token_metadata: add count_normal_token_owners method

locator/token_metadata.cc

@@ -556,6 +556,14 @@ future<> token_metadata::calculate_pending_ranges(abstract_replication_strategy&
 
 }
 
+size_t token_metadata::count_normal_token_owners() const {
+    std::set<inet_address> eps;
+    for (auto [t, ep]: _token_to_endpoint_map) {
+        eps.insert(ep);
+    }
+    return eps.size();
+}
+
 sstring token_metadata::print_pending_ranges() {
     std::stringstream ss;
 

locator/token_metadata.hh

@@ -679,6 +679,10 @@ public:
         return _endpoint_to_host_id_map.size();
     }
 
+    /* Returns the number of different endpoints that own tokens in the ring.
+     * Bootstrapping tokens are not taken into account. */
+    size_t count_normal_token_owners() const;
+
 #if 0
     public Set<InetAddress> getAllEndpoints()
     {