From e713fc38aa5f1593a2c86724e764ca003496f546 Mon Sep 17 00:00:00 2001
From: Andrew Mayorov <encube.ul@gmail.com>
Date: Mon, 18 Sep 2023 14:46:31 +0400
Subject: [PATCH] feat(broker): reflect persisted messages in publish result

In order for callers to distinguish between silently dropped and
durably persisted message w/o matching subscribers.
---
 apps/emqx/src/emqx_broker.erl | 13 +++++++++++--
 apps/emqx/src/emqx_types.erl  |  1 +
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/apps/emqx/src/emqx_broker.erl b/apps/emqx/src/emqx_broker.erl
index 54c8bd3c4..403e3757f 100644
--- a/apps/emqx/src/emqx_broker.erl
+++ b/apps/emqx/src/emqx_broker.erl
@@ -224,8 +224,17 @@ publish(Msg) when is_record(Msg, message) ->
             }),
             [];
         Msg1 = #message{topic = Topic} ->
-            _ = emqx_persistent_message:persist(Msg1),
-            route(aggre(emqx_router:match_routes(Topic)), delivery(Msg1))
+            PersistRes = persist_publish(Msg1),
+            PersistRes ++ route(aggre(emqx_router:match_routes(Topic)), delivery(Msg1))
+    end.
+
+persist_publish(Msg) ->
+    case emqx_persistent_message:persist(Msg) of
+        ok ->
+            [persisted];
+        {_SkipOrError, _Reason} ->
+            % TODO: log errors?
+            []
     end.
 
 %% Called internally
diff --git a/apps/emqx/src/emqx_types.erl b/apps/emqx/src/emqx_types.erl
index cc937f81c..504540cf6 100644
--- a/apps/emqx/src/emqx_types.erl
+++ b/apps/emqx/src/emqx_types.erl
@@ -244,6 +244,7 @@
 -type publish_result() :: [
     {node(), topic(), deliver_result()}
     | {share, topic(), deliver_result()}
+    | persisted
 ].
 -type route() :: #route{}.
 -type route_entry() :: {topic(), node()} | {topic, group()}.