rllib/utils/threading.py

from typing import Callable

from ray.rllib.utils.annotations import OldAPIStack


@OldAPIStack
def with_lock(func: Callable) -> Callable:
    """Use as decorator (@withlock) around object methods that need locking.

    Note: The object must have a self._lock = threading.Lock() property.
    Locking thus works on the object level (no two locked methods of the same
    object can be called asynchronously).

    Args:
        func: The function to decorate/wrap.

    Returns:
        The wrapped (object-level locked) function.
    """

    def wrapper(self, *a, **k):
        try:
            with self._lock:
                return func(self, *a, **k)
        except AttributeError as e:
            if "has no attribute '_lock'" in e.args[0]:
                raise AttributeError(
                    "Object {} must have a `self._lock` property (assigned "
                    "to a threading.RLock() object in its "
                    "constructor)!".format(self)
                )
            raise e

    return wrapper