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-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}.
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