Megatest

;; set up a connection to the current owner of the dbfile associated with rid
;; then send the query to that dbfile owner and wait for a response.
;;
(define (rmt:send-receive cmd rid params #!key (attemptnum 1)(area-dat #f)) ;; start attemptnum at 1 so the modulo below works as expected
  (let* ((alldat   *alldat*)
	 (areapath (alldat-areapath alldat))
	 (dbtype   (if (or (not rid)(< rid 1)) ;; this is the criteria for "main.db"
		       'main 'runs))
	 (dbfname  (if (eq? dbtype 'main)
		       "main.db"
		       (conc rid ".db")))
	 (dbfile   (conc areapath "/.db/" dbfname))

	 (udata    (alldat-ulexdat alldat))
	 (ulexconn (rmt:connect alldat dbfname dbtype)))  ;; ulexconn is our new *runremote*, it is a dbowner struct < pdat lastrefresh >
    	(ulex:remote-request udata ulexconn 'immediate dbfile 'execute rid params)))
    ;; need to call this on the other side 
    ;; (api:execute-requests dbstruct-local (vector (symbol->string cmd) params))))
    
    #;(with-input-from-string
	(ulex:remote-request udata ulexconn 'immediate dbfile 'execute rid (with-output-to-string (lambda ()(serialize params))))
       (lambda ()(deserialize)))

		  (remove-captain-pkt udata captn)
		  (setup)))))
	(begin
	  (setup-as-captain udata)  ;; this saves the thread to captain-thread and starts the thread
	  (setup)))))

;; connect to a specific dbfile
;;   - if already connected - return the pdat
;;   - ask the captain who to talk to for this db
;;   - put the entry in the dbowners hash
;;
(define (connect udata dbfname dbtype)
  (or (hash-table-ref/default (udat-dbowners udata) dbfname #f)
      (let-values (((success dbowner-host-port)(get-db-owner udata dbfname dbtype)))
	(if success
	    (let* ((pdat     (udat-get-peer udata dbowner-host-port))
		   (dbowner  (make-dbowner pdat: pdat)))
	      ;; just clobber the record, this is the new data no matter what
	      (hash-table-set! (udat-dbowners udata) dbowner-host-port dbowner)
	      dbowner)
	    #f))))

;; returns: success pingtime
;;
;; NOTE: causes the callee to store the info on this host along with the dbs this host currently owns
;;
(define (ping udata host-port)

  (let* ((dbrec (ulex-open-db udata dbname))     ;; this will be a dbconn record, looks for in udata first
	 (proc  (hash-table-ref udata prockey)))
    (let* ((result (proc dbrec procparam data)))
      result)))

;; remote-request - send to remote to process in process-request
;; uconn comes from a call to connect and can be used instead of calling connect again
;; uconn is somewhat redundant with dbname but it tells us what host-port to call
;; uconn is a dbowner struct < pdat lastupdate >
;; we send dbname to the worker so they know which file to open
;; data must be a string with no newlines, it will be handed to the proc
;; at the remote site unchanged. It is up to the user to encode/decode it's contents
;;
;;   rtype: immediate, read-only, normal, low-priority
;; 
(define (remote-request udata uconn rtype dbname prockey procparam data)
  (let* ((cookie    (make-cookie))
	 (pdat      (dbowner-pdat uconn))
	 (host-port (peer-addr-port pdat)))
    (send-receive udata host-port rtype cookie data `(,prockey procparam))))

(define (ulex-open-db udata dbname)
  #f)

;;======================================================================
;; network utilities
;;======================================================================

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

(defstruct dbowner
  (pdat        #f)
  (last-update (current-seconds)))

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

     peers)))

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

(define (make-cookie udata)
  (let ((newcnum (+ (udat-cnum udata))))
    (udat-cnum-set! udata newcnum)
    (conc (udat-my-address udata) ":"
	  (udat-my-port    udata) "-"
	  (udat-my-pid     udata) "-"
	  newcnum)))

;; create a tcp listener and return a populated udat struct with

       ((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))
	       (dbshash (udat-dbowners udata)))
	  (peer-dbs-set! peer params) ;; params for ping is list of dbs owned by pinger
	  (for-each (lambda (dbfile)
		      (hash-table-set! dbshash dbfile host-port))
		    params) ;; register each db in the dbshash
	  (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
	  qrykey)) ;; End of ping
       ((goodbye)
	;; remove all traces of the caller in db ownership etc.
	(let* ((peer  (hash-table-ref/default (udat-peers udata) host-port #f))

       ((db-owner) ;; 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
	(match params
	  ((dbfile dbtype)
	   (let* ((curr-owner (hash-table-ref/default (udat-dbowners udata) dbfile #f))
		  (owner-host-port (and curr-owner (peer-addr-port curr-owner))))
	     (if owner-host-port
		 (conc qrykey " " owner-host-port)
		 (let* ((pdat (or (hash-table-ref/default (udat-peers udata) host-port #f) ;; no owner - caller gets to own it!
				  (make-peer addr-port: host-port pid: pid dbs: `(,dbfile)))))

		   (hash-table-set! (udat-dbowners udata) dbfile pdat)
		   (conc qrykey " " host-port)))))
	  (else (conc qrykey " BADDATA"))))
       ;; for work items:
       ;;    handler is one of; immediate, read-only, read-write, high-priority
       ((immediate read-only normal low-priority) ;; do this work immediately
	;; host-port (caller), pid (caller), qrykey (cookie), params <= all from first line
	;; data => a single line encoded however you want, or should I build json into it?
	(let* ((pdat (get-peer-dat udata host-port)))
	  (match params ;; dbfile prockey procparam
	    ((dbfile prockey procparam)
	     (case (string->symbol handlerkey)
	       ((immediate read-only)
		(process-request udata pdat dbfile qrykey prockey procparam data))
	       ((normal low-priority) ;; split off later and add logic to support low priority
		(add-to-work-queue udata pdat dbfile qrykey prockey procparam data))
	       (else
		#f))))))

       (else
	;; (add-to-work-queue udata (get-peer-dat udata host-port) handlerkey qrykey data)
	#f)))
    (else
     (print "BAD DATA? controldat=" controldat " data=" data)
     #f)));; handles the incoming messages and dispatches to queues