From: Ivo Palli <ivo@...>
Date: 2005-01-26T02:37:36+09:00
Subject: Re: In need of Win32 fcntl (non-blocking)

You are correct, sysread() returns without blocking. However this is a 
workaround at best. In the interest of portability over platforms, I 
still recommend for fcntl() to be implemented in the Win32 platform. 
Afterall Ruby aims to provide a unified platform regardless of OS. Right?

Are there any ways to detect the OS btw? If I'm going to run my script 
on multiple platforms, and I need to workaround, how can I do this 
automatically?

Regards,

   Ivo Palli

Tanaka Akira wrote:
> In article <41F65F1B.80706@palli.nl>,
>   Ivo Palli <ivo@palli.nl> writes:
> 
> 
>>Instead I want to use a select, which is thankfully support in Ruby.
>>However a read to a socket which has data open always seems to block,
>>unless I specifically read what is available. Since I cannot know how
>>much data is waiting for me, I really need to do a non-blocking read. In
>>Linux it works, in Windows the fcntl call is not supported. :( As far as
>>I searched and tried, there is no other way to read data without blocking.
> 
> 
> sysread might be usable because sysread doesn't block when some data
> available.  If sysread is usable, you don't need non-blocking read.
> 
> require "socket"
> 
> gs = TCPserver.open(0)
> addr = gs.addr
> addr.shift
> printf("server is on %s\n", addr.join(":"))
> socks = [gs]
> 
> loop do
>   nsock = select(socks);
>   next if nsock == nil
>   for s in nsock[0]
>     if s == gs
>       ns = s.accept
>       socks.push(ns)
>       print(s, " is accepted\n")
>     else
>       begin
>         print "[" + s.sysread(4096) + "]\n"
>       rescue EOFError
>         print(s, " is gone\n")
>         s.close
>         socks.delete(s)
>       end
>     end
>   end
> end