From 86720c8aad8d8329e8c029a0f9c5fa90d9e04adf Mon Sep 17 00:00:00 2001
From: Brad Anderson <brad@cloudant.com>
Date: Tue, 15 Jun 2010 10:23:38 -0400
Subject: add membership events back into mem3, and add dbs handlers

---
 ebin/membership.app    |  1 +
 src/dbs.erl            |  2 +-
 src/mem3.erl           | 12 +++++++++++-
 src/membership_sup.erl |  8 +++++++-
 4 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/ebin/membership.app b/ebin/membership.app
index 82f0b299..4773b636 100644
--- a/ebin/membership.app
+++ b/ebin/membership.app
@@ -8,6 +8,7 @@
    [
       dbs,
       dbs_cache,
+      dbs_event,
       membership,
       membership_app,
       membership_sup,
diff --git a/src/dbs.erl b/src/dbs.erl
index b5e17b6a..345788ef 100644
--- a/src/dbs.erl
+++ b/src/dbs.erl
@@ -12,7 +12,7 @@ init([]) ->
     {ok, MemNodes} = mem3:nodes(),
     LiveNodes = nodes(),
     ChildSpecs = [childspec(N) || N <- MemNodes, lists:member(N, LiveNodes)],
-    %gen_event:add_handler(membership_events, showroom_dbs_event, []),
+    gen_event:add_handler(membership_events, dbs_event, []),
     {ok, {{one_for_one, 10, 8}, ChildSpecs}}.
 
 childspec(Node) ->
diff --git a/src/mem3.erl b/src/mem3.erl
index 55a8a541..d715e657 100644
--- a/src/mem3.erl
+++ b/src/mem3.erl
@@ -202,12 +202,14 @@ handle_cast(Msg, State) ->
 %%      net_kernel:monitor_nodes(true)
 handle_info({nodedown, Node}, State) ->
     showroom_log:message(alert, "membership: nodedown ~p", [Node]),
+    notify(nodedown, [Node]),
     {noreply, State};
 
 %% @doc handle nodeup messages because we have
 %%      net_kernel:monitor_nodes(true)
 handle_info({nodeup, Node}, State) ->
     showroom_log:message(alert, "membership: nodeup   ~p", [Node]),
+    notify(nodeup, [Node]),
     {noreply, State};
 
 %% ignored info
@@ -296,10 +298,12 @@ handle_join(replace, {OldNode, NewOpts}, PingNode, _State) ->
     OldState = #mem{nodes=OldNodes} = get_pingnode_state(PingNode),
     {Order, OldNode, _OldOpts} = lists:keyfind(OldNode, 2, OldNodes),
     NewNodes = lists:keyreplace(OldNode, 2, OldNodes, {Order, node(), NewOpts}),
+    notify(node_leave, [OldNode]),
     int_join([], OldState#mem{nodes=NewNodes});
 % leave
-handle_join(leave, [_OldNode | _], _PingNode, _State) ->
+handle_join(leave, [OldNode | _], _PingNode, _State) ->
     % TODO implement me
+    notify(node_leave, [OldNode]),
     ok;
 
 handle_join(JoinType, _, PingNode, _) ->
@@ -311,6 +315,7 @@ handle_join(JoinType, _, PingNode, _) ->
 int_join(ExtNodes, #mem{nodes=Nodes, clock=Clock} = State) ->
     NewNodes = lists:foldl(fun({Pos, N, _Options}=New, AccIn) ->
         check_pos(Pos, N, Nodes),
+        notify(node_join, [N]),
         [New|AccIn]
     end, Nodes, ExtNodes),
     NewNodes1 = lists:sort(NewNodes),
@@ -530,3 +535,8 @@ compare_state_with_rest(#mem{clock=Clock} = _State, States) ->
     length(BadResults) == 0 -> match;
     true -> {bad_state_match, node(), BadResults}
     end.
+
+notify(Type, Nodes) ->
+  lists:foreach(fun(Node) ->
+      gen_event:notify(membership_events, {Type, Node})
+  end, Nodes).
diff --git a/src/membership_sup.erl b/src/membership_sup.erl
index 27e547ff..f203924d 100644
--- a/src/membership_sup.erl
+++ b/src/membership_sup.erl
@@ -21,6 +21,12 @@ init(_Args) ->
                   1000,
                   worker,
                   [mem3]},
+    MemEventMgr = {mem_event_manager,
+                   {gen_event, start_link, [{local, membership_events}]},
+                   permanent,
+                   1000,
+                   worker,
+                   []},
     DbsRepl =
         {dbs,
          {dbs, start_link, []},
@@ -35,4 +41,4 @@ init(_Args) ->
          1000,
          worker,
          [dbs_cache]},
-    {ok, {{one_for_one,10,1}, [Membership, DbsRepl, DbsCache]}}.
+    {ok, {{one_for_one,10,1}, [Membership, MemEventMgr, DbsRepl, DbsCache]}}.
-- 
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