From 5b48b06d4a2178b474561ca070f0dccd9fb88be0 Mon Sep 17 00:00:00 2001
From: Serge Tupchii <serge.tupchii@protonmail.com>
Date: Mon, 26 Feb 2024 14:17:36 +0200
Subject: [PATCH 1/2] fix: trace throttled log events

---
 apps/emqx/include/logger.hrl                      | 13 +++++++++----
 apps/emqx/src/emqx_trace/emqx_trace_formatter.erl |  4 +++-
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/apps/emqx/include/logger.hrl b/apps/emqx/include/logger.hrl
index 59285e9d5..313358bcd 100644
--- a/apps/emqx/include/logger.hrl
+++ b/apps/emqx/include/logger.hrl
@@ -51,7 +51,7 @@
         true ->
             ?SLOG(Level, Data, Meta);
         false ->
-            ok
+            ?_DO_TRACE(Level, maps:get(msg, Data), maps:merge(Data, Meta))
     end
 ).
 
@@ -61,8 +61,8 @@
 
 -define(TRACE(Tag, Msg, Meta), ?TRACE(debug, Tag, Msg, Meta)).
 
-%% Only evaluate when necessary
--define(TRACE(Level, Tag, Msg, Meta), begin
+%% Internal macro
+-define(_DO_TRACE(Tag, Msg, Meta),
     case persistent_term:get(?TRACE_FILTER, []) of
         [] -> ok;
         %% We can't bind filter list to a variable because we pollute the calling scope with it.
@@ -70,7 +70,12 @@
         %% because this adds overhead to the happy path.
         %% So evaluate `persistent_term:get` twice.
         _ -> emqx_trace:log(persistent_term:get(?TRACE_FILTER, []), Msg, (Meta)#{trace_tag => Tag})
-    end,
+    end
+).
+
+%% Only evaluate when necessary
+-define(TRACE(Level, Tag, Msg, Meta), begin
+    ?_DO_TRACE(Tag, Msg, Meta),
     ?SLOG(
         Level,
         (emqx_trace_formatter:format_meta_map(Meta))#{msg => Msg, tag => Tag},
diff --git a/apps/emqx/src/emqx_trace/emqx_trace_formatter.erl b/apps/emqx/src/emqx_trace/emqx_trace_formatter.erl
index 4dd22966b..6cbcc0510 100644
--- a/apps/emqx/src/emqx_trace/emqx_trace_formatter.erl
+++ b/apps/emqx/src/emqx_trace/emqx_trace_formatter.erl
@@ -35,7 +35,9 @@ format(
     ClientId = to_iolist(maps:get(clientid, Meta, "")),
     Peername = maps:get(peername, Meta, ""),
     MetaBin = format_meta(Meta, PEncode),
-    [Time, " [", Tag, "] ", ClientId, "@", Peername, " msg: ", Msg, ", ", MetaBin, "\n"];
+    Msg1 = to_iolist(Msg),
+    Tag1 = to_iolist(Tag),
+    [Time, " [", Tag1, "] ", ClientId, "@", Peername, " msg: ", Msg1, ", ", MetaBin, "\n"];
 format(Event, Config) ->
     emqx_logger_textfmt:format(Event, Config).
 

From 5d4c85cd84644000fd69e92fa876471908e91a39 Mon Sep 17 00:00:00 2001
From: Serge Tupchii <serge.tupchii@protonmail.com>
Date: Mon, 26 Feb 2024 14:18:46 +0200
Subject: [PATCH 2/2] chore: list throttled log events in the change-log

---
 apps/emqx/include/logger.hrl | 4 ++--
 changes/ce/feat-12520.en.md  | 6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/apps/emqx/include/logger.hrl b/apps/emqx/include/logger.hrl
index 313358bcd..8974eace4 100644
--- a/apps/emqx/include/logger.hrl
+++ b/apps/emqx/include/logger.hrl
@@ -59,8 +59,6 @@
 -define(TRACE_FILTER, emqx_trace_filter).
 -define(OWN_KEYS, [level, filters, filter_default, handlers]).
 
--define(TRACE(Tag, Msg, Meta), ?TRACE(debug, Tag, Msg, Meta)).
-
 %% Internal macro
 -define(_DO_TRACE(Tag, Msg, Meta),
     case persistent_term:get(?TRACE_FILTER, []) of
@@ -73,6 +71,8 @@
     end
 ).
 
+-define(TRACE(Tag, Msg, Meta), ?TRACE(debug, Tag, Msg, Meta)).
+
 %% Only evaluate when necessary
 -define(TRACE(Level, Tag, Msg, Meta), begin
     ?_DO_TRACE(Tag, Msg, Meta),
diff --git a/changes/ce/feat-12520.en.md b/changes/ce/feat-12520.en.md
index 593b66ec4..99d29fb2e 100644
--- a/changes/ce/feat-12520.en.md
+++ b/changes/ce/feat-12520.en.md
@@ -1,2 +1,8 @@
 Implement log throttling. The feature reduces the number of potentially flooding logged events by
 dropping all but the first event within a configured time window.
+Throttling is applied to the following log events:
+ - authorization_permission_denied,
+ - cannot_publish_to_topic_due_to_not_authorized,
+ - cannot_publish_to_topic_due_to_quota_exceeded,
+ - connection_rejected_due_to_license_limit_reached,
+ - dropped_msg_due_to_mqueue_is_full.