[erlang-questions] Supervising UDP listener

[Steve Strong]

You create udp_listener with spawn_link, which would kill the parent *if* udp_listener terminates abnormally. In your case, udp_listener is exiting cleanly, so it won't cause the parent to die.


Cheers.

Steve

--
Steve Strong
Sent with Airmail

On 20 Nov 2015, 17:38 +0000, Kamrul Khan<dodul@REDACTED>, wrote:
> I didnt get any response for my question. I am posting it again ( with the typo fix)
> 
> I am trying to make a UDP listener that will be supervised by a supervisor module (Just for learning purpose).below id my Supervisor code:
> 
> -module(pdmanager_sup).
> -behaviour(supervisor).
> 
> -export([start_link/1]).
> -export([init/1]).
> 
> start_link(Port) ->
> supervisor:start_link({local,?MODULE}, ?MODULE, Port).
> 
> init(Port) ->
> {ok, {{one_for_one, 5, 60},
> [{listener,
> {pdmanager, start_link, Port},
> permanent, 1000, worker, [pdmanager]}
> ]}}.
> 
> 
> And my udp listener (pdmanager) looks like the below:
> 
> -module(pdmanager).
> -behaviour(gen_server).
> 
> -export([start_link/1]).
> -export([init/1]).
> -export([
> udplistener/1,
> handleudp/1
> ]).
> 
> -record(state, {socket}).
> 
> start_link(Port) ->
> gen_server:start_link({local, pdmanager}, pdmanager, Port, []).
> 
> init(Port) ->
> io:format("UDP Server starting ~n",[]),
> {ok, Socket} = gen_udp:open(Port, [binary, {active, false}]),
> spawn_link(pdmanager,udplistener,[Socket]),
> {ok, #state{socket=Socket}}.
> 
> udplistener(Socket) ->
> {ok,Packet} = gen_udp:recv(Socket,0),
> {_,_,Msg} = Packet,
> if
> Msg /= "stop" ->
> io:format("Stoping UDP listener ~n", []);
> true ->
> spawn(pdmanager,handleudp,[Packet]),
> udplistener(Socket)
> end.
> 
> handleudp(Packet) ->
> {_,_, Msg} = Packet,
> io:format("I have got message : ~s ~n",[Msg]),
> {handeling, Packet}.
> 
> 
> 
> Now: after compiling I start my program with :
> 
> pdmanager_sup:start_link(5678).
> 
> It gets started and I can see the "UDP server starting" message in my screen. Next, when I send a message to UDP 5678 port I see the message "stoping UDP listener" as expected.However, it doesnt restart my server.I called udplistener/1 function from init/1 using spawn_link. I expected spawn_link will link the new process (udp listener) with the calling process (the worker process in this case) and if udplistener goes down the worker will go down aswell and that will cause the supervisor to restart the worker. However, I didnt work that way.
> 
> How should I do it ?
> From: dodul@REDACTED
> To: ulf@REDACTED
> Date: Fri, 20 Nov 2015 13:33:13 +0600
> CC: erlang-questions@REDACTED
> Subject: Re: [erlang-questions] Supervising UDP listener
> 
> Typo. Sorry about that. should be
> pdmanager_sup:start_link(5678).
> 
> Subject: Re: [erlang-questions] Supervising UDP listener
> From: ulf@REDACTED
> Date: Thu, 19 Nov 2015 21:56:09 -0800
> CC: erlang-questions@REDACTED
> To: dodul@REDACTED
> 
> 
> > On 19 Nov 2015, at 15:45, Kamrul Khan<dodul@REDACTED(mailto:dodul@REDACTED)>wrote:
> > Now: after compiling I start my program with :
> > 
> > pdmanager:start_link(5678).
> 
> Not pdmanager_sup:start_link(5678)?
> 
> BR,
> Ulf W
> 
> 
> 
> 
> _______________________________________________ erlang-questions mailing list erlang-questions@REDACTED http://erlang.org/mailman/listinfo/erlang-questions_______________________________________________
> erlang-questions mailing list
> erlang-questions@REDACTED
> http://erlang.org/mailman/listinfo/erlang-questions
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://erlang.org/pipermail/erlang-questions/attachments/20151120/c2b8f1b9/attachment.htm>