refactor(metrics): more clear for acl metrics

For clarity in the meaning of metrics, we put `client.acl.allow`,
`client.acl.deny` into emqx_metrics and increased after a acl checking
returned.

src/emqx_access_control.erl

@@ -45,10 +45,11 @@ authenticate(ClientInfo = #{zone := Zone}) ->
 -spec(check_acl(emqx_types:clientinfo(), emqx_types:pubsub(), emqx_types:topic())
       -> allow | deny).
 check_acl(ClientInfo, PubSub, Topic) ->
-    case emqx_acl_cache:is_enabled() of
+    Result = case emqx_acl_cache:is_enabled() of
         true  -> check_acl_cache(ClientInfo, PubSub, Topic);
         false -> do_check_acl(ClientInfo, PubSub, Topic)
-    end.
+    end,
+    inc_acl_metrics(Result), Result.
 
 check_acl_cache(ClientInfo, PubSub, Topic) ->
     case emqx_acl_cache:get_acl_cache(PubSub, Topic) of
@@ -56,7 +57,9 @@ check_acl_cache(ClientInfo, PubSub, Topic) ->
             AclResult = do_check_acl(ClientInfo, PubSub, Topic),
             emqx_acl_cache:put_acl_cache(PubSub, Topic, AclResult),
             AclResult;
-        AclResult -> AclResult
+        AclResult ->
+            inc_acl_metrics(cache_hit),
+            AclResult
     end.
 
 do_check_acl(ClientInfo = #{zone := Zone}, PubSub, Topic) ->
@@ -76,6 +79,14 @@ default_auth_result(Zone) ->
 run_hooks(Name, Args, Acc) ->
     ok = emqx_metrics:inc(Name), emqx_hooks:run_fold(Name, Args, Acc).
 
+-compile({inline, [inc_acl_metrics/1]}).
+inc_acl_metrics(allow) ->
+    emqx_metrics:inc('client.acl.allow');
+inc_acl_metrics(deny) ->
+    emqx_metrics:inc('client.acl.deny');
+inc_acl_metrics(cache_hit) ->
+    emqx_metrics:inc('client.acl.cache_hit').
+
 -compile({inline, [return_auth_result/1]}).
 return_auth_result(Result = #{auth_result := success}) ->
     {ok, Result};

src/emqx_metrics.erl

@@ -65,8 +65,11 @@
         , code_change/3
         ]).
 
-%% BACKW: v4.3.0
+%% BACKW
--export([ upgrade_retained_delayed_counter_type/0
+-export([%% v4.3.0
+         upgrade_retained_delayed_counter_type/0,
+         %% e4.4.0, e4.3.0-e4.3.6, v4.3.0-v4.3.11
+         assign_acl_stats_from_ets_to_counter/0
         ]).
 
 -export_type([metric_idx/0]).
@@ -186,6 +189,12 @@
          {counter, 'session.discarded'},
          {counter, 'session.terminated'}
         ]).
+%% Statistic metrics for ACL checking
+-define(STASTS_ACL_METRICS,
+        [ {counter, 'client.acl.allow'},
+          {counter, 'client.acl.deny'},
+          {counter, 'client.acl.cache_hit'}
+        ]).
 
 -record(state, {next_idx = 1}).
 
@@ -204,6 +213,21 @@ upgrade_retained_delayed_counter_type() ->
     Ks = ['messages.retained', 'messages.delayed'],
     gen_server:call(?SERVER, {set_type_to_counter, Ks}, infinity).
 
+%% BACKW: %% e4.4.0, e4.3.0-e4.3.6, v4.3.0-v4.3.11
+assign_acl_stats_from_ets_to_counter() ->
+    CRef = persistent_term:get(?MODULE),
+    Names = ['client.acl.allow', 'client.acl.deny', 'client.acl.cache_hit'],
+    lists:foreach(fun(Name) ->
+        Val = case emqx_metrics:val(Name) of
+            undefined -> 0;
+            Val0 -> Val0
+        end,
+        Idx = reserved_idx(Name),
+        Metric = #metric{name = Name, type = counter, idx = Idx},
+        ok = gen_server:call(?SERVER, {set, Metric}),
+        ok = counters:put(CRef, Idx, Val)
+    end, Names).
+
 %%--------------------------------------------------------------------
 %% Metrics API
 %%--------------------------------------------------------------------
@@ -433,7 +457,8 @@ init([]) ->
                             ?MESSAGE_METRICS,
                             ?DELIVERY_METRICS,
                             ?CLIENT_METRICS,
-                            ?SESSION_METRICS
+                            ?SESSION_METRICS,
+                            ?STASTS_ACL_METRICS
                            ]),
     % Store reserved indices
     ok = lists:foreach(fun({Type, Name}) ->
@@ -466,6 +491,10 @@ handle_call({set_type_to_counter, Keys}, _From, State) ->
       end, Keys),
     {reply, ok, State};
 
+handle_call({set, Metric}, _From, State) ->
+    true = ets:insert(?TAB, Metric),
+    {reply, ok, State};
+
 handle_call(Req, _From, State) ->
     ?LOG(error, "Unexpected call: ~p", [Req]),
     {reply, ignored, State}.
@@ -574,6 +603,10 @@ reserved_idx('session.resumed')              -> 221;
 reserved_idx('session.takeovered')           -> 222;
 reserved_idx('session.discarded')            -> 223;
 reserved_idx('session.terminated')           -> 224;
+%% Stats metrics
+reserved_idx('client.acl.allow')             -> 300;
+reserved_idx('client.acl.deny')              -> 301;
+reserved_idx('client.acl.cache_hit')         -> 302;
 
 reserved_idx(_)                              -> undefined.