chore: extend RouteProvider trait with routes_stats() (#629)

CHANGELOG.md

@@ -14,6 +14,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * Added `CanisterInfo` to `MgmtMethod`.
 
+* Extended `RouteProvider` trait with `fn routes_stats()`, returning the number of total and healthy routes.
+
 ## [0.39.2] - 2024-12-20
 
 * Bumped `ic-certification` to `3.0.0`.

ic-agent/src/agent/route_provider.rs

@@ -36,6 +36,25 @@ const ICP0_SUB_DOMAIN: &str = ".icp0.io";
 const ICP_API_SUB_DOMAIN: &str = ".icp-api.io";
 const LOCALHOST_SUB_DOMAIN: &str = ".localhost";
 
+/// Statistical info about routing urls.
+#[derive(Debug, PartialEq)]
+pub struct RoutesStats {
+    /// Total number of existing routes (both healthy and unhealthy).
+    pub total: usize,
+
+    /// Number of currently healthy routes, or None if health status information is unavailable.
+    /// A healthy route is one that is available and ready to receive traffic.
+    /// The specific criteria for what constitutes a "healthy" route is implementation dependent.
+    pub healthy: Option<usize>,
+}
+
+impl RoutesStats {
+    /// Creates an new instance of [`RoutesStats`].
+    pub fn new(total: usize, healthy: Option<usize>) -> Self {
+        Self { total, healthy }
+    }
+}
+
 /// A [`RouteProvider`] for dynamic generation of routing urls.
 pub trait RouteProvider: std::fmt::Debug + Send + Sync {
     /// Generates the next routing URL based on the internal routing logic.
@@ -51,6 +70,9 @@ pub trait RouteProvider: std::fmt::Debug + Send + Sync {
     /// appearing first. The returned vector can contain fewer than `n` URLs if
     /// fewer are available.
     fn n_ordered_routes(&self, n: usize) -> Result<Vec<Url>, AgentError>;
+
+    /// Returns statistics about the total number of existing routes and the number of healthy routes.
+    fn routes_stats(&self) -> RoutesStats;
 }
 
 /// A simple implementation of the [`RouteProvider`] which produces an even distribution of the urls from the input ones.
@@ -94,6 +116,10 @@ impl RouteProvider for RoundRobinRouteProvider {
 
         Ok(urls)
     }
+
+    fn routes_stats(&self) -> RoutesStats {
+        RoutesStats::new(self.routes.len(), None)
+    }
 }
 
 impl RoundRobinRouteProvider {
@@ -133,6 +159,9 @@ impl RouteProvider for Url {
     fn n_ordered_routes(&self, _: usize) -> Result<Vec<Url>, AgentError> {
         Ok(vec![self.route()?])
     }
+    fn routes_stats(&self) -> RoutesStats {
+        RoutesStats::new(1, None)
+    }
 }
 
 /// A [`RouteProvider`] that will attempt to discover new boundary nodes and cycle through them, optionally prioritizing those with low latency.
@@ -215,6 +244,9 @@ impl RouteProvider for DynamicRouteProvider {
     fn n_ordered_routes(&self, n: usize) -> Result<Vec<Url>, AgentError> {
         self.inner.n_ordered_routes(n)
     }
+    fn routes_stats(&self) -> RoutesStats {
+        self.inner.routes_stats()
+    }
 }
 
 /// Strategy for [`DynamicRouteProvider`]'s routing mechanism.
@@ -270,6 +302,9 @@ impl<R: RouteProvider> RouteProvider for UrlUntilReady<R> {
             self.url.route()
         }
     }
+    fn routes_stats(&self) -> RoutesStats {
+        RoutesStats::new(1, None)
+    }
 }
 
 #[cfg(test)]

ic-agent/src/agent/route_provider/dynamic_routing/dynamic_route_provider.rs

@@ -23,7 +23,7 @@ use crate::{
                 snapshot::routing_snapshot::RoutingSnapshot,
                 type_aliases::AtomicSwap,
             },
-            RouteProvider,
+            RouteProvider, RoutesStats,
         },
         HttpService,
     },
@@ -186,6 +186,11 @@ where
         let urls = nodes.iter().map(|n| n.to_routing_url()).collect();
         Ok(urls)
     }
+
+    fn routes_stats(&self) -> RoutesStats {
+        let snapshot = self.routing_snapshot.load();
+        snapshot.routes_stats()
+    }
 }
 
 impl<S> DynamicRouteProvider<S>
@@ -291,7 +296,7 @@ mod tests {
                     assert_routed_domains, route_n_times, NodeHealthCheckerMock, NodesFetcherMock,
                 },
             },
-            RouteProvider,
+            RouteProvider, RoutesStats,
         },
         Agent, AgentError,
     };
@@ -417,6 +422,7 @@ mod tests {
         tokio::time::sleep(snapshot_update_duration).await;
         let routed_domains = route_n_times(6, Arc::clone(&route_provider));
         assert_routed_domains(routed_domains, vec![node_1.domain()], 6);
+        assert_eq!(route_provider.routes_stats(), RoutesStats::new(1, Some(1)));
 
