WIP: add lifespan support (monkay based)

[devkral]

Changes:

• add lifespan support via monkay.asgi
• Bump minimum python version (near EOL, needs discussion)

[devkral]

if needed, I can readd python 3.9 support in monkay

[carltongibson]

No problem with Python 3.10 as a minimum version.

[mjvankampen]

I'm not sure if the lifespan cleanup is going right :(. When using --noreload I do see kill_all_applications being run. But not the actual lifespan code.

[devkral]

not sure where the bug results from. I think twisted ignores the return value despite documented

[devkral]

I rewrote the code for test purposes:

    def kill_all_applications(self):
        """
        Kills all application coroutines before reactor exit.
        """

        # Make Twisted wait until they're all dead and cleanup lifespan
        async def cleanup():
            # Send cancel to all coroutines
            wait_for = []
            for details in self.connections.values():
                application_instance = details["application_instance"]
                if not application_instance.done():
                    application_instance.cancel()
                    wait_for.append(application_instance)
            logger.info("Killed %i pending application instances", len(wait_for))
            try:
                await asyncio.gather(*wait_for)
            finally:
                if self.lifespan_context:
                    await self.lifespan_context.__aexit__()

        return defer.Deferred.fromFuture(cleanup())

Effect: silence (no info output). Seemingly they ignore the return value

[devkral]

    def kill_all_applications(self):
        """
        Kills all application coroutines before reactor exit.
        """

        # Make Twisted wait until they're all dead and cleanup lifespan
        async def cleanup():
            # Send cancel to all coroutines
            wait_for = []
            for details in self.connections.values():
                application_instance = details["application_instance"]
                if not application_instance.done():
                    application_instance.cancel()
                    wait_for.append(application_instance)
            logger.info("Killed %i pending application instances", len(wait_for))
            try:
                await asyncio.gather(*wait_for)
            finally:
                if self.lifespan_context:
                    await self.lifespan_context.__aexit__()

        reactor._asyncioEventloop.run_until_complete(cleanup())

Gives me a resource warning

[devkral]

Found a solution. But I doubt that the kill_app code is working.

[XEDGit]

I have noticed a native implementation of lifespan on this fork: https://github.com/imAsparky/daphne/tree/issue-264, it'd avoid removing support for 3.9 (even if over EOL) and avoid adding dependencies, which can be preferred. What is the status of this PR? is a native implementation preferred over this one?

Edit: The link was not clickable