Megatest

;; transaction protected lock aquisition
;; either:
;;    fails    returns  (#f . lock-creation-time)
;;    succeeds (returns (#t . lock-creation-time)
;; use (db:no-sync-del! db keyname) to release the lock
;;
(define (db:no-sync-get-lock db keyname)
  (sqlite3:with-transaction
   (db:no-sync-db db)
   (lambda ()
     (handle-exceptions
	 exn
	 (let ((lock-time (current-seconds)))
	   (sqlite3:execute db "INSERT INTO no_sync_metadat (var,val) VALUES(?,?);" keyname lock-time)
	   `(#t . ,lock-time))
       `(#f . ,(sqlite3:first-result db "SELECT val FROM no_sync_metadat WHERE var=?;" keyname))))))
(define (db:no-sync-get-lock db-in keyname)
  (let ((db (db:no-sync-db db-in)))
    (sqlite3:with-transaction
     db
     (lambda ()
       (handle-exceptions
	   exn
	   (let ((lock-time (current-seconds)))
	     (sqlite3:execute db "INSERT INTO no_sync_metadat (var,val) VALUES(?,?);" keyname lock-time)
	     `(#t . ,lock-time))
	 `(#f . ,(sqlite3:first-result db "SELECT val FROM no_sync_metadat WHERE var=?;" keyname)))))))



;; use a global for some primitive caching, it is just silly to
;; re-read the db over and over again for the keys since they never
;; change