         // Test 2: multiple route() calls return 3 different domains with equal fairness (repetition).
         // Two healthy nodes are added to the topology.
@@ -431,13 +437,15 @@ mod tests {
             vec![node_1.domain(), node_2.domain(), node_3.domain()],
             2,
         );
+        assert_eq!(route_provider.routes_stats(), RoutesStats::new(3, Some(3)));
 
         // Test 3:  multiple route() calls return 2 different domains with equal fairness (repetition).
         // One node is set to unhealthy.
         checker.overwrite_healthy_nodes(vec![node_1.clone(), node_3.clone()]);
         tokio::time::sleep(snapshot_update_duration).await;
         let routed_domains = route_n_times(6, Arc::clone(&route_provider));
         assert_routed_domains(routed_domains, vec![node_1.domain(), node_3.domain()], 3);
+        assert_eq!(route_provider.routes_stats(), RoutesStats::new(3, Some(2)));
 
         // Test 4: multiple route() calls return 3 different domains with equal fairness (repetition).
         // Unhealthy node is set back to healthy.
@@ -449,6 +457,7 @@ mod tests {
             vec![node_1.domain(), node_2.domain(), node_3.domain()],
             2,
         );
+        assert_eq!(route_provider.routes_stats(), RoutesStats::new(3, Some(3)));
 
         // Test 5: multiple route() calls return 3 different domains with equal fairness (repetition).
         // One healthy node is added, but another one goes unhealthy.
@@ -467,6 +476,7 @@ mod tests {
             vec![node_2.domain(), node_3.domain(), node_4.domain()],
             2,
         );
+        assert_eq!(route_provider.routes_stats(), RoutesStats::new(4, Some(3)));
 
         // Test 6: multiple route() calls return a single domain=api1.com.
         // One node is set to unhealthy and one is removed from the topology.
@@ -475,6 +485,7 @@ mod tests {
         tokio::time::sleep(snapshot_update_duration).await;
         let routed_domains = route_n_times(3, Arc::clone(&route_provider));
         assert_routed_domains(routed_domains, vec![node_2.domain()], 3);
+        assert_eq!(route_provider.routes_stats(), RoutesStats::new(3, Some(1)));
     }
 
     #[tokio::test]

ic-agent/src/agent/route_provider/dynamic_routing/snapshot/latency_based_routing.rs

@@ -5,8 +5,11 @@ use std::{
 
 use rand::Rng;
 
-use crate::agent::route_provider::dynamic_routing::{
-    health_check::HealthCheckStatus, node::Node, snapshot::routing_snapshot::RoutingSnapshot,
+use crate::agent::route_provider::{
+    dynamic_routing::{
+        health_check::HealthCheckStatus, node::Node, snapshot::routing_snapshot::RoutingSnapshot,
+    },
+    RoutesStats,
 };
 
 // Determines the size of the sliding window used for storing latencies and availabilities of nodes.
@@ -157,6 +160,7 @@ fn compute_score(
 pub struct LatencyRoutingSnapshot {
     nodes_with_metrics: Vec<NodeWithMetrics>,
     existing_nodes: HashSet<Node>,
+    healthy_nodes: HashSet<Node>,
     window_weights: Vec<f64>,
     window_weights_sum: f64,
     use_availability_penalty: bool,
@@ -174,6 +178,7 @@ impl LatencyRoutingSnapshot {
         Self {
             nodes_with_metrics: vec![],
             existing_nodes: HashSet::new(),
+            healthy_nodes: HashSet::new(),
             use_availability_penalty: true,
             window_weights,
             window_weights_sum,
@@ -302,6 +307,12 @@ impl RoutingSnapshot for LatencyRoutingSnapshot {
                 self.nodes_with_metrics.len() - 1
             });
 
+        if health.is_healthy() {
+            self.healthy_nodes.insert(node.clone());
+        } else {
+            self.healthy_nodes.remove(node);
+        }
+
         self.nodes_with_metrics[idx].add_latency_measurement(health.latency());
 
         self.nodes_with_metrics[idx].score = compute_score(
@@ -314,6 +325,10 @@ impl RoutingSnapshot for LatencyRoutingSnapshot {
 
         true
     }
+
+    fn routes_stats(&self) -> RoutesStats {
+        RoutesStats::new(self.existing_nodes.len(), Some(self.healthy_nodes.len()))
+    }
 }
 
 #[cfg(test)]
@@ -323,15 +338,18 @@ mod tests {
         time::Duration,
     };
 
