Function flock

openkb/locks.py:23–37

Acquire an advisory lock on an open file handle (cross-platform). Delegates to :mod:`portalocker`: - **POSIX** — ``fcntl.flock``; the call blocks indefinitely until acquired. - **Windows** — shared locks use the Win32 ``LockFileEx`` API (``pywin32``, which portalocker pulls in au

(fh: IO, *, exclusive: bool)

def flock(fh: IO, *, exclusive: bool) -> None:
    """Acquire an advisory lock on an open file handle (cross-platform).

    Delegates to :mod:`portalocker`:

    - **POSIX** — ``fcntl.flock``; the call blocks indefinitely until acquired.
    - **Windows** — shared locks use the Win32 ``LockFileEx`` API (``pywin32``,
      which portalocker pulls in automatically on Windows), so concurrent
      readers are honoured; exclusive locks use ``msvcrt.locking``, which
      retries for ~10s and then raises rather than blocking indefinitely.

    On failure portalocker raises :class:`portalocker.LockException` — note this
    is *not* an ``OSError`` (e.g. on filesystems without working lock support).
    """
    portalocker.lock(fh, portalocker.LOCK_EX if exclusive else portalocker.LOCK_SH)


def funlock(fh: IO) -> None: