self.details == other.details
85
71
 
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
 
 
108
 
try:
109
 
    import fcntl
110
 
    have_fcntl = True
111
 
except ImportError:
112
 
    have_fcntl = False
113
 
 
114
 
have_pywin32 = False
115
 
have_ctypes_win32 = False
116
 
if sys.platform == 'win32':
117
 
    import msvcrt
118
 
    try:
119
 
        import win32file, pywintypes, winerror
120
 
        have_pywin32 = True
121
 
    except ImportError:
122
 
        pass
123
 
 
124
 
    try:
125
 
        import ctypes
126
 
        have_ctypes_win32 = True
127
 
    except ImportError:
128
 
        pass
129
 
 
130
72
 
131
73
class _OSLock(object):
132
74
 
167
109
        raise NotImplementedError()
168
110
 
169
111
 
 
112
try:
 
113
    import fcntl
 
114
    have_fcntl = True
 
115
except ImportError:
 
116
    have_fcntl = False
 
117
try:
 
118
    import win32con, win32file, pywintypes, winerror, msvcrt
 
119
    have_pywin32 = True
 
120
except ImportError:
 
121
    have_pywin32 = False
 
122
try:
 
123
    import ctypes, msvcrt
 
124
    have_ctypes = True
 
125
except ImportError:
 
126
    have_ctypes = False
 
127
 
 
128
 
170
129
_lock_classes = []
171
130
 
172
131
 
173
132
if have_fcntl:
 
133
    LOCK_SH = fcntl.LOCK_SH
 
134
    LOCK_NB = fcntl.LOCK_NB
 
135
    lock_EX = fcntl.LOCK_EX
 
136
 
174
137
 
175
138
    class _fcntl_FileLock(_OSLock):
176
139
 
190
153
            if self.filename in _fcntl_WriteLock._open_locks:
191
154
                self._clear_f()
192
155
                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
156
 
201
157
            self._open(self.filename, 'rb+')
202
158
            # 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.
 
159
            # at thisi point unlock() will be called, because self.f is set.
204
160
            # TODO: make this fully threadsafe, if we decide we care.
205
161
            _fcntl_WriteLock._open_locks.add(self.filename)
206
162
            try:
213
169
                    self.unlock()
214
170
                # we should be more precise about whats a locking
215
171
                # error and whats a random-other error
216
 
                raise errors.LockContention(self.filename, e)
 
172
                raise errors.LockContention(e)
217
173
 
218
174
        def unlock(self):
219
175
            _fcntl_WriteLock._open_locks.remove(self.filename)
227
183
        def __init__(self, filename):
228
184
            super(_fcntl_ReadLock, self).__init__()
229
185
            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
186
            _fcntl_ReadLock._open_locks.setdefault(self.filename, 0)
239
187
            _fcntl_ReadLock._open_locks[self.filename] += 1
240
188
            self._open(filename, 'rb')
245
193
            except IOError, e:
246
194
                # we should be more precise about whats a locking
247
195
                # error and whats a random-other error
248
 
                raise errors.LockContention(self.filename, e)
 
196
                raise errors.LockContention(e)
249
197
 
250
198
        def unlock(self):
251
199
            count = _fcntl_ReadLock._open_locks[self.filename]
313
261
                fcntl.lockf(new_f, fcntl.LOCK_EX | fcntl.LOCK_NB)
314
262
            except IOError, e:
315
263
                # TODO: Raise a more specific error based on the type of error
316
 
                raise errors.LockContention(self.filename, e)
 
264
                raise errors.LockContention(e)
317
265
            _fcntl_WriteLock._open_locks.add(self.filename)
318
266
 
319
267
            self.f = new_f
335
283
 
336
284
 
337
285
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
 
286
    LOCK_SH = 0 # the default
 
287
    LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
 
288
    LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
 
289
 
344
290
 
345
291
    class _w32c_FileLock(_OSLock):
346
292
 
347
 
        def _open(self, filename, access, share, cflags, pymode):
348
 
            self.filename = osutils.realpath(filename)
 
293
        def _lock(self, filename, openmode, lockmode):
 
294
            self._open(filename, openmode)
 
295
 
 
296
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
 
297
            overlapped = pywintypes.OVERLAPPED()
349
298
            try:
350
 
                self._handle = win32file_CreateFile(filename, access, share,
351
 
                    None, win32file.OPEN_ALWAYS,
352
 
                    win32file.FILE_ATTRIBUTE_NORMAL, None)
 
299
                win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
 
300
                                     overlapped)
353
301
            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)
 
302
                self._clear_f()
 
303
                if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
 
304
                    raise errors.LockContention(filename)
 
305
                ## import pdb; pdb.set_trace()
358
306
                raise
359
 
            fd = win32file._open_osfhandle(self._handle, cflags)
360
 
            self.f = os.fdopen(fd, pymode)
361
 
            return self.f
 
307
            except Exception, e:
 
308
                self._clear_f()
 
309
                raise errors.LockContention(e)
362
310
 
363
311
        def unlock(self):
364
 
            self._clear_f()
365
 
            self._handle = None
 
312
            overlapped = pywintypes.OVERLAPPED()
 
313
            try:
 
314
                win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
 
315
                self._clear_f()
 
316
            except Exception, e:
 
317
                raise errors.LockContention(e)
366
318
 
367
319
 
368
320
    class _w32c_ReadLock(_w32c_FileLock):
369
321
        def __init__(self, filename):
370
322
            super(_w32c_ReadLock, self).__init__()
371
 
            self._open(filename, win32file.GENERIC_READ,
372
 
                win32file.FILE_SHARE_READ, os.O_RDONLY, "rb")
 
323
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
373
324
 
374
325
        def temporary_write_lock(self):
375
326
            """Try to grab a write lock on the file.
394
345
    class _w32c_WriteLock(_w32c_FileLock):
395
346
        def __init__(self, filename):
396
347
            super(_w32c_WriteLock, self).__init__()
397
 
            self._open(filename,
398
 
                win32file.GENERIC_READ | win32file.GENERIC_WRITE, 0,
399
 
                os.O_RDWR, "rb+")
 
348
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
400
349
 
401
350
        def restore_read_lock(self):
402
351
            """Restore the original ReadLock."""
409
358
    _lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
410
359
 
411
360
 
412
 
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
 
361
if have_ctypes and sys.platform == 'win32':
 
362
    # These constants were copied from the win32con.py module.
 
