Megatest

(define (db:process-cached-writes db)
  (let ((queries    (make-hash-table))
	(data       #f))
    (mutex-lock! *incoming-mutex*)
    ;; data is a list of query packets <vector qry-sig query params
    (set! data (reverse *incoming-writes*)) ;;  (sort ... (lambda (a b)(< (vector-ref a 1)(vector-ref b 1)))))
    (set! *server:last-write-flush* (current-milliseconds))
    (set! *incoming-writes* '())
    (mutex-unlock! *incoming-mutex*)
    (if (> (length data) 0)
	;; Process if we have data
	(begin
	  (debug:print-info 7 "Writing cached data " data)
    

	  (let ((cache-size (length data)))
	    (if (> cache-size *max-cache-size*)
		(set! *max-cache-size* cache-size)))
	  #t)
	#f)))

(define *db:process-queue-mutex* (make-mutex))

(define *number-of-writes*   0)
(define *writes-total-delay* 0)

;; The queue is a list of vectors where the zeroth slot indicates the type of query to
;; apply and the second slot is the time of the query and the third entry is a list of 
;; values to be applied
;;
(define (db:queue-write-and-wait db qry-sig query params)
  (let ((queue-len  0)
	(res        #f)
	(got-it     #f)
	(qry-pkt    (vector qry-sig query params))
	(start-time (current-milliseconds))
	(timeout    (+ 10 (current-seconds)))) ;; set the time out to 10 secs in future

    ;; Put the item in the queue *incoming-writes* 
    (mutex-lock! *incoming-mutex*)
    (set! *incoming-writes* (cons qry-pkt *incoming-writes*))
    (set! queue-len (length *incoming-writes*))
    (mutex-unlock! *incoming-mutex*)

	  (begin
	    (hash-table-delete! *completed-writes* qry-sig)
	    (set! got-it #t)))
      (mutex-unlock! *completed-mutex*)
      (if (and (not got-it)
	       (< (current-seconds) timeout))
	  (loop)))
    (set! *number-of-writes*   (+ *number-of-writes*   1))
    (set! *writes-total-delay* (+ *writes-total-delay* 1))
    got-it))
	  
(define (db:process-queue-item db item)
  (let* ((stmt-key       (cdb:packet-get-qtype item))
	 (qry-sig        (cdb:packet-get-query-sig item))
	 (return-address (cdb:packet-get-client-sig item))
	 (params         (cdb:packet-get-params item))

              (loop 0))
            (begin
              (debug:print-info 0 "Starting to shutdown the server.")
              ;; need to delete only *my* server entry (future use)
              (set! *time-to-exit* #t)
              (tasks:server-deregister-self tdb (get-host-name))
              (thread-sleep! 1)
              (debug:print-info 0 "Max cached queries was    " *max-cache-size*)
	      (debug:print-info 0 "Number of cached writes   " *number-of-writes*)
	      (debug:print-info 0 "Average cached write time " (/ *writes-total-delay* *number-of-writes*) " ms")
              (debug:print-info 0 "Server shutdown complete. Exiting")
              (exit)))))))

;; all routes though here end in exit ...
(define (http-transport:launch)
  (if (not *toppath*)
      (if (not (setup-for-run))

    (else
     (debug:print "WARNING: unrecognised transport " transport)
     (exit))))

;;======================================================================
;; Q U E U E   M A N A G E M E N T
;;======================================================================

;; We don't want to flush the queue if it was just flushed
(define *server:last-write-flush* (current-milliseconds))

;; Flush the queue every third of a second. Can we assume that setup-for-run 
;; has already been done?
(define (server:write-queue-handler)
  (if (setup-for-run)
      (let ((db (open-db)))
	(let loop ()
	  (let ((last-write-flush-time #f))
	    (mutex-lock! *incoming-mutex*)
	    (set! last-write-flush-time *server:last-write-flush*)
	    (mutex-unlock! *incoming-mutex*)
	    (if (> (- (current-milliseconds) last-write-flush-time) 400)
		(begin
		  (mutex-lock! *db:process-queue-mutex*)
		  (db:process-cached-writes db)
		  (mutex-unlock! *db:process-queue-mutex*)
		  (thread-sleep! 0.5))))
	  (loop)))
      (begin
	(debug:print 0 "ERROR: failed to setup for Megatest in server:write-queue-handler")
	(exit 1))))
    
;;======================================================================
;; S E R V E R   U T I L I T I E S