From: Ernie <erne@...>
Date: 2002-12-20T01:16:39+09:00
Subject: Re: Socket problem


"Child" <child@t9.ds.pwr.wroc.pl> wrote in message
news:slrnb02blb.ejn.child@child.t9.ds.pwr.wroc.pl...
> Hello
>
> I am new to ruby, but I think it's excellent language - no doubt the
> best one (cleanest, fastest to write in etc.) I ever used :)
>
> I'm trying to write a NNTP client and I encountered some problems with
> sockets. I have to read server response from socket. The response is
> multiline and ends with ".\r\n". Is there any way to get whole response
> at once? At the moment I use gets and read the response line by line,
> which is horribly inefficient. In C program I used ioctl FIONREAD call
> to read number of available bytes and then fetched them with read, but
> can't get this call working in ruby - always get "Bad address
> (Errno::EFAULT" error. And if I use recv with arbitrary number (eg.
> 10000) it hangs forever.
>
> Thanks for any help.
>
> --
> Marek Janukowicz
> http://starware.one.pl

Below is a pretty basic server that makes use of  "select"  to do what you
want to do.
You have to be a little careful with "select".  I returns nil if nothing is
going on
with the read end of the socket.  If something is there to  read.  It will
return an
array.  However, it will also return an array of three empty arrays if the
socket is closed
on the other end, at least it does in Windows.  Thus, the begin and rescue
sections.
Of course I'm assuming the protocol you are using doesn't permit lines with
only a \r\n unless
the line marks the end of the data.

class SocketProc
    def initalize(session)
       @sess=session
    end
def readIn()
      dataIn=""
      while true
           begin
                foo=select([@sess],nil, nil, timeoutvalue)
                if foo
                    bar=@sess.readline
                   @dataIn.concat(bar)
                   break if bar=~/^\r\n/
               end
         rescue
               @sess.close
         end
     end
     processData (dataIn)
end
def processData(dataIn)
        #do what you want including writing to @sess
         @sess.close
end
end

server=TCPServer.new(port)
BasicSocket.do_not_reverse_lookup=true
#the do_not_reverse_lookup is necessary if you want some speed.  By default
it is false.
while (session=server.accept) do
    Thread.new(session) do |aSession|
          z=SocketProc.new(aSession)
          while aSession
               z.readIn
           end
     end
end