4082f3ade2
Before this change, the stats callback provided by emqx_broker_helper was an anonymous function with module local context. This commit changes it to a full fun M:F/A style callback for: 1. More robust to hot beam reload 2. Faster/smaller variable to construct 3. Easier test
79 lines
2.6 KiB
Erlang
79 lines
2.6 KiB
Erlang
%% Copyright (c) 2018 EMQ Technologies Co., Ltd. All Rights Reserved.
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%%
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%% Licensed under the Apache License, Version 2.0 (the "License");
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%% you may not use this file except in compliance with the License.
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%% You may obtain a copy of the License at
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%%
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%% http://www.apache.org/licenses/LICENSE-2.0
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%%
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%% Unless required by applicable law or agreed to in writing, software
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%% distributed under the License is distributed on an "AS IS" BASIS,
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%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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%% See the License for the specific language governing permissions and
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%% limitations under the License.
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-module(emqx_broker_helper).
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-behaviour(gen_server).
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-export([start_link/0]).
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-export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]).
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%% internal export
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-export([stats_fun/0]).
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-define(HELPER, ?MODULE).
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-record(state, {}).
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-spec(start_link() -> {ok, pid()} | ignore | {error, any()}).
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start_link() ->
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gen_server:start_link({local, ?HELPER}, ?MODULE, [], []).
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%%------------------------------------------------------------------------------
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%% gen_server callbacks
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%%------------------------------------------------------------------------------
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init([]) ->
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%% Use M:F/A for callback, not anonymous function because
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%% fun M:F/A is small, also no badfun risk during hot beam reload
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emqx_stats:update_interval(broker_stats, fun ?MODULE:stats_fun/0),
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{ok, #state{}, hibernate}.
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handle_call(Req, _From, State) ->
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emqx_logger:error("[BrokerHelper] unexpected call: ~p", [Req]),
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{reply, ignored, State}.
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handle_cast(Msg, State) ->
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emqx_logger:error("[BrokerHelper] unexpected cast: ~p", [Msg]),
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{noreply, State}.
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handle_info(Info, State) ->
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emqx_logger:error("[BrokerHelper] unexpected info: ~p", [Info]),
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{noreply, State}.
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terminate(_Reason, #state{}) ->
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emqx_stats:cancel_update(broker_stats).
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code_change(_OldVsn, State, _Extra) ->
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{ok, State}.
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%%------------------------------------------------------------------------------
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%% Internal functions
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%%------------------------------------------------------------------------------
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stats_fun() ->
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safe_update_stats(emqx_subscriber,
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'subscribers/count', 'subscribers/max'),
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safe_update_stats(emqx_subscription,
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'subscriptions/count', 'subscriptions/max'),
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safe_update_stats(emqx_suboptions,
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'suboptions/count', 'suboptions/max').
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safe_update_stats(Tab, Stat, MaxStat) ->
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case ets:info(Tab, size) of
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undefined -> ok;
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Size -> emqx_stats:setstat(Stat, MaxStat, Size)
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end.
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