_logs.py 文件源码

def _lock(fileno):
    """Try to lock a file. Return True on success."""
    # closing the file unlocks it, so we don't need to unlock here
    if platform.system() == 'Windows':
        try:
            msvcrt.locking(fileno, msvcrt.LK_NBLCK, 10)
            return True
        except PermissionError:
            return False
    else:
        try:
            fcntl.lockf(fileno, fcntl.LOCK_EX | fcntl.LOCK_NB)
            return True
        # the docs recommend catching both of these
        except (BlockingIOError, PermissionError):
            return False