ekka

%%--------------------------------------------------------------------
%% Copyright (c) 2019 EMQ Technologies Co., Ltd. All Rights Reserved.
%%
%% 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(ekka_node_ttl).

-behaviour(gen_statem).

%% API
-export([start_link/2, stop/0]).

%% gen_statem callbacks
-export([ init/1
        , callback_mode/0
        , handle_event/4
        , terminate/3
        , code_change/4
        ]).

-record(state, {ttl, mfa}).

start_link(Ttl, MFA) ->
    gen_statem:start_link({local, ?MODULE}, ?MODULE, [Ttl, MFA], []).

stop() -> gen_statem:stop(?MODULE).

%%--------------------------------------------------------------------
%% gen_statem callbacks
%%--------------------------------------------------------------------

init([Ttl, MFA]) ->
    {ok, alive, #state{ttl = Ttl, mfa = MFA}, Ttl div 2}.

callback_mode() -> handle_event_function.

handle_event(timeout, _Timeout, alive, State = #state{ttl = Ttl, mfa = {M, F, A}}) ->
    try
        erlang:apply(M, F, A)
    catch
        _:Error:Stacktrace ->
            logger:error("TTL error: ~p Statcktrace:~n~p", [Error, Stacktrace])
    end,
    {next_state, alive, State, Ttl div 2}.

terminate(_Reason, _StateName, _State) ->
    ok.

code_change(_OldVsn, StateName, State, _Extra) ->
    {ok, StateName, State}.