moved server to common (used from server and client)

1 files changed, 49 insertions, 0 deletions

diff --git a/common/server.erl b/common/server.erl
new file mode 100644
index 0000000..06922cc
--- /dev/null
+++ b/common/server.erl
@@ -0,0 +1,49 @@
+%%  Inspired by  "Programming Erlang",
+%%  published by The Pragmatic Bookshelf.
+%%  Copyrights apply to this code.
+%%  We make no guarantees that this code is fit for any purpose.
+%%  Visit http://www.pragmaticprogrammer.com/titles/jaerlang for more book information.
+
+-module(server).
+-export([start/2, start/3, rpc/2, swap_code/2]).
+
+start(Name, Mod) ->
+    register(Name, spawn(fun() -> loop(Name, Mod, Mod:init()) end)).
+
+start(Name, Mod, State) ->
+    register(Name, spawn(fun() -> loop(Name, Mod, State) end)).
+
+swap_code(Name, Mod) -> rpc(Name, {swap_code, Mod}).
+
+rpc(Name, Request) ->
+    Name ! {self(), Request},
+    receive
+        {Name, crash} -> exit(rpc);
+        {Name, ok, Response} -> Response
+    end.
+
+loop(Name, Mod, OldState) ->
+    receive
+        {From, {swap_code, NewCallbackMod}} ->
+            From ! {Name, ok, ack},
+            loop(Name, NewCallbackMod, OldState);
+        {From, Request} ->
+	    {Response, NewState} = Mod:handle(From, Request, OldState),
+	    From ! {Name, ok, Response},
+	    loop(Name, Mod, NewState)
+            %% try Mod:handle(From, Request, OldState) of
+            %%     {Response, NewState} ->
+            %%         From ! {Name, ok, Response},
+            %%         loop(Name, Mod, NewState)
+            %% catch
+            %%     _: Why ->
+            %%         log_the_error(Name, Request, Why),
+            %%         From ! {Name, crash},
+            %%         loop(Name, Mod, OldState)
+            %% end
+    end.
+
+log_the_error(Name, Request, Why) ->
+    io:format("Server ~p request ~p ~n"
+              "caused exception ~p~n",
+              [Name, Request, Why]).