.

wcfs/δbtail.go

@@ -538,8 +538,18 @@ func (prs *rangeSplit) Expand(rnode *nodeInRange) (children rangeSplit) {
 // Leaf is usually bucket node, but, in the sole single case of empty tree, can be that root tree node.
 // GetToLeaf expands step-by-step every tree through which it has to traverse to next depth level.
 //
+// GetToLeaf panics if k is not covered.
 // XXX also return path?
-func (prs *rangeSplit) GetToLeaf(ctx context.Context, k Key) (rnode *nodeInRange, ok bool, err error) {
+func (prs *rangeSplit) GetToLeaf(ctx context.Context, k Key) (*nodeInRange, error) {
+	rnode, ok, err := prs.GetToLeaf_(ctx, k)
+	if err == nil && !ok {
+		panicf("key %v not covered;  coverage: %s", k, *prs)
+	}
+	return rnode, err
+}
+
+// GetToLeaf_ is comma-ok version of GetToLeaf.
+func (prs *rangeSplit) GetToLeaf_(ctx context.Context, k Key) (rnode *nodeInRange, ok bool, err error) {
 	rnode, ok = prs.Get_(k)
 	if !ok {
 		return nil, false, nil // key not covered
@@ -561,7 +571,7 @@ func (prs *rangeSplit) GetToLeaf(ctx context.Context, k Key) (rnode *nodeInRange
 		defer tree.PDeactivate()
 
 		// empty tree -> don't expand - it is already leaf
-		if len(tree.Entryv()) == 0{
+		if len(tree.Entryv()) == 0 {
 			return rnode, true, nil
 		}