query unknown first (#2277)

Signed-off-by: turuslan <[email protected]>

core/authority_discovery/query/query_impl.cpp

@@ -174,7 +174,19 @@ namespace kagome::authority_discovery {
       }
     }
     std::shuffle(authorities.begin(), authorities.end(), random_);
-    queue_ = std::move(authorities);
+
+    // reorder queue to query unknown authorities first
+    queue_.resize(0);
+    queue_.reserve(authorities.size());
+    // `queue_` is a stack, so push known first
+    for (auto &known : {true, false}) {
+      for (auto &id : authorities) {
+        if (auth_to_peer_cache_.contains(id) == known) {
+          queue_.emplace_back(id);
+        }
+      }
+    }
+
     pop();
     return outcome::success();
   }