From 776aabda7da55c78f7769027c99d806fe02f605b Mon Sep 17 00:00:00 2001
From: DDDHuang <904897578@qq.com>
Date: Wed, 11 Aug 2021 14:13:07 +0800
Subject: [PATCH] fix: merge counters each node

---
 .../src/emqx_dashboard_collection.erl         | 17 +++-
 .../src/emqx_dashboard_monitor_api.erl        | 80 ++++++++++++++-----
 2 files changed, 71 insertions(+), 26 deletions(-)

diff --git a/apps/emqx_dashboard/src/emqx_dashboard_collection.erl b/apps/emqx_dashboard/src/emqx_dashboard_collection.erl
index bf172ee97..91d60e1ab 100644
--- a/apps/emqx_dashboard/src/emqx_dashboard_collection.erl
+++ b/apps/emqx_dashboard/src/emqx_dashboard_collection.erl
@@ -56,7 +56,7 @@ start_link() ->
 get_collect() -> gen_server:call(whereis(?MODULE), get_collect).
 
 init([]) ->
-    timer(timer:seconds(interval()), collect),
+    timer(next_interval(), collect),
     timer(get_today_remaining_seconds(), clear_expire_data),
     ExpireInterval = emqx_config:get([emqx_dashboard, monitor, interval], ?EXPIRE_INTERVAL),
     State = #{
@@ -68,6 +68,15 @@ init([]) ->
     },
     {ok, State}.
 
+%% @doc every whole interval seconds;
+%% example:
+%% interval is 10s
+%% now 15:01:07 (or 15:07:01 ~ 15:07:10)
+%% next will be 15:01:10, 15:01:20, 15:01:30 ...
+%% ensure all counters in cluster have sync time
+next_interval() ->
+    (1000 * interval()) - (erlang:system_time(millisecond) rem (1000 * interval())) - 1.
+
 interval() ->
     emqx_config:get([?APP, sample_interval], ?DEFAULT_INTERVAL).
 
@@ -82,17 +91,17 @@ handle_cast(_Req, State) ->
     {noreply, State}.
 
 handle_info(collect, State = #{collect := Collect, count := 1, temp_collect := TempCollect, last_collects := LastCollect}) ->
+    timer(next_interval(), collect),
     NewLastCollect = flush(collect_all(Collect), LastCollect),
     TempCollect1 = temp_collect(TempCollect),
-    timer(timer:seconds(interval()), collect),
     {noreply, State#{count => count(),
                      collect => ?COLLECT,
                      temp_collect => TempCollect1,
                      last_collects => NewLastCollect}};
 
 handle_info(collect, State = #{count := Count, collect := Collect, temp_collect := TempCollect}) ->
+    timer(next_interval(), collect),
     TempCollect1 = temp_collect(TempCollect),
-    timer(timer:seconds(interval()), collect),
     {noreply, State#{count => Count - 1,
                      collect => collect_all(Collect),
                      temp_collect => TempCollect1}, hibernate};
@@ -170,4 +179,4 @@ get_today_remaining_seconds() ->
 
 get_local_time() ->
     (calendar:datetime_to_gregorian_seconds(calendar:local_time()) -
-        calendar:datetime_to_gregorian_seconds({{1970,1,1}, {0,0,0}})) * 1000.
+        calendar:datetime_to_gregorian_seconds({{1970,1,1}, {0,0,0}})).
diff --git a/apps/emqx_dashboard/src/emqx_dashboard_monitor_api.erl b/apps/emqx_dashboard/src/emqx_dashboard_monitor_api.erl
index 130139780..277b0b1fd 100644
--- a/apps/emqx_dashboard/src/emqx_dashboard_monitor_api.erl
+++ b/apps/emqx_dashboard/src/emqx_dashboard_monitor_api.erl
@@ -8,11 +8,6 @@
 
 -behaviour(minirest_api).
 
--export([ sampling/1
-        , sampling/2
-        , get_collect/1
-        ]).
-
 -export([api_spec/0]).
 
