ajj 0.6.2

Simple, modern, ergonomic JSON-RPC 2.0 router built with tower and axum
Documentation 
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use crate::{
    types::{InboundData, Response},
    HandlerCtx, TaskSet, TracingInfo,
};
use axum::{
    extract::FromRequest,
    http::{header, HeaderValue},
    response::IntoResponse,
};
use bytes::Bytes;
use std::{
    future::Future,
    pin::Pin,
    sync::{atomic::AtomicU32, Arc},
};
use tokio::runtime::Handle;
use tracing::{Instrument, Span};

/// A wrapper around an [`Router`] that implements the
/// [`axum::handler::Handler`] trait. This struct is an implementation detail
/// of the [`Router::into_axum`] and [`Router::into_axum_with_handle`] methods.
///
/// [`Router`]: crate::Router
/// [`Router::into_axum`]: crate::Router::into_axum
/// [`Router::into_axum_with_handle`]: crate::Router::into_axum_with_handle
#[derive(Debug, Clone)]
pub(crate) struct IntoAxum<S> {
    pub(crate) router: crate::Router<S>,

    pub(crate) task_set: TaskSet,

    /// Counter for OTEL messages received.
    pub(crate) rx_msg_id: Arc<AtomicU32>,
    /// Counter for OTEL messages sent.
    pub(crate) tx_msg_id: Arc<AtomicU32>,
}

impl<S> From<crate::Router<S>> for IntoAxum<S> {
    fn from(router: crate::Router<S>) -> Self {
        Self {
            router,
            task_set: Default::default(),
            rx_msg_id: Arc::new(AtomicU32::new(1)),
            tx_msg_id: Arc::new(AtomicU32::new(1)),
        }
    }
}

impl<S> IntoAxum<S> {
    /// Create a new `IntoAxum` from a router and task set.
    pub(crate) fn new(router: crate::Router<S>, handle: Handle) -> Self {
        Self {
            router,
            task_set: handle.into(),
            rx_msg_id: Arc::new(AtomicU32::new(1)),
            tx_msg_id: Arc::new(AtomicU32::new(1)),
        }
    }
}

impl<S> IntoAxum<S>
where
    S: Clone + Send + Sync + 'static,
{
    fn ctx(&self, req: &axum::extract::Request) -> HandlerCtx {
        let parent_context = opentelemetry::global::get_text_map_propagator(|propagator| {
            propagator.extract(&opentelemetry_http::HeaderExtractor(req.headers()))
        });

        HandlerCtx::new(
            None,
            self.task_set.clone(),
            TracingInfo::new_with_context(self.router.service_name(), parent_context),
        )
    }
}

impl<S> axum::handler::Handler<Bytes, S> for IntoAxum<S>
where
    S: Clone + Send + Sync + 'static,
{
    type Future = Pin<Box<dyn Future<Output = axum::response::Response> + Send>>;

    fn call(self, req: axum::extract::Request, state: S) -> Self::Future {
        Box::pin(async move {
            let ctx = self.ctx(&req);
            ctx.init_request_span(&self.router, Some(&Span::current()));

            let Ok(bytes) = Bytes::from_request(req, &state).await else {
                crate::metrics::record_parse_error(self.router.service_name());
                return Box::<str>::from(Response::parse_error()).into_response();
            };

            // https://github.com/open-telemetry/semantic-conventions/blob/main/docs/rpc/rpc-spans.md#message-event
            let req = ctx.span().in_scope(|| {
                message_event!(
                    @received,
                    counter: &self.rx_msg_id,
                    bytes: bytes.len(),
                );

                // If the inbound data is not currently parsable, we
                // send an empty one it to the router, as the router enforces
                // the specification.
                InboundData::try_from(bytes).unwrap_or_default()
            });

            let span = ctx.span().clone();
            if let Some(response) = self
                .router
                .call_batch_with_state(ctx, req, state)
                .instrument(span.clone())
                .await
            {
                let headers = [(
                    header::CONTENT_TYPE,
                    HeaderValue::from_static(mime::APPLICATION_JSON.as_ref()),
                )];

                let body = Box::<str>::from(response);

                span.in_scope(|| {
                    message_event!(
                        @sent,
                        counter: &self.tx_msg_id,
                        bytes: body.len(),
                    );
                });

                (headers, body).into_response()
            } else {
                ().into_response()
            }
        })
    }
}