From a26c9d2475beaa9398d8815f861ed0b1025edc58 Mon Sep 17 00:00:00 2001
From: Alexey Shchepin <alexey@process-one.net>
Date: Mon, 20 Dec 2021 09:31:01 +0300
Subject: [PATCH] Optimize user removal handling in mod_muc

---
 src/mod_muc.erl      |  4 ++--
 src/mod_muc_room.erl | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/mod_muc.erl b/src/mod_muc.erl
index 2853632cc..72f386b00 100644
--- a/src/mod_muc.erl
+++ b/src/mod_muc.erl
@@ -1143,9 +1143,9 @@ remove_user(User, Server) ->
       fun(Host) ->
               lists:foreach(
                 fun({_, _, Pid}) ->
-                        mod_muc_room:change_item(
+                        mod_muc_room:change_item_async(
                           Pid, JID, affiliation, none, <<"User removed">>),
-                        mod_muc_room:change_item(
+                        mod_muc_room:change_item_async(
                           Pid, JID, role, none, <<"User removed">>)
                 end,
                 get_online_rooms(LServer, Host))
diff --git a/src/mod_muc_room.erl b/src/mod_muc_room.erl
index ec1c551e4..25bc7d8b6 100644
--- a/src/mod_muc_room.erl
+++ b/src/mod_muc_room.erl
@@ -50,6 +50,7 @@
 	 set_config/2,
 	 get_state/1,
 	 change_item/5,
+	 change_item_async/5,
 	 config_reloaded/1,
 	 subscribe/4,
 	 unsubscribe/2,
@@ -202,6 +203,11 @@ change_item(Pid, JID, Type, AffiliationOrRole, Reason) ->
 	    {error, notfound}
     end.
 
+-spec change_item_async(pid(), jid(), affiliation | role, affiliation() | role(), binary()) -> ok.
+change_item_async(Pid, JID, Type, AffiliationOrRole, Reason) ->
+    p1_fsm:send_all_state_event(
+      Pid, {process_item_change, {JID, Type, AffiliationOrRole, Reason}, undefined}).
+
 -spec get_state(pid()) -> {ok, state()} | {error, notfound | timeout}.
 get_state(Pid) ->
     try p1_fsm:sync_send_all_state_event(Pid, get_state)
@@ -675,6 +681,16 @@ handle_event({set_affiliations, Affiliations},
 	     StateName, StateData) ->
     NewStateData = set_affiliations(Affiliations, StateData),
     {next_state, StateName, NewStateData};
+handle_event({process_item_change, Item, UJID}, StateName, StateData) ->
+    case process_item_change(Item, StateData, UJID) of
+	{error, _} ->
+            {next_state, StateName, StateData};
+        StateData ->
+            {next_state, StateName, StateData};
+	NSD ->
+	    store_room(NSD),
+            {next_state, StateName, NSD}
+    end;
 handle_event(_Event, StateName, StateData) ->
     {next_state, StateName, StateData}.
 
@@ -723,6 +739,8 @@ handle_sync_event({process_item_change, Item, UJID}, _From, StateName, StateData
     case process_item_change(Item, StateData, UJID) of
 	{error, _} = Err ->
 	    {reply, Err, StateName, StateData};
+        StateData ->
+            {reply, {ok, StateData}, StateName, StateData};
 	NSD ->
 	    store_room(NSD),
 	    {reply, {ok, NSD}, StateName, NSD}