如何在 erlang 中停止作为 gen_server 实现的 tcp_listener

Question

我将 tcp_listener 实现为 gen_server()。我有一个名为 start_link(Port) 的函数在该端口创建一个 tcp_listener。现在，我很难理解如何通过 stop() 告诉 tcp_listener 停止收听。我试着用 stop 调用这样的函数。

 stop() -> gen_server:cast(?MODULE, shutdown)

在 terminate/2 函数中我尝试关闭侦听套接字但失败了。

 terminate(_Reason, State = #state{lsocket = LSocket}) ->
 gen_tcp:close(LSocket),
 NewState = State#state{lsocket = null},
 {ok, NewState}.

如果我关闭侦听套接字，我生成的已接受连接会发生什么情况。

谢谢！

   start_link(Port) when is_integer(Port) ->
   State = #state{port = Port},
   gen_server:start_link({local, ?MODULE}, ?MODULE, State, []).

  init(State = #state{port = Port}) ->
  io:format("Supervisor started me and I am listening at ~p ~n", [Port]),
  case gen_tcp:listen(Port, ?TCP_OPTIONS) of
    {ok, LSocket} ->
     NewState = State#state{lsocket = LSocket},
     spawn(fun() -> accept(NewState) end),
     {ok, NewState};
    {error, Reason} ->
     {stop, Reason}
   end.

   accept(State = #state{lsocket = LSocket}) ->
   case gen_tcp:accept(LSocket) of
   {ok, Socket} ->
    Pid = spawn(fun() ->
    io:format("Connection accepted ~n"),
    loop(Socket)
              end),
    gen_tcp:controlling_process(Socket, Pid),
    accept(State);
    {error, closed} -> error
    end.

     loop(Socket) ->
    case gen_tcp:recv(Socket, 0) of
      {ok, Data} ->
       gen_tcp:send(Socket, Data),
     loop(Socket);
    {error, closed} ->
       ok
     end.

Answer 1

我建议你看看 this chapter in the Learn You Some Erlang book，特别是：

Both sockets can send messages in the same way, and can then be closed with gen_tcp:close(Socket). Note that closing an accept socket will close that socket alone, and closing a listen socket will close none of the related and established accept sockets, but will interrupt currently running accept calls by returning {error, closed}.

所以它应该只是在所有套接字上调用 gen_tcp:close(Socket) 的问题。

如何在 erlang 中停止作为 gen_server 实现的 tcp_listener

How to stop a tcp_listener implemented as a gen_server in erlang

erlang

erlang-otp

gen-server

gen-tcp