source: branches/home/psmith/restructure/src/event/epoll.lisp

#|
Copyright (c) 2006 Risto Laakso
All rights reserved.

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   notice, this list of conditions and the following disclaimer.
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   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
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   derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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|#
(in-package :event-notification)

#+linux
(progn

  (defconstant +epoll-size+ 1000)

  (defun make-event-queue ()
    (%epoll-create +epoll-size+))

  (defun read-event-p (event)
    (not (eql (logand event +epoll-in+) 0)))

  (defun write-event-p (event)
    (not (eql (logand event +epoll-out+) 0)))

  (defun error-event-p (event)
    (not (eql (logand event +epoll-error+) 0)))

  (defun hup-event-p (event)
    (not (eql (logand event +epoll-hup+) 0)))

  (defun add-fd (event-queue fd mode &key (trigger :edge))
    (with-foreign-object (ev 'epoll-event)
      (memzero ev +epoll-event-size+)
      (let ((actual-mode (logior (if (eql :read mode) +epoll-in+ 0) 
                                 (if (eql :write mode) +epoll-out+ 0)
                                 (if (eql :read-write mode) (logior +epoll-in+ +epoll-out+) 0)
                                 (if (eql trigger :edge) +epoll-et+ 0))))
        #+nio-debug     (format t "Add-fd called with :fd ~A :event-queue ~A :mode ~A :trigger ~A :actual-mode ~A~%" fd event-queue mode trigger actual-mode)
        
        (setf (foreign-slot-value ev 'epoll-event 'fd)  fd
              (foreign-slot-value ev 'epoll-event 'events)
              actual-mode))
      
      (if (eql (%epoll-ctl event-queue +epoll-ctl-add+ fd ev) -1)
          (progn
            (format t "add-fd (epoll_ctl) error occurred: ~A~%" (get-errno))
            ;;      (error 'poll-error)
            ))))
  
  (defun remove-fd (event-queue fd mode)
    (with-foreign-object (ev 'epoll-event)
      (memzero ev +epoll-event-size+)

      (setf (foreign-slot-value ev 'epoll-event 'fd) fd)

      (%epoll-ctl event-queue +epoll-ctl-del+ fd ev)))


  (define-condition poll-error (error) ())

  (defun poll-events (event-queue)
#+nio-debug2    (format t "poll-events called with :event-queue ~A~%" event-queue)
    (with-foreign-object (events 'epoll-event +epoll-size+)
      (memzero events (* +epoll-event-size+ +epoll-size+))
      (loop for res = (%epoll-wait event-queue events +epoll-size+ 100)
           
           do
           (progn
#+nio-debug2         (format t "poll-events - dealing with ~A~%" res)
             (case res
               (-1 
                (let ((errno (get-errno)))
                  (if (eql errno 4) ;EINTR - interrupted by a system call
                      (progn
                        (format t "epoll-wait interrupted~%")
                        (return nil))
                      (progn
                        (format t "-1 returned from epoll-wait, errno:")
                        (perror)
                        (error 'poll-error)))))
               (return nil)
               (t 
                (let ((idents nil))
                  (loop for i from 0 below res do
                       (push (cons (foreign-slot-value 
                                    (mem-aref events 'epoll-event i) 
                                    'epoll-event 'fd)
                                   (foreign-slot-value 
                                    (mem-aref events 'epoll-event i) 
                                    'epoll-event 'events)) 
                             idents))
                  (return idents))))))))
)