Lockfile lib

lockfile.py

import os
import fcntl
from contextlib import contextmanager


@contextmanager
def file_lock(lock_file):
    if os.path.exists(lock_file):
        raise RuntimeError("Lockfile exists: %s" % lock_file)
    else:
        with open(lock_file, 'w') as fp:
            try:
                fcntl.lockf(fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
                yield
            finally:
                os.remove(lock_file)