Megatest

	    (debug:print-info 13 *default-log-port* "after db:setup with dbstruct=" dbstruct)
	    (cond
	     ((dbr:dbstruct-read-only dbstruct)
	      (debug:print-info 13 *default-log-port* "loading read-only watchdog")
	      (common:readonly-watchdog dbstruct))
	     (else
	      (debug:print-info 13 *default-log-port* "loading writable-watchdog.")
              (let* ((syncer (or (configf:lookup *configdat* "server" "sync-method") "copy-sync"))) ;; "delta-sync"))) ;; "brute-force-sync")))
                (cond
                 ((equal? syncer "brute-force-sync")
                  (server:writable-watchdog-bruteforce dbstruct))
                 ((equal? syncer "delta-sync")
                  (server:writable-watchdog-deltasync dbstruct))
                 ((equal? syncer "copy-sync")
                  (server:writable-watchdog-copysync dbstruct))
                 (else
                  (debug:print-error 0 *default-log-port* "Unknown server/sync-method specified ("syncer") - valid values are brute-force-sync and delta-sync.")
                  (exit 1)))
                ;;(debug:print 1 *default-log-port* "INFO: ["(common:human-time)"] Syncer started (method="syncer")")
                )))
	    (debug:print-info 13 *default-log-port* "watchdog done."))
	  (debug:print-info 13 *default-log-port* "no need for watchdog on non-homehost"))))

      ;; time to exit, close the no-sync db here
      (final-sync)

      (if (common:low-noise-print 30)
	  (debug:print-info 0 *default-log-port* "Exiting watchdog timer, *time-to-exit* = " *time-to-exit*" pid="(current-process-id)
			    )))))


(define (db:lock-and-sync no-sync-db from-db to-db)
  (assert (not *db-sync-in-progress*) "FATAL: db:lock-and-sync called while a sync is in progress.")
  (let* ((lockdat  (db:no-sync-get-lock no-sync-db from-db))
	 (gotlock  (car lockdat))
	 (locktime (cdr lockdat)))
    (if gotlock
	(begin
	  (file-copy from-db to-db)
	  (db:no-sync-del! no-sync-db keyname)
	  #t)
	#f)))

;; straight forward copy based sync
;;  1. for each .db file
;;  2. next if file changed since last sync cycle
;;  2. next if time delta /tmp file to MTRA less than 3 seconds
;;  3. get a lock for the file in nosyncdb
;;  4. copy the file
;;  5. when copy is done release the lock
;;
;;  DONE
(define (server:writable-watchdog-copysync dbstruct)
  (thread-sleep! 0.05) ;; delay for startup
  (let ((legacy-sync        (common:run-sync?))
	(sync-stale-seconds (configf:lookup-number *configdat* "server" "sync-stale-seconds" default: 300))
 	(debug-mode         (debug:debug-mode 1))
 	(last-time          (current-seconds))     ;; last time through the sync loop
 	(no-sync-db         (db:open-no-sync-db))
 	(sync-duration      0)  ;; run time of the sync in milliseconds
	(tmp-area           (common:get-db-tmp-area)))
    (set! *no-sync-db* no-sync-db) ;; make the no sync db available to api calls
    (debug:print-info 2 *default-log-port* "Periodic sync thread started.")
    (debug:print-info 3 *default-log-port* "watchdog starting. legacy-sync is "legacy-sync" pid="(current-process-id));;  " this-wd-num="this-wd-num)
    
    (if (and legacy-sync (not *time-to-exit*))
 	(begin
 	  (debug:print-info 0 *default-log-port* "Server running, periodic sync started.")
	  (let loop ()
 	    ;; sync for filesystem local db writes
 	    ;;
	    (let* ((dbfiles    (glob (conc tmp-area"/.db/*.db"))))
	      (for-each
	       (lambda (file)
		 (let* ((fname (pathname-file file))
			(fulln (conc *top-level*"/.db/"fname))
			(time1 (file-modification-time fname))
			(time2 (file-modification-time fulln))
			(changed (>= time1 time2))
			(do-cp (cond
				((not (file-exists? fulln)) ;; shouldn't happen, but this might recover
				 (debug:print-info 0 "File "fulln" not found! Copying "fname" to "fulln)
				 #t)
				((and changed
				      (> (- (current-seconds) time1) 3)) ;; if file is changed and three seconds have passed.
				 #t)
				((and changed *time-to-exit*) ;; last copy
				 #t)
				(else
				 #f))))
		   (if do-cp
		       (let* ((start-time (current-milliseconds)))
			 (db:lock-and-sync no-sync-db fname fulln)
			 (set! sync-duration (- (current-milliseconds) start-time))))))
	       dbfile))
	    ;; keep going unless time to exit
	    ;;
	    (if (not *time-to-exit*)
		(let delay-loop ((count 0))
		  ;;(debug:print-info 13 *default-log-port* "delay-loop top; count="count" pid="(current-process-id)" this-wd-num="this-wd-num" *time-to-exit*="*time-to-exit*)
		  
		  (if (and (not *time-to-exit*)
			   (< count 6)) ;; was 11, changing to 4. 
		      (begin
			(thread-sleep! 1)
			(delay-loop (+ count 1))))
		  (if (not *time-to-exit*) (loop))))
	    
	    ;; ==> 	       ;; time to exit, close the no-sync db here
	    ;; ==> 	       (db:no-sync-close-db no-sync-db stmt-cache)
	    (if (common:low-noise-print 30)
		(debug:print-info 0 *default-log-port* "Exiting watchdog timer, *time-to-exit* = "
				  *time-to-exit*" pid="(current-process-id) )))))))

(define (server:writable-watchdog-deltasync dbstruct)
  ;; This is awful complex and convoluted. Plan to redo?
  ;; for now ... skip it.
;; ==> 
;; ==> (thread-sleep! 0.05) ;; delay for startup
;; ==> (let ((legacy-sync  (common:run-sync?))
;; ==>       (sync-stale-seconds (configf:lookup-number *configdat* "server" "sync-stale-seconds" default: 300))