Lifetime in StreamServer with &Status<Arc<...>>

[expploitt]

I'm trying to expose an async get function in my API but I can't find how to implemented in order to compile. I read the documentation for borrowing values, but is not working.

What I want is:

pub async fn sse_update_foo_information(status: &State<Arc<Mutex<HashMap<Uuid, Foo>>>>) -> EventStream![] {
    EventStream! {
        loop {
            let mutex = status.lock().await;
            let nodes: HashMap<Uuid, Foo> = mutex.clone();
            drop(mutex);
            let values: Vec<AgentInformation> = nodes.clone().into_values().collect();
            yield Event::data(&serde_json::to_string(&values).unwrap())
        }
    }

The error I get is:

error[E0759]: `status` has an anonymous lifetime `'_` but it needs to satisfy a `'static` lifetime requirement
  --> 
   |
46 | pub async fn sse_update_foo_information(status: &State<Arc<Mutex<HashMap<Uuid, Foo>>>>) -> EventStream![] {
   |                                           ^^^^^^  ---------------------------------------------------     -------------- ...and is required to live as long as `'static` here
   |                                           |       |
   |                                           |       this data with an anonymous lifetime `'_`...
   |                                           ...is captured here...
   |
help: to declare that the `impl Trait` captures data from argument `status`, you can add an explicit `'_` lifetime bound
   |
240|         } + '_

And if I add EventStream![Event + '_] then:

error[E0404]: expected trait, found struct `Event`
  --> 
   |
46 | pub async fn sse_update_foo_information(status: &State<Arc<Mutex<HashMap<Uuid, Foo>>>>) -> EventStream![Event + '_] {
   |                                                                                                                        ^^^^^ not a trait
   |
help: `+` is used to constrain a "trait object" type with lifetimes or auto-traits; structs and enums can't be bound in that way
  -->
   |
46 | pub async fn sse_update_foo_information(status: &State<Arc<Mutex<HashMap<Uuid, Foo>>>>) -> EventStream![Event + '_] {
   |                                                                                                                        -----   ^^ ...because of this bound
   |                                                                                                                        |
   |                                                                                                                        expected this type to be a trait...
help: if you meant to use a type and not a trait here, remove the bounds
   |
46 - pub async fn sse_update_foo_information(status: &State<Arc<Mutex<HashMap<Uuid, Foo>>>>) -> EventStream![Event + '_] {
46 + pub async fn sse_update_foo_information(status: &State<Arc<Mutex<HashMap<Uuid, Foo>>>>) -> EventStream![Event] {

If someone can help me please! Thanks

[SergioBenitez]

Your yield is the culprit. Use the dedicated Json method, which should solve your problem: https://api.rocket.rs/master/rocket/response/stream/struct.Event.html#method.json.

[expploitt]

With the yield Event::json(&serde_json::to_string(&values).unwrap()) the output error compile is the same...

[SergioBenitez]

You should never be calling serde_json directly in Rocket. Please see the documentation for how to use this method correctly.

[expploitt]

I solved that issue, but I still have the status has an anonymous lifetime '_ but it needs to satisfy a 'static lifetime requirement error that I can't solved yet...

[expploitt]

I can't resolve the issue, but it is due to the async fn. I don't know yet whats happening with lifetimes...