MulticastRequest timeout does not put end on QueueWithEnd

[pwhitey86]

In running:

client_context = yield from aiocoap.Context.create_client_context(loggername='client')
responsesFuture = client_context.multicast_request(message)
responses = []
while (yield from responsesFuture.can_peek()):
  r = responsesFuture.get_nowait()
  print('got future response: %s'%r)
  responses.append(r)
print('while done')

the print('while done') is never reached even after the _timeout() function is reached.

If the queuewithend.py line 822 is changed to

asyncio.async(self.responses.finish())

the end is placed on the queue and the while loop terminates. Is this an issue?

[pauluap]

I bumped into the same issue with aiocoap 0.3 and implemented essentially the same workaround.

However, when I look at the code in master, it seems that the multicast request method has been removed. Does that mean that the project is dropping multicast request support?

[chrysn]

Multicast was removed because it didn't actually work -- but if it does for you, I'll have to re-evaluate that.

(The current state of multicast in the 0.4 pre-releases is that it works server-side, but client-side you can only do pseudo-anycast, meaning you send a request to a multicast address, but only receive the first response as "the" response).

I'll have a closer look at this (also to reinstate multicast -- how well does it work for you in 0.3? Do you reliably get all the expected answers?), but can't promise when exactly at the moment.

[pauluap]

Thanks for continuing to maintain this project, I appreciate it!

Rather than what the OP did, I wrote asyncio.get_running_loop().run_until_complete(self.responses.finish()) but that amounts to the same thing. Doing that does get things going for me.

I'm not sure what you mean by 'reliably' - it's udp multicast after all, but on my small quiet network with a small number of servers, I'm able to see responses from all of my servers every time I make a multicast request.

I'll eventually need DTLS support, so I took a hack at trying to implement multicast support in master. I'll make up a pull request for that soon. I expect that I made a grievous error somewhere so a code review would be appreciated.