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filelock.py
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136 lines (106 loc) · 3.75 KB
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# The MIT License
#
# Copyright (c) 2015-2021 Sebastian Ramacher
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
fromtypingimportIO,Literal
fromtypesimportTracebackType
classBaseLock:
"""Base class for file locking"""
def__init__(self)->None:
self.locked=False
defacquire(self)->None:
pass
defrelease(self)->None:
pass
def__enter__(self)->"BaseLock":
self.acquire()
returnself
def__exit__(
self,
exc_type:type[BaseException]|None,
exc:BaseException|None,
exc_tb:TracebackType|None,
)->Literal[False]:
ifself.locked:
self.release()
returnFalse
def__del__(self)->None:
ifself.locked:
self.release()
try:
importfcntl
importerrno
classUnixFileLock(BaseLock):
"""Simple file locking for Unix using fcntl"""
def__init__(self,fileobj,mode:int=0)->None:
super().__init__()
self.fileobj=fileobj
self.mode=mode|fcntl.LOCK_EX
defacquire(self)->None:
try:
fcntl.flock(self.fileobj,self.mode)
self.locked=True
exceptOSErrorase:
ife.errno!=errno.ENOLCK:
raisee
defrelease(self)->None:
self.locked=False
fcntl.flock(self.fileobj,fcntl.LOCK_UN)
has_fcntl=True
exceptImportError:
has_fcntl=False
try:
importmsvcrt
importos
classWindowsFileLock(BaseLock):
"""Simple file locking for Windows using msvcrt"""
def__init__(self,filename:str)->None:
super().__init__()
self.filename=f"{filename}.lock"
self.fileobj=-1
defacquire(self)->None:
# create a lock file and lock it
self.fileobj=os.open(
self.filename,os.O_RDWR|os.O_CREAT|os.O_TRUNC
)
msvcrt.locking(self.fileobj,msvcrt.LK_NBLCK,1)
self.locked=True
defrelease(self)->None:
self.locked=False
# unlock lock file and remove it
msvcrt.locking(self.fileobj,msvcrt.LK_UNLCK,1)
os.close(self.fileobj)
self.fileobj=-1
try:
os.remove(self.filename)
exceptOSError:
pass
has_msvcrt=True
exceptImportError:
has_msvcrt=False
defFileLock(
fileobj:IO,mode:int=0,filename:str|None=None
)->BaseLock:
ifhas_fcntl:
returnUnixFileLock(fileobj,mode)
elifhas_msvcrtandfilenameisnotNone:
returnWindowsFileLock(filename)
returnBaseLock()
# vim: sw=4 ts=4 sts=4 ai et