feat: use emqx_mgmt_cache to cache sys_memory
This commit is contained in:
Zhongwen Deng
parent
c2bdb9faa7
commit
7a9f477267
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@ -0,0 +1,104 @@
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%%--------------------------------------------------------------------
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%% Copyright (c) 2020-2023 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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%%--------------------------------------------------------------------
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-module(emqx_mgmt_cache).
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-behaviour(gen_server).
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-define(SYS_MEMORY_KEY, sys_memory).
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-define(EXPIRED_MS, 3000).
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%% -100ms to early update cache
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-define(REFRESH_MS, ?EXPIRED_MS - 100).
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-define(DEFAULT_BAD_MEMORY, {0, 0}).
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-export([start_link/0, get_sys_memory/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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get_sys_memory() ->
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Now = now_millisecond(),
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{CacheMem, ExpiredAt} = get_memory_from_cache(),
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case Now > ExpiredAt of
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true ->
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erlang:send(?MODULE, fresh_sys_memory),
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CacheMem;
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%% stale cache value, try to recalculate
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false ->
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get_sys_memory_sync()
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end.
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get_sys_memory_sync() ->
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try
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gen_server:call(?MODULE, get_sys_memory, ?EXPIRED_MS)
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catch
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exit:{timeout, _} ->
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?DEFAULT_BAD_MEMORY
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end.
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start_link() ->
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gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
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init([]) ->
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ets:new(?MODULE, [set, named_table, public, {keypos, 1}]),
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{ok, #{fresh_at => 0}}.
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handle_call(get_sys_memory, _From, State) ->
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{Mem, NewState} = fresh_sys_memory(State),
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{reply, Mem, NewState};
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handle_call(_Request, _From, State) ->
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{reply, ok, State}.
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handle_cast(_Request, State) ->
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{noreply, State}.
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handle_info(fresh_sys_memory, State) ->
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{_, NewState} = fresh_sys_memory(State),
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{noreply, NewState};
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handle_info(_Info, State) ->
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{noreply, State}.
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terminate(_Reason, _State) ->
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ok.
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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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fresh_sys_memory(State = #{fresh_at := LastFreshAt}) ->
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Now = now_millisecond(),
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{Mem, ExpiredAt} = get_memory_from_cache(),
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case Now >= ExpiredAt orelse Now - LastFreshAt >= ?REFRESH_MS of
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true ->
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%% NOTE: Now /= UpdateAt, because
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%% load_ctl:get_sys_memory/0 maybe a heavy operation,
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%% so record update_at timestamp after get_sys_memory/0.
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NewMem = load_ctl:get_sys_memory(),
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NewExpiredAt = now_millisecond() + ?EXPIRED_MS,
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ets:insert(?MODULE, {?SYS_MEMORY_KEY, {NewMem, NewExpiredAt}}),
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{NewMem, State#{fresh_at => Now}};
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false ->
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{Mem, State}
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end.
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get_memory_from_cache() ->
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case ets:lookup(?MODULE, ?SYS_MEMORY_KEY) of
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[] -> {?DEFAULT_BAD_MEMORY, 0};
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[{_, CacheVal}] -> CacheVal
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end.
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now_millisecond() ->
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erlang:system_time(millisecond).
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@ -26,7 +26,7 @@ start_link() ->
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supervisor:start_link({local, ?MODULE}, ?MODULE, []).
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init([]) ->
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LC = child_spec(emqx_mgmt_sys_memory, 5000, worker),
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LC = child_spec(emqx_mgmt_cache, 5000, worker),
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{ok, {{one_for_one, 1, 5}, [LC]}}.
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child_spec(Mod, Shutdown, Type) ->
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@ -1,79 +0,0 @@
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%%--------------------------------------------------------------------
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%% Copyright (c) 2020-2023 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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%%--------------------------------------------------------------------
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-module(emqx_mgmt_sys_memory).
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-behaviour(gen_server).
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-define(SYS_MEMORY_CACHE_KEY, ?MODULE).
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-define(TIMEOUT, 2200).
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-export([start_link/0, get_sys_memory/0, get_sys_memory/1]).
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-export([
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init/1,
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handle_call/3,
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handle_cast/2,
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handle_info/2,
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terminate/2,
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code_change/3
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]).
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get_sys_memory() ->
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get_sys_memory(?TIMEOUT).
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get_sys_memory(Timeout) ->
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try
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gen_server:call(?MODULE, get_sys_memory, Timeout)
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catch
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exit:{timeout, _} ->
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get_memory_from_cache()
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end.
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start_link() ->
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gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
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init([]) ->
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{ok, #{last_time => 0}}.
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handle_call(get_sys_memory, _From, State = #{last_time := LastTime}) ->
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Now = erlang:system_time(millisecond),
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case Now - LastTime >= ?TIMEOUT of
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true ->
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Memory = load_ctl:get_sys_memory(),
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persistent_term:put(?SYS_MEMORY_CACHE_KEY, Memory),
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{reply, Memory, State#{last_time => Now}};
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false ->
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{reply, get_memory_from_cache(), State}
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end;
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handle_call(_Request, _From, State = #{}) ->
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{reply, ok, State}.
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handle_cast(_Request, State = #{}) ->
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{noreply, State}.
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handle_info(_Info, State = #{}) ->
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{noreply, State}.
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terminate(_Reason, _State = #{}) ->
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ok.
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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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get_memory_from_cache() ->
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persistent_term:get(?SYS_MEMORY_CACHE_KEY, {0, 0}).
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