.

wcfs/δbtail.go

@@ -143,6 +143,14 @@ func NewΔBtail(at0 zodb.Tid) *ΔBtail {
 	}
 }
 
+// XXX
+func newΔTtail() *ΔTreeTail {
+	return &ΔTreeTail{
+		KVAtTail:  make(map[Key]Value),
+		lastRevOf: make(map[Key]zodb.Tid),
+	}
+}
+
 // Head is similar to zodb.ΔTail.Head .		XXX ok?
 func (δBtail *ΔBtail) Head() zodb.Tid {
 	//return δb.head
@@ -187,6 +195,11 @@ func (δBtail *ΔBtail) Track(path []Node) {	// XXX Tree|Bucket; path[0] = root
 		nodeRoots.Add(root)
 	}
 
+	_, ok := δBtail.byRoot[root]
+	if !ok {
+		δBtail.byRoot[root] = newΔTtail()
+	}
+
 	// XXX update diff	XXX here? or as separate step?
 	// XXX update lastRevOf
 }