mod_register: Migrate from one treap in ets to all in ets

The old logic stores a single data structure in the ets table, a "treap", which
is then cleaned and scan, but we can do the same using a table of type
'ordered_set' and cleaning records in a similar fashion. Same logic, simpler
code, and potentially even more performant.

src/mod_register.erl

@@ -52,7 +52,11 @@
 start(HostType, #{iqdisc := IQDisc}) ->
     [gen_iq_handler:add_iq_handler_for_domain(HostType, ?NS_REGISTER, Component, Fn, #{}, IQDisc) ||
         {Component, Fn} <- iq_handlers()],
-    ejabberd_sup:create_ets_table(?TABLE, [named_table, public, {read_concurrency, true}]).
+    Concurrency = case IQDisc of
+                      one_queue -> [];
+                      _ -> [{read_concurrency, true}]
+                  end,
+    ejabberd_sup:create_ets_table(?TABLE, [named_table, public | Concurrency]).
 
 -spec stop(mongooseim:host_type()) -> ok.
 stop(HostType) ->
@@ -61,7 +65,8 @@ stop(HostType) ->
     ok.
 
 iq_handlers() ->
-    [{ejabberd_local, fun ?MODULE:process_iq/5}, {ejabberd_sm, fun ?MODULE:process_iq/5}].
+    [{ejabberd_local, fun ?MODULE:process_iq/5},
+     {ejabberd_sm, fun ?MODULE:process_iq/5}].
 
 -spec hooks(mongooseim:host_type()) -> gen_hook:hook_list().
 hooks(HostType) ->
@@ -433,40 +438,24 @@ check_timeout(Source) ->
     Timeout = mongoose_config:get_opt(registration_timeout),
     case is_integer(Timeout) of
         true ->
-            Priority = -(erlang:system_time(second)),
-            CleanPriority = Priority + Timeout,
-            check_and_store_ip_entry(Source, Priority, CleanPriority);
+            TS = erlang:system_time(second),
+            clean_ets(TS - Timeout),
+            check_and_store_ip_entry(Source, TS);
         false ->
             true
     end.
 
-check_and_store_ip_entry(Source, Priority, CleanPriority) ->
-    Treap = case ets:lookup(?TABLE, treap) of
-                [] -> treap:empty();
-                [{treap, T}] -> T
-            end,
-    Treap1 = clean_treap(Treap, CleanPriority),
-    case treap:lookup(Source, Treap1) of
-        error ->
-            Treap2 = treap:insert(Source, Priority, [], Treap1),
-            ets:insert(?TABLE, {treap, Treap2}),
+check_and_store_ip_entry(Source, Timestamp) ->
+    case ets:member(?TABLE, Source) of
+        false ->
+            ets:insert(?TABLE, {Source, Timestamp}),
             true;
-        {ok, _, _} ->
-            ets:insert(?TABLE, {treap, Treap1}),
+        true ->
             false
     end.
 
-clean_treap(Treap, CleanPriority) ->
-    case treap:is_empty(Treap) of
-        true ->
-            Treap;
-        false ->
-            {_Key, Priority, _Value} = treap:get_root(Treap),
-            case Priority > CleanPriority of
-                true -> clean_treap(treap:delete_root(Treap), CleanPriority);
-                false -> Treap
-            end
-    end.
+clean_ets(CleanPriority) ->
+    ets:select_delete(?TABLE, [{ {'_', '$1'}, [{'<', '$1', CleanPriority}], [true]}]).
 
 ip_to_string(Source) when is_tuple(Source) -> inet_parse:ntoa(Source);
 ip_to_string(undefined) -> "undefined";