201 lines
7.5 KiB
Erlang
201 lines
7.5 KiB
Erlang
%%%-------------------------------------------------------------------
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%%% @author anlicheng
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%%% @copyright (C) 2025, <COMPANY>
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%%% @doc
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%%%
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%%% @end
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%%% Created : 28. 4月 2025 23:50
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%%%-------------------------------------------------------------------
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-module(efka_subscription).
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-author("anlicheng").
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-behaviour(gen_server).
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%% API
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-export([start_link/0]).
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-export([subscribe/2, publish/2]).
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-export([match_components/2, is_valid_components/1, of_components/1]).
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%% gen_server callbacks
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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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-define(SERVER, ?MODULE).
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%% 定义订阅者
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-record(subscriber, {
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topic :: binary(),
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subscriber_pid :: pid(),
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components = [],
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%% 优先级
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%% 1. 完全匹配的topic优先级别最高
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%% 2. 带 * 的订阅
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%% 3. 带 + 的订阅
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order :: integer()
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}).
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-record(state, {
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subscribers = []
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}).
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%%%===================================================================
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%%% API
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%%%===================================================================
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-spec subscribe(Topic :: binary(), SubscriberPid :: pid()) -> ok | {error, Reason :: binary()}.
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subscribe(Topic, SubscriberPid) when is_binary(Topic), is_pid(SubscriberPid) ->
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gen_server:call(?SERVER, {subscribe, Topic, SubscriberPid}).
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-spec publish(Topic :: binary(), Content :: binary()) -> no_return().
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publish(Topic, Content) when is_binary(Topic), is_binary(Content) ->
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gen_server:cast(?SERVER, {publish, Topic, Content}).
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%% @doc Spawns the server and registers the local name (unique)
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-spec(start_link() ->
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{ok, Pid :: pid()} | ignore | {error, Reason :: term()}).
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start_link() ->
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gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
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%%%===================================================================
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%%% gen_server callbacks
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%%%===================================================================
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%% @private
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%% @doc Initializes the server
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-spec(init(Args :: term()) ->
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{ok, State :: #state{}} | {ok, State :: #state{}, timeout() | hibernate} |
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{stop, Reason :: term()} | ignore).
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init([]) ->
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{ok, #state{}}.
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%% @private
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%% @doc Handling call messages
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-spec(handle_call(Request :: term(), From :: {pid(), Tag :: term()},
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State :: #state{}) ->
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{reply, Reply :: term(), NewState :: #state{}} |
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{reply, Reply :: term(), NewState :: #state{}, timeout() | hibernate} |
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{noreply, NewState :: #state{}} |
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{noreply, NewState :: #state{}, timeout() | hibernate} |
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{stop, Reason :: term(), Reply :: term(), NewState :: #state{}} |
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{stop, Reason :: term(), NewState :: #state{}}).
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%% 同一个SubscriberPid只能订阅同一个topic一次
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handle_call({subscribe, Topic, SubscriberPid}, _From, State = #state{subscribers = Subscribers}) ->
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Components = of_components(Topic),
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case is_valid_components(Components) of
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true ->
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Sub = #subscriber{topic = Topic, subscriber_pid = SubscriberPid, components = Components, order = order_num(Components)},
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%% 建立到SubscriberPid的monitor，进程退出需要清理订阅
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erlang:monitor(process, SubscriberPid),
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{reply, ok, State#state{subscribers = Subscribers ++ [Sub]}};
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false ->
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{reply, {error, <<"invalid topic name">>}, State}
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end.
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%% @private
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%% @doc Handling cast messages
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-spec(handle_cast(Request :: term(), State :: #state{}) ->
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{noreply, NewState :: #state{}} |
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{noreply, NewState :: #state{}, timeout() | hibernate} |
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{stop, Reason :: term(), NewState :: #state{}}).
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%% 发布消息
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handle_cast({publish, Topic, Content}, State = #state{subscribers = Subscribers}) ->
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MatchedSubscribers = match_subscribers(Subscribers, Topic),
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lists:foreach(fun(#subscriber{subscriber_pid = SubscriberPid}) ->
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SubscriberPid ! {topic_broadcast, Topic, Content}
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end, MatchedSubscribers),
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lager:debug("[efka_subscription] topic: ~p, content: ~p, match subscribers: ~p", [Topic, Content, MatchedSubscribers]),
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{noreply, State}.
