Make max_connections a multiplier of cassandra nodes

Author: jaynel

src/elysium_default_config.erl

@@ -83,11 +83,11 @@ cassandra_send_timeout() -> 1000.
 
 -spec cassandra_max_sessions() -> max_connections().
 %% @doc Allow a max of 16 simultaneous live Cassandra sessions.
-cassandra_max_sessions() -> 5.
+cassandra_max_sessions() -> 3.
 
 -spec cassandra_max_checkout_retry() -> max_retries().
 %% @doc Retry up to 20 times when session queue races occur.
-cassandra_max_checkout_retry() -> 3.
+cassandra_max_checkout_retry() -> 5.
 
 -spec cassandra_session_decay_probability() -> decay_prob().
 %% @doc Kill a live session 100,000 out of 1 Billion times it is used.

src/elysium_queue.erl

@@ -190,9 +190,11 @@ terminate(Reason, _State_Name,
 %% @private
 %% @doc Move to 'ACTIVE' if requested, otherwise stay in 'INACTIVE' state.
 ?inactive(activate, _From, #ef_state{config=Config, connection_sup=Conn_Sup} = State) ->
-    Max_Connections = elysium_config:session_max_count(Config),
+    Max_Connections = elysium_config:session_max_count   (Config),
+    Lb_Queue_Name   = elysium_config:load_balancer_queue (Config),
+    Num_Nodes       = ets_buffer:num_entries_dedicated (Lb_Queue_Name),
     _ = [spawn_monitor(elysium_connection_sup, start_child, [Conn_Sup, [Config]])
-         || _N <- lists:seq(1, Max_Connections)],
+         || _N <- lists:seq(1, Max_Connections * Num_Nodes)],
     {reply, Max_Connections, ?active, State};
 ?inactive(_Any, _From, #ef_state{} = State) ->
     {reply, ok, ?inactive, State}.
@@ -227,9 +229,11 @@ terminate(Reason, _State_Name,
 %% @private
 %% @doc Activate if requested, from the 'INACTIVE' state.
 ?inactive(activate, #ef_state{config=Config, connection_sup=Conn_Sup} = State) ->
-    Max_Connections = elysium_config:session_max_count(Config),
+    Max_Connections = elysium_config:session_max_count   (Config),
+    Lb_Queue_Name   = elysium_config:load_balancer_queue (Config),
+    Num_Nodes       = ets_buffer:num_entries_dedicated (Lb_Queue_Name),
     _ = [spawn_monitor(elysium_connection_sup, start_child, [Conn_Sup, [Config]])
-         || _N <- lists:seq(1, Max_Connections)],
+         || _N <- lists:seq(1, Max_Connections * Num_Nodes)],
     {next_state, ?active, State};
 ?inactive(_Other, #ef_state{} = State) ->
     {next_state, ?inactive, State}.