Finally, I figured out the callback from this letter: http://lists.racket-lang.org/users/archive/2010-July/040409.html . I wish I red this letter early.
After realized that the foreign function blocks the caller thread, I used dynamic-place to create worker thread. The code is here : https://github.com/highfly22/alert/blob/master/inotify.rkt Racket is amazing simple after you know the bloody details. Haiwei On 30 January 2013 14:23, Haiwei Zhou <[email protected]> wrote: > Hi, > > 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. > > (define _read (get-ffi-obj "read" libc (_fun #:async-apply (lambda (f) (f)) > #:save-errno 'posix > _fd_t > (output : (_bytes o size)) > (size : _uint32) > -> (r : _int32) > -> (values r saved-errno > output)))) > > I am confused by the term callback. Is the callback called in the racket > thread or another OS thread? > > Thanks, > Haiwei >
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