Commit fc5f0397 authored by Robert K's avatar Robert K
Browse files

Merge branch 'bugfix/partial-revert-locking' into 'master'

[bugfix][Python] Revert cleanup in locking.py.

See merge request !1063
parents 8084df46 91ea1984
Pipeline #41587 passed with stages
in 13 minutes and 3 seconds
from portalocker import Lock as _Lock
from portalocker.constants import LOCK_EX, LOCK_SH
## By default use portalocker, if available.
## However, portalocker is not available on all systems
## and therefore a fallback implementation is also provided
try:
from portalocker import Lock as _Lock
from portalocker.constants import LOCK_EX, LOCK_SH
class Lock(_Lock):
def __init__(self, path, flags, *args, **kwargs):
_Lock.__init__(self,path,*args,flags=flags,timeout=None,**kwargs)
except ModuleNotFoundError:
## Fallback implementation if portalocker was not found
## This is still needed! Do not remove it.
import os
import fcntl
from fcntl import LOCK_EX, LOCK_SH
# file locking from fcntl
def lock_file(f, cmd=fcntl.LOCK_EX):
fcntl.flock(f, cmd)
return f
def unlock_file(f):
fcntl.flock(f, fcntl.LOCK_UN)
return f
class Lock(_Lock):
"""A lock to prevent data races in situations with multiple processes"""
def __init__(self, path, flags, *args, **kwargs):
_Lock.__init__(self, path, *args, flags=flags, timeout=None, **kwargs)
# This file opener *must* be used in a "with" block.
class Lock:
# Open the file with arguments provided by user. Then acquire
# a lock on that file object (WARNING: Advisory locking).
def __init__(self, path, flags, *args, **kwargs):
# Open the file and acquire a lock on the file before operating
self.file = open(path, mode='w+', *args, **kwargs)
# Lock the opened file
self.file = lock_file(self.file, flags) # flags are either LOCK_EX or LOCK_SH
# Return the opened file object (knowing a lock has been obtained).
def __enter__(self, *args, **kwargs): return self.file
# Unlock the file and close the file object.
def __exit__(self, exc_type=None, exc_value=None, traceback=None):
# Flush to make sure all buffered contents are written to file.
self.file.flush()
os.fsync(self.file.fileno())
# Release the lock on the file.
self.file = unlock_file(self.file)
self.file.close()
# Handle exceptions that may have come up during execution, by
# default any exceptions are raised to the user.
return exc_type == None
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