Refactor definition import functions to log less

 * Only log the intent to import for categories that are not empty/missing
 * Log how many entities will be imported

Current logging frequency is reasonable for occasional manual
or automated imports but with continuous automated imports
(say, a hot standby) it is too excessive.

(cherry picked from commit 3be5483)

Author: michaelklishin

src/rabbit_definitions.erl

@@ -224,29 +224,19 @@ apply_defs(Map, ActingUser, VHost) when is_binary(VHost) ->
 apply_defs(Map, ActingUser, SuccessFun) when is_function(SuccessFun) ->
     Version = maps:get(rabbitmq_version, Map, maps:get(rabbit_version, Map, undefined)),
     try
-        rabbit_log:info("Importing users..."),
         for_all(users, ActingUser, Map,
                 fun(User, _Username) ->
                     rabbit_auth_backend_internal:put_user(User, Version, ActingUser)
                 end),
-        rabbit_log:info("Importing vhosts..."),
         for_all(vhosts,             ActingUser, Map, fun add_vhost/2),
         validate_limits(Map),
-        rabbit_log:info("Importing user permissions..."),
         for_all(permissions,        ActingUser, Map, fun add_permission/2),
-        rabbit_log:info("Importing topic permissions..."),
         for_all(topic_permissions,  ActingUser, Map, fun add_topic_permission/2),
-        rabbit_log:info("Importing parameters..."),
         for_all(parameters,         ActingUser, Map, fun add_parameter/2),
-        rabbit_log:info("Importing global parameters..."),
         for_all(global_parameters,  ActingUser, Map, fun add_global_parameter/2),
-        rabbit_log:info("Importing policies..."),
         for_all(policies,           ActingUser, Map, fun add_policy/2),
-        rabbit_log:info("Importing queues..."),
         for_all(queues,             ActingUser, Map, fun add_queue/2),
-        rabbit_log:info("Importing exchanges..."),
         for_all(exchanges,          ActingUser, Map, fun add_exchange/2),
-        rabbit_log:info("Importing bindings..."),
         for_all(bindings,           ActingUser, Map, fun add_binding/2),
         SuccessFun(),
         ok
@@ -264,15 +254,10 @@ apply_defs(Map, ActingUser, SuccessFun, VHost) when is_binary(VHost) ->
                     [VHost, ActingUser]),
     try
         validate_limits(Map, VHost),
-        rabbit_log:info("Importing parameters..."),
         for_all(parameters, ActingUser, Map, VHost, fun add_parameter/3),
-        rabbit_log:info("Importing policies..."),
         for_all(policies,   ActingUser, Map, VHost, fun add_policy/3),
-        rabbit_log:info("Importing queues..."),
         for_all(queues,     ActingUser, Map, VHost, fun add_queue/3),
-        rabbit_log:info("Importing exchanges..."),
         for_all(exchanges,  ActingUser, Map, VHost, fun add_exchange/3),
-        rabbit_log:info("Importing bindings..."),
         for_all(bindings,   ActingUser, Map, VHost, fun add_binding/3),
         SuccessFun()
     catch {error, E} -> {error, format(E)};
@@ -290,27 +275,31 @@ apply_defs(Map, ActingUser, SuccessFun, ErrorFun, VHost) ->
                     [VHost, ActingUser]),
     try
         validate_limits(Map, VHost),
-        rabbit_log:info("Importing parameters..."),
         for_all(parameters, ActingUser, Map, VHost, fun add_parameter/3),
-        rabbit_log:info("Importing policies..."),
         for_all(policies,   ActingUser, Map, VHost, fun add_policy/3),
-        rabbit_log:info("Importing queues..."),
         for_all(queues,     ActingUser, Map, VHost, fun add_queue/3),
-        rabbit_log:info("Importing exchanges..."),
         for_all(exchanges,  ActingUser, Map, VHost, fun add_exchange/3),
-        rabbit_log:info("Importing bindings..."),
         for_all(bindings,   ActingUser, Map, VHost, fun add_binding/3),
         SuccessFun()
     catch {error, E} -> ErrorFun(format(E));
           exit:E     -> ErrorFun(format(E))
     end.
 
-for_all(Name, ActingUser, Definitions, Fun) ->
-    case maps:get(rabbit_data_coercion:to_atom(Name), Definitions, undefined) of
+for_all(Category, ActingUser, Definitions, Fun) ->
+    case maps:get(rabbit_data_coercion:to_atom(Category), Definitions, undefined) of
         undefined -> ok;
-        List      -> [Fun(maps:from_list([{atomise_name(K), V} || {K, V} <- maps:to_list(M)]),
-                          ActingUser) ||
-                         M <- List, is_map(M)]
+        List      ->
+            case length(List) of
+                0 -> ok;
+                N -> rabbit_log:info("Importing ~p ~s...", [N, human_readable_category_name(Category)])
+            end,
+            [begin
+                 %% keys are expected to be atoms
+                 Atomized = maps:fold(fun (K, V, Acc) ->
+                                maps:put(rabbit_data_coercion:to_atom(K), V, Acc)
+                            end, #{}, M),
+                 Fun(Atomized, ActingUser)
+             end || M <- List, is_map(M)]
     end.
 
 for_all(Name, ActingUser, Definitions, VHost, Fun) ->
@@ -322,6 +311,14 @@ for_all(Name, ActingUser, Definitions, VHost, Fun) ->
                          M <- List, is_map(M)]
     end.
 
+-spec human_readable_category_name(definition_category()) -> string().
+
+human_readable_category_name(topic_permissions) -> "topic permissions";
+human_readable_category_name(parameters) -> "runtime parameters";
+human_readable_category_name(global_parameters) -> "global runtime parameters";
+human_readable_category_name(Other) -> rabbit_data_coercion:to_list(Other).
+
+
 format(#amqp_error{name = Name, explanation = Explanation}) ->
     rabbit_data_coercion:to_binary(rabbit_misc:format("~s: ~s", [Name, Explanation]));
 format({no_such_vhost, undefined}) ->