From 613e8778e9f6a1107d7563a60574f557a71c6e4c Mon Sep 17 00:00:00 2001
From: Nathan Lasseter <nathan.je.lasseter@googlemail.com>
Date: Fri, 28 Jan 2011 22:32:34 +0000
Subject: Added tests, fixed state

---
 README.textile   |  5 +++++
 erlbal.erl       | 12 ++++++------
 erlbal_tests.erl | 36 +++++++++++++++++++++++++++++++++---
 3 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/README.textile b/README.textile
index 42f05f3..8af6e41 100644
--- a/README.textile
+++ b/README.textile
@@ -18,6 +18,11 @@ h2. Request calls:
 * make_request/1 takes a balancer and returns the response from the server.
 * make_request/2 takes a balancer and an argument and returns the response from the server.
 
+h2. The function:
+
+p. The function must take two lists, some arguments and some state.
+p. It must return a tuple of {Return value, new state}.
+
 h2. Info
 
 p. The balancer round robins requests between erlang processes.
diff --git a/erlbal.erl b/erlbal.erl
index 84830a7..e03d5e1 100644
--- a/erlbal.erl
+++ b/erlbal.erl
@@ -1,8 +1,8 @@
 -module(erlbal).
--export([make_request/2, start_bal/0, stop_bal/1, start_server/3, stop_server/2, list_servers/1]).
+-export([make_request/2, start_bal/0, stop_bal/1, start_server/4, stop_server/2, list_servers/1]).
 
-start_server(Balancer, Node, Fun) when is_function(Fun, 1) ->
-	PID = spawn(Node, fun() -> server_loop(Fun) end),
+start_server(Balancer, Node, Fun, INITSTATE) when is_function(Fun, 2) andalso is_list(INITSTATE) ->
+	PID = spawn(Node, fun() -> server_loop(Fun, INITSTATE) end),
 	Balancer ! {add_node, PID}.
 
 stop_server(Balancer, PID) ->
@@ -13,12 +13,12 @@ list_servers(Balancer) ->
 	Balancer ! {list_nodes, self()},
 	receive Nodes -> Nodes end.
 
-server_loop(Fun) ->
+server_loop(Fun, STATE) ->
 	receive
 		{request, From, ARGS} ->
-			Ret = Fun(ARGS),
+			{Ret, NEWSTATE} = Fun(ARGS, STATE),
 			From ! Ret,
-			server_loop(Fun);
+			server_loop(Fun, NEWSTATE);
 		die ->
 			ok
 	end.
diff --git a/erlbal_tests.erl b/erlbal_tests.erl
index df68706..cee35fc 100644
--- a/erlbal_tests.erl
+++ b/erlbal_tests.erl
@@ -3,8 +3,38 @@
 
 start(simple) ->
 	Bal = erlbal:start_bal(),
-	erlbal:start_server(Bal, node(), fun(_) -> 7 end),
-	erlbal:start_server(Bal, node(), fun(_) -> 8 end),
+	erlbal:start_server(Bal, node(), fun(_, _) -> {7, []} end, []),
+	erlbal:start_server(Bal, node(), fun(_, _) -> {8, []} end, []),
 	7 = erlbal:make_request(Bal, []),
 	8 = erlbal:make_request(Bal, []),
-	erlbal:stop_bal(Bal).
+	erlbal:stop_bal(Bal),
+	ok;
+
+start(args) ->
+	Bal = erlbal:start_bal(),
+	erlbal:start_server(Bal, node(), fun([X], _) -> {X+1, []} end, []),
+	erlbal:start_server(Bal, node(), fun([X], _) -> {X+2, []} end, []),
+	7 = erlbal:make_request(Bal, [6]),
+	8 = erlbal:make_request(Bal, [6]),
+	erlbal:stop_bal(Bal),
+	ok;
+
+start(state) ->
+	Bal = erlbal:start_bal(),
+	erlbal:start_server(Bal, node(), fun([X], [S]) -> Y = X + S, {Y, [S]} end, [1]),
+	erlbal:start_server(Bal, node(), fun([X], [S]) -> Y = X + S, {Y, [S]} end, [10]),
+	7 = erlbal:make_request(Bal, [6]),
+	16 = erlbal:make_request(Bal, [6]),
+	erlbal:stop_bal(Bal),
+	ok;
+
+start(complex_state) ->
+	Bal = erlbal:start_bal(),
+	erlbal:start_server(Bal, node(), fun([X], [S]) -> Y = X + S, {Y, [S+1]} end, [1]),
+	erlbal:start_server(Bal, node(), fun([X], [S]) -> Y = X + S, {Y, [S+1]} end, [10]),
+	7 = erlbal:make_request(Bal, [6]),
+	16 = erlbal:make_request(Bal, [6]),
+	8 = erlbal:make_request(Bal, [6]),
+	17 = erlbal:make_request(Bal, [6]),
+	erlbal:stop_bal(Bal),
+	ok.
-- 
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