Return error if invalid range

bitcask.go

@@ -57,6 +57,7 @@ var (
 	// (typically opened by another process)
 	ErrDatabaseLocked = errors.New("error: database locked")
 
+	ErrInvalidRange   = errors.New("error: invalid range")
 	ErrInvalidVersion = errors.New("error: invalid db version")
 
 	// ErrMergeInProgress is the error returned if merge is called when already a merge
@@ -276,15 +277,18 @@ func (b *Bitcask) Scan(prefix []byte, f func(key []byte) error) (err error) {
 // If the function returns an error no further keys are processed and the
 // first error returned.
 func (b *Bitcask) Range(start, end []byte, f func(key []byte) error) (err error) {
+	if bytes.Compare(start, end) == 1 {
+		return ErrInvalidRange
+	}
+
 	b.trie.ForEach(func(node art.Node) bool {
 		if bytes.Compare(node.Key(), start) >= 0 && bytes.Compare(node.Key(), end) <= 0 {
 			if err = f(node.Key()); err != nil {
 				return false
 			}
 			return true
-		} else {
-			return false
 		}
+		return false
 	})
 	return
 }

bitcask_test.go

@@ -1679,6 +1679,14 @@ func TestRange(t *testing.T) {
 		assert.Error(err)
 		assert.Equal(ErrMockError, err)
 	})
+
+	t.Run("InvalidRange", func(t *testing.T) {
+		err = db.Range([]byte("foo_3"), []byte("foo_1"), func(key []byte) error {
+			return nil
+		})
+		assert.Error(err)
+		assert.Equal(ErrInvalidRange, err)
+	})
 }
 
 func TestLocking(t *testing.T) {

cmd/bitcask/range.go

@@ -53,7 +53,7 @@ func _range(path, start, end string) int {
 		return nil
 	})
 	if err != nil {
-		log.WithError(err).Error("error rangening keys")
+		log.WithError(err).Error("error ranging over keys")
 		return 1
 	}