Megatest

;; not used, intended to indicate to run in calling process
(define db:run-local-queries '()) ;; rollup-tests-pass-fail))

(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! *incoming-writes* '())
    (mutex-unlock! *incoming-mutex*)
    (if (> (length data) 0)
	;; Process if we have data
	(begin
	  (debug:print-info 7 "Writing cached data " data)
    
	  ;; Prepare the needed sql statements
	  ;;
	  (for-each (lambda (request-item)
		      (let ((stmt-key (vector-ref request-item 0))

			    (query    (vector-ref request-item 1)))

			(hash-table-set! queries stmt-key (sqlite3:prepare db query))))

		    data)
	  
	  ;; No outer loop needed. Single loop for write items only. Reads trigger flush of queue
	  ;; and then are executed.
	  (sqlite3:with-transaction 
	   db
	   (lambda ()

	     (for-each
	      (lambda (hed)
		(let* ((params   (vector-ref hed 2))
		       (stmt-key (vector-ref hed 0))
		       (stmt     (hash-table-ref/default queries stmt-key #f)))
		  (if stmt
		      (apply sqlite3:execute stmt params)
		      (debug:print 0 "ERROR: Problem Executing " stmt-key " for " params))))
	      data)))
	  
	  ;; let all the waiting calls know all is done
	  (mutex-lock! *completed-mutex*)
	  (for-each (lambda (item)
		      (let ((qry-sig (cdb:packet-get-client-sig item)))
			(debug:print-info 7 "Registering query " qry-sig " as done")
			(hash-table-set! *completed-writes* qry-sig #t)))
		    data)
	  (mutex-unlock! *completed-mutex*)
	  
	  ;; Finalize the statements. Should this be done inside the mutex above?
	  ;; I think sqlite3 mutexes will keep the data safe
	  (for-each (lambda (stmt-key)
		      (sqlite3:finalize! (hash-table-ref queries stmt-key)))
		    (hash-table-keys queries))
	  
	  ;; Do a little record keeping
	  (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))

;; 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))
	(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*)

    (debug:print-info 7 "Current write queue length is " queue-len)

    ;; poll for the write to complete, timeout after 10 seconds
    ;; periodic flushing of the queue is taken care of by 
    ;; db:flush-queue
    (let loop ()
      (thread-sleep! 0.1)
      (mutex-lock! *completed-mutex*)

	 (return-address (cdb:packet-get-client-sig item))
	 (params         (cdb:packet-get-params item))
	 (query          (let ((q (alist-ref stmt-key db:queries)))
			   (if q (car q) #f))))
    (debug:print-info 11 "Special queries/requests stmt-key=" stmt-key ", return-address=" return-address ", query=" query ", params=" params)
    (if query
	;; hand queries off to the write queue

	(let ((response (case *transport-type*
			  ((http)
			   (debug:print-info 7 "Queuing item " item " for wrapped write")
			   (db:queue-write-and-wait db qry-sig query params))
			  (else  
			   (apply sqlite3:execute db query params)
			   #t))))
	  (debug:print-info 7 "Received " response " from wrapped write")
	  (server:reply return-address qry-sig response response))
	;; otherwise if appropriate flush the queue (this is a read or complex query)
	(begin
	  (case *transport-type*
	    ((http)(db:process-cached-writes db)))
	  (cond
	   ((member stmt-key db:special-queries)
	    (debug:print-info 11 "Handling special statement " stmt-key)