[erlang-questions] gen_tcp:recv and hairloss

Kevin <>
Mon Nov 10 21:39:30 CET 2008


> .... this and see what happens:
>
> ....() ->
>    {ok,LS} = gen_tcp:listen(7000,[binary,{active,false}]),
>    {ok,Sock} = gen_tcp:accept(LS),
>    spawn(fun() ->  do_recv(Sock) end),
>    spawn(fun() ->  do_recv(Sock) end),
>    ok.
>
>
> do_recv(Socket) ->
>    io:format("Recv: ~p~n", [ gen_tcp:recv(Socket,0)]).
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>   

Point taken.  I solved my problem by simply embracing 
gen_fsm:sync_send_event, which I was probably
conceptually visualizing when I was using gen_fsm:send_event.

A lot of advice I got was to use gen_tcp:controlling_process, but 
doesn't my success with passing a socket
and reading in a Fsm, as well as the example above, show thats its a 
common myth that  you need to use controlling_process if you
wish to use gen_tcp:recv in a process that didn't accept the socket in 
the first place?  I believe you only need to use
controlling_process if you want the socket data sent as a erlang message 
to the process, and for that to happen it has to be {active, true}.





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