From 3aa84eeaac713cff6df91f6193207b8c5a3b968f Mon Sep 17 00:00:00 2001
From: zhouzb <zhouzb@emqx.io>
Date: Wed, 22 Jul 2020 10:44:53 +0800
Subject: [PATCH] refactor(add-log): log when subscription fails

---
 src/emqx_channel.erl | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/emqx_channel.erl b/src/emqx_channel.erl
index e96ffe2ed..d0f951596 100644
--- a/src/emqx_channel.erl
+++ b/src/emqx_channel.erl
@@ -522,6 +522,10 @@ process_subscribe([], Acc, Channel) ->
 
 process_subscribe([{TopicFilter, SubOpts}|More], Acc, Channel) ->
     {RC, NChannel} = do_subscribe(TopicFilter, SubOpts, Channel),
+    case RC > ?RC_GRANTED_QOS_2 of
+        false -> ok;
+        true -> ?LOG(warning, "Cannot subscribe ~s due to ~s.", [TopicFilter, emqx_reason_codes:text(RC)])
+    end,
     process_subscribe(More, [RC|Acc], NChannel).
 
 do_subscribe(TopicFilter, SubOpts = #{qos := QoS}, Channel =