Add generic immutable interface.

[enzious]

I added a GenericClient trait over Client and Transaction, and replaced &mut with & to support the same style of trait as in previous versions.

I'm using GenericConnection in the old versions and I just wanted to try to add it back. I just named it GenericClient to match the new Client struct.

Thoughts?

Related issue:
#329

[sfackler]

The methods should take &mut self.

[enzious]

Could you explain that? It wasn't like this in the previous versions. Is this because of tokio?

In the old version I was using Rc<Connection>, but with this I'll have to use Rc<RefCell<Client>> everywhere.

[sfackler]

Internal mutability is very rare in Rust APIs. It only existed in this library because of an old, pre-Rust 1.0 API design that was overhauled significantly in the latest release.

If you want to use internal mutability in your code, you can use a RefCell as you've noted, but a connection pool like r2d2 is possibly a more appropriate choice.

[enzious]

r2d2 uses an Arc which is little heavy for what I need.

[sfackler]

What percentage of your runtime has your profiling indicated is spent in Arc code?

[enzious]

It's a discord/twitch clone (weird I know), but if users are spamming I don't want a ton of Arc locks.

I'm using Actix websockets, which are sorta-kinda single-threaded from what I understand.

[sfackler]

That wasn't really an answer to my question.

[enzious]

I haven't profiled this app, but in a previous experience with Arcs it was pretty bad locking for every request when you have a large number of messages.

[sfackler]

Arcs are used in proximity to all kinds of high performance code (and an Arc is not a lock in the first place). I'm not interested in adding a bunch of internal mutability back to this crate.

[enzious]

What about a GenericClient trait?

[sfackler]

Sure, I'd be happy to add that trait back.

[enzious]

And you're right, I was thinking of Arc<Mutex<T>>

[colingm]

@sfackler did you ever look at bringing back the GenericConnection trait into the newer versions?

[sfackler]

Ah, I have not yet but it seems reasonable to do!

[colingm]

@sfackler was there a specific change or re-architecture that prompted its removal? Just wanting to make sure there wasn't a better way to handle that need that I was missing.

[sfackler]

The crate was rewritten from scratch, and the trait just never made it back in.