Values inserted into State::pub_sub HashMap are never removed, leaky.

[cheako]

mini-redis/src/db.rs

Line 225 in 85e19aa

e.insert(tx);

I'm working on my own project and find it hard to implement a pub_sub system that isn't either manually managing memory(an anti-rust patter IMHO) or forgetting about it altogether as this code does.

Edit/Replace:
I wrote what maybe a working solution:
https://gitlab.com/cheako/websuite-rs/-/blob/21e9c2e7e2bb31dd0e3f94cc5ae23a17ece8e2c0/naomi/src/lib.rs
I didn't use a mpsc for the locking here, because I didn't want to be sending messages in a Drop handler... What do you think?

I'm playing with some ideas, but nothing is working out:
tov/weak-table-rs#5
https://gitlab.com/cheako/websuite-rs/-/blob/77258e059853acf9b678049c8016d3545394d2f6/naomi/src/lib.rs#L69
https://gitlab.com/cheako/websuite-rs/-/blob/af387566968a48bb8a8cb574d1baf30eb953d141/naomi/src/lib.rs#L138

Another project struggling with this is feather a minecraft server:
https://github.com/feather-rs/feather/blob/e6927044246e258cd0529645429ae83b45a23628/server/chunk/src/chunk_manager.rs#L84

As such, solutions welcome.