Unneeded RwLock

[hgzimmerman]

Is your feature request related to a problem? Please describe.
I think there is a RwLock that isn't needed here: https://github.com/jetli/rust-yew-realworld-example-app/blob/master/crates/conduit-wasm/src/agent.rs#L23

Describe the solution you'd like
I think you could use a RefCell instead.

Additional context
Because your app is only running in a single "thread", there isn't a reason to use an RwLock.
It appears that you are only using it to enable interior mutability, which can be provided by a RefCell instead.

In fact you don't need to keep the token in memory and instead just get/set the token directly via the bowser's storage API, but I understand that you could want to avoid that in order to improve performance by a small amount.

[jetli]

Yep, it's kind of "cache" here, I'll see RefCell later.

[jetli]

@hgzimmerman It seems that lazy_static does not support RefCell due to thread safety:

`std::cell::RefCell<std::option::Option<std::string::String>>` cannot be shared between threads safely
the trait `std::marker::Sync` is not implemented for `std::cell::RefCell<std::option::Option<std::string::String>>`
required by `lazy_static::lazy::Lazy`

[hgzimmerman]

Look into https://doc.rust-lang.org/std/macro.thread_local.html instead

[jetli]

@hgzimmerman I tried thread_local!, It works:

thread_local! {
    pub static TOKEN: RefCell<Option<String>> = RefCell::new(None);
}

of course I have to move the initialization of TOKEN to App component's create.

But I'm thinking that yew supports multi-threading & concurrency, it's totally possible that we might need to use TOKEN in web workers someday or other multi-threading senarios, so I think we'd better use lazy_static for now, and leave it as a demonstration for multi-threading support.
What do you think?

[jetli]

or a type Reach = Global agent to manage global state like token/current user info etc? a kind of session for current user.
for now, I have to pass around a current_user info from App to sub components via props, a little tedious.
and we can use agent as a event bus to notify changes, like when a user logs out, the page is redirected to login page.

ok, a related issue: yewstack/yew#576

[jetli]

Leave it alone for multi-threading demonstration, closing this