From 86d20b060c66aa86d090f0559827941aea8553d8 Mon Sep 17 00:00:00 2001
From: Shawn <506895667@qq.com>
Date: Fri, 18 Dec 2020 16:22:50 +0800
Subject: [PATCH] fix(metrics): counters not created before incr 'rule.matched'

---
 apps/emqx_rule_engine/src/emqx_rule_metrics.erl     | 13 ++++++++++++-
 .../test/emqx_rule_metrics_SUITE.erl                | 10 +++++++---
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/apps/emqx_rule_engine/src/emqx_rule_metrics.erl b/apps/emqx_rule_engine/src/emqx_rule_metrics.erl
index 4a1ef7da7..90554d982 100644
--- a/apps/emqx_rule_engine/src/emqx_rule_metrics.erl
+++ b/apps/emqx_rule_engine/src/emqx_rule_metrics.erl
@@ -163,7 +163,18 @@ inc(Id, Metric) ->
 
 -spec inc(rule_id(), atom(), pos_integer()) -> ok.
 inc(Id, Metric, Val) ->
-    counters:add(couters_ref(Id), metrics_idx(Metric), Val),
+    case couters_ref(Id) of
+        not_found ->
+            %% this may occur when increasing a counter for
+            %% a rule that was created from a remove node.
+            case atom_to_list(Metric) of
+                "rules." ++ _ -> create_rule_metrics(Id);
+                _ -> create_metrics(Id)
+            end,
+            counters:add(couters_ref(Id), metrics_idx(Metric), Val);
+        Ref ->
+            counters:add(Ref, metrics_idx(Metric), Val)
+    end,
     inc_overall(Metric, Val).
 
 -spec(inc_overall(atom(), pos_integer()) -> ok).
diff --git a/apps/emqx_rule_engine/test/emqx_rule_metrics_SUITE.erl b/apps/emqx_rule_engine/test/emqx_rule_metrics_SUITE.erl
index c006f704c..0fa8b6625 100644
--- a/apps/emqx_rule_engine/test/emqx_rule_metrics_SUITE.erl
+++ b/apps/emqx_rule_engine/test/emqx_rule_metrics_SUITE.erl
@@ -34,7 +34,8 @@ groups() ->
         [ t_action
         , t_rule
         , t_clear
-        , t_no_creation
+        , t_no_creation_1
+        , t_no_creation_2
         ]},
     {speed, [sequence],
         [ rule_speed
@@ -60,8 +61,11 @@ init_per_testcase(_, Config) ->
 end_per_testcase(_, _Config) ->
     ok.
 
-t_no_creation(_) ->
-    ?assertError(_, emqx_rule_metrics:inc_actions_taken(<<"action:0">>)).
+t_no_creation_1(_) ->
+    ?assertEqual(ok, emqx_rule_metrics:inc_rules_matched(<<"rule1">>)).
+
+t_no_creation_2(_) ->
+    ?assertEqual(ok, emqx_rule_metrics:inc_actions_taken(<<"action:0">>)).
 
 t_action(_) ->
     ?assertEqual(0, emqx_rule_metrics:get_actions_taken(<<"action:1">>)),