[RTI-17070] Add a little introspection function (#125)

Author: pehuen-rodriguez

src/mero.erl

@@ -35,7 +35,7 @@
          gets/2, gets/3, delete/3, mdelete/3, mget/2, mget/3, mgets/2, mgets/3, set/5, mset/3,
          cas/6, mcas/3, add/5, madd/3, flush_all/1, shard_phash2/2, shard_crc32/2,
          clustering_key/1, storage_key/1]).
--export([state/0, state/1, deep_state/0, deep_state/1]).
+-export([state/0, state/1, deep_state/0, deep_state/1, is_cluster_available/1]).
 
 -include_lib("mero/include/mero.hrl").
 
@@ -354,3 +354,25 @@ deep_state(ClusterName) ->
 %% @doc: Returns the state of the sockets for all clusters
 deep_state() ->
     [{Cluster, deep_state(Cluster)} || Cluster <- mero_cluster:clusters()].
+
+%% @doc: Returns current availability of a cluster
+-spec is_cluster_available(atom()) -> true | {false, atom()}.
+is_cluster_available(ClusterName) ->
+    try
+        Clusters = mero_cluster:clusters(),
+        case lists:member(ClusterName, Clusters) of
+            false ->
+                {false, cluster_not_found};
+            true ->
+                true
+        end
+    catch
+        error:undef ->
+            {false, cluster_util_not_loaded};
+        error:function_clause ->
+            {false, invalid_sharding_algorithm};
+        error:badarg ->
+            {false, invalid_sharding_algorithm};
+        _:_ ->
+            {false, cluster_config_error}
+    end.

test/mero_SUITE.erl

@@ -38,7 +38,7 @@
          increase_counter_clustered_key/1, increment/1, mdelete/1, multiget_defineds/1,
          multiget_defineds_clustered_keys/1, multiget_undefineds/1, set/1, undefined_counter/1,
          mincrease_counter/1, cas/1, madd/1, mset/1, mcas/1, state_ok/1, state_error/1,
-         state_timeout/1, get_clustered_key/1]).
+         state_timeout/1, get_clustered_key/1, cluster_availability/1]).
 
 %%%=============================================================================
 %%% common_test callbacks
@@ -66,7 +66,8 @@ groups() ->
        cas,
        state_ok,
        state_error,
-       state_timeout]},
+       state_timeout,
+       cluster_availability]},
      {binary_protocol,
       [shuffle, {repeat_until_any_fail, 1}],
       [add,
@@ -89,7 +90,8 @@ groups() ->
        mcas,
        state_ok,
        state_error,
-       state_timeout]}].
+       state_timeout,
+       cluster_availability]}].
 
 init_per_group(text_protocol, Config) ->
     ClusterConfig =
@@ -525,6 +527,11 @@ state_timeout(_) ->
                  lists:sort(
                      proplists:get_value(cluster, State))).
 
+cluster_availability(_) ->
+    ?assertEqual(true, mero:is_cluster_available(cluster)),
+    ?assertEqual(true, mero:is_cluster_available(cluster2)),
+    ?assertEqual({false, cluster_not_found}, mero:is_cluster_available(non_existing_cluster)).
+
 %%%=============================================================================
 %%% Internal functions
 %%%=============================================================================