lecture 07

lectures/07/counter_worker.erl

@@ -0,0 +1,30 @@
+-module(counter_worker).
+-behaviour(gen_server).
+-export([init/1, handle_call/3, handle_cast/2]).
+-export([start_link/1, inc/1, value/0]).
+-define(SERVER, ?MODULE).
+-define(TABLE, counter_table).
+
+start_link(N) ->
+	gen_server:start_link({local, ?SERVER}, ?MODULE, N, []).
+
+inc(Amt) ->
+	gen_server:cast(?SERVER, {inc, Amt}).
+
+value() ->
+	gen_server:call(?SERVER, value).
+
+init(N) ->
+	case ets:lookup(?TABLE, value) of
+		[] -> {ok, N};
+		[{_, M} | _] -> {ok, M}
+	end.
+
+handle_call(value, _From, N) ->
+	{reply, N, N}. % {reply, actual_reply, state}
+
+handle_cast({inc, Amt}, N) ->
+	{noreply, N + Amt}.
+
+termintate(_Reason, N) ->
+	ets:insert(?TABLE, {value, N}).