From: "Ara.T.Howard" <ahoward@...>
Date: 2004-06-10T00:43:49+09:00
Subject: Re: oddities with select

On Wed, 9 Jun 2004, Ben Giddings wrote:

> What I'm actually using is pretty close to that:
>
>    def internal_read(timeout=DEFAULT_TIMEOUT, stop_pattern=nil)
>     retval = ""
>
>     timed_out = false
>
>     begin
>       timeout(timeout) do
>         while true
>           if select([@sock], [], [], 0.1)
>             retval += @sock.recv(256)
>             if stop_pattern
>               if retval =~ stop_pattern
>                 break
>               end
>             end
>           end
>         end
>       end
>     rescue Timeout::Error
>       timed_out = true
>     end
>
>
> #     if timed_out
> #       puts "Timed out"
> #       raise
> #     end
>
>     retval
>   end
>
> The problem is that although I've seen a newline go over the network to
> my PC, it is never spotted by the Ruby app, which sits there doing the
> 'select' forever.
>
> Your code looks slightly different, but I think it would do the exact
> same thing.
>
> For some reason, the newline goes over the network, but doesn't make it
> far enough (in 5s) that the 'select()' call sees it.
>
> Ben

didn't you say something about your socket being in non-blocking mode?  if so,
isn't this just a busy loop since select will keep returning 'true - a read
will not block':

   man 2 select

     ...
     three independent sets of descriptors are  watched.   those  listed  in
            readfds will be watched to see if characters become available for read-
            ing (more precisely, to see if a read will not block - in particular, a
            file  descriptor  is also ready on end-of-file)
     ...

if not in non-blocking mode, perhaps your pattern is bad?  what happens if you
do this:

<snip>
>         while true
>           if select([@sock], [], [], 0.1)
>             retval += @sock.recv(256)
               p retval
</snip>

??

do you see retval growing?


-a
--
===============================================================================
| EMAIL   :: Ara [dot] T [dot] Howard [at] noaa [dot] gov
| PHONE   :: 303.497.6469
| A flower falls, even though we love it; and a weed grows, even though we do
| not love it. --Dogen
===============================================================================