From 077231a02a7872a10a4cb642e493718c0be21059 Mon Sep 17 00:00:00 2001
From: Jeffrey Massung <massung@gmail.com>
Date: Fri, 18 Nov 2011 13:49:48 -0700
Subject: [PATCH] Cache handoffs in the manager so we can query and see which
 ones are active.

---
 src/riak_core_handoff_manager.erl | 38 ++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/src/riak_core_handoff_manager.erl b/src/riak_core_handoff_manager.erl
index b67e44065..33a2f15f3 100644
--- a/src/riak_core_handoff_manager.erl
+++ b/src/riak_core_handoff_manager.erl
@@ -21,13 +21,26 @@
 -export([add_exclusion/2, get_handoff_lock/1, get_exclusions/1]).
 -export([remove_exclusion/2]).
 -export([release_handoff_lock/2]).
--record(state, {excl}).
+-export([add_handoff/3,remove_handoff/2,all_handoffs/0,get_handoffs/1]).
+-record(state, {excl,handoffs}).
 
 start_link() ->
     gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
 
 init([]) ->
-    {ok, #state{excl=ordsets:new()}}.
+    {ok, #state{excl=ordsets:new(), handoffs=[]}}.
+
+add_handoff(Module, Idx, Node) ->
+    gen_server:cast(?MODULE, {add_handoff, {Module, Idx, Node}}).
+
+remove_handoff(Module, Idx) ->
+    gen_server:cast(?MODULE, {remove_handoff, {Module, Idx}}).
+
+all_handoffs() ->
+    gen_server:call(?MODULE, all_handoffs).
+
+get_handoffs(Idx) ->
+    gen_server:call(?MODULE, {get_handoffs, Idx}).
 
 add_exclusion(Module, Index) ->
     gen_server:cast(?MODULE, {add_exclusion, {Module, Index}}).
@@ -57,8 +70,27 @@ release_handoff_lock(LockId, Token) ->
     
 handle_call({get_exclusions, Module}, _From, State=#state{excl=Excl}) ->
     Reply =  [I || {M, I} <- ordsets:to_list(Excl), M =:= Module],
-    {reply, {ok, Reply}, State}.
+    {reply, {ok, Reply}, State};
+handle_call(all_handoffs, _From, State=#state{handoffs=Hoffs}) ->
+    {reply, {ok, Hoffs}, State};
+handle_call({get_handoffs, Idx}, _From, State=#state{handoffs=Hoffs}) ->
+    All=[{Mod,dict:find(Idx,ModHoffs)} || {Mod,ModHoffs} <- Hoffs],
+    Filtered=lists:filter(fun ({_,{ok,_}}) -> true;
+                              (_) -> false
+                          end,
+                          All),
+    {reply, {ok, [{Mod,Value} || {Mod,{ok,Value}} <- Filtered]}, State}.
 
+handle_cast({add_handoff, {Mod, Idx, Node}}, State=#state{handoffs=Hoffs}) ->
+    ModHoffs=proplists:get_value(Mod,Hoffs,dict:new()),
+    NewModHoffs=dict:store(Idx,Node,ModHoffs),
+    NewHoffs=lists:keystore(Mod,1,Hoffs,{Mod,NewModHoffs}),
+    {noreply, State#state{handoffs=NewHoffs}};
+handle_cast({remove_handoff, {Mod, Idx}}, State=#state{handoffs=Hoffs}) ->
+    ModHoffs=proplists:get_value(Mod,Hoffs,dict:new()),
+    NewModHoffs=dict:erase(Idx,ModHoffs),
+    NewHoffs=lists:keystore(Mod,1,Hoffs,{Mod,NewModHoffs}),
+    {noreply, State#state{handoffs=NewHoffs}};
 handle_cast({del_exclusion, {Mod, Idx}}, State=#state{excl=Excl}) ->
     {noreply, State#state{excl=ordsets:del_element({Mod, Idx}, Excl)}};
 handle_cast({add_exclusion, {Mod, Idx}}, State=#state{excl=Excl}) ->