Re: Glib::IO->add_watch and reading the filehandle

["Matthew Braid" <ptkperl mdb id au>]

Hi,

2008/7/17 muppet <scott asofyet org>:
> The trick in C code is to mark the file as non-blocking, and read chunks until
> read returns 0 bytes.  I can't take the time to experiment right now, but i'm
> reasonably certain that this works in perl, as well.

Gah. I'm still thinking in Perl/Tk terms. I was trying to figure out
why the filehandle wasn't being picked up as 'still readable' instead
of looking for a lower level solution. I've been doing a lot of head
slapping lately....

> Unless you're using datagram sockets, there is no guarantee that an entire
> message showed up at once, so you always have to be able to handle partial
> reads.

Partial reads aren't a problem (the main program just buffers the data
until it gets a whole message as long as the message so far is
structurally valid) it was just that sometimes that 'too big' message
wasn't followed by another message for a very long time, so the buffer
was never getting flushed.

If I use:

use Fcntl;
fcntl($FROM_CHILD, F_SETFL, fcntl($FROM_CHILD, F_GETFL, 0) | O_NONBLOCK);

that should do the trick.

Ta :)

MB