Megatest

    (if (and (file-write-access? fname)
	     (file-exists? busy-file))
	(begin
	  (if (common:low-noise-print 120 busy-file)
	      (dbfile:print-err "INFO: dbfile:cautious-open-database: journal file "
				busy-file" exists, trying again in few seconds."))
	  (thread-sleep! 1)
	  (if (eq? tries-left 2)
	      (begin
	  	(dbfile:print-err "INFO: forcing journal rollup "busy-file)
	  	(dbfile:brute-force-salvage-db fname)))
	  (dbfile:cautious-open-database fname init-proc (- tries-left 1)))

	(let* ((result (condition-case
		         (if dir-access
			   (dbfile:with-simple-file-lock
			    (conc fname ".lock")
			    (lambda ()

      (exn (busy)
	   (db:generic-error-printout exn "ERROR: database " fname
				      " is locked. Try copying to another location, remove original and copy back."))
      (exn (permission)(db:generic-error-printout exn "ERROR: database " fname " has some permissions problem."))
      (exn ()
	   (db:generic-error-printout exn "ERROR: Unknown error with database " fname " message: "
				      ((condition-property-accessor 'exn 'message) exn))))))

;;======================================================================
;; another attempt at a transactionized queue
;;======================================================================

;; ;; ;; (define *transaction-queues* (make-hash-table))
;; ;; ;; 
;; ;; ;; (define (db:get-queue run-id)
;; ;; ;;   (let* ((res (hash-table-ref/default *transaction-queues* run-id #f)))
;; ;; ;;     (if res
;; ;; ;; 	res
;; ;; ;; 	(let* ((newq (make-queue)))
;; ;; ;; 	  (hash-table-set! *transaction-queues* run-id newq)
;; ;; ;; 	  newq))))
;; ;; ;; 
;; ;; ;; (define (db:add-to-transaction-queue dbstruct proc params)
;; ;; ;;   (let* ((mbox (make-mailbox))
;; ;; ;; 	 (q    (db:get-queue run-id)))
;; ;; ;;     (queue-add! *transaction-queue* (list dbstruct proc mbox))
;; ;; ;;     (mailbox-receive mbox)))
;; ;; ;; 
;; ;; ;; (define (db:process-transaction-queue *dbstruct-dbs*)
;; ;; ;;   (for-each
;; ;; ;;    (lambda (run-id)
;; ;; ;;      (let* ((q (hash-table-ref *transaction-queue* run-id)))
;; ;; ;;        ;; with-transaction
;; ;; ;;        ;;     dbstruct
;; ;; ;;        ;; pop items from queue and execute them, return results via mailbox
;; ;; ;;        q
;; ;; ;;        ;; pop 
;; ;; ;;        ))
;; ;; ;;    (hash-table-keys *transaction-queues*)))

;;======================================================================
;; file utils
;;======================================================================

;;======================================================================
;; lazy-safe get file mod time. on any error (file not existing etc.) return 0