mod_message_log: Run as a supervised gen_server

mod_message_log/src/mod_message_log.erl

@@ -9,12 +9,22 @@
 -author('holger@zedat.fu-berlin.de').
 
 -behaviour(gen_mod).
+-behaviour(gen_server).
 
--export([start/2,
-	 stop/1,
-	 init/1,
-	 perform_upgrade/1]).
+%% gen_mod/supervisor callbacks.
+-export([start_link/1,
+	 start/2,
+	 stop/1]).
 
+%% gen_server callbacks.
+-export([init/1,
+	 handle_call/3,
+	 handle_cast/2,
+	 handle_info/2,
+	 terminate/2,
+	 code_change/3]).
+
+%% ejabberd_hooks callbacks.
 -export([log_packet_send/3,
 	 log_packet_receive/4,
 	 log_packet_offline/3,
@@ -27,7 +37,15 @@
 -define(DEFAULT_FILENAME, <<"message.log">>).
 -define(FILE_MODES, [append, raw]).
 
--record(config, {filename = ?DEFAULT_FILENAME, iodevice}).
+-record(state, {filename = ?DEFAULT_FILENAME :: binary(),
+		iodevice                     :: io:device()}).
+
+%% -------------------------------------------------------------------
+%% gen_mod/supervisor callbacks.
+%% -------------------------------------------------------------------
+
+start_link(Opts) ->
+    gen_server:start_link({local, ?PROCNAME}, ?MODULE, Opts, []).
 
 start(Host, Opts) ->
     ejabberd_hooks:add(user_send_packet, Host, ?MODULE,
@@ -36,17 +54,15 @@ start(Host, Opts) ->
 		       log_packet_receive, 42),
     ejabberd_hooks:add(offline_message_hook, Host, ?MODULE,
 		       log_packet_offline, 42),
-    case whereis(?PROCNAME) of
-      undefined ->
-	  ejabberd_hooks:add(reopen_log_hook, ?MODULE, reopen_log, 42),
-	  Filename = gen_mod:get_opt(filename, Opts, fun(V) -> V end,
-				     ?DEFAULT_FILENAME),
-	  register(?PROCNAME, spawn(?MODULE, init,
-				    [#config{filename = Filename}])),
-	  ok;
-      _ ->
-	  ok
-    end.
+    Spec = {
+	?PROCNAME,
+	{?MODULE, start_link, [Opts]},
+	permanent,
+	3000,
+	worker,
+	[?MODULE]
+    },
+    supervisor:start_child(ejabberd_sup, Spec).
 
 stop(Host) ->
     ejabberd_hooks:delete(user_send_packet, Host, ?MODULE,
@@ -55,18 +71,53 @@ stop(Host) ->
 			  log_packet_receive, 42),
     ejabberd_hooks:delete(offline_message_hook, Host, ?MODULE,
 			  log_packet_offline, 42),
-    case whereis(?PROCNAME) of
-      undefined ->
-	  ok;
-      _ ->
-	  ejabberd_hooks:delete(reopen_log_hook, ?MODULE, reopen_log, 42),
-	  gen_mod:get_module_proc(Host, ?PROCNAME) ! stop,
-	  ok
+    case supervisor:terminate_child(ejabberd_sup, ?PROCNAME) of
+      ok ->
+	  ok = supervisor:delete_child(ejabberd_sup, ?PROCNAME);
+      {error, not_found} ->
+	  ok % We just run one process per node.
     end.
 
-init(Config) ->
-    {ok, IoDevice} = file:open(Config#config.filename, ?FILE_MODES),
-    loop(Config#config{iodevice = IoDevice}).
+%% -------------------------------------------------------------------
+%% gen_server callbacks.
+%% -------------------------------------------------------------------
+
+init(Opts) ->
+    process_flag(trap_exit, true),
+    ejabberd_hooks:add(reopen_log_hook, ?MODULE, reopen_log, 42),
+    Filename = gen_mod:get_opt(filename, Opts, fun(V) -> V end,
+			       ?DEFAULT_FILENAME),
+    {ok, IoDevice} = file:open(Filename, ?FILE_MODES),
+    {ok, #state{filename = Filename, iodevice = IoDevice}}.
+
+handle_call(_Request, _From, State) ->
+    {noreply, State}.
+
+handle_cast({message, Direction, From, To, Type}, #state{iodevice = IoDevice} =
+	    State) ->
+    write_log(IoDevice, Direction, From, To, Type),
+    {noreply, State};
+handle_cast(reopen_log, #state{filename = Filename, iodevice = IoDevice} =
+	    State) ->
+    ok = file:close(IoDevice),
+    {ok, NewIoDevice} = file:open(Filename, ?FILE_MODES),
+    {noreply, State#state{iodevice = NewIoDevice}};
+handle_cast(_Request, State) ->
+    {noreply, State}.
+
+handle_info(_Info, State) ->
+    {noreply, State}.
+
+terminate(_Reason, State) ->
+    ejabberd_hooks:delete(reopen_log_hook, ?MODULE, reopen_log, 42),
+    ok = file:close(State#state.iodevice).
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+%% -------------------------------------------------------------------
+%% ejabberd_hooks callbacks.
+%% -------------------------------------------------------------------
 
 log_packet_send(From, To, Packet) ->
     log_packet(outgoing, From, To, Packet).
@@ -78,19 +129,22 @@ log_packet_offline(From, To, Packet) ->
     log_packet(offline, From, To, Packet).
 
 reopen_log() ->
-    ?PROCNAME ! reopen.
+    gen_server:cast(?PROCNAME, reopen_log).
 
+%% -------------------------------------------------------------------
 %% Internal functions.
+%% -------------------------------------------------------------------
 
 log_packet(Direction, From, To, #xmlel{name = <<"message">>} = Packet) ->
     case xml:get_subtag(Packet, <<"body">>) of
       #xmlel{children = Body} when length(Body) > 0 ->
 	  Type = get_message_type(Packet),
-	  ?PROCNAME ! {message, Direction, From, To, Type};
+	  gen_server:cast(?PROCNAME, {message, Direction, From, To, Type});
       _ ->
 	  case is_carbon(Packet) of
 	    {true, OrigDirection} ->
-		?PROCNAME ! {message, OrigDirection, From, To, carbon};
+		gen_server:cast(?PROCNAME, {message, OrigDirection, From, To,
+					    carbon});
 	    false ->
 		ok
 	  end
@@ -128,21 +182,6 @@ is_carbon(Packet) ->
 	  false
     end.
 
-loop(Config) ->
-    receive
-      {message, Direction, From, To, Type} ->
-	  write_log(Config#config.iodevice, Direction, From, To, Type),
-	  loop(Config);
-      reopen ->
-	  file:close(Config#config.iodevice),
-	  {ok, IoDevice} = file:open(Config#config.filename, ?FILE_MODES),
-	  loop(Config#config{iodevice = IoDevice});
-      upgrade ->
-	  mod_message_log:perform_upgrade(Config);
-      stop ->
-	  exit(normal)
-    end.
-
 write_log(IoDevice, Direction, From, To, Type) ->
     Date = format_date(calendar:local_time()),
     Record = io_lib:format("~s [~s, ~s] ~s -> ~s~n",
@@ -154,6 +193,3 @@ write_log(IoDevice, Direction, From, To, Type) ->
 format_date({{Year, Month, Day}, {Hour, Minute, Second}}) ->
     Format = "~B-~2..0B-~2..0B ~2..0B:~2..0B:~2..0B",
     io_lib:format(Format, [Year, Month, Day, Hour, Minute, Second]).
-
-perform_upgrade(Config) ->
-    loop(Config).