Watcher state and constant

apps/log_monitor/src/watcher.erl

@@ -18,8 +18,9 @@
          terminate/2, code_change/3]).
 
 -define(SERVER, ?MODULE).
+-define(TAIL_CMD, "/usr/bin/tail -n0 --follow=name ").
 
--record(state, {}).
+-record(state, {file, supervisor, port}).
 
 %%%===================================================================
 %%% API
@@ -53,9 +54,9 @@ start_link(SupPid, File) ->
 init([SupPid, File]) ->
     timer:sleep(1000),
     config ! {watcher_init, File},
-    Cmd = "/usr/bin/tail -n0 --follow=name " ++ File,
+    Cmd = ?TAIL_CMD ++ File,
     Port = open_port({spawn, Cmd}, [stderr_to_stdout, exit_status, binary]),
-    {ok, [File, SupPid, Port]}.
+    {ok, #state{file = File, supervisor = SupPid, port = Port}}.
 
 %%--------------------------------------------------------------------
 %% @private
@@ -98,14 +99,14 @@ handle_cast(_Msg, State) ->
 %%                                   {stop, Reason, State}
 %% @end
 %%--------------------------------------------------------------------
-handle_info(Msg, [File, SupPid, Port]) ->
+handle_info(Msg, State = #state{file = _, supervisor = SupPid, port = Port}) ->
     case Msg of
         {Port, {data, Text}} ->
             GathererPid = gatherer_pid(SupPid),
             GathererPid ! {log_line, binary_to_list(Text)},
-            {noreply, [File, SupPid, Port]};
+            {noreply, State};
         {Port, {exit_status, _Status}} ->
-            {stop, tail_exit, [File]}
+            {stop, tail_exit, State}
     end.
 
 %%--------------------------------------------------------------------
@@ -119,8 +120,8 @@ handle_info(Msg, [File, SupPid, Port]) ->
 %% @spec terminate(Reason, State) -> void()
 %% @end
 %%--------------------------------------------------------------------
-terminate(_Reason, [File]) ->
-    config ! {watcher_terminate, File},
+terminate(_Reason, State) ->
+    config ! {watcher_terminate, State#state.file},
     shutdown.
 
 %%--------------------------------------------------------------------