feat(discv4): add soft_remove_node (paradigmxyz#11970)

crates/net/discv4/Cargo.toml

@@ -46,7 +46,7 @@ serde = { workspace = true, optional = true }
 [dev-dependencies]
 assert_matches.workspace = true
 rand.workspace = true
-tokio = { workspace = true, features = ["macros"] }
+tokio = { workspace = true, features = ["macros", "rt-multi-thread"] }
 reth-tracing.workspace = true
 
 [features]

crates/net/discv4/src/lib.rs

@@ -829,6 +829,24 @@ impl Discv4Service {
     /// table. Returns `true` if the node was in the table and `false` otherwise.
     pub fn remove_node(&mut self, node_id: PeerId) -> bool {
         let key = kad_key(node_id);
+        self.remove_key(node_id, key)
+    }
+
+    /// Removes a `node_id` from the routing table but only if there are enough other nodes in the
+    /// bucket (bucket must be at least half full)
+    ///
+    /// Returns `true` if the node was removed
+    pub fn soft_remove_node(&mut self, node_id: PeerId) -> bool {
+        let key = kad_key(node_id);
+        let Some(bucket) = self.kbuckets.get_bucket(&key) else { return false };
+        if bucket.num_entries() < MAX_NODES_PER_BUCKET / 2 {
+            // skip half empty bucket
+            return false;
+        }
+        self.remove_key(node_id, key)
+    }
+
+    fn remove_key(&mut self, node_id: PeerId, key: discv5::Key<NodeKey>) -> bool {
         let removed = self.kbuckets.remove(&key);
         if removed {
             trace!(target: "discv4", ?node_id, "removed node");
@@ -1491,13 +1509,7 @@ impl Discv4Service {
             // the table, but only if there are enough other nodes in the bucket (bucket must be at
             // least half full)
             if failures > (self.config.max_find_node_failures as usize) {
-                if let Some(bucket) = self.kbuckets.get_bucket(&key) {
-                    if bucket.num_entries() < MAX_NODES_PER_BUCKET / 2 {
-                        // skip half empty bucket
-                        continue
-                    }
-                }
-                self.remove_node(node_id);
+                self.soft_remove_node(node_id);
             }
         }
     }