Megatest

  (my-address      #f)
  (my-hostname     #f)
  (my-port         #f)
  (my-pid          (current-process-id))
  ;; server and handler thread
  (serv-listener   #f)                 ;; this processes server info
  (handler-thread  #f)
  (mboxes          (make-hash-table))  ;; key => mbox
  ;; other servers
  (peers           (make-hash-table))  ;; host-port => peer record
  (handlers        (make-hash-table))  ;; dbfile => peer record
  (outgoing-conns  (make-hash-table))  ;; host:port -> conn

  (work-queue      (make-queue))       ;; most stuff goes here
  ;; (fast-queue      (make-queue))       ;; super quick stuff goes here (e.g. ping)
  (busy            #f)                 ;; is either of the queues busy, use to switch between queuing tasks or doing immediately
  ;; app info
  (appname         #f)
  (dbtypes         (make-hash-table))  ;; this should be an alist but hash is easier. dbtype => [ initproc syncproc ]
  ;; cookies
  (cnum            0) ;; cookie num
  )

;; struct for keeping track of others we are talking to

(defstruct peer
  (addr-port       #f)
  (hostname        #f)
  (pid             #f)
  (inp             #f)
  (oup             #f)
  (owns            '()) ;; list of databases this peer is currently handling
  )

(defstruct work
  (peer-dat   #f)
  (handlerkey #f)
  (qrykey     #f)
  (data       #f)
  (start      (current-milliseconds)))

;;======================================================================
;; Captain functions
;;======================================================================

;; NB// This needs to be started in a thread
;;
;; setup to be a captain
;;   - start server
;;   - create pkt
;;   - start server port handler
;;
(define (setup-as-captain udata)
  (if (start-server-find-port udata) ;; puts the server in udata
      (if (create-captain-pkt udata)
	  (let* ((th (make-thread (lambda ()
				    (ulex-handler udata)) "Captain handler")))
	    (udat-handler-thread-set! udata th)
	    (thread-start! th))
	  #f)
      #f))

;; given a pkts dir read 
;;
(define (get-all-captain-pkts udata)
  (let* ((pktsdir       (let ((d (udat-cpkts-dir udata)))
			  (if (file-exists? d)
			      d

			(let ((ad (string->number (alist-ref 'D a)))
			      (bd (string->number (alist-ref 'D b))))
			  (if (eq? a b)
			      (let ((az (alist-ref 'Z a))
				    (bz (alist-ref 'Z b)))
				(string>=? az bz))
			      (> ad bd))))))))

;; put the host, ip, port and pid into a pkt in
;; the captain pkts dir
;;  - assumes user has already fired up a server
;;    which will be in the udata struct
;;
(define (create-captain-pkt udata)
  (if (not (udat-serv-listener udata))
      (begin
	(print "ERROR: create-captain-pkt called with out a listener")
	#f)
      (let* ((pktdat `((port   . ,(udat-my-port udata))
		       (host   . ,(udat-my-hostname udata))
		       (ipaddr . ,(udat-my-address udata))
		       (pid    . ,(udat-my-pid     udata))))
	     (pktdir  (udat-cpkts-dir udata))
	     (pktspec (udat-cpkt-spec udata))
	     )
	(udat-my-cpkt-key-set!
	 udata
	 (write-alist->pkt
	  pktdir
	  pktdat
	  pktspec: pktspec
	  ptype:   'captain))
	(udat-my-cpkt-key udata))))

;; remove pkt associated with captn (the Z key .pkt)
;;
(define (remove-captain-pkt udata captn)
  (let ((Z       (alist-ref 'Z captn))
	(cpktdir (udat-cpkts-dir udata)))
    (delete-file* (conc cpktdir "/" Z ".pkt"))))


;;======================================================================
;; server primitives
;;======================================================================

(define (make-cookie udata)
  (let ((newcnum (+ (udat-cnum udata))))

