/usr/lib/python2.7/dist-packages/twext/python/filepath.py is in calendarserver 5.2+dfsg-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 | # -*- test-case-name: twext.python.test.test_filepath -*-
##
# Copyright (c) 2010-2014 Apple Inc. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
##
"""
Extend L{twisted.python.filepath} to provide performance enhancements for
calendar server.
"""
from os import listdir as _listdir
from os.path import (join as _joinpath,
basename as _basename,
exists as _exists,
dirname as _dirname)
from time import sleep as _sleep
from types import FunctionType, MethodType
from errno import EINVAL
from twisted.python.filepath import FilePath as _FilePath
from stat import S_ISDIR
class CachingFilePath(_FilePath, object):
"""
A descendent of L{_FilePath} which implements a more aggressive caching
policy.
"""
_listdir = _listdir # integration points for tests
_sleep = _sleep
BACKOFF_MAX = 5.0 # Maximum time to wait between calls to
# listdir()
def __init__(self, path, alwaysCreate=False):
super(CachingFilePath, self).__init__(path, alwaysCreate)
self.existsCached = None
self.isDirCached = None
@property
def siblingExtensionSearch(self):
"""
Dynamically create a version of L{_FilePath.siblingExtensionSearch} that
uses a pluggable 'listdir' implementation.
"""
return MethodType(FunctionType(
_FilePath.siblingExtensionSearch.im_func.func_code,
{'listdir': self._retryListdir,
'basename': _basename,
'dirname': _dirname,
'joinpath': _joinpath,
'exists': _exists}), self, self.__class__)
def changed(self):
"""
This path may have changed in the filesystem, so forget all cached
information about it.
"""
self.statinfo = None
self.existsCached = None
self.isDirCached = None
def _retryListdir(self, pathname):
"""
Implementation of retry logic for C{listdir} and
C{siblingExtensionSearch}.
"""
delay = 0.1
while True:
try:
return self._listdir(pathname)
except OSError, e:
if e.errno == EINVAL:
self._sleep(delay)
delay = min(self.BACKOFF_MAX, delay * 2.0)
else:
raise
raise RuntimeError("unreachable code.")
def listdir(self):
"""
List the directory which C{self.path} points to, compensating for
EINVAL from C{os.listdir}.
"""
return self._retryListdir(self.path)
def restat(self, reraise=True):
"""
Re-cache stat information.
"""
try:
return super(CachingFilePath, self).restat(reraise)
finally:
if self.statinfo:
self.existsCached = True
self.isDirCached = S_ISDIR(self.statinfo.st_mode)
else:
self.existsCached = False
self.isDirCached = None
def moveTo(self, destination, followLinks=True):
"""
Override L{_FilePath.moveTo}, updating extended cache information if
necessary.
"""
result = super(CachingFilePath, self).moveTo(destination, followLinks)
self.changed()
# Work with vanilla FilePath destinations to pacify the tests.
if hasattr(destination, "changed"):
destination.changed()
return result
def remove(self):
"""
Override L{_FilePath.remove}, updating extended cache information if
necessary.
"""
try:
return super(CachingFilePath, self).remove()
finally:
self.changed()
CachingFilePath.clonePath = CachingFilePath
__all__ = ["CachingFilePath"]
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