Error prone pattern with background tasks that we wait till they are started.

[pipermerriam]

What was wrong?

We have a growing amount of code like this:

lahja/lahja/asyncio/endpoint.py

Lines 368 to 375 in 595a0f5

	self._receiving_loop_running = asyncio.Event()
	self._receiving_queue = asyncio.Queue()
	self._running = True
	self._endpoint_tasks.add(asyncio.ensure_future(self._connect_receiving_queue()))
	await self._receiving_loop_running.wait()

• an asyncio.Event to signal something that starts asynchronously in-fact running.
• a coroutine that needs to be run in the background which will set the event once it has started.
• a statement that waits for the event to be set..

This code is error prone.

• easy to forget to wait for the event.
• easy to forget to remove the event if the function gets refactored such that it isn't needed anymore.

How can it be fixed?

Not sure yet.