From db5cdb674242164a6abc2562d21808d1ada12e45 Mon Sep 17 00:00:00 2001
From: "Zaiming (Stone) Shi" <zmstone@gmail.com>
Date: Tue, 31 Oct 2023 16:46:36 +0100
Subject: [PATCH] perf: no need to format event message if no bridge matched

---
 apps/emqx_bridge/src/emqx_bridge.erl | 74 +++++++++++++++-------------
 1 file changed, 40 insertions(+), 34 deletions(-)

diff --git a/apps/emqx_bridge/src/emqx_bridge.erl b/apps/emqx_bridge/src/emqx_bridge.erl
index a3e06a819..8098072c0 100644
--- a/apps/emqx_bridge/src/emqx_bridge.erl
+++ b/apps/emqx_bridge/src/emqx_bridge.erl
@@ -191,45 +191,50 @@ unload_hook() ->
 on_message_publish(Message = #message{topic = Topic, flags = Flags}) ->
     case maps:get(sys, Flags, false) of
         false ->
-            {Msg, _} = emqx_rule_events:eventmsg_publish(Message),
-            send_to_matched_egress_bridges(Topic, Msg);
+            send_to_matched_egress_bridges(Topic, Message);
         true ->
             ok
     end,
     {ok, Message}.
 
-send_to_matched_egress_bridges(Topic, Msg) ->
-    MatchedBridgeIds = get_matched_egress_bridges(Topic),
-    lists:foreach(
-        fun(Id) ->
-            try send_message(Id, Msg) of
-                {error, Reason} ->
-                    ?SLOG(error, #{
-                        msg => "send_message_to_bridge_failed",
-                        bridge => Id,
-                        error => Reason
-                    });
-                _ ->
-                    ok
-            catch
-                throw:Reason ->
-                    ?SLOG(error, #{
-                        msg => "send_message_to_bridge_exception",
-                        bridge => Id,
-                        reason => emqx_utils:redact(Reason)
-                    });
-                Err:Reason:ST ->
-                    ?SLOG(error, #{
-                        msg => "send_message_to_bridge_exception",
-                        bridge => Id,
-                        error => Err,
-                        reason => emqx_utils:redact(Reason),
-                        stacktrace => emqx_utils:redact(ST)
-                    })
-            end
-        end,
-        MatchedBridgeIds
-    ).
+send_to_matched_egress_bridges(Topic, Message) ->
+    case get_matched_egress_bridges(Topic) of
+        [] ->
+            ok;
+        Ids ->
+            {Msg, _} = emqx_rule_events:eventmsg_publish(Message),
+            send_to_matched_egress_bridges_loop(Topic, Msg, Ids)
+    end.
+
+send_to_matched_egress_bridges_loop(_Topic, _Msg, []) ->
+    ok;
+send_to_matched_egress_bridges_loop(Topic, Msg, [Id | Ids]) ->
+    try send_message(Id, Msg) of
+        {error, Reason} ->
+            ?SLOG(error, #{
+                msg => "send_message_to_bridge_failed",
+                bridge => Id,
+                error => Reason
+            });
+        _ ->
+            ok
+    catch
+        throw:Reason ->
+            ?SLOG(error, #{
+                msg => "send_message_to_bridge_exception",
+                bridge => Id,
+                reason => emqx_utils:redact(Reason)
+            });
+        Err:Reason:ST ->
+            ?SLOG(error, #{
+                msg => "send_message_to_bridge_exception",
+                bridge => Id,
+                error => Err,
+                reason => emqx_utils:redact(Reason),
+                stacktrace => emqx_utils:redact(ST)
+            })
+    end,
+    send_to_matched_egress_bridges_loop(Topic, Msg, Ids).
 
 send_message(BridgeId, Message) ->
     {BridgeType, BridgeName} = emqx_bridge_resource:parse_bridge_id(BridgeId),
@@ -571,6 +576,7 @@ flatten_confs(Conf0) ->
 do_flatten_confs(Type, Conf0) ->
     [{{Type, Name}, Conf} || {Name, Conf} <- maps:to_list(Conf0)].
 
+%% TODO: create a topic index for this
 get_matched_egress_bridges(Topic) ->
     Bridges = emqx:get_config([bridges], #{}),
     maps:fold(