ks-transaction added.

keystore.rkt

@@ -108,7 +108,9 @@
 (define-syntax ks-transaction
   (syntax-rules ()
     ((_ ks b1 ...)
-     (begin
+     (with-handlers ([exn? (λ (e)
+                             (query-exec (keystore-dbh ks) "ROLLBACK")
+                             (raise e))])
        (query-exec (keystore-dbh ks) "BEGIN")
        (let ((r (begin b1 ...)))
          (query-exec (keystore-dbh ks) "COMMIT")

scrbl/keystore.scrbl

@@ -121,6 +121,14 @@ Returns raw key-value rows in the form:
 ]
 }
 
+
+@defform[(ks-transaction [ks keystore?] b1 ...)]{
+
+Puts b1 ... in a "BEGIN/COMMIT" transaction.
+It uses with-handlers exn?, so if you raise an exception,
+it will do a "BEGIN/ROLLBACK" abd re-raise the exception. 
+}
+
 @section{Examples}
 
 @subsection{Basic Usage}