from __future__ import annotations import os import sys from abc import ABC from typing import cast from ._api import BaseFileLock #: a flag to indicate if the fcntl API is available has_fcntl = False if sys.platform == "win32": # pragma: win32 cover class UnixFileLock(BaseFileLock, ABC): """Uses the :func:`fcntl.flock` to hard lock the lock file on unix systems.""" else: # pragma: win32 no cover try: import fcntl except ImportError: pass else: has_fcntl = True class UnixFileLock(BaseFileLock): """Uses the :func:`fcntl.flock` to hard lock the lock file on unix systems.""" def _acquire(self) -> None: open_mode = os.O_RDWR | os.O_CREAT | os.O_TRUNC fd = os.open(self._lock_file, open_mode) try: fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB) except OSError: os.close(fd) else: self._lock_file_fd = fd def _release(self) -> None: # Do not remove the lockfile: # https://github.com/tox-dev/py-filelock/issues/31 # https://stackoverflow.com/questions/17708885/flock-removing-locked-file-without-race-condition fd = cast(int, self._lock_file_fd) self._lock_file_fd = None fcntl.flock(fd, fcntl.LOCK_UN) os.close(fd) __all__ = [ "has_fcntl", "UnixFileLock", ]