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% Licensed under the Apache License, Version 2.0 (the "License"); you may not
% use this file except in compliance with the License. You may obtain a copy of
% the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.
-module(mem3_sync_event).
-behaviour(gen_event).
-vsn(1).
-export([init/1, handle_event/2, handle_call/2, handle_info/2, terminate/2,
code_change/3]).
init(_) ->
net_kernel:monitor_nodes(true),
{ok, nil}.
handle_event({add_node, Node}, State) when Node =/= node() ->
net_kernel:connect_node(Node),
mem3_sync_nodes:add([Node]),
{ok, State};
handle_event({remove_node, Node}, State) ->
mem3_sync:remove_node(Node),
{ok, State};
handle_event(_Event, State) ->
{ok, State}.
handle_call(_Request, State) ->
{ok, ok, State}.
handle_info({nodeup, Node}, State) ->
Nodes0 = lists:usort([node() | drain_nodeups([Node])]),
Nodes = lists:filter(fun(N) -> lists:member(N, mem3:nodes()) end, Nodes0),
wait_for_rexi(Nodes, 5),
{ok, State};
handle_info({nodedown, Node}, State) ->
mem3_sync:remove_node(Node),
{ok, State};
handle_info(_Info, State) ->
{ok, State}.
terminate(_Reason, _State) ->
ok.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
drain_nodeups(Acc) ->
receive
{nodeup, Node} ->
drain_nodeups([Node | Acc])
after 0 ->
Acc
end.
wait_for_rexi([], _Retries) ->
ok;
wait_for_rexi(Waiting, Retries) ->
% Hack around rpc:multicall/4 so that we can
% be sure which nodes gave which response
Msg = {call, rexi_server_mon, status, [], group_leader()},
{Resp, _Bad} = gen_server:multi_call(Waiting, rex, Msg, 1000),
Up = [N || {N, R} <- Resp, R == ok],
NotUp = Waiting -- Up,
case length(Up) > 0 of
true ->
mem3_sync_nodes:add(Up);
false -> ok
end,
case length(NotUp) > 0 andalso Retries > 0 of
true ->
timer:sleep(1000),
wait_for_rexi(NotUp, Retries-1);
false ->
ok
end.
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