	 (addr (get-my-best-address))) ;; (hostinfo-addresses (host-information (current-hostname)))
    (udat-my-address-set!    udata addr)
    (udat-my-port-set!       udata port)
    (udat-my-hostname-set!   udata (get-host-name))
    (udat-serv-listener-set! udata tlsn)
    udata))












































(define (get-peer-dat udata host-port #!optional (hostname #f)(pid #f))
  ;; I'm currently very fuzzy on whether it makes sense to be reusing the outgoing connections.
  ;; at the other end of the line I think the reciever has closed the ports - thus each message
  ;; requires new connection?
  (let* ((pdat (or (hash-table-ref/default (udat-outgoing-conns udata) host-port #f)
		   (handle-exceptions ;; ERROR - MAKE THIS EXCEPTION HANDLER MORE SPECIFIC
		    exn
		    #f
		    (let ((npdat (make-peer addr-port: host-port)))
		      (if hostname (peer-hostname-set! npdat hostname))
		      (if pid (peer-pid-set! npdat pid))

;;  NOTE: qrykey is what was called the "cookie" previously
;;
;;     retval tells send to expect and wait for return data (one line) and return it or time out
;;       this is for ping where we don't want to necessarily have set up our own server yet.
;;
(define (send udata host-port handler qrykey data #!key (hostname #f)(pid #f)(params '())(retval #f))
  (let-values (((inp oup)(get-peer-ports udata host-port hostname pid)))
    ;;
    ;; CONTROL LINE: (note: removed the hostname - I don't think it adds much value
    ;;
    ;;    handlerkey host:port pid qrykey params ...
    ;;
    (if (and inp oup)
	(let* ((myhost (udat-my-address udata))
	       (myport (udat-my-port    udata))

  (let ((wqueue (udat-work-queue udata)))
    (if (not (queue-empty? wqueue))
	(let loop ((wd (queue-remove! wqueue)))
	  (do-work udata wd)
	  (if (not (queue-empty? wqueue))
	      (loop (queue-remove! wqueue)))))))








;; 
;;
(define (ulex-handler udata)
  (let* ((serv-listener (udat-serv-listener udata)))
    (print "serv-listner: " serv-listener)
    ;; data comes as two lines
    ;;   handlerkey resp-addr:resp-port hostname pid qrykey [dbpath/dbfile.db]

	  (match (string-split controldat)
		 ((handlerkey host-port pid qrykey params ...)
		  (print "handlerkey: " handlerkey " host-port: " host-port " pid: " pid " qrykey: " qrykey " params: " params)
		  (case (string->symbol handlerkey)
		    ((ack)(print "Got ack!"))
		    ((ping) ;; special case - return result immediately on the same connection
		     (let* ((proc (hash-table-ref/default (udat-handlers udata) 'ping #f))
			    (val  (if proc (proc) "gotping"))
			    (peer (make-peer addr-port: host-port pid: pid)))
		       (if (not (hash-table-exists? (udat-peers udata) host-port))
			   (hash-table-set! (udat-peers udata) host-port peer)) ;; save the details of this caller in peers
		       (write-line qrykey oup)
		       #;(send udata host-port "version" qrykey val)
		       )
		     (close-input-port inp)
		     (close-output-port oup))

		    ((rucaptain) ;; remote is asking if I'm the captain
		     (write-line (if (udat-my-cpkt-key udata) "yes" "no"))
		     (close-input-port inp)
		     (close-output-port oup))
		    ((whoowns) ;; given a db name who do I send my queries to
		     ;; look up the file in handlers, if have an entry ping them to be sure
		     ;; they are still alive and then return that host:port.
		     ;; if no handler found or if the ping fails pick from peers the oldest that
		     ;; is managing the fewest dbs

		     #f)
		    (else

		     (add-to-work-queue udata (get-peer-dat udata host-port) handlerkey qrykey data))))
		 (else (print "BAD DATA? controldat=" controldat " data=" data)))))
	(loop state))))

;; add a proc to the handler list
(define (register-handler udata key proc)
  (hash-table-set! (udat-handlers udata) key proc))