A beginner’s question about middleware: error[E0277]: the trait bound `axum::middleware::FromFn<fn(hyper::Request<axum::body::Body>, Next) -> impl Future<Output = #2766

blackcats1999 · 2024-06-04T12:55:19Z

blackcats1999
Jun 4, 2024

Bug Report

Version

axum = "0.7.5"
hyper = "1.3.1"
tokio = { version = "1.37.0", features = ["full"] }

Description

pub async fn app(mut request: Request, next: Next) -> Result<Response, Json<Rsp<rsp::Default>>> {
    let uri = request.uri().clone();

    let now = plier::time::unix_second();
    let uuid = plier::uid::uid_v4();
    request.headers_mut().insert("x-uuid", uuid.parse().unwrap());
    request.headers_mut().insert("x-begin-time", now.into());

    let xip = common::net::get_request_ip(&mut request);
    let user_token = request.headers().get("userToken").cloned();

    tracing::info!("request uid {:?} ip {:?} path {:?} user_token {:?}",uuid, xip, uri.path(), user_token);

    let req = buffer_request_body(request).await.unwrap();


    for v in WHITE_LIST_URL {
        if v == uri.path() {
            let res = next.run(req).await;
            tracing::info!("request uid {} time {} ", uuid, plier::time::unix_second() - now);
            return Ok(res)
        }
    }

    if let Some(x) = user_token {
        let ut = x.to_str().unwrap().to_string();
        let res = common::cache::member_rds::get_user_by_token(ut).await;
        if res.is_err() {
            tracing::error!("get_user_by_token：{:?}", res);
            return Err(Json(Rsp::<rsp::Default>::not_login()))
        }
        
        let member = res.unwrap();
        if let Some(u) = member{
        
        } else{
            return Err(Json(Rsp::<rsp::Default>::not_login()))
        }
    }else{
        return Err(Json(Rsp::<rsp::Default>::not_login()))
    }

    let res = next.run(req).await;
    tracing::info!("request uid {} time {} ", uuid, plier::time::unix_second() - now);
    Ok(res)
}

In the above code,
let res = common::cache::member_rds::get_user_by_token(ut).await;
will cause a problem, causing the compilation to fail. Comment it out and the compilation will be successful, but it will not achieve the function I want. , can anyone explain the reason? I'm really confused as to why:

error[E0277]: the trait bound `axum::middleware::FromFn<fn(hyper::Request<axum::body::Body>, Next) -> impl Future<Output = Result<hyper::Response<axum::body::Body>, Json<Rsp<common::net::rsp::Default>>>> {app}, (), Route, _>: tower_service::Service<hyper::Request<axum::body::Body>>` is not satisfied
   --> server-manage\src\main.rs:74:27
    |
74  |     router = router.layer(middleware::from_fn(ctrl::interceptor::app));
    |                     ----- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `tower_service::Service<hyper::Request<axum::body::Body>>` is not implemented for `FromFn<fn(Request<Body>, Next) -> impl Future<Output = Result<Response<Body>, ...>> {app}, ..., ..., ...>`
    |                     |
    |                     required by a bound introduced by this call
    |
    = help: the following other types implement trait `tower_service::Service<Request>`:
              axum::middleware::FromFn<F, S, I, (T1,)>
              axum::middleware::FromFn<F, S, I, (T1, T2)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4, T5)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4, T5, T6)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4, T5, T6, T7)>
              axum::middleware::FromFn<F, S, I, (T1, T2, T3, T4, T5, T6, T7, T8)>
            and 8 others
note: required by a bound in `Router::<S>::layer`
   --> C:\Users\p\.cargo\registry\src\index.crates.io-6f17d22bba15001f\axum-0.7.5\src\routing\mod.rs:278:21
    |
275 |     pub fn layer<L>(self, layer: L) -> Router<S>
    |            ----- required by a bound in this associated function
...
278 |         L::Service: Service<Request> + Clone + Send + 'static,
    |                     ^^^^^^^^^^^^^^^^ required by this bound in `Router::<S>::layer`

According to my idea, calling another async in async should be completely unrelated, but it was beyond my expectation.

redis fred = "9.0.1" is used in get_user_by_token

pub async fn get_user_by_token(user_token: String) -> Result<Option<BlogAuthor>, RedisError> {
    let rd = RDS.get().expect("RDS is not initialized").read().unwrap();
    let res = rd.get_string(&format!("UT:{}", user_token)).await;

    if res.is_err() {
        return Err(res.err().unwrap());
    }

    let r = res.unwrap();
    if "" == r {
        return Ok(None);
    }

    let deserialized: BlogAuthor = serde_json::from_str(&r).unwrap();
    return Ok(Some(deserialized));
}

mladedav · 2024-06-04T16:33:49Z

mladedav
Jun 4, 2024
Collaborator

These kinds of problems usually happen when the future generated by the function stops being Send. Nothing in the code but me but you might be holding some variable across the newly introduced await point so when it disappears, everything works. Either clippy has a lint for non-send futures or you can try constructing the future and putting it in a function that expects a Send parameter. If this really is the issue, the error should also tell you why the future isn't Send.

1 reply

jplatte Jun 5, 2024
Maintainer

The clippy lint is this: https://rust-lang.github.io/rust-clippy/master/index.html#/future_not_send
I would recommended putting #[warn(clippy::future_not_send)] on fn app.

blackcats1999 · 2024-06-07T04:24:15Z

blackcats1999
Jun 7, 2024
Author

I successfully dealt with this issue,https://stackoverflow.com/questions/76307624/unexplained-trait-bound-no-longer-satisfied-when-modifying-axum-handler-body
use std::sync::RwLock; -> use tokio::sync::RwLock;

0 replies

blackcats1999 · 2024-06-07T04:25:26Z

blackcats1999
Jun 7, 2024
Author

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blackcats1999 Jun 4, 2024

Bug Report

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blackcats1999
Jun 4, 2024

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mladedav
Jun 4, 2024
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Jun 7, 2024
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blackcats1999
Jun 7, 2024
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