138 lines
4.8 KiB
Erlang
138 lines
4.8 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 : 17. 8月 2025 00:26
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%%%-------------------------------------------------------------------
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-module(iot_name_server).
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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([whereis_alias/1, register/2]).
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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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-define(TAB, iot_name_server).
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-record(state, {
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%% #{Pid => Name}
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pid_names = #{},
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refs = []
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}).
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%%%===================================================================
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%%% API
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%%%===================================================================
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-spec register(Name :: atom(), Pid :: pid()) -> ok.
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register(Name, Pid) when is_atom(Name), is_pid(Pid) ->
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gen_server:call(?SERVER, {register, Name, Pid}).
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-spec whereis_alias(Name :: atom()) -> undefined | pid().
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whereis_alias(Name) when is_atom(Name) ->
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case ets:lookup(?TAB, Name) of
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[] ->
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undefined;
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[{Name, Pid}|_] ->
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case is_process_alive(Pid) of
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true ->
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Pid;
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false ->
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undefined
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end
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end.
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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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%% 初始化存储
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ets:new(?TAB, [named_table, ordered_set, public, {keypos, 1}]),
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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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handle_call({register, Name, Pid}, _From, State = #state{refs = Refs, pid_names = PidNames}) ->
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true = ets:insert(?TAB, {Name, Pid}),
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MRef = erlang:monitor(process, Pid),
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{reply, ok, State#state{refs = [MRef|Refs], pid_names = maps:put(Pid, Name, PidNames)}}.
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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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handle_cast(_Request, State = #state{}) ->
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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', MRef, process, Pid, Reason}, State = #state{refs = Refs, pid_names = PidNames}) ->
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% lager:debug("[iot_name_server] pid: ~p, down with reason: ~p", [Reason]),
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case lists:member(MRef, Refs) of
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true ->
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case maps:take(Pid, PidNames) of
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error ->
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{noreply, State#state{refs = lists:delete(MRef, Refs)}};
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{Name, NPidNames} ->
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true = ets:delete(?TAB, Name),
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{noreply, State#state{pid_names = NPidNames, refs = lists:delete(MRef, Refs)}}
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end;
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false ->
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{noreply, State}
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end.
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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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