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%% @private
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%% @doc Handling all non call/cast messages
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-spec(handle_info(Info :: timeout() | term(), State :: #state{}) ->
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{noreply, NewState :: #state{}} |
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{noreply, NewState :: #state{}, timeout() | hibernate} |
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{stop, Reason :: term(), NewState :: #state{}}).
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handle_info({'DOWN', _Ref, process, SubscriberPid, Reason}, State = #state{subscribers = Subscribers}) ->
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lager:debug("[efka_subscription] subscriber: ~p, down with reason: ~p", [SubscriberPid, Reason]),
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NSubscribers = lists:filter(fun(#subscriber{subscriber_pid = Pid0}) -> SubscriberPid /= Pid0 end, Subscribers),
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{noreply, State#state{subscribers = NSubscribers}};
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handle_info(Info, State = #state{}) ->
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lager:debug("[efka_subscription] get unknown info: ~p", [Info]),
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{noreply, State}.
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%% @private
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%% @doc This function is called by a gen_server when it is about to
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%% terminate. It should be the opposite of Module:init/1 and do any
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%% necessary cleaning up. When it returns, the gen_server terminates
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%% with Reason. The return value is ignored.
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-spec(terminate(Reason :: (normal | shutdown | {shutdown, term()} | term()),
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State :: #state{}) -> term()).
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terminate(_Reason, _State = #state{}) ->
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ok.
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%% @private
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%% @doc Convert process state when code is changed
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-spec(code_change(OldVsn :: term() | {down, term()}, State :: #state{},
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Extra :: term()) ->
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{ok, NewState :: #state{}} | {error, Reason :: term()}).
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code_change(_OldVsn, State = #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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%% 查找满足条件订阅者
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-spec match_subscribers(Subscribers :: [#subscriber{}], Topic :: binary()) -> [#subscriber{}].
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match_subscribers(Subscribers, Topic) when is_list(Subscribers), is_binary(Topic) ->
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Components = of_components(Topic),
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lists:foldl(fun(S = #subscriber{components = Components0, subscriber_pid = Pid0}, Acc) ->
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case match_components(Components0, Components) andalso not contain_channel(Pid0, Acc) of
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true ->
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[S|Acc];
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false ->
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Acc
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end
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end, [], Subscribers).
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-spec contain_channel(Pid :: pid(), Subscribers :: list()) -> boolean().
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contain_channel(Pid, Subscribers) when is_pid(Pid), is_list(Subscribers) ->
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lists:search(fun(#subscriber{subscriber_pid = Pid0}) -> Pid == Pid0 end, Subscribers) /= false.
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%% 开始对比订阅的topic和发布的topic的Components信息
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%% *表示单级匹配，+表示多级匹配；+只能出现一次，并且只能在末尾
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-spec match_components(list(), list()) -> boolean().
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match_components(A, B) when is_list(A), is_list(B) ->
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match_components(A, B, false).
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match_components([<<"+">>], [_|_], _) ->
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true;
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match_components([], [], _) ->
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true;
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match_components([<<"*">>|T0], [_|T1], _) ->
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match_components(T0, T1, false);
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match_components([C0|T0], [C0|T1], _) ->
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match_components(T0, T1, false);
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match_components(_, _, _) ->
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false.
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-spec of_components(Topic :: binary()) -> [binary()].
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of_components(Topic) when is_binary(Topic) ->
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binary:split(Topic, <<$/>>, [global]).
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is_valid_components([]) ->
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true;
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is_valid_components([<<$+>>|T]) ->
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length(T) =:= 0;
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is_valid_components([<<$*>>|T]) ->
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is_valid_components(T);
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is_valid_components([_|T]) ->
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is_valid_components(T).
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-spec order_num(Components :: list()) -> integer().
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order_num([]) ->
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1;
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order_num([<<$*>>|_]) ->
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2;
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order_num([<<$+>>|_]) ->
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3;
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order_num([_|Tail]) ->
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order_num(Tail). |