From cffdb06b66233d58f2bee763cc14e4eaba3b6454 Mon Sep 17 00:00:00 2001
From: Evgeniy Khramtsov <ekhramtsov@process-one.net>
Date: Fri, 16 Feb 2018 20:50:22 +0300
Subject: [PATCH] Cache 'isuser' queries to external auth program

---
 src/ejabberd_auth.erl | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/ejabberd_auth.erl b/src/ejabberd_auth.erl
index df75be9eb..03eee9de4 100644
--- a/src/ejabberd_auth.erl
+++ b/src/ejabberd_auth.erl
@@ -526,7 +526,10 @@ db_get_password(User, Server, Mod) ->
     UseCache = use_cache(Mod, Server),
     case erlang:function_exported(Mod, get_password, 2) of
 	false when UseCache ->
-	    ets_cache:lookup(?AUTH_CACHE, {User, Server});
+	    case ets_cache:lookup(?AUTH_CACHE, {User, Server}) of
+		{ok, exists} -> error;
+		Other -> Other
+	    end;
 	false ->
 	    error;
 	true when UseCache ->
@@ -544,7 +547,20 @@ db_user_exists(User, Server, Mod) ->
 	error ->
 	    case Mod:store_type(Server) of
 		external ->
-		    Mod:user_exists(User, Server);
+		    case ets_cache:update(
+			   ?AUTH_CACHE, {User, Server}, {ok, exists},
+			   fun() ->
+				   case Mod:user_exists(User, Server) of
+				       true -> {ok, exists};
+				       false -> error;
+				       {error, _} = Err -> Err
+				   end
+			   end, cache_nodes(Mod, Server)) of
+			{ok, _} ->
+			    true;
+			error ->
+			    false
+		    end;
 		_ ->
 		    false
 	    end
-- 
2.40.0