refactor(rumqttd): let Broker derive Clone and remove start mut self

[crimx]

fixes #699

[swanandx]

Hey, I'm curious how does this PR solves the mentioned discussion? can you elaborate more on this 😅

[crimx]

With the current implementation, we are moving a mut broker to a thread and start. There is no way to access the broker outside the thread afterwards.

By removing mut self on start, we can simply share the broker via Arc.

Or since both Broker.config and Broker.router_tx are thread safe and clonable, we can just move a broker.clone() to a thread and start, move another clone to other thread and link.

[h3nill]

while sharing would be possible, it would also allow start to be called multiple times which shouldn't happen.

Can you share why do you want to share the broker to another thread?

[crimx]

You are right this could be an issue.

Mu use case is that I want to link and subscribe to dynamic topics that are created after broker starts.

[swanandx]

I want to link and subscribe to dynamic topics that are created after broker starts.

You can create link using LinkBuilder with just client id and router_tx like here .

So you might not need whole Broker, just router_tx should be enough!

[crimx]

Yes that'll do. I've read this but therouter_tx and LinkBuilder are private so I assumed you want to hide the details.

[swanandx]

I've read this but therouter_tx and LinkBuilder are private

Good catch, i somehow managed to miss this detail 😬😅