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Re: [Chicken-users] Asynchronous I/O Egg Release

From: Peter Bex
Subject: Re: [Chicken-users] Asynchronous I/O Egg Release
Date: Thu, 30 Jun 2016 19:18:29 +0200
User-agent: Mutt/1.5.23 (2014-03-12)

On Thu, Jun 30, 2016 at 04:11:57PM +0100, Chris Vine wrote:
> On Thu, 30 Jun 2016 16:24:52 +0200
> > The OP (IIUC) states that this doesn't happen automatically for
> > anything but the TCP unit's sockets, which is incorrect AFAICT.  Any
> > port created by the system's core procedures should be nonblocking.
> I think you are wrong.  On my limited testing it happens with chicken if
> you use R5RS's open-input-file on any file which is not on the file
> system, such as "/dev/tty".  open-input-file is on any basis part of
> the system's core procedures.  And of course, reads of files on the file
> system never block at all: they just return end-of-file when the end is
> reached, so the issue doesn't arise with them in the first place.

Dammit, you're right!  I had no idea, sorry for being so dense.
I've created for this.

> > This a reasonably low-level procedure that you should only need to
> > call when writing your own procedures that use file descriptors.  When
> > you are using ports, this should be done automatically, in all cases.
> It appears not.

Indeed, and that is certainly a bug!

> Obviously you can always win if any use other than opening a file on the
> file system (which never blocks anyway) or opening a socket (for which
> chicken makes special provision) is considered "a low level use".
> However, that just means you are agreeing with what I and the original
> poster said, maybe without realising it.

No, I realise completely.  I was just confused as to what you were
saying.  For some reason I never ran into this, and this hasn't been
reported before (by my knowledge).

But AFAIK the manual states that all ports are nonblocking, or am I just
too confused right now?


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