Monitor routes

Clean route table from the process that died unexpectedly.
This usually may happen when the corresponding process
gets killed by OOM killer during overload.

diff --git a/src/ejabberd_router.erl b/src/ejabberd_router.erl
index eeacbd930a63ce1366852d534fcb89863a5fda01..9c5c4e5057fb8df69bc0e750e54815f388ab5976 100644 (file)
--- a/src/ejabberd_router.erl
+++ b/src/ejabberd_router.erl
@@ -65,6 +65,7 @@
 
 %% This value is used in SIP and Megaco for a transaction lifetime.
 -define(IQ_TIMEOUT, 32000).
+-define(CALL_TIMEOUT, timer:minutes(10)).
 
 -include("logger.hrl").
 -include("ejabberd_router.hrl").
@@ -78,7 +79,7 @@
 -callback find_routes(binary()) -> {ok, [#route{}]} | {error, any()}.
 -callback get_all_routes() -> {ok, [binary()]} | {error, any()}.
 
--record(state, {}).
+-record(state, {route_monitors = #{} :: #{{binary(), pid()} => reference()}}).
 
 %%====================================================================
 %% API
@@ -176,6 +177,7 @@ register_route(Domain, ServerHost, LocalHint, Pid) ->
                                    get_component_number(LDomain), Pid) of
                ok ->
                    ?DEBUG("Route registered: ~s", [LDomain]),
+                   monitor_route(LDomain, Pid),
                    ejabberd_hooks:run(route_registered, [LDomain]),
                    delete_cache(Mod, LDomain);
                {error, Err} ->
@@ -205,6 +207,7 @@ unregister_route(Domain, Pid) ->
                   LDomain, get_component_number(LDomain), Pid) of
                ok ->
                    ?DEBUG("Route unregistered: ~s", [LDomain]),
+                   demonitor_route(LDomain, Pid),
                    ejabberd_hooks:run(route_unregistered, [LDomain]),
                    delete_cache(Mod, LDomain);
                {error, Err} ->
@@ -324,16 +327,47 @@ init([]) ->
     clean_cache(),
     {ok, #state{}}.
 
-handle_call(_Request, _From, State) ->
-    Reply = ok,
-    {reply, Reply, State}.
+handle_call({monitor, Domain, Pid}, _From, State) ->
+    MRefs = State#state.route_monitors,
+    MRefs1 = case maps:is_key({Domain, Pid}, MRefs) of
+                true -> MRefs;
+                false ->
+                    MRef = erlang:monitor(process, Pid),
+                    MRefs#{{Domain, Pid} => MRef}
+            end,
+    {reply, ok, State#state{route_monitors = MRefs1}};
+handle_call({demonitor, Domain, Pid}, _From, State) ->
+    MRefs = State#state.route_monitors,
+    MRefs1 = case maps:find({Domain, Pid}, MRefs) of
+                {ok, MRef} ->
+                    erlang:demonitor(MRef, [flush]),
+                    maps:remove({Domain, Pid}, MRefs);
+                error ->
+                    MRefs
+            end,
+    {reply, ok, State#state{route_monitors = MRefs1}};
+handle_call(Request, From, State) ->
+    ?WARNING_MSG("Unexpected call from ~p: ~p", [From, Request]),
+    {noreply, State}.
 
-handle_cast(_Msg, State) ->
+handle_cast(Msg, State) ->
+    ?WARNING_MSG("Unexpected cast: ~p", [Msg]),
     {noreply, State}.
 
 handle_info({route, Packet}, State) ->
     route(Packet),
     {noreply, State};
+handle_info({'DOWN', MRef, _, Pid, Info}, State) ->
+    MRefs = maps:filter(
+             fun({Domain, P}, M) when P == Pid, M == MRef ->
+                     ?DEBUG("Process ~p with route registered to ~s "
+                            "has terminated unexpectedly with reason: ~p",
+                            [P, Domain, Info]),
+                     false;
+                (_, _) ->
+                     true
+             end, State#state.route_monitors),
+    {noreply, State#state{route_monitors = MRefs}};
 handle_info(Info, State) ->
     ?ERROR_MSG("Unexpected info: ~p", [Info]),
     {noreply, State}.
@@ -427,6 +461,14 @@ get_domain_balancing(From, To, LDomain) ->
            end
     end.
 
+-spec monitor_route(binary(), pid()) -> ok.
+monitor_route(Domain, Pid) ->
+    ?GEN_SERVER:call(?MODULE, {monitor, Domain, Pid}, ?CALL_TIMEOUT).
+
+-spec demonitor_route(binary(), pid()) -> ok.
+demonitor_route(Domain, Pid) ->
+    ?GEN_SERVER:call(?MODULE, {demonitor, Domain, Pid}, ?CALL_TIMEOUT).
+
 -spec get_backend() -> module().
 get_backend() ->
     DBType = ejabberd_option:router_db_type(),