1 files changed, 74 insertions, 0 deletions
diff --git a/src/mem3_event.erl b/src/mem3_event.erl
new file mode 100644
index 00000000..59156adc
--- /dev/null
+++ b/src/mem3_event.erl
@@ -0,0 +1,74 @@
+-module(mem3_event).
+
+-behaviour(gen_event).
+
+-export([init/1, handle_event/2, handle_call/2, handle_info/2, terminate/2,
+    code_change/3]).
+
+-include("mem3.hrl").
+
+init([]) ->
+    {ok, []}.
+
+handle_event({node_join, Node}, State) ->
+    start_repl({node_join, Node}, State);
+
+handle_event({nodeup, Node}, State) ->
+    start_repl({nodeup, Node}, State);
+
+handle_event({node_leave, Node}, State) ->
+    stop_repl({node_leave, Node}, State);
+
+handle_event({nodedown, Node}, State) ->
+    stop_repl({nodedown, Node}, State);
+
+handle_event(Event, State) ->
+    ?LOG_ERROR("unexpected event in dbs handler ~p", [Event]),
+    {ok, State}.
+
+handle_call(Request, State) ->
+    ?LOG_ERROR("unexpected call in dbs handler ~p", [Request]),
+    {ok, ok, State}.
+
+handle_info(Info, State) ->
+    ?LOG_ERROR("unexpected msg in dbs handler ~p", [Info]),
+    {ok, State}.
+
+terminate(_Reason, _State) ->
+    ok.
+
+code_change(_OldVsn, State, _Extra) ->
+    {ok, State}.
+
+%%
+%% internal
+%%
+
+start_repl({Reason, Node}, State) ->
+    ChildSpec = dbs:childspec(Node),
+    case supervisor:start_child(dbs, ChildSpec) of
+    {ok, _} ->
+        ok;
+    {error, {already_started, _Child}} ->
+        ok;
+    {error, running} ->
+        ok;
+    {error, already_present} ->
+        case supervisor:restart_child(dbs, ChildSpec) of
+        {ok, _} ->
+            ok;
+        {error, running} ->
+            ok;
+        {error, Reason} ->
+            ?LOG_ERROR("dbs repl restart failed ~p", [Reason])
+        end;
+    {error, Reason} ->
+        ?LOG_ERROR("dbs repl start failed ~p", [Reason])
+    end,
+    {ok, State}.
+
+stop_repl({Reason, Node}, State) ->
+    ?LOG_INFO("dbs repl ~p --> ~p terminating (~p)", [node(), Node, Reason]),
+    supervisor:terminate_child(dbs, Node),
+    supervisor:delete_child(dbs, Node),
+    {ok, State}.