-    use crate::agent::route_provider::dynamic_routing::{
-        health_check::HealthCheckStatus,
-        node::Node,
-        snapshot::{
-            latency_based_routing::{
-                compute_score, weighted_sample, LatencyRoutingSnapshot, NodeWithMetrics,
+    use crate::agent::route_provider::{
+        dynamic_routing::{
+            health_check::HealthCheckStatus,
+            node::Node,
+            snapshot::{
+                latency_based_routing::{
+                    compute_score, weighted_sample, LatencyRoutingSnapshot, NodeWithMetrics,
+                },
+                routing_snapshot::RoutingSnapshot,
             },
-            routing_snapshot::RoutingSnapshot,
         },
+        RoutesStats,
     };
 
     #[test]
@@ -344,6 +362,7 @@ mod tests {
         assert!(!snapshot.has_nodes());
         assert!(snapshot.next_node().is_none());
         assert!(snapshot.next_n_nodes(1).is_empty());
+        assert_eq!(snapshot.routes_stats(), RoutesStats::new(0, Some(0)));
     }
 
     #[test]
@@ -359,6 +378,7 @@ mod tests {
         assert!(snapshot.nodes_with_metrics.is_empty());
         assert!(!snapshot.has_nodes());
         assert!(snapshot.next_node().is_none());
+        assert_eq!(snapshot.routes_stats(), RoutesStats::new(0, Some(0)));
     }
 
     #[test]
@@ -370,13 +390,15 @@ mod tests {
         let node = Node::new("api1.com").unwrap();
         let health = HealthCheckStatus::new(Some(Duration::from_secs(1)));
         snapshot.existing_nodes.insert(node.clone());
+        assert_eq!(snapshot.routes_stats(), RoutesStats::new(1, Some(0)));
         // Check first update
         let is_updated = snapshot.update_node(&node, health);
         assert!(is_updated);
         assert!(snapshot.has_nodes());
         let node_with_metrics = snapshot.nodes_with_metrics.first().unwrap();
         assert_eq!(node_with_metrics.score, (2.0 / 1.0) / 2.0);
         assert_eq!(snapshot.next_node().unwrap(), node);
+        assert_eq!(snapshot.routes_stats(), RoutesStats::new(1, Some(1)));
         // Check second update
         let health = HealthCheckStatus::new(Some(Duration::from_secs(2)));
         let is_updated = snapshot.update_node(&node, health);
@@ -399,6 +421,7 @@ mod tests {
         assert_eq!(snapshot.nodes_with_metrics.len(), 1);
         assert_eq!(snapshot.existing_nodes.len(), 1);
         assert!(snapshot.next_node().is_none());
+        assert_eq!(snapshot.routes_stats(), RoutesStats::new(1, Some(0)));
     }
 
     #[test]

ic-agent/src/agent/route_provider/dynamic_routing/snapshot/round_robin_routing.rs

@@ -6,8 +6,11 @@ use std::{
     },
 };
 
-use crate::agent::route_provider::dynamic_routing::{
-    health_check::HealthCheckStatus, node::Node, snapshot::routing_snapshot::RoutingSnapshot,
+use crate::agent::route_provider::{
+    dynamic_routing::{
+        health_check::HealthCheckStatus, node::Node, snapshot::routing_snapshot::RoutingSnapshot,
+    },
+    RoutesStats,
 };
 
 /// Routing snapshot, which samples nodes in a round-robin fashion.
@@ -106,6 +109,10 @@ impl RoutingSnapshot for RoundRobinRoutingSnapshot {
             self.healthy_nodes.remove(node)
         }
     }
+
+    fn routes_stats(&self) -> RoutesStats {
+        RoutesStats::new(self.existing_nodes.len(), Some(self.healthy_nodes.len()))
+    }
 }
 
 #[cfg(test)]

ic-agent/src/agent/route_provider/dynamic_routing/snapshot/routing_snapshot.rs

@@ -1,6 +1,9 @@
 use std::fmt::Debug;
 
-use crate::agent::route_provider::dynamic_routing::{health_check::HealthCheckStatus, node::Node};
+use crate::agent::route_provider::{
+    dynamic_routing::{health_check::HealthCheckStatus, node::Node},
+    RoutesStats,
+};
 
 /// A trait for interacting with the snapshot of nodes (routing table).
 pub trait RoutingSnapshot: Send + Sync + Clone + Debug {
@@ -15,4 +18,6 @@ pub trait RoutingSnapshot: Send + Sync + Clone + Debug {
     fn sync_nodes(&mut self, nodes: &[Node]) -> bool;
     /// Updates the health status of a specific node, returning `true` if the node was found and updated.
     fn update_node(&mut self, node: &Node, health: HealthCheckStatus) -> bool;
+    /// Returns statistics about the routes (nodes).
+    fn routes_stats(&self) -> RoutesStats;
 }