refactor(dashboard): Decorate remote procedure calls

apps/emqx_dashboard/src/emqx_dashboard_collection.erl

@@ -20,7 +20,7 @@
         , code_change/3
         ]).
 
--export([get_collect/0]).
+-export([get_collect/0, select_data/0]).
 
 -export([get_universal_epoch/0]).
 
@@ -52,6 +52,11 @@ start_link() ->
 
 get_collect() -> gen_server:call(whereis(?MODULE), get_collect).
 
+-spec select_data() -> [#mqtt_collect{}].
+select_data() ->
+    Time = emqx_dashboard_collection:get_universal_epoch() - 7200000,
+    ets:select(?TAB_COLLECT, [{{mqtt_collect,'$1','$2'}, [{'>', '$1', Time}], ['$_']}]).
+
 init([]) ->
     timer(next_interval(), collect),
     timer(get_today_remaining_seconds(), clear_expire_data),

apps/emqx_dashboard/src/emqx_dashboard_monitor_api.erl

@@ -215,10 +215,8 @@ list_collect(Aggregate) ->
             merger_counters(Counters)
     end.
 
-get_collect(Node) when Node =:= node() ->
-    emqx_dashboard_collection:get_collect();
 get_collect(Node) ->
-    case rpc:call(Node, emqx_dashboard_collection, get_collect, []) of
+    case emqx_dashboard_proto_v1:get_collect(Node) of
         {badrpc, _Reason} -> ?EMPTY_COLLECTION;
         Res -> Res
     end.
@@ -267,19 +265,13 @@ key_replace([Term | List], All, Comparison, Default) ->
             key_replace(List, All, Comparison, Default)
     end.
 
-sampling(Node) when Node =:= node() ->
-    format(lists:sort(select_data()));
 sampling(Node) ->
-    rpc:call(Node, ?MODULE, sampling, [Node]).
+    Data = emqx_dashboard_proto_v1:select_data(Node),
+    format(lists:sort(Data)).
 
-sampling(Node, Counter) when Node =:= node() ->
-    format_single(lists:sort(select_data()), Counter);
 sampling(Node, Counter) ->
-    rpc:call(Node, ?MODULE, sampling, [Node, Counter]).
-
-select_data() ->
-    Time = emqx_dashboard_collection:get_universal_epoch() - 7200000,
-    ets:select(?TAB_COLLECT, [{{mqtt_collect,'$1','$2'}, [{'>', '$1', Time}], ['$_']}]).
+    Data = emqx_dashboard_proto_v1:select_data(Node),
+    format_single(lists:sort(Data), Counter).
 
 format(Collects) ->
     format(Collects, {[],[],[],[],[],[]}).

apps/emqx_dashboard/src/proto/emqx_dashboard_proto_v1.erl

@@ -0,0 +1,40 @@
+%%--------------------------------------------------------------------
+%% Copyright (c) 2022 EMQ Technologies Co., Ltd. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%%
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%--------------------------------------------------------------------
+
+-module(emqx_dashboard_proto_v1).
+
+-behaviour(emqx_bpapi).
+
+-export([ introduced_in/0
+
+        , get_collect/1
+        , select_data/1
+        ]).
+
+-include("emqx_dashboard.hrl").
+-include_lib("emqx/include/bpapi.hrl").
+
+introduced_in() ->
+    "5.0.0".
+
+-spec get_collect(node()) -> _.
+get_collect(Node) ->
+    rpc:call(Node, emqx_dashboard_collection, get_collect, []).
+
+-spec select_data(node()) -> [#mqtt_collect{}]
+                           | emqx_rpc:badrpc().
+select_data(Node) ->
+    rpc:call(Node, emqx_dashboard_collection, select_data, []).