Merge pull request #21 from duomark/max_sessions

TS-1025 Make max_sessions be a multiplier per cassandra node

Author: georgeye

src/elysium.app.src

@@ -1,7 +1,7 @@
 {application, elysium,
  [
   {description, "Elysium for Cassandra"},
-  {vsn, "0.1.6i"},
+  {vsn, "0.1.6j"},
   {id, "elysium"},
   {registered, [elysium_sup, elysium_connection_sup]},
   {applications, [kernel, stdlib]},

src/elysium_default_config.erl

@@ -82,13 +82,13 @@ cassandra_send_timeout() -> 1000.
 
 -spec cassandra_max_sessions() -> max_sessions().
 %% @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 1000 out of 1M times it is used.
-cassandra_session_decay_probability() -> 1000.
+%% @doc Kill a live session 100000 out of 1B times it is used.
+cassandra_session_decay_probability() -> 100000.
 

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_Sessions = elysium_config:session_max_count(Config),
+    Max_Sessions  = 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_Sessions)],
+         || _N <- lists:seq(1, Max_Sessions * Num_Nodes)],
     {reply, Max_Sessions, ?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_Sessions = elysium_config:session_max_count(Config),
+    Max_Sessions  = 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_Sessions)],
+         || _N <- lists:seq(1, Max_Sessions * Num_Nodes)],
     {next_state, ?active, State};
 ?inactive(_Other, #ef_state{} = State) ->
     {next_state, ?inactive, State}.