rumqttc v5

[abhikjain360]

Add supports for MQTTv5 to rumqttc, along with following changes (only in v5, v4 not changed):

• Use Arc<Mutex<VecDeque<Request>>> instead of async-channel to send requests from client to eventloop
• pkids are returned when calling subscribe from client.
• code for parsing v5 packets copied from mqttbytes, remove its use
• use flume instead of async_channel and pollster
• different (and hopefully more intuitive) APIs, with option to run eventloop in background by default
• No longer supporting informing about outgoing events via eventloop

[de-sh]

NOTE: GitHub action fails since the PR doesn't contain the changes included in master that are necessary to run cargo-clippy with RUSTFLAGS="-D warnings". Consider only cargo-test(offline) results for PR merge.

Update, Mar 13:
Also, seems like 75 millis is not good enough Deviation for some test runs on macos, case in point.

[flxo]

Hello @abhikjain360

just a quick question to be sure: Your plan is to support v5 in a complete separated way from v4? Means a client needs to decide at build time which version to use? Any plans to add the possibility to choose the protocol version at runtime?

Thanks!

[tekjar]

They'll completely be separate for now @flxo. Helps us move faster

[mladedav]

Hi, I just want to check on this and provide support if needed. I am interested in getting packet IDs for which I understand this is a prerequisite.

Last commit here is a month old so I am just wondering if this is still being worked on or someone should pick it up.