 -export([counters/2, current_counters/2]).
@@ -36,8 +31,7 @@ monitor_api() ->
                     name => node,
                     in => query,
                     required => false,
-                    schema => #{type => string},
-                    example => node()
+                    schema => #{type => string}
                 },
                 #{
                     name => counter,
@@ -47,7 +41,7 @@ monitor_api() ->
                 }
             ],
             responses => #{
-                <<"200">> => emqx_mgmt_util:response_array_schema(<<"Monitor count data">>, counters)}}},
+                <<"200">> => emqx_mgmt_util:response_schema(<<"Monitor count data">>, counters)}}},
     {"/monitor", Metadata, counters}.
 monitor_current_api() ->
     Metadata = #{
@@ -62,9 +56,6 @@ current_counters_schema() ->
     #{
         type => object,
         properties => #{
-            nodes => #{
-                type => integer,
-                description => <<"Nodes count">>},
             connection => #{type => integer},
             sent => #{type => integer},
             received => #{type => integer},
@@ -72,13 +63,11 @@ current_counters_schema() ->
     }.
 
 counters_schema() ->
-    Node = #{
-        node => #{
-            type => string,
-            example => node()
-        }
-    },
-    Properties = lists:foldl(fun(K, M) -> maps:merge(M, counters_schema(K)) end, Node, ?COUNTERS),
+    Fun =
+        fun(K, M) ->
+            maps:merge(M, counters_schema(K))
+        end,
+    Properties = lists:foldl(Fun, #{}, ?COUNTERS),
     #{
         counters => #{
             type => object,
@@ -100,8 +89,7 @@ counters_schema(Name) ->
 counters(get, Request) ->
     case cowboy_req:parse_qs(Request) of
         [] ->
-            Response = [sampling(Node) || Node <- ekka_mnesia:running_nodes()],
-            {200, Response};
+            {200, get_collect()};
         Params ->
             lookup(Params)
     end.
@@ -144,6 +132,10 @@ format_current_metrics([], Acc) ->
 format_current_metrics([{Received, Sent, Sub, Conn} | Collects], {Received1, Sent1, Sub1, Conn1}) ->
     format_current_metrics(Collects, {Received1 + Received, Sent1 + Sent, Sub1 + Sub, Conn1 + Conn}).
 
+get_collect() ->
+    Counters = [sampling(Node) || Node <- ekka_mnesia:running_nodes()],
+    merger_counters(Counters).
+
 get_collect(Node) when Node =:= node() ->
     emqx_dashboard_collection:get_collect();
 get_collect(Node) ->
@@ -152,17 +144,61 @@ get_collect(Node) ->
         Res -> Res
     end.
 
+merger_counters(ClusterCounters) ->
+    lists:foldl(fun merger_node_counters/2, #{}, ClusterCounters).
+
+merger_node_counters(NodeCounters, Counters) ->
+    maps:fold(fun merger_counter/3, Counters, NodeCounters).
+
+merger_counter(Key, Counters, Res) ->
+    case maps:get(Key, Res, undefined) of
+        undefined ->
+            Res#{Key => Counters};
+        OldCounters ->
+            NCounters = lists:foldl(fun merger_counter/2, OldCounters, Counters),
+            Res#{Key => NCounters}
+    end.
+
+merger_counter(#{timestamp := Timestamp, count := Value}, Counters) ->
+    Comparison =
+        fun(Counter) ->
+            case maps:get(timestamp, Counter) =:= Timestamp of
+                true ->
+                    Count = maps:get(count, Counter),
+                    {ok, Counter#{count => Count + Value}};
+                false ->
+                    ignore
+            end
+        end,
+    key_replace(Counters, Comparison, #{timestamp => Timestamp, count => Value}).
+
+key_replace(List, Comparison, Default) ->
+    key_replace(List, List, Comparison, Default).
+
+key_replace([], All, _Comparison, Default) ->
+    [Default | All];
+
+key_replace([Term | List], All, Comparison, Default) ->
+    case Comparison(Term) of
+        {ok, NTerm} ->
+            Tail = [NTerm | List],
+            Header = lists:sublist(All, length(All) - length(Tail)),
+            lists:append(Header, Tail);
+        _ ->
+            key_replace(List, All, Comparison, Default)
+    end.
+
 sampling(Node) when Node =:= node() ->
     Time = emqx_dashboard_collection:get_local_time() - 7200000,
     All = dets:select(emqx_collect, [{{mqtt_collect,'$1','$2'}, [{'>', '$1', Time}], ['$_']}]),
-    maps:put(node, Node, format(lists:sort(All)));
+    format(lists:sort(All));
 sampling(Node) ->
     rpc:call(Node, ?MODULE, sampling, [Node]).
 
 sampling(Node, Counter) when Node =:= node() ->
     Time = emqx_dashboard_collection:get_local_time() - 7200000,
     All = dets:select(emqx_collect, [{{mqtt_collect,'$1','$2'}, [{'>', '$1', Time}], ['$_']}]),
-    maps:put(node, Node, format_single(lists:sort(All), Counter));
+    format_single(lists:sort(All), Counter);
 sampling(Node, Counter) ->
     rpc:call(Node, ?MODULE, sampling, [Node, Counter]).