From e48a96aa0225e720e685437e48b81394d3112d7f Mon Sep 17 00:00:00 2001
From: Richard Jones <rj@metabrew.com>
Date: Wed, 16 Mar 2011 17:45:27 +0000
Subject: [PATCH] implement prod and num_prods, add num_prods to gen_server
 state, bump to ver 3

---
 apps/dummy_app/ebin/dummy_app.appup     | 11 +++++
 apps/dummy_app/src/dummy_app.app.src    |  2 +-
 apps/dummy_app/src/dummy_app_server.erl | 60 ++++++++++++++++---------
 rel/reltool.config                      |  2 +-
 4 files changed, 52 insertions(+), 23 deletions(-)

diff --git a/apps/dummy_app/ebin/dummy_app.appup b/apps/dummy_app/ebin/dummy_app.appup
index f9ea3f2..e8c6aff 100644
--- a/apps/dummy_app/ebin/dummy_app.appup
+++ b/apps/dummy_app/ebin/dummy_app.appup
@@ -1,3 +1,14 @@
+{"3", 
+    %% Upgrade instructions
+    [{"2", [
+        {update,dummy_app_server,{advanced,[from2to3]}}
+    ]}], 
+    %% Downgrade instructions
+    [{"2",[
+        {update,dummy_app_server,{advanced,[from3to2]}}
+    ]}]
+}.
+
 {"2",
     %% Upgrade instructions from 1 to 2
     [{"1", [
diff --git a/apps/dummy_app/src/dummy_app.app.src b/apps/dummy_app/src/dummy_app.app.src
index 2fe9fb5..38f70b4 100644
--- a/apps/dummy_app/src/dummy_app.app.src
+++ b/apps/dummy_app/src/dummy_app.app.src
@@ -1,7 +1,7 @@
 {application, dummy_app,
  [
   {description, "Dummy project to test release process"},
-  {vsn, "2"},
+  {vsn, "3"},
   {registered, []},
   {applications, [
                   kernel,
diff --git a/apps/dummy_app/src/dummy_app_server.erl b/apps/dummy_app/src/dummy_app_server.erl
index 54a77d3..d4f4688 100644
--- a/apps/dummy_app/src/dummy_app_server.erl
+++ b/apps/dummy_app/src/dummy_app_server.erl
@@ -3,26 +3,35 @@
 -behaviour(gen_server).
 
 %% API
--export([start_link/0, poke/0, num_pokes/0, poke_twice/0]).
+%% API
+-export([ start_link/0
+        , poke/0
+        , poke/1
+        , poke_twice/0
+        , num_pokes/0
+        , prod/0
+        , prod/1
+        , num_prods/0
+        ]).
 
 %% gen_server callbacks
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
      terminate/2, code_change/3]).
 
--record(state, {num_pokes = 0}).
+-record(state, {num_pokes = 0, num_prods = 0}).
 
 %% API
-start_link() ->
-    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+start_link()    -> gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
 
-poke() ->
-    gen_server:call(?MODULE, poke).
+poke()          -> poke(1).
+poke_twice()    -> poke(2).
+poke(N)         -> gen_server:call(?MODULE, {poke, N}).
 
-poke_twice() ->
-    gen_server:call(?MODULE, poke_twice).
+prod()          -> prod(1).
+prod(N)         -> gen_server:call(?MODULE, {prod, N}).
 
-num_pokes() ->
-    gen_server:call(?MODULE, num_pokes).
+num_pokes()     -> gen_server:call(?MODULE, num_pokes).
+num_prods()     -> gen_server:call(?MODULE, num_prods).
 
 
 %% gen_server callbacks
@@ -32,14 +41,17 @@ init([]) ->
 handle_call(num_pokes, _From, State = #state{ num_pokes = PokeCount }) ->
     {reply, PokeCount, State};
 
-handle_call(poke_twice, _From, State) ->
-    NewPokeCount = State#state.num_pokes + 2,
-    NewState     = State#state{num_pokes = NewPokeCount},
-    Reply        = {ok, NewPokeCount},
+handle_call(num_prods, _From, State = #state{ num_prods = ProdCount }) ->
+    {reply, ProdCount, State};
+
+handle_call({prod, N}, _From, State) ->
+    NewProdCount = State#state.num_prods + N,
+    NewState     = State#state{num_prods = NewProdCount},
+    Reply        = {ok, NewProdCount},
     {reply, Reply, NewState};
 
-handle_call(poke, _From, State) ->
-    NewPokeCount = State#state.num_pokes + 1,
+handle_call({poke, N}, _From, State) ->
+    NewPokeCount = State#state.num_pokes + N,
     NewState     = State#state{num_pokes = NewPokeCount},
     Reply        = {ok, NewPokeCount},
     {reply, Reply, NewState}.
@@ -53,9 +65,15 @@ handle_info(_Info, State) ->
 terminate(_Reason, _State) ->
     ok.
 
-code_change(OldVsn, State, Extra) ->
-    error_logger:info_msg("code_change, oldvsn:~p state:~p extra:~p~n",
-                          [OldVsn, State, Extra]),
-    {ok, State}.
+%% Upgrade from 2
+code_change(_OldVsn, State, [from2to3]) ->
+    error_logger:info_msg("CODE_CHANGE from 2~n"),
+    {state, NumPokes} = State, %% State here is the 'old' format, with 1 field
+    NewState = #state{num_pokes=NumPokes}, %% will assume default for num_prods
+    {ok, NewState}.
+
+%% Note downgrade code_change not implemented
+    
+    
 
-%%% Internal functions
+%%% Internal functions
\ No newline at end of file
diff --git a/rel/reltool.config b/rel/reltool.config
index 28f1012..fcbd3d4 100644
--- a/rel/reltool.config
+++ b/rel/reltool.config
@@ -1,6 +1,6 @@
 {sys, [
        {lib_dirs, ["../apps"]},
-       {rel, "dummy", "2",
+       {rel, "dummy", "3",
         [
          kernel,
          stdlib,