[FIXED] Is it possible to make a decorator to run blocking functions in the asyncio executor?

Issue

I may may need help phrasing this question better. I'm writing an async api interface, via python3.7, & with a class (called Worker()). Worker has a few blocking methods I want to run using loop.run_in_executor().

I'd like to build a decorator I can just add above all of the non-async methods in Worker, but I keep running into problems.

I am being told that I need to await wraps() in the decorator below:

def run_method_in_executor(func, *, loop=None):
    async def wraps(*args):
        _loop = loop if loop is not None else asyncio.get_event_loop()
        return await _loop.run_in_executor(executor=None, func=func, *args)
    return wraps

which throws back: RuntimeWarning: coroutine 'run_method_in_executor.<locals>.wraps' was never awaited

I'm not seeing how I could properly await wraps() since the containing function & decorated functions aren't asynchronous. Not sure if this is due to misunderstanding asyncio, or misunderstanding decorators.

Any help (or help clarifying) would be greatly appreciated!

Solution

Not_a_Golfer answered my question in the comments.

Changing the inner wraps() function from a coroutine into a generator solved the problem:

def run_method_in_executor(func, *, loop=None):
    def wraps(*args):
        _loop = loop if loop is not None else asyncio.get_event_loop()
        yield _loop.run_in_executor(executor=None, func=func, *args)
    return wraps

Edit: This has been really useful for IO, but I haven't figured out how to await the yielded executor function, which means it will create a race condition if I'm relying on a decorated function to update some value used by any of my other async functions.

Answered By - Rob Truxal