Better handle nodes in propagate gossip cross thread when none are connected (#901)

* Better handle nodes in propagate gossip cross thread

* resolved PR comment

Author: KolbyML

portalnet/src/overlay_service.rs

@@ -2502,7 +2502,7 @@ pub fn propagate_gossip_cross_thread<TContentKey: OverlayContentKey>(
 ) -> usize {
     // Get all connected nodes from overlay routing table
     let kbuckets = kbuckets.read();
-    let all_nodes: Vec<&kbucket::Node<NodeId, Node>> = kbuckets
+    let mut all_nodes: Vec<&kbucket::Node<NodeId, Node>> = kbuckets
         .buckets_iter()
         .flat_map(|kbucket| {
             kbucket
@@ -2512,6 +2512,24 @@ pub fn propagate_gossip_cross_thread<TContentKey: OverlayContentKey>(
         })
         .collect();
 
+    if all_nodes.is_empty() {
+        warn!("No connected nodes, using disconnected nodes for gossip.");
+        all_nodes = kbuckets
+            .buckets_iter()
+            .flat_map(|kbucket| {
+                kbucket
+                    .iter()
+                    .collect::<Vec<&kbucket::Node<NodeId, Node>>>()
+            })
+            .collect();
+    }
+
+    if all_nodes.is_empty() {
+        // If there are no nodes whatsoever in the routing table the gossip cannot proceed.
+        warn!("No nodes in routing table, gossip cannot proceed.");
+        return 0;
+    }
+
     // HashMap to temporarily store all interested ENRs and the content.
     // Key is base64 string of node's ENR.
     let mut enrs_and_content: HashMap<String, Vec<(RawContentKey, Vec<u8>)>> = HashMap::new();