From 0b116bc208096b03686284f12e59d584c0342317 Mon Sep 17 00:00:00 2001
From: tradingtrace <tradingtrace@outlook.com>
Date: Sun, 23 Jun 2019 11:20:22 +0800
Subject: [PATCH] Fix the massages order when batch dispatching

---
 src/emqx_session.erl | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/emqx_session.erl b/src/emqx_session.erl
index 49454d8ac..7d8722c68 100644
--- a/src/emqx_session.erl
+++ b/src/emqx_session.erl
@@ -798,7 +798,7 @@ handle_dispatch(Msgs, State = #state{inflight = Inflight,
                                      subscriptions = SubMap}) ->
     SessProps = #{client_id => ClientId, username => Username},
     %% Drain the mailbox and batch deliver
-    Msgs1 = drain_m(batch_n(Inflight), Msgs),
+    Msgs1 = Msgs ++ drain_m(batch_n(Inflight)),
     %% Ack the messages for shared subscription
     Msgs2 = maybe_ack_shared(Msgs1, State),
     %% Process suboptions
@@ -821,6 +821,9 @@ batch_n(Inflight) ->
         Sz -> Sz - emqx_inflight:size(Inflight)
     end.
 
+drain_m(Cnt) ->
+    drain_m(Cnt, []).
+
 drain_m(Cnt, Msgs) when Cnt =< 0 ->
     lists:reverse(Msgs);
 drain_m(Cnt, Msgs) ->