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# Copyright (C) 2005, 2006, 2007 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""Locking using OS file locks or file existence.
Note: This method of locking is generally deprecated in favour of LockDir, but
is used to lock local WorkingTrees, and by some old formats. It's accessed
through Transport.lock_read(), etc.
This module causes two methods, lock() and unlock() to be defined in
any way that works on the current platform.
It is not specified whether these locks are reentrant (i.e. can be
taken repeatedly by a single process) or whether they exclude
different threads in a single process. That reentrancy is provided by
LockableFiles.
This defines two classes: ReadLock and WriteLock, which can be
implemented in different ways on different platforms. Both have an
unlock() method.
"""
import errno
import os
import sys
from bzrlib import errors
from bzrlib.errors import LockError, LockContention
from bzrlib.osutils import realpath
from bzrlib.trace import mutter
class _base_Lock(object):
def __init__(self):
self.f = None
def _open(self, filename, filemode):
try:
self.f = open(filename, filemode)
return self.f
except IOError, e:
if e.errno in (errno.EACCES, errno.EPERM):
raise errors.ReadOnlyLockError(e)
if e.errno != errno.ENOENT:
raise
# maybe this is an old branch (before may 2005)
mutter("trying to create missing branch lock %r", filename)
self.f = open(filename, 'wb+')
return self.f
def _clear_f(self):
"""Clear the self.f attribute cleanly."""
if self.f:
self.f.close()
self.f = None
def __del__(self):
if self.f:
from warnings import warn
warn("lock on %r not released" % self.f)
self.unlock()
def unlock(self):
raise NotImplementedError()
have_ctypes = have_pywin32 = have_fcntl = False
try:
import fcntl
have_fcntl = True
except ImportError:
have_fcntl = False
try:
import win32con, win32file, pywintypes, winerror, msvcrt
have_pywin32 = True
except ImportError:
have_pywin32 = False
try:
import ctypes, msvcrt
have_ctypes = True
except ImportError:
have_ctypes = False
_lock_classes = []
if have_fcntl:
LOCK_SH = fcntl.LOCK_SH
LOCK_NB = fcntl.LOCK_NB
lock_EX = fcntl.LOCK_EX
class _fcntl_FileLock(_base_Lock):
def _unlock(self):
fcntl.lockf(self.f, fcntl.LOCK_UN)
self._clear_f()
class _fcntl_WriteLock(_fcntl_FileLock):
open_locks = {}
def __init__(self, filename):
# standard IO errors get exposed directly.
super(_fcntl_WriteLock, self).__init__()
self._open(filename, 'rb+')
self.filename = realpath(filename)
if self.filename in self.open_locks:
self._clear_f()
raise LockContention(self.filename)
# reserve a slot for this lock - even if the lockf call fails,
# at thisi point unlock() will be called, because self.f is set.
# TODO: make this fully threadsafe, if we decide we care.
self.open_locks[self.filename] = self.filename
try:
# LOCK_NB will cause IOError to be raised if we can't grab a
# lock right away.
fcntl.lockf(self.f, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError, e:
if e.errno in (errno.EAGAIN, errno.EACCES):
# We couldn't grab the lock
self.unlock()
# we should be more precise about whats a locking
# error and whats a random-other error
raise LockError(e)
def unlock(self):
del self.open_locks[self.filename]
self._unlock()
class _fcntl_ReadLock(_fcntl_FileLock):
open_locks = {}
def __init__(self, filename):
super(_fcntl_ReadLock, self).__init__()
self._open(filename, 'rb')
try:
# LOCK_NB will cause IOError to be raised if we can't grab a
# lock right away.
fcntl.lockf(self.f, fcntl.LOCK_SH | fcntl.LOCK_NB)
except IOError, e:
# we should be more precise about whats a locking
# error and whats a random-other error
raise LockError(e)
def unlock(self):
self._unlock()
_lock_classes.append(('fcntl', _fcntl_WriteLock, _fcntl_ReadLock))
if have_pywin32:
LOCK_SH = 0 # the default
LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
class _w32c_FileLock(_base_Lock):
def _lock(self, filename, openmode, lockmode):
self._open(filename, openmode)
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
overlapped = pywintypes.OVERLAPPED()
try:
win32file.LockFileEx(self.hfile, lockmode, 0, 0x7fff0000,
overlapped)
except pywintypes.error, e:
self._clear_f()
if e.args[0] in (winerror.ERROR_LOCK_VIOLATION,):
raise errors.LockContention(filename)
## import pdb; pdb.set_trace()
raise
except Exception, e:
self._clear_f()
raise LockError(e)
def unlock(self):
overlapped = pywintypes.OVERLAPPED()
try:
win32file.UnlockFileEx(self.hfile, 0, 0x7fff0000, overlapped)
self._clear_f()
except Exception, e:
raise LockError(e)
class _w32c_ReadLock(_w32c_FileLock):
def __init__(self, filename):
super(_w32c_ReadLock, self).__init__()
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
class _w32c_WriteLock(_w32c_FileLock):
def __init__(self, filename):
super(_w32c_WriteLock, self).__init__()
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
_lock_classes.append(('pywin32', _w32c_WriteLock, _w32c_ReadLock))
if have_ctypes:
