Setup common configuration support

Author: Prashanth Menon

conf/storage.properties

@@ -0,0 +1 @@
+{port, 8080}.

conf/thor.conf

@@ -7,6 +7,6 @@
                 thor_socket ]},
     {registered, [ thor_sup ]},
 	{applications, [kernel, stdlib]},
-	{mod, {thor, []}},
-	{env, [{conf, "/conf/storage.properties"}]}
+	{mod, {thor, [ "/Users/menonp/development/thor/conf/thor.conf" ]}},
+	{env, [{conf, "/conf/thor.conf"}]}
  ]}.

ebin/thor.app

@@ -11,10 +11,10 @@ start() ->
     io:format("in thor:start/0~n", []),
     application:start(thor).
 
-start(_Type, _StartArgs) ->
+start(_Type, DefaultConfigFile) ->
     print_banner(),
     io:format("Starting Thor ...~n"),
-    case thor_sup:start_link() of 
+    case thor_sup:start_link(DefaultConfigFile) of 
         {ok, Pid} ->
             %%alarm_handler:clear_alarm({application_stopped, thor}),
             {ok, Pid};

src/thor.erl

@@ -0,0 +1,64 @@
+-module(thor_config).
+-behaviour(gen_server).
+
+-include("thor.hrl").
+
+%%API
+-export([start_link/1, get/1, set/2]).
+
+%% gen_server callbacks
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
+
+-define(SERVER, ?MODULE).
+
+-record(conf, {conf}).
+
+start_link(ConfFiles) ->
+    gen_server:start_link({local, ?SERVER}, ?MODULE, [ConfFiles], []).
+
+get(Key) ->
+    gen_server:call(?SERVER, {get, Key}).
+
+set(Key, Value) ->
+    gen_server:cast(?SERVER, {set, Key, Value}).
+
+init(ConfFiles) ->
+    io:format("Reading configuration file: ~p~n", [ConfFiles]),
+    Terms = lists:foldl(fun(ConfFile, Acc) ->
+                            Terms = case file:consult(ConfFile) of
+                                        {ok, T} -> T;
+                                        _ -> []
+                                    end,
+                            lists:append(Acc, Terms)
+                        end, [], ConfFiles),
+    {ok, #conf{conf = Terms}}.
+
+get_key(Key, []) ->
+    {error, not_found};
+get_key(Key, [{Key, Value} | Rest]) ->
+    {ok, Value};
+get_key(Key, [{_Key, _Value} | Rest]) ->
+    get_key(Key, Rest).
+
+handle_call({get, Key}, From, State) ->
+    Reply = get_key(Key, State#conf.conf),
+    {reply, Reply, State};
+
+handle_call(_Request, _From, State) ->
+    {reply, ok, State}.
+
+handle_cast({set, Key, Value}, State) ->
+    {noreply, State};
+
+handle_cast(_Request, State) ->
+    {noreply, State}.
+
+handle_info(_Info, State) ->
+    {noreply, State}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+

src/thor_config.erl

@@ -4,21 +4,39 @@
 -include("thor.hrl").
 
 %% supervisor behaviour callbacks
--export([start_link/0, init/1]).
+-export([start_link/1, init/1]).
 
 -define(SERVER, ?MODULE).
 
-start_link() ->
-    supervisor:start_link({local, ?SERVER}, ?MODULE, []).
+start_link(DefaultConfigFile) ->
+    supervisor:start_link({local, ?SERVER}, ?MODULE, [DefaultConfigFile]).
 
-init([]) ->
-    Port = 8080,
+init(DefaultConfigFiles) ->
+    ConfigFile = get_config_file(DefaultConfigFiles),
+    thor_config:start_link(ConfigFile),
+
+    %%Config = {thor_config, {thor_config, start_link, [ConfigFile]},
+    %%          permanent, 2000, worker, [thor_config]},
+    Log = {thor_log, {thor_log, start_link, [?DEFAULT_LOGGER]},
+            permanent, 2000, worker, [thor_log]},
+
+    {ok, Port} = thor_config:get(port),
+    io:format("port = ~p~n", [Port]),
     HttpServer = {thor_server, {thor_server, start_link, [Port]},
               permanent, 2000, worker, [thor_server]},
+
     ChannelServer = {thor_channel_server, {thor_channel_server, start_link, []},
                      permanent, 2000, worker, [thor_channel_server]},
-    Log = {thor_log, {thor_log, start_link, [?DEFAULT_LOGGER]},
-            permanent, 2000, worker, [thor_log]},
 
     {ok, {{one_for_one, 10, 1}, [Log, HttpServer, ChannelServer]}}.
 
+get_config_file(Default) ->
+    case init:get_argument(conf) of
+    error ->
+        Default;
+    {ok, [[]]} ->
+        Default;
+    {ok, [Values]} ->
+        Values
+    end.
+