New API to update host config on the fly (thanks to Juan Pablo Carlino)

Adds ejabberd_hosts:update_host_conf/2 to update a host with a new
configuration on the fly. Typically this is useful to enable / disable
specific modules for a given host without restarting the whole app.
Also fixes a problem with mod_disco, after config refreshing to include
global services if there are not locally available.

src/ejabberd_hosts.erl

@@ -33,6 +33,7 @@
          ,running/1
          ,registered/0
          ,remove/1
+         ,update_host_conf/2
         ]).
 
 %% Host control API
@@ -87,6 +88,16 @@ register(Host, Config) when is_list(Host), is_list(Config) ->
     reload(),
     ok.
 
+%% Updates host configuration
+update_host_conf(Host, Config) when is_list(Host), is_list(Config) ->
+    true = jlib:is_nodename(Host),
+    case registered(Host) of
+	false -> {error, host_process_not_registered};
+	true ->
+	    remove(Host),
+	    ?MODULE:register(Host, Config)
+    end.
+   
 %% Removes a vhost from the system,
 %% XXX deleting all ODBC data.
 remove(Host) when is_list(Host) ->
@@ -222,6 +233,18 @@ handle_info(reload, State = #state{state=wait_odbc}) ->
     ?ERROR_MSG("Tried to reload vhosts while waiting for odbc startup.", []),
     handle_info(timeout, State);
 
+handle_info({reload, Host}, State = #state{state=running}) ->
+    try reload_host(Host)
+    catch
+        Class:Error ->
+            StackTrace = erlang:get_stacktrace(),
+            ?ERROR_MSG("~p while synchonising running ~p with database: ~p~n~p", [Host, Class, Error, StackTrace])
+    end,
+    {noreply, State};
+handle_info({reload, Host}, State = #state{state=wait_odbc}) ->
+    ?ERROR_MSG("Tried to reload ~p while waiting for odbc startup.", [Host]),
+    handle_info(timeout, State);
+
 handle_info(_Info, State) ->
     {noreply, State}.
 
@@ -264,6 +287,21 @@ reload_hosts(NewHosts) ->
     ejabberd_local:refresh_iq_handlers(),
     {DeletedHosts, AddedHosts}.
 
+%% updates the configuration of an existing virtual host
+reload_host(Host) ->
+    Config = get_host_config(odbc,Host),
+    F = fun() ->
+		mnesia:write_lock_table(local_config),
+		ejabberd_config:configure_host(Host, Config),
+		ok
+        end,
+    {atomic, ok} = mnesia:transaction(F),
+    % restart host
+    stop_host(Host),
+    start_host(Host),
+    ejabberd_local:refresh_iq_handlers(),
+    ok.
+
 %% Apply the vhost changes (new, removed vhosts, configuration) to mnesia
 update_config(AddHostConfig, RemoveHosts) ->
     F = fun() ->
@@ -321,7 +359,7 @@ stop_host(Host) ->
     ?DEBUG("Stopping host ~p", [Host]),
     ejabberd_router:force_unregister_route(Host),
     lists:foreach(fun(Module) ->
-                          gen_mod:stop_module(Host, Module)
+                          gen_mod:stop_module_keep_config(Host, Module)
                   end, gen_mod:loaded_modules(Host)),
     case auth_method(Host) of
         use_global_auth_method -> ok;

src/mod_disco.erl

@@ -126,10 +126,8 @@ process_local_iq_items(From, To, #iq{type = get, payload = SubEl,
   lang = Lang} = IQ_Rec) ->
     Node = exmpp_xml:get_attribute_as_binary(SubEl, 'node', <<>>),
 
-    case ejabberd_hooks:run_fold(disco_local_items,
-				 exmpp_jid:prep_domain(To),
-				 empty,
-				 [From, To, Node, Lang]) of
+    Host = exmpp_jid:prep_domain(To),
+    case find_items(disco_local_items, Host, From, To, Node, Lang) of
 	{result, Items} ->
 	    ANode = case Node of
 			<<>> -> [];
@@ -156,10 +154,7 @@ process_local_iq_info(From, To, #iq{type = get, payload = SubEl,
     Host = exmpp_jid:prep_domain_as_list(To),
     Info = ejabberd_hooks:run_fold(disco_info, HostB, [],
 				   [Host, ?MODULE, Node, Lang]),
-    case ejabberd_hooks:run_fold(disco_local_features,
-				 exmpp_jid:prep_domain(To),
-				 empty,
-				 [From, To, Node, Lang]) of
+    case find_items(disco_local_features, HostB, From, To, Node, Lang) of
 	{result, Features} ->
 	    ANode = case Node of
 			<<>> -> [];
@@ -290,10 +285,8 @@ get_vh_services(Host) ->
 process_sm_iq_items(From, To, #iq{type = get, payload = SubEl,
   lang = Lang} = IQ_Rec) ->
     Node = exmpp_xml:get_attribute_as_binary(SubEl, 'node', <<>>),
-    case ejabberd_hooks:run_fold(disco_sm_items,
-				 exmpp_jid:prep_domain(To),
-				 empty,
-				 [From, To, Node, Lang]) of
+    Host = exmpp_jid:prep_domain(To),
+    case find_items(disco_sm_items, Host, From, To, Node, Lang) of
 	{result, Items} ->
 	    ANode = case Node of
 			<<>> -> [];
@@ -374,10 +367,8 @@ process_sm_iq_info(From, To, #iq{type = get, payload = SubEl,
                                                exmpp_jid:prep_domain(To),
                                                [],
                                                [From, To, Node, Lang]),
-            case ejabberd_hooks:run_fold(disco_sm_features,
-                                         exmpp_jid:prep_domain(To),
-                                         empty,
-                                         [From, To, Node, Lang]) of
+            Host = exmpp_jid:prep_domain(To),
+            case find_items(disco_sm_features, Host, From, To, Node, Lang) of
                 {result, Features} ->
                     ANode = case Node of
                                 <<>> -> [];
@@ -496,3 +487,13 @@ values_to_xml(Values) ->
       end,
       Values
      ).
+
+%%%%%% private functions 
+find_items(Hook, global, From, To, Node, Lang) ->
+    ejabberd_hooks:run_fold(Hook, global, empty, [From, To, Node, Lang]);
+find_items(Hook, Host, From, To, Node, Lang) ->
+    case ejabberd_hooks:run_fold(Hook, Host, empty, [From, To, Node, Lang]) of
+	empty ->
+	    find_items(Hook, global, From, To, Node, Lang);
+	Items -> Items
+    end.