mod_push_mnesia: Apply cosmetic changes

Improve the readability of the 'max_user_sessions' check.

diff --git a/src/mod_push_mnesia.erl b/src/mod_push_mnesia.erl
index b00f93c1fdfd593f7f4858ace31e4660ed7f0e5f..355c8ef6d909e388c549808249b9e6f5e955ccc3 100644 (file)
--- a/src/mod_push_mnesia.erl
+++ b/src/mod_push_mnesia.erl
@@ -52,11 +52,7 @@ store_session(LUser, LServer, TS, PushJID, Node, XData) ->
     PushLJID = jid:tolower(PushJID),
     MaxSessions = ejabberd_sm:get_max_user_sessions(LUser, LServer),
     F = fun() ->
-               if is_integer(MaxSessions) ->
-                       enforce_max_sessions(US, MaxSessions - 1);
-                  MaxSessions == infinity ->
-                       ok
-               end,
+               enforce_max_sessions(US, MaxSessions),
                mnesia:write(#push_session{us = US,
                                           timestamp = TS,
                                           service = PushLJID,
@@ -185,19 +181,21 @@ transform({push_session, US, TS, Service, Node, XData}) ->
 %%--------------------------------------------------------------------
 %% Internal functions.
 %%--------------------------------------------------------------------
--spec enforce_max_sessions({binary(), binary()}, non_neg_integer()) -> ok.
-enforce_max_sessions({U, S} = US, Max) ->
-    Recs = mnesia:wread({push_session, US}),
-    NumRecs = length(Recs),
-    if NumRecs > Max ->
-           NumOldRecs = NumRecs - Max,
-           Recs1 = lists:keysort(#push_session.timestamp, Recs),
-           Recs2 = lists:reverse(Recs1),
-           OldRecs = lists:sublist(Recs2, Max + 1, NumOldRecs),
-           ?INFO_MSG("Disabling ~B old push session(s) of ~s@~s",
-                     [NumOldRecs, U, S]),
+-spec enforce_max_sessions({binary(), binary()}, non_neg_integer() | infinity)
+      -> ok.
+enforce_max_sessions(_US, infinity) ->
+    ok;
+enforce_max_sessions({U, S} = US, MaxSessions) ->
+    case mnesia:wread({push_session, US}) of
+       Recs when length(Recs) >= MaxSessions ->
+           Recs1 = lists:sort(fun(#push_session{timestamp = TS1},
+                                  #push_session{timestamp = TS2}) ->
+                                      TS1 >= TS2
+                              end, Recs),
+           OldRecs = lists:nthtail(MaxSessions - 1, Recs1),
+           ?INFO_MSG("Disabling old push session(s) of ~s@~s", [U, S]),
            lists:foreach(fun(Rec) -> mnesia:delete_object(Rec) end, OldRecs);
-       true ->
+       _ ->
            ok
     end.