support custom cost calculate func when generating route table

easytier/src/peers/route_trait.rs

@@ -5,6 +5,18 @@ use tokio_util::bytes::Bytes;
 
 use crate::common::{error::Error, PeerId};
 
+#[derive(Clone, Debug)]
+pub enum NextHopPolicy {
+    LeastHop,
+    LeastCost,
+}
+
+impl Default for NextHopPolicy {
+    fn default() -> Self {
+        NextHopPolicy::LeastHop
+    }
+}
+
 #[async_trait]
 pub trait RouteInterface {
     async fn list_peers(&self) -> Vec<PeerId>;
@@ -19,6 +31,28 @@ pub trait RouteInterface {
 
 pub type RouteInterfaceBox = Box<dyn RouteInterface + Send + Sync>;
 
+#[auto_impl::auto_impl(Box, Arc, &)]
+pub trait RouteCostCalculatorInterface: Send + Sync {
+    fn calculate_cost(&self, _src: PeerId, _dst: PeerId) -> i32 {
+        1
+    }
+
+    fn need_update(&self) -> bool {
+        false
+    }
+
+    fn dump(&self) -> String {
+        "All routes have cost 1".to_string()
+    }
+}
+
+#[derive(Clone, Debug, Default)]
+pub struct DefaultRouteCostCalculator;
+
+impl RouteCostCalculatorInterface for DefaultRouteCostCalculator {}
+
+pub type RouteCostCalculator = Box<dyn RouteCostCalculatorInterface>;
+
 #[async_trait]
 #[auto_impl::auto_impl(Box, Arc)]
 pub trait Route {
@@ -26,11 +60,21 @@ pub trait Route {
     async fn close(&self);
 
     async fn get_next_hop(&self, peer_id: PeerId) -> Option<PeerId>;
+    async fn get_next_hop_with_policy(
+        &self,
+        peer_id: PeerId,
+        _policy: NextHopPolicy,
+    ) -> Option<PeerId> {
+        self.get_next_hop(peer_id).await
+    }
+
     async fn list_routes(&self) -> Vec<crate::rpc::Route>;
 
     async fn get_peer_id_by_ipv4(&self, _ipv4: &Ipv4Addr) -> Option<PeerId> {
         None
     }
+
+    async fn set_route_cost_fn(&self, _cost_fn: RouteCostCalculator) {}
 }
 
 pub type ArcRoute = Arc<Box<dyn Route + Send + Sync>>;