363
    LOCKFILE_FAIL_IMMEDIATELY = 1
 
364
    LOCKFILE_EXCLUSIVE_LOCK = 2
 
365
    # Constant taken from winerror.py module
 
366
    ERROR_LOCK_VIOLATION = 33
 
367
 
 
368
    LOCK_SH = 0
 
369
    LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
 
370
    LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
 
371
    _LockFileEx = ctypes.windll.kernel32.LockFileEx
 
372
    _UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
 
373
    _GetLastError = ctypes.windll.kernel32.GetLastError
 
374
 
 
375
    ### Define the OVERLAPPED structure.
 
376
    #   http://msdn2.microsoft.com/en-us/library/ms684342.aspx
 
377
    # typedef struct _OVERLAPPED {
 
378
    #   ULONG_PTR Internal;
 
379
    #   ULONG_PTR InternalHigh;
 
380
    #   union {
 
381
    #     struct {
 
382
    #       DWORD Offset;
 
383
    #       DWORD OffsetHigh;
 
384
    #     };
 
385
    #     PVOID Pointer;
 
386
    #   };
 
387
    #   HANDLE hEvent;
 
388
    # } OVERLAPPED,
 
389
 
 
390
    class _inner_struct(ctypes.Structure):
 
391
        _fields_ = [('Offset', ctypes.c_uint), # DWORD
 
392
                    ('OffsetHigh', ctypes.c_uint), # DWORD
 
393
                   ]
 
394
 
 
395
    class _inner_union(ctypes.Union):
 
396
        _fields_  = [('anon_struct', _inner_struct), # struct
 
397
                     ('Pointer', ctypes.c_void_p), # PVOID
 
398
                    ]
 
399
 
 
400
    class OVERLAPPED(ctypes.Structure):
 
401
        _fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
 
402
                    ('InternalHigh', ctypes.c_void_p), # ULONG_PTR
 
403
                    ('_inner_union', _inner_union),
 
404
                    ('hEvent', ctypes.c_void_p), # HANDLE
 
405
                   ]
447
406
 
448
407
    class _ctypes_FileLock(_OSLock):
449
408
 
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
 
409
        def _lock(self, filename, openmode, lockmode):
 
410
            self._open(filename, openmode)
 
411
 
 
412
            self.hfile = msvcrt.get_osfhandle(self.f.fileno())
 
413
            overlapped = OVERLAPPED()
 
414
            result = _LockFileEx(self.hfile, # HANDLE hFile
 
415
                                 lockmode,   # DWORD dwFlags
 
416
                                 0,          # DWORD dwReserved
 
417
                                 0x7fffffff, # DWORD nNumberOfBytesToLockLow
 
418
                                 0x00000000, # DWORD nNumberOfBytesToLockHigh
 
419
                                 ctypes.byref(overlapped), # lpOverlapped
 
420
                                )
 
421
            if result == 0:
 
422
                self._clear_f()
 
423
                last_err = _GetLastError()
 
424
                if last_err in (ERROR_LOCK_VIOLATION,):
 
425
                    raise errors.LockContention(filename)
 
426
                raise errors.LockContention('Unknown locking error: %s'
 
427
                                            % (last_err,))
464
428
 
465
429
        def unlock(self):
 
430
            overlapped = OVERLAPPED()
 
431
            result = _UnlockFileEx(self.hfile, # HANDLE hFile
 
432
                                   0,          # DWORD dwReserved
 
433
                                   0x7fffffff, # DWORD nNumberOfBytesToLockLow
 
434
                                   0x00000000, # DWORD nNumberOfBytesToLockHigh
 
435
                                   ctypes.byref(overlapped), # lpOverlapped
 
436
                                  )
466
437
            self._clear_f()
 
438
            if result == 0:
 
439
                self._clear_f()
 
440
                last_err = _GetLastError()
 
441
                raise errors.LockContention('Unknown unlocking error: %s'
 
442
                                            % (last_err,))
467
443
 
468
444
 
469
445
    class _ctypes_ReadLock(_ctypes_FileLock):
470
446
        def __init__(self, filename):
471
447
            super(_ctypes_ReadLock, self).__init__()
472
 
            self._open(filename, GENERIC_READ, FILE_SHARE_READ, os.O_RDONLY,
473
 
                "rb")
 
448
            self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
474
449
 
475
450
        def temporary_write_lock(self):
476
451
            """Try to grab a write lock on the file.
494
469
    class _ctypes_WriteLock(_ctypes_FileLock):
495
470
        def __init__(self, filename):
496
471
            super(_ctypes_WriteLock, self).__init__()
497
 
            self._open(filename, GENERIC_READ | GENERIC_WRITE, 0, os.O_RDWR,
498
 
                "rb+")
 
472
            self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
499
473
 
500
474
        def restore_read_lock(self):
501
475
            """Restore the original ReadLock."""
518
492
# We default to using the first available lock class.
519
493
_lock_type, WriteLock, ReadLock = _lock_classes[0]
520
494
 
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