<div dir="ltr"><div>For the record, Kevin Tew's function makes it easy to use:<br><a href="https://github.com/kazzmir/x11-racket/blob/master/fd.rkt">https://github.com/kazzmir/x11-racket/blob/master/fd.rkt</a><br><br></div> <div>For example, that's what I use in my own version of libinotify FFI:<br><a href="https://github.com/Metaxal/linux-tools/blob/master/inotify.rkt">https://github.com/Metaxal/linux-tools/blob/master/inotify.rkt</a><br> </div><div><br></div>Laurent<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, Jan 30, 2013 at 12:28 PM, Tim Brown <span dir="ltr"><<a href="mailto:tim@timb.net" target="_blank">tim@timb.net</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Resend... original (and previous resend!) sent from an address not<br> valid for the list.<br> <br> ---------- Forwarded message ----------<br> From: Tim Brown <<a href="mailto:tim.brown@timb.net">tim.brown@timb.net</a>><br> Date: 30 January 2013 10:01<br> Subject: Re: [racket] How to invoke a blocking foreign function<br> without blocking whole racket?<br> To: Haiwei Zhou <<a href="mailto:highfly22@gmail.com">highfly22@gmail.com</a>><br> Cc: <a href="mailto:users@racket-lang.org">users@racket-lang.org</a><br> <br> <br> There are internal FFI calls: scheme_make_fd_input_port and<br> scheme_make_fd_output_port, documented in<br> <a href="http://docs.racket-lang.org/inside/Ports_and_the_Filesystem.html?q=to%20port#(idx._(gentag._480._(lib._scribblings/inside/inside..scrbl)))" target="_blank">http://docs.racket-lang.org/inside/Ports_and_the_Filesystem.html?q=to%20port#(idx._(gentag._480._(lib._scribblings/inside/inside..scrbl)))</a><br> <br> If you would normally be able to poll (or select) from the port, then<br> a little bit of work will allow you to tie your IO closer to the<br> racket events system.<br> <br> There are more involved variants, I've mostly only needed this level<br> of access at the racket level; servicing the known-to-be ready fd is<br> done by your FFI library.<br> <span class="HOEnZb"><font color="#888888"><br> Tim<br> </font></span><div class="HOEnZb"><div class="h5"><br> On 30 Jan 2013 09:44, "Haiwei Zhou" <<a href="mailto:highfly22@gmail.com">highfly22@gmail.com</a>> wrote:<br> ><br> > Finally, I figured out the callback from this letter: <a href="http://lists.racket-lang.org/users/archive/2010-July/040409.html" target="_blank">http://lists.racket-lang.org/users/archive/2010-July/040409.html</a> . I wish I red this letter early.<br> ><br> > After realized that the foreign function blocks the caller thread, I used dynamic-place to create worker thread. The code is here : <a href="https://github.com/highfly22/alert/blob/master/inotify.rkt" target="_blank">https://github.com/highfly22/alert/blob/master/inotify.rkt</a><br> ><br> > Racket is amazing simple after you know the bloody details.<br> ><br> > Haiwei<br> ><br> ><br> > On 30 January 2013 14:23, Haiwei Zhou <<a href="mailto:highfly22@gmail.com">highfly22@gmail.com</a>> wrote:<br> >><br> >> Hi,<br> >><br> >> I try to wrap inotify API. After adding a watcher, I try to read events from file descriptor. But the racket thread is blocking until the read operation is done. Here is the definition of read.<br> >><br> >> (define _read (get-ffi-obj "read" libc (_fun #:async-apply (lambda (f) (f))<br> >> #:save-errno 'posix<br> >> _fd_t<br> >> (output : (_bytes o size))<br> >> (size : _uint32)<br> >> -> (r : _int32)<br> >> -> (values r saved-errno output))))<br> >><br> >> I am confused by the term callback. Is the callback called in the racket thread or another OS thread?<br> >><br> >> Thanks,<br> >> Haiwei<br> ><br> ><br> ><br> </div></div><div class="HOEnZb"><div class="h5">> ____________________<br> > Racket Users list:<br> > <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a><br> ><br> ____________________<br> Racket Users list:<br> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a><br> </div></div></blockquote></div><br></div>