From 97e27faf05a2c24a6115e0c06f5f592b9d1a8f28 Mon Sep 17 00:00:00 2001
From: Shawn <506895667@qq.com>
Date: Tue, 18 May 2021 10:34:23 +0800
Subject: [PATCH] fix(emqx): check if the congestion alarm was sent before
 clearing (#4824)

---
 src/emqx.appup.src      | 4 ++++
 src/emqx_congestion.erl | 5 ++++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/emqx.appup.src b/src/emqx.appup.src
index 937f31eff..7e21ef4ed 100644
--- a/src/emqx.appup.src
+++ b/src/emqx.appup.src
@@ -2,10 +2,12 @@
 {VSN,
  [
    {"4.3.1", [
+     {load_module, emqx_congestion, brutal_purge, soft_purge, []},
      {load_module, emqx_node_dump, brutal_purge, soft_purge, []}
    ]},
    {"4.3.0", [
      {load_module, emqx_logger_jsonfmt, brutal_purge, soft_purge, []},
+     {load_module, emqx_congestion, brutal_purge, soft_purge, []},
      {load_module, emqx_connection, brutal_purge, soft_purge, []},
      {load_module, emqx_frame, brutal_purge, soft_purge, []},
      {load_module, emqx_trie, brutal_purge, soft_purge, []},
@@ -16,11 +18,13 @@
  ],
  [
    {"4.3.1", [
+     {load_module, emqx_congestion, brutal_purge, soft_purge, []},
      {load_module, emqx_node_dump, brutal_purge, soft_purge, []}
    ]},
    {"4.3.0", [
      {load_module, emqx_logger_jsonfmt, brutal_purge, soft_purge, []},
      {load_module, emqx_connection, brutal_purge, soft_purge, []},
+     {load_module, emqx_congestion, brutal_purge, soft_purge, []},
      {load_module, emqx_frame, brutal_purge, soft_purge, []},
      {load_module, emqx_trie, brutal_purge, soft_purge, []},
      %% Just load the module. We don't need to change the 'messages.retained'
diff --git a/src/emqx_congestion.erl b/src/emqx_congestion.erl
index ea99a63b1..4ec20034d 100644
--- a/src/emqx_congestion.erl
+++ b/src/emqx_congestion.erl
@@ -48,7 +48,10 @@ maybe_alarm_conn_congestion(Socket, Transport, Channel) ->
 
 cancel_alarms(Socket, Transport, Channel) ->
     lists:foreach(fun(Reason) ->
-        do_cancel_alarm_congestion(Socket, Transport, Channel, Reason)
+        case has_alarm_sent(Reason) of
+            true -> do_cancel_alarm_congestion(Socket, Transport, Channel, Reason);
+            false -> ok
+        end
     end, ?ALL_ALARM_REASONS).
 
 is_alarm_enabled(Channel) ->