Optionally disable ACK and REP responses to SET requests

[klanclos]

This pull request disables all responses from the server that would normally be triggered in response to a SET request. If a normal blocking SET request can be issued 5000 times per second, a client not waiting for a full response can instead issue 5500 requests per second, a client not waiting for any response can issue 40000 requests per second.

[tylertucker202]

I'm seeing a lot of repeated code. Would it be possible to implement a function here?

def get_reply(message):
    try:
        reply = message.payload.reply
    except SomeExpectedException:
        reply = True
    return reply

Then you can reuse this method wherever.

[klanclos]

I'm leaning towards setting up the logic as a property in the Payload class, which would eliminate the need to carry the what's a reasonable-default logic around.

[klanclos]

That looks cleaner to me. I still need to test it more thoroughly, then I'll move it out of draft status.

[klanclos]

Tests check out, there doesn't appear to be a performance impact from handling the 'reply' attribute as a property.

[mattkbrown]

These changes look good.

[klanclos]

The suggestion at today's discussion was that this functionality needs to be in the envelope as a 'flags' field rather than in the payload.

[klanclos]

OK, this feature is now working purely from the envelope and not involving the payload at all. I thought there was a reason why the payload had to carry around the 'no reply' status, but I'm not seeing it any more-- and it works fine without it.