mirror of https://github.com/zulip/zulip.git
37 lines
1.0 KiB
Python
37 lines
1.0 KiB
Python
"""
|
|
Context managers, i.e. things you can use with the 'with' statement.
|
|
"""
|
|
|
|
import fcntl
|
|
from os import path
|
|
from contextlib import contextmanager
|
|
|
|
@contextmanager
|
|
def flock(lockfile, shared=False):
|
|
"""Lock a file object using flock(2) for the duration of a 'with' statement.
|
|
|
|
If shared is True, use a LOCK_SH lock, otherwise LOCK_EX."""
|
|
|
|
fcntl.flock(lockfile, fcntl.LOCK_SH if shared else fcntl.LOCK_EX)
|
|
try:
|
|
yield
|
|
finally:
|
|
fcntl.flock(lockfile, fcntl.LOCK_UN)
|
|
|
|
@contextmanager
|
|
def lockfile(filename, shared=False):
|
|
"""Lock a file using flock(2) for the duration of a 'with' statement.
|
|
|
|
If shared is True, use a LOCK_SH lock, otherwise LOCK_EX.
|
|
|
|
The file is given by name and will be created if it does not exist."""
|
|
|
|
if not path.exists(filename):
|
|
with open(filename, 'w') as lock:
|
|
lock.write('0')
|
|
|
|
# TODO: Can we just open the file for writing, and skip the above check?
|
|
with open(filename, 'r') as lock:
|
|
with flock(lock, shared=shared):
|
|
yield
|