sausage-plugin part 2: import! with typed clients (sausage_interface::client_rs), TCP endpoints with rpc.endpoint, examples

Part 1 fixes: complete stdout writes, buffered stdin, Rust type names
in schemas, enum variant docs, -32603 for serde errors in handlers,
crate docs and modules. End-to-end check of a generated consumer through
a fake core.

examples/www/src/main.rs

@@ -0,0 +1,75 @@
+//! Serve files from `/state/www` and expose a control endpoint at `/self/control`.
+use sausage_plugin::{Ctx, Result, background, listen, pid, rpc, schema, state_dir};
+use std::{cell::Cell, rc::Rc};
+use wstd::{
+    io::{AsyncRead, AsyncWrite},
+    iter::AsyncIterator,
+    net::TcpListener,
+};
+struct Www;
+/// The server configuration.
+#[schema]
+struct StartParams {
+    /// The HTTP port on all network interfaces.
+    port: u16,
+}
+#[rpc(endpoints(control=Control),grace_seconds=5)]
+impl Www {
+    /// Start the HTTP server and return its process ID.
+    async fn start(&self, p: StartParams) -> Result<String> {
+        let tcp = TcpListener::bind(&format!("0.0.0.0:{}", p.port)).await?;
+        let control = Rc::new(Control { hits: Cell::new(0) });
+        listen("/self/control", control.clone()).await?;
+        background(serve(tcp, control));
+        Ok(pid())
+    }
+}
+struct Control {
+    hits: Cell<u64>,
+}
+#[rpc]
+impl Control {
+    /// Count the HTTP requests this server answered.
+    fn stats(&self) -> Result<u64> {
+        Ok(self.hits.get())
+    }
+    /// End this process after the response reaches the client.
+    fn stop(&self, ctx: &Ctx) -> Result<()> {
+        ctx.exit_after_response();
+        Ok(())
+    }
+}
+async fn serve(tcp: TcpListener, control: Rc<Control>) {
+    let mut incoming = tcp.incoming();
+    while let Some(Ok(mut stream)) = incoming.next().await {
+        let mut request = [0; 8192];
+        let Ok(size) = stream.read(&mut request).await else {
+            continue;
+        };
+        let line = String::from_utf8_lossy(&request[..size]);
+        let path = line
+            .split_whitespace()
+            .nth(1)
+            .unwrap_or("/")
+            .trim_start_matches('/');
+        let (status, body) = match std::fs::read(state_dir().join(if path.is_empty() {
+            "index.html"
+        } else {
+            path
+        })) {
+            Ok(body) => ("200 OK", body),
+            Err(_) => ("404 Not Found", b"Not found".to_vec()),
+        };
+        control.hits.set(control.hits.get() + 1);
+        let header = format!(
+            "HTTP/1.1 {status}\r\nContent-Length: {}\r\nConnection: close\r\n\r\n",
+            body.len()
+        );
+        let _ = stream.write_all(header.as_bytes()).await;
+        let _ = stream.write_all(&body).await;
+        let _ = stream.flush().await;
+    }
+}
+fn main() {
+    sausage_plugin::run(Www)
+}