[router] Refactor router and policy traits with dependency injection (#7987)

Co-authored-by: Jin Pan <jpan236@wisc.edu>
Co-authored-by: Keru Yang <rukeyang@gmail.com>
Co-authored-by: Yingyi Huang <yingyihuang2000@outlook.com>
Co-authored-by: Philip Zhu <phlipzhux@gmail.com>

sgl-router/src/routers/mod.rs

@@ -0,0 +1,101 @@
+//! Router implementations
+
+use actix_web::{HttpRequest, HttpResponse};
+use async_trait::async_trait;
+use reqwest::Client;
+use std::fmt::Debug;
+
+pub mod factory;
+pub mod pd_router;
+pub mod pd_types;
+pub mod request_adapter;
+pub mod router;
+
+pub use factory::RouterFactory;
+
+/// Worker management trait for administrative operations
+///
+/// This trait is separate from RouterTrait to allow Send futures
+/// for use in service discovery and other background tasks
+#[async_trait]
+pub trait WorkerManagement: Send + Sync {
+    /// Add a worker to the router
+    async fn add_worker(&self, worker_url: &str) -> Result<String, String>;
+
+    /// Remove a worker from the router
+    fn remove_worker(&self, worker_url: &str);
+
+    /// Get all worker URLs
+    fn get_worker_urls(&self) -> Vec<String>;
+}
+
+/// Core trait for all router implementations
+///
+/// This trait provides a unified interface for routing requests,
+/// regardless of whether it's a regular router or PD router.
+#[async_trait(?Send)]
+pub trait RouterTrait: Send + Sync + Debug + WorkerManagement {
+    /// Get a reference to self as Any for downcasting
+    fn as_any(&self) -> &dyn std::any::Any;
+    /// Route a health check request
+    async fn health(&self, client: &Client, req: &HttpRequest) -> HttpResponse;
+
+    /// Route a health generate request
+    async fn health_generate(&self, client: &Client, req: &HttpRequest) -> HttpResponse;
+
+    /// Get server information
+    async fn get_server_info(&self, client: &Client, req: &HttpRequest) -> HttpResponse;
+
+    /// Get available models
+    async fn get_models(&self, client: &Client, req: &HttpRequest) -> HttpResponse;
+
+    /// Get model information
+    async fn get_model_info(&self, client: &Client, req: &HttpRequest) -> HttpResponse;
+
+    /// Route a generate request
+    async fn route_generate(
+        &self,
+        client: &Client,
+        req: &HttpRequest,
+        body: serde_json::Value,
+    ) -> HttpResponse;
+
+    /// Route a chat completion request
+    async fn route_chat(
+        &self,
+        client: &Client,
+        req: &HttpRequest,
+        body: serde_json::Value,
+    ) -> HttpResponse;
+
+    /// Route a completion request
+    async fn route_completion(
+        &self,
+        client: &Client,
+        req: &HttpRequest,
+        body: serde_json::Value,
+    ) -> HttpResponse;
+
+    /// Flush cache on all workers
+    async fn flush_cache(&self, client: &Client) -> HttpResponse;
+
+    /// Get worker loads (for monitoring)
+    async fn get_worker_loads(&self, client: &Client) -> HttpResponse;
+
+    /// Get router type name
+    fn router_type(&self) -> &'static str;
+
+    /// Check if this is a PD router
+    fn is_pd_mode(&self) -> bool {
+        self.router_type() == "pd"
+    }
+
+    /// Server liveness check - is the server process running
+    fn liveness(&self) -> HttpResponse {
+        // Simple liveness check - if we can respond, we're alive
+        HttpResponse::Ok().body("OK")
+    }
+
+    /// Server readiness check - is the server ready to handle requests
+    fn readiness(&self) -> HttpResponse;
+}