[feat] modularized backend with plugin architecture, added module-api, module-host, and summarizer crates, and integrated dynamic module loading into main.rs

backend-rust/crates/app/src/main.rs

@@ -1,8 +1,8 @@
 use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
 
-#[tokio::main]
+#[tokio::main(flavor = "multi_thread")]
 async fn main() -> anyhow::Result<()> {
-    // Basic tracing setup (adjust as needed)
+    // Tracing setup
     tracing_subscriber::registry()
         .with(
             tracing_subscriber::EnvFilter::try_from_default_env()
@@ -11,9 +11,35 @@ async fn main() -> anyhow::Result<()> {
         .with(tracing_subscriber::fmt::layer())
         .init();
 
-    // TODO: invoke your API server bootstrap here.
-    // For example, if you have a function like `owly-news-api::run_server().await`
-    // call it here. This is just a placeholder:
-    tracing::info!("owly-news app starting...");
+    // Limit worker threads for CPU control (can be tuned via env)
+    // Note: When using #[tokio::main], configure via env TOKIO_WORKER_THREADS.
+    // Alternatively, build a Runtime manually for stricter control.
+    if let Ok(threads) = std::env::var("TOKIO_WORKER_THREADS") {
+        tracing::warn!(
+            "TOKIO_WORKER_THREADS is set to {threads}, ensure it matches deployment requirements"
+        );
+    } else {
+        // Provide a sane default via env if not set
+        let default_threads = std::cmp::max(1, num_cpus::get_physical() / 2);
+        unsafe { std::env::set_var("TOKIO_WORKER_THREADS", default_threads.to_string()); }
+        tracing::info!("Defaulting worker threads to {}", default_threads);
+    }
+
+    // Example: lazily load and invoke the "summarizer" module when needed
+    let host = owly_news_module_host::ModuleHost::default();
+
+    // Simulate an on-demand call (e.g., from an HTTP handler)
+    let summarizer = host.get("summarizer").await?;
+    let resp = summarizer.invoke_json(
+        "summarize",
+        serde_json::json!({
+            "text": "Rust enables fearless concurrency with strong guarantees over memory safety.",
+            "ratio": 0.3
+        }),
+    )?;
+    tracing::info!(?resp, "summarizer response");
+
+    // TODO: wire this into your API routes/handlers, using the host.get("<module>").await when needed.
+    tracing::info!("owly-news daemon running");
     Ok(())
 }