Megatest

                                 (sqlite3:set-busy-handler! db (sqlite3:make-busy-timeout 30000))
				 (if sync-mode
				     (sqlite3:execute db (conc "PRAGMA synchronous = "sync-mode";")))
				 (if journal-mode
				     (sqlite3:execute db (conc "PRAGMA journal_mode = "journal-mode";")))
				 (if (and init-proc (not db-exists))
				     (init-proc db))
				 db))
			     expire-time: 30)
                            (begin
			      (if (file-exists? fname )
                                  (let ((db (sqlite3:open-database fname)))
				    ;; pragmas synchronous not needed because this db is used read-only
				    ;; (sqlite3:execute db (conc "PRAGMA synchronous = "mode";")
				    (sqlite3:set-busy-handler! db (sqlite3:make-busy-timeout 30000)) ;; read-only but still need timeout
				    db )
                                  (print "cautious-open-database: file doesn't exist: " fname))))
			(exn (io-error)
			     (dbfile:print-err exn "ERROR: i/o error with " fname ". Check permissions, disk space etc. and try again.")
			     (retry))
			(exn (corrupt)
			     (dbfile:print-err exn "ERROR: database " fname " is corrupt. Repair it to proceed.")
			     (retry))
			(exn (busy)

	  (thread-sleep! 0.25)
	  (if (file-exists? fname)
	      (handle-exceptions exn
                #f 
                (with-input-from-file fname
	  	  (lambda ()
		    (equal? key-string (read-line)))))
              (begin
                (dbfile:print-err "dbfile:simple-file-lock created " fname " but it was gone 0.25 seconds later")
	      #f
              )
          )
       )
    )
  )
)

(define (dbfile:simple-file-lock-and-wait fname #!key (expire-time 300))
  (let ((end-time (+ expire-time (current-seconds))))