# These constants were copied from the win32con.py module.
LOCKFILE_FAIL_IMMEDIATELY = 1
LOCKFILE_EXCLUSIVE_LOCK = 2
# Constant taken from winerror.py module
ERROR_LOCK_VIOLATION = 33
LOCK_SH = 0
LOCK_EX = LOCKFILE_EXCLUSIVE_LOCK
LOCK_NB = LOCKFILE_FAIL_IMMEDIATELY
_LockFileEx = ctypes.windll.kernel32.LockFileEx
_UnlockFileEx = ctypes.windll.kernel32.UnlockFileEx
_GetLastError = ctypes.windll.kernel32.GetLastError
### Define the OVERLAPPED structure.
# http://msdn2.microsoft.com/en-us/library/ms684342.aspx
# typedef struct _OVERLAPPED {
# ULONG_PTR Internal;
# ULONG_PTR InternalHigh;
# union {
# struct {
# DWORD Offset;
# DWORD OffsetHigh;
# };
# PVOID Pointer;
# };
# HANDLE hEvent;
# } OVERLAPPED,
class _inner_struct(ctypes.Structure):
_fields_ = [('Offset', ctypes.c_uint), # DWORD
('OffsetHigh', ctypes.c_uint), # DWORD
]
class _inner_union(ctypes.Union):
_fields_ = [('anon_struct', _inner_struct), # struct
('Pointer', ctypes.c_void_p), # PVOID
]
class OVERLAPPED(ctypes.Structure):
_fields_ = [('Internal', ctypes.c_void_p), # ULONG_PTR
('InternalHigh', ctypes.c_void_p), # ULONG_PTR
('_inner_union', _inner_union),
('hEvent', ctypes.c_void_p), # HANDLE
]
class _ctypes_FileLock(_base_Lock):
def _lock(self, filename, openmode, lockmode):
self._open(filename, openmode)
self.hfile = msvcrt.get_osfhandle(self.f.fileno())
overlapped = OVERLAPPED()
p_overlapped = ctypes.pointer(overlapped)
result = _LockFileEx(self.hfile, # HANDLE hFile
lockmode, # DWORD dwFlags
0, # DWORD dwReserved
0x7fffffff, # DWORD nNumberOfBytesToLockLow
0x00000000, # DWORD nNumberOfBytesToLockHigh
p_overlapped, # lpOverlapped
)
if result == 0:
self._clear_f()
last_err = _GetLastError()
if last_err in (ERROR_LOCK_VIOLATION,):
raise errors.LockContention(filename)
raise errors.LockError('Unknown locking error: %s'
% (last_err,))
def unlock(self):
overlapped = OVERLAPPED()
p_overlapped = ctypes.pointer(overlapped)
result = _UnlockFileEx(self.hfile, # HANDLE hFile
0, # DWORD dwReserved
0x7fffffff, # DWORD nNumberOfBytesToLockLow
0x00000000, # DWORD nNumberOfBytesToLockHigh
p_overlapped, # lpOverlapped
)
self._clear_f()
if result == 0:
self._clear_f()
last_err = _GetLastError()
raise errors.LockError('Unknown unlocking error: %s'
% (last_err,))
class _ctypes_ReadLock(_ctypes_FileLock):
def __init__(self, filename):
super(_ctypes_ReadLock, self).__init__()
self._lock(filename, 'rb', LOCK_SH + LOCK_NB)
class _ctypes_WriteLock(_ctypes_FileLock):
def __init__(self, filename):
super(_ctypes_WriteLock, self).__init__()
self._lock(filename, 'rb+', LOCK_EX + LOCK_NB)
_lock_classes.append(('ctypes', _ctypes_WriteLock, _ctypes_ReadLock))
if len(_lock_classes) == 0:
raise NotImplementedError("We only have support for"
" fcntl, pywin32 or ctypes locking."
" If your platform (windows) does not"
" support fcntl locks, you must have"
" either pywin32 or ctypes installed.")
# We default to using the first available lock class.
_lock_type, WriteLock, ReadLock = _lock_classes[0]
class LockTreeTestProviderAdapter(object):
"""A tool to generate a suite testing multiple lock formats at once.
This is done by copying the test once for each lock and injecting the
read_lock and write_lock classes.
They are also given a new test id.
"""
def __init__(self, lock_classes):
self._lock_classes = lock_classes
def _clone_test(self, test, write_lock, read_lock, variation):
"""Clone test for adaption."""
new_test = deepcopy(test)
new_test.write_lock = write_lock
new_test.read_lock = read_lock
def make_new_test_id():
new_id = "%s(%s)" % (test.id(), variation)
return lambda: new_id
new_test.id = make_new_test_id()
return new_test
def adapt(self, test):
from bzrlib.tests import TestSuite
result = TestSuite()
for name, write_lock, read_lock in self._lock_classes:
new_test = self._clone_test(test, write_lock, read_lock, name)
result.addTest(new_test)
return result
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