Bill Kelly
3/11/2005 10:51:00 PM
From: "Berger, Daniel" <Daniel.Berger@qwest.com>
>
> From: Bill Kelly [mailto:billk@cts.com]
>
> > There must be *some* way to do a non-blocking pipe read
> > on windows...??? (I saw Nobu's io-wait module on RAA,
> > that would add a #ready? method. Even that might help;
> > although I don't know if io-wait works on Windows or not. The
> > download link seems to be broken...)
>
> With the standard Ruby library? Dunno.
>
> However, perhaps win32-pipe can do what you want, though the API will be
> different. Oh, and ignore the docs that say asynchronous pipes aren't
> supported. Support was added in 0.1.0 - I need to update the docs.
Cool, thanks. I'll probably go with sockets so my solution
is platform-portable. But you guys seem to be doing fantastic
work on the win32 utils. Do you anticipate that things like
your win32 fork() will become part of the ruby core?
BTW, for completeness in the context of the nonblocking thread,
my planned solution is to make a small wrapper module for spawning
an external process, which can use popen() to run the desired
subprocess, but talk back to the parent process via sockets.
I.e. instead of
io = IO.popen("command...")
do
sock, child_io = socket_popen("command...")
which will have to do something like:
def socket_popen(cmd)
sv = TCPServer.new(0)
sv_port = sv.addr[1]
middleman = IO.popen("ruby -rsocket -e 'in=IO.popen(#{cmd}); " +
"out=TCPSocket.new(%{localhost}, #{sv_port}); " +
"out.puts(line) while(line=in.gets); " +
"in.close; out.close'")
sock = sv.accept # TO-DO: add timeout
sv.close
[sock, middleman]
end
... Bleah :( And that implementation is only for
reading for the child process, but that's all I need
at present.
And so the idea is:
sock, child_io = socket_popen("command...")
child_io is effectively a dummy as no data will ever
be returned on that pipe, but can be used to obtain
the pid of the child. All the child's output will
come back on sock, which - yay - at least select()
will work on in win32 (and with the earlier mentioned
patch from Jean-Francois Nadeau could even be nonblocking.)
If anyone knows a less ugly way to do what I'm trying to
do above that's platform-portable, please do comment....
Thanks,
Bill