(lmdb): Fix error-handlingHEADmain

1 files changed, 46 insertions, 34 deletions

diff --git a/lmdb.scm b/lmdb.scm
index 39d3846..e1f2b8e 100644
--- a/lmdb.scm
+++ b/lmdb.scm
@@ -68,8 +68,9 @@
     (raise-lmdb-error txn))
 
   ;; open a database
-  ;; TODO error handling
-  (define dbi (mdb-dbi-open txn))
+  (define dbi (mdb-dbi-open txn #:name db-name))
+  (unless (mdb-dbi? dbi)
+    (raise-lmdb-error dbi))
 
   ;; commit transaction so that database handle can now be used from other
   ;; transactions
@@ -126,35 +127,46 @@
      (else (raise-lmdb-error return-value)))))
 
 (define (lmdb-range db start-key end-key)
-  (let* ((txn (mdb-txn-begin (lmdb-db-env db)))
-         (cursor (mdb-cursor-open txn (lmdb-db-dbi db)))
-         ;; wrap start-key and end-key as mdb-val
-         (start-key-val (make-mdb-val start-key))
-         (end-key-val (make-mdb-val end-key))
-         ;; get an initial value with mdb-cursor-set
-         (init-value (mdb-cursor-set cursor start-key-val MDB_SET_RANGE)))
-    (make-coroutine-generator
-     (lambda (yield)
-       (let next ((return-value init-value))
-         (cond
-
-          ;; returned value is a key-value pair
-          ((pair? return-value)
-           ;; compare value with end-key and only yield if within range
-           (if (>= 0 (mdb-cmp txn (lmdb-db-dbi db) (car return-value) end-key-val))
-               (begin
-                 ;; yield key-value pair
-                 (yield (cons (mdb-val-data (car return-value))
-                              (mdb-val-data (cdr return-value))))
-                 ;; loop with next value
-                 (next (mdb-cursor-get cursor MDB_NEXT)))
-               (mdb-txn-abort txn)))
-
-          ;; no value found, end generator
-          ((equal? MDB_NOTFOUND return-value)
-           (mdb-txn-abort txn))
-
-          ;; unexpected return code, raise an error
-          ((integer? return-value)
-           (mdb-txn-abort txn)
-           (raise-lmdb-error return-value))))))))
+
+  ;; create a new read-only transaction
+  (define txn (mdb-txn-begin (lmdb-db-env db) #:flags MDB_RDONLY))
+  (unless (mdb-txn? txn)
+    (raise-lmdb-error txn))
+
+  ;; create a new cursor
+  (define cursor (mdb-cursor-open txn (lmdb-db-dbi db)))
+  (unless (mdb-cursor? cursor)
+    (raise-lmdb-error cursor))
+
+  ;; wrap start-key and end-key as mdb-val
+  (define start-key-val (make-mdb-val start-key))
+  (define end-key-val (make-mdb-val end-key))
+
+  ;; get an initial value with mdb-cursor-set
+  (define init-value (mdb-cursor-set cursor start-key-val MDB_SET_RANGE))
+
+  (make-coroutine-generator
+   (lambda (yield)
+     (let next ((return-value init-value))
+       (cond
+
+        ;; returned value is a key-value pair
+        ((pair? return-value)
+         ;; compare value with end-key and only yield if within range
+         (if (>= 0 (mdb-cmp txn (lmdb-db-dbi db) (car return-value) end-key-val))
+             (begin
+               ;; yield key-value pair
+               (yield (cons (mdb-val-data (car return-value))
+                            (mdb-val-data (cdr return-value))))
+               ;; loop with next value
+               (next (mdb-cursor-get cursor MDB_NEXT)))
+             (mdb-txn-abort txn)))
+
+        ;; no value found, end generator
+        ((equal? MDB_NOTFOUND return-value)
+         (mdb-txn-abort txn))
+
+        ;; unexpected return code, raise an error
+        ((integer? return-value)
+         (mdb-txn-abort txn)
+         (raise-lmdb-error return-value)))))))