4.13.7 Polling for events

The poll function is an alternative to the select function: it allows to wait for events on file descriptors. Meaningless example:

#!vicare
(import (vicare)
  (prefix (vicare posix) px.)
  (vicare platform constants))

(define-values (in ou)
  (px.pipe))

(px.write ou '#vu8(1))

(define vec
  `#(#(,in ,POLLIN  0)
     #(,ou ,POLLOUT 0)))

(px.poll vec 10)        ⇒ 2

vec ⇒ `#(#(,in ,POLLIN ,POLLIN) #(,ou ,POLLOUT ,POLLOUT))

Function: poll fds timeout

Interface to the C function poll(), (*manpages*)Wait for some event on a file descriptor. Poll for events the file descriptors selected by fds; timeout must be an exact integer representing the timeout in milliseconds. If successful: return the number of file descriptors ready for an event, else raise an exception.

fds must be a vector of vectors each having 3 elements: a fixnum representing the file descriptor, a fixnum representing the events field of a struct pollfd, a fixnum representing the revents field of a struct pollfd. On successful return: the third element of the subvectors is mutated to represent the events for which the file descriptor is ready.