source: branches/home/psmith/restructure/src/statemachine/state-machine.lisp

#|
Copyright (c) 2007
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|#
(in-package :nio-sm)

(declaim (optimize (debug 3) (speed 3) (space 0)))

;
;Base class for state machines
;
;Converts incoming data between bytes and packets using the supplied packet-factory.
;Converts outgoing data between packets and bytes using the write-bytes method on packet.
;
;This way only the protocols packet heirarchy knows about binary representations and 
;  the SM can deal with protocol logic and state maintenance
;
(defclass state-machine (async-fd)
 ((state :initform 0
         :accessor state)))

(defmethod print-object ((sm state-machine) stream)
  (format stream "#<STATE-MACHINE ~A >" (call-next-method sm nil)))

(defgeneric process-incoming-packet(state-machine packet))


(defgeneric process-outgoing-packet(state-machine))


(defgeneric get-packet-factory(state-machine))

;The connection is read ready. 
;Use the packet factory to obtain any valid packet and pass it through
(defmethod process-read((sm state-machine))
  (with-slots (foreign-read-buffer) sm
    (let ((incoming-packet 
           (handler-case
               (get-packet (get-packet-factory sm) foreign-read-buffer)
             (buffer-too-small-error (read-err)
               (if (recommend-buffer-size sm :read (recommended-size read-err))
                   (progn
#+nio-debug          (format-log t "state-machine::process-read - resized incomming buffer ~A~%"foreign-read-buffer)
                     nil)
                   (error 'not-implemented-yet-read-resize-failure))))))
#+nio-debug (format-log t "state-machine::process-read - incoming packet: ~A~%" incoming-packet)
      (when incoming-packet 
          (process-incoming-packet sm incoming-packet)))))

;The connection is write ready.
;See if theres anything ready to be written in the SM
(defmethod process-write((sm state-machine))
  (with-slots (foreign-write-buffer) sm
  (let ((outgoing-packet (process-outgoing-packet sm)))
    (when outgoing-packet 
#+nio-debug    (format-log t "state-machine::process-write - outgoing packet: ~A~%" outgoing-packet)
      (handler-case
          (write-bytes outgoing-packet foreign-write-buffer)
        (buffer-too-small-error (write-error1) 
          (let ((new-size (get-packet-size outgoing-packet)))
            (format-log t "state-machine::process-write - write-error1 trying resize to ~A" new-size)
            (if (recommend-buffer-size sm :write new-size)
              (handler-case
                  (write-bytes outgoing-packet foreign-write-buffer)
                (buffer-too-small-error (write-error2) (format t "Failed to write packet after resize (something already in write buffer?, dropping packet ~A~% out buffer:~%~A~%" outgoing-packet foreign-write-buffer)))
              (format t "Failed to resize io buffer, dropping packet: ~A~%" outgoing-packet)))))))))




(defclass packet-factory ()
  ())
  
; Get the packet in buf using the packet factory
(defgeneric get-packet (packet-factory buf))

; Get size of packet
(defgeneric get-packet (packet-factory buf))