chore: initial commit

backend/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "backend"
+edition = "2024"
+
+[dependencies]
+axum = { workspace = true, features = ["tokio", "ws"] }
+axum-extra = { version = "0.12.5", features = ["typed-routing"] }
+futures = { workspace = true }
+postage = { version = "0.5.0", default-features = false, features = [
+    "futures-traits",
+] }
+serde = { version = "1.0.228", features = ["derive"] }
+tokio = { workspace = true, features = ["rt"] }
+tracing = { workspace = true }

backend/src/lib.rs

@@ -0,0 +1,75 @@
+use std::num::NonZero;
+
+use axum::{
+    Router,
+    extract::{State, WebSocketUpgrade, ws::WebSocket},
+    response::IntoResponse,
+};
+use axum_extra::routing::{RouterExt, TypedPath};
+use futures::{SinkExt, Stream, StreamExt};
+use serde::Deserialize;
+use tokio::{runtime::Handle, task::LocalSet};
+
+#[derive(Debug, Clone)]
+struct AppState {
+    websocket_tx: postage::dispatch::Sender<WebSocket>,
+}
+
+#[derive(Deserialize, TypedPath)]
+#[typed_path("/ws")]
+struct Ws {}
+
+#[tracing::instrument]
+async fn get_ws(
+    Ws {}: Ws,
+    upgrade: WebSocketUpgrade,
+    State(app_state): State<AppState>,
+) -> impl IntoResponse {
+    let mut websocket_tx = app_state.websocket_tx;
+
+    upgrade.on_upgrade(|websocket| async move {
+        websocket_tx.send(websocket).await.unwrap();
+    })
+}
+
+async fn run_rpc_server(mut websockets: impl Stream<Item = WebSocket> + Unpin) {
+    let local_set = LocalSet::new();
+
+    local_set
+        .run_until(async move {
+            while let Some(websocket) = websockets.next().await {
+                tracing::debug!(?websocket);
+            }
+        })
+        .await;
+
+    local_set.await;
+}
+
+fn create_router() -> Router<AppState> {
+    Router::new().typed_get(get_ws)
+}
+
+#[derive(Debug)]
+pub struct CreateAppArgs {
+    tokio_runtime_handle: Handle,
+    websocket_channel_capacity: NonZero<usize>,
+    rpc_workers: NonZero<usize>,
+}
+
+pub fn create_app(
+    CreateAppArgs {
+        tokio_runtime_handle,
+        websocket_channel_capacity,
+        rpc_workers,
+    }: CreateAppArgs,
+) -> Router<()> {
+    let (websocket_tx, websocket_rx) = postage::dispatch::channel(websocket_channel_capacity.get());
+
+    for _ in 0..=rpc_workers.get() {
+        let websocket_rx = websocket_rx.clone();
+    }
+
+    let state = AppState { websocket_tx };
+    create_router().with_state(state)
+}