如何接收发送到 gen_server 内运行的 PID 的消息

Question

我有一个 ejabberd 服务器

我有一个自定义模块，my_apns_module.erl 由 ejabberd 服务器运行像这样：

start_link(Host, Opts) ->
  Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
  ?GEN_SERVER:start_link({local, Proc}, ?MODULE,
                         [Host, Opts], []).
start(Host, Opts) ->
  Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
  ChildSpec = {Proc, {?MODULE, start_link, [Host, Opts]},
               temporary, 1000, worker, [?MODULE]},
  supervisor:start_child(ejabberd_sup, ChildSpec).

stop(Host) ->
  Proc = gen_mod:get_module_proc(Host, ?PROCNAME),
  ?GEN_SERVER:call(Proc, stop),
  supervisor:delete_child(ejabberd_sup, Proc),
  ok.

init([Host, _Opts]) ->
   ...

handle_call(stop, _From, State) ->
  {stop, normal, ok, State}.

handle_cast(_Msg, State) -> {noreply, State}.

handle_info(#offline_msg{us = _UserServer,
          from = From, to = To, packet = Packet} = _Msg, State) ->
  ...

handle_info(_Info, State) ->
  {noreply, State}.

terminate(_Reason, State) ->
  Host = State#state.host,
  ok.

code_change(_OldVsn, State, _Extra) -> {ok, State}.

在 init 内部我运行另一个 APNs 应用程序发送推送通知。 https://github.com/inaka/apns4erl

init([Host, _Opts]) ->
      apns:start(),
      case apns:connect(cert, ?APNS_CONNECTION) of
           {ok, PID} -> ?INFO_MSG("apns connection successful with PID ~p~n", [PID]);
           {error, timeout} -> ?ERROR_MSG("apns connection unsuccessful reason timed out", [])
      end,
      {ok, #state{host = Host}}.

我可以发送通知了。
现在文档 (https://github.com/inaka/apns4erl) 说：

If network goes down or something unexpected happens the gun connection with APNs will go down. In that case apns4erl will send a message {reconnecting, ServerPid} to the client process, that means apns4erl lost the connection and it is trying to reconnect. Once the connection has been recover a {connection_up, ServerPid} message will be send.

我的问题是：

我应该在my_apns_module.erl里面写什么代码来接收{reconnecting, ServerPid}或{connection_up, ServerPid}？

Answer 1

发送到 gen_server 进程的消息，例如GenServerPid ! {ok, 10}}，由以下人员处理：

handle_info(Msg, State)

所以，你可以这样做：

handle_info({reconnecting, ServerPid}=Msg, State) ->
     %%do something here, like log Msg or change State;
handl_info({connection_up, ServerPid}=Msg, State) ->
     %%do something here, like log Msg or change State;   
handle_info(#offline_msg{us = _UserServer,
          from = From, to = To, packet = Packet} = _Msg, State) ->
     %%do something.

回复评论：

这是您当前的代码：

init([Host, _Opts]) ->
      apns:start(),
      case apns:connect(cert, ?APNS_CONNECTION) of
           {ok, PID} -> ?INFO_MSG("apns connection successful with PID ~p~n", [PID]);
           {error, timeout} -> ?ERROR_MSG("apns connection unsuccessful reason timed out", [])
      end,
      {ok, #state{host = Host}}.

你可以把它改成这样：

init([Host, _Opts]) ->
    spawn(?MODULE, start_apns, []),
    ...


start_apns() ->

          apns:start(),
          case apns:connect(cert, ?APNS_CONNECTION) of
               {ok, PID} -> ?INFO_MSG("apns connection successful with PID ~p~n", [PID]);
               {error, timeout} -> ?ERROR_MSG("apns connection unsuccessful reason timed out", [])
          end,
          apns_loop().

apns_loop() ->
    receive
        {reconnecting, ServerPid} -> %%do something;
        {connection_up, ServerPid} -> %% do something;
        Other -> %% do something
    end,
    apns_loop().

启动apns进程后，apns进程会进入循环等待消息

如何接收发送到 gen_server 内运行的 PID 的消息

How can I receive messages sent to a PID which running inside a gen_server

erlang

ejabberd

ejabberd-module

erlang-supervisor

如何接收发送到 gen_server 内 运行 的 PID 的消息

How can I receive messages sent to a PID which running inside a gen_server

erlang

ejabberd

ejabberd-module

erlang-supervisor

如何接收发送到 gen_server 内运行的 PID 的消息