Add osiris_counters:counters/2 to get n counters

Instead of using osiris_counters:overview/1 and get all counters, this
is more efficient.

Author: acogoluegnes

src/osiris_counters.erl

@@ -12,6 +12,7 @@
          fetch/1,
          overview/0,
          overview/1,
+         counters/2,
          delete/1
         ]).
 
@@ -45,3 +46,7 @@ overview() ->
 -spec overview(name()) -> #{atom() => non_neg_integer()} | undefined.
 overview(Name) ->
     seshat:counters(osiris, Name).
+
+-spec counters(name(), [atom()]) -> #{atom() => non_neg_integer()} | undefined.
+counters(Name, Fields) ->
+    seshat:counters(osiris, Name, Fields).

src/osiris_writer.erl

@@ -77,7 +77,7 @@
          data_listeners = [] :: [{pid(), osiris:offset()}],
          offset_listeners = [] ::
              [{pid(), osiris:offset(), mfa() | undefined}],
-         committed_chk_id = -1 :: osiris:offset()}). %% committed chunk ID
+         committed_chk_id = -1 :: osiris:offset()}).
 
 -opaque state() :: #?MODULE{}.
 

test/osiris_SUITE.erl

@@ -843,9 +843,9 @@ cluster_restart_large(Config) ->
 
     %% wait for replica key counters to match writer
     await_condition(fun () ->
-                            RC = erpc:call(hd(Replicas), osiris_counters, overview,
-                                           [{osiris_replica, Name}]),
-                            maps:with(Keys, CountersPre) == maps:with(Keys, RC)
+                            RC = erpc:call(hd(Replicas), osiris_counters, counters,
+                                           [{osiris_replica, Name}, Keys]),
+                            maps:with(Keys, CountersPre) == RC
                     end, 1000, 20),
     Replica1CountersPre = erpc:call(hd(Replicas), osiris_counters, overview,
                                     [{osiris_replica, Name}]),