ruststream 0.7.5

//! Routers: each module groups its handlers in a `Router`, the groups merge into one, and the
//! service mounts the result on a broker. A router carries its own middleware and its own codec.
//! Each scenario is a test; the codec one needs the `cbor` feature.
//!
//! ```text
//! cargo test --example routing --features testing,macros,memory,json,cbor
//! ```

// A plain build compiles the services; the tests that use them exist only in the test build.
#![cfg_attr(not(test), allow(dead_code, unused_imports))]

use ruststream::memory::prelude::*;
use serde::{Deserialize, Serialize};

#[derive(Debug, PartialEq, Deserialize, Serialize, Outgoing)]
#[outgoing(name = "orders")]
struct Order {
    id: u64,
}

#[derive(Debug, PartialEq, Deserialize, Serialize, Outgoing)]
#[outgoing(name = "shipments")]
struct Shipment {
    order_id: u64,
}

mod router {
    use std::error::Error;

    use ruststream::memory::prelude::*;
    use ruststream::testing::TestApp;

    use super::{Order, Shipment};

    // --8<-- [start:router]
    #[subscriber("orders")]
    async fn accept(order: &Order) -> HandlerOutcome {
        tracing::info!(order.id, "accepted");
        HandlerOutcome::ack()
    }

    #[subscriber("shipments")]
    async fn dispatch(shipment: &Shipment) -> HandlerOutcome {
        tracing::info!(shipment.order_id, "dispatched");
        HandlerOutcome::ack()
    }

    /// The orders module's handlers.
    fn orders() -> Router<MemoryBroker, impl RouterDef<MemoryBroker>> {
        Router::new().include(accept)
    }

    /// The shipping module's handlers.
    fn shipping() -> Router<MemoryBroker, impl RouterDef<MemoryBroker>> {
        Router::new().include(dispatch)
    }

    fn app() -> impl App {
        RustStream::new(AppInfo::new("shop", "0.1.0")).with_broker(MemoryBroker::new(), |b| {
            b.include_router(orders().merge(shipping()));
        })
    }
    // --8<-- [end:router]

    #[tokio::test]
    async fn both_modules_are_mounted() -> Result<(), Box<dyn Error>> {
        let tb = TestApp::start(app()).await?;
        let broker = tb.broker::<MemoryBroker>();
        broker.message(&Order { id: 7 }).publish().await?;
        broker.message(&Shipment { order_id: 7 }).publish().await?;

        broker.subscriber("orders").assert_called_once();
        broker.subscriber("shipments").assert_called_once();
        Ok(())
    }
}

mod layer {
    use std::error::Error;
    use std::sync::Arc;
    use std::sync::atomic::{AtomicUsize, Ordering};

    use ruststream::memory::prelude::*;
    use ruststream::runtime::{BlanketLayer, Handler};
    use ruststream::testing::TestApp;

    use super::{Order, Shipment};

    // --8<-- [start:layer]
    /// Counts the deliveries of the handlers it wraps.
    #[derive(Clone)]
    struct Count(Arc<AtomicUsize>);

    struct Counted<H> {
        inner: H,
        count: Arc<AtomicUsize>,
    }

    // A router hides its handlers' types, so its layer wraps a handler of any type.
    impl BlanketLayer for Count {
        fn apply<M, C, S, H>(&self, handler: H) -> impl Handler<M, C, S> + 'static
        where
            M: Send + Sync + 'static,
            C: Send + 'static,
            S: Send + Sync + 'static,
            H: Handler<M, C, S> + 'static,
        {
            Counted {
                inner: handler,
                count: Arc::clone(&self.0),
            }
        }
    }

    impl<M, C, S, H> Handler<M, C, S> for Counted<H>
    where
        M: Send + Sync,
        C: Send,
        S: Send + Sync,
        H: Handler<M, C, S>,
    {
        async fn handle(&self, msg: &M, ctx: &mut Context<'_, C, S>) -> HandlerOutcome {
            self.count.fetch_add(1, Ordering::Relaxed);
            self.inner.handle(msg, ctx).await
        }
    }

    #[subscriber("orders")]
    async fn accept(order: &Order) -> HandlerOutcome {
        tracing::info!(order.id, "accepted");
        HandlerOutcome::ack()
    }

    #[subscriber("shipments")]
    async fn dispatch(shipment: &Shipment) -> HandlerOutcome {
        tracing::info!(shipment.order_id, "dispatched");
        HandlerOutcome::ack()
    }

    fn app(orders_seen: Arc<AtomicUsize>) -> impl App {
        RustStream::new(AppInfo::new("shop", "0.1.0")).with_broker(MemoryBroker::new(), |b| {
            // The layer comes first and wraps every handler of this router.
            b.include_router(Router::new().layer(Count(orders_seen)).include(accept));
            // Mounted on the scope, outside the router's layer.
            b.include(dispatch);
        })
    }
    // --8<-- [end:layer]

    #[tokio::test]
    async fn the_layer_wraps_only_its_router() -> Result<(), Box<dyn Error>> {
        let orders_seen = Arc::new(AtomicUsize::new(0));
        let tb = TestApp::start(app(Arc::clone(&orders_seen))).await?;
        let broker = tb.broker::<MemoryBroker>();
        broker.message(&Order { id: 7 }).publish().await?;
        broker.message(&Shipment { order_id: 7 }).publish().await?;

        assert_eq!(orders_seen.load(Ordering::Relaxed), 1);
        Ok(())
    }
}

#[cfg(feature = "cbor")]
mod codec {
    use std::error::Error;

    use ruststream::codec::CborCodec;
    use ruststream::memory::prelude::*;
    use ruststream::testing::TestApp;

    use super::Order;

    // --8<-- [start:codec]
    #[subscriber("orders")]
    async fn accept(order: &Order) -> HandlerOutcome {
        tracing::info!(order.id, "accepted");
        HandlerOutcome::ack()
    }

    /// The registrations after `with_codec` decode CBOR.
    fn orders() -> impl RouterDef<MemoryBroker> {
        Router::new().with_codec(CborCodec).include(accept)
    }

    fn app() -> impl App {
        RustStream::new(AppInfo::new("shop", "0.1.0")).with_broker(MemoryBroker::new(), |b| {
            b.include_router(orders());
        })
    }
    // --8<-- [end:codec]

    #[tokio::test]
    async fn the_router_decodes_cbor() -> Result<(), Box<dyn Error>> {
        let tb = TestApp::start(app()).await?;
        let broker = tb.broker::<MemoryBroker>();
        broker
            .message(&Order { id: 7 })
            .with_codec(CborCodec)
            .publish()
            .await?;

        broker
            .subscriber("orders")
            .assert_called_once()
            .with_codec(&CborCodec, &Order { id: 7 })
            .settled(HandlerOutcome::ack());
        Ok(())
    }
}

// The scenarios are the tests above; the command in the header runs them.
fn main() {}