.

wcfs/internal/xbtree/δbtail.go

@@ -225,18 +225,19 @@ func (δBtail *ΔBtail) Tail() zodb.Tid { return δBtail.δZtail.Tail() }
 // Track adds tree path to tracked set.
 //
 // path[0] signifies tree root.
-// All path elements must be Tree except last one which must be Bucket.
+// All path elements must be Tree except last one which, for non-empty tree, must be Bucket.
 //
 // Besides key (which might point to value or hole), δBtail will also track all
-// keys covered by tracked leaf nodes. In particular after request for KeyMax or
-// KeyMin to be tracked, δBtail will keep on tracking changes to maximum or
-// minimum keys correspondingly.
+// keys covered by leaf node. In particular after request for KeyMax or KeyMin
+// to be tracked, δBtail will keep on tracking changes to maximum or minimum
+// keys correspondingly.
 //
-// XXX objects in path must be with .PJar().At() == .head
-//
-// XXX catch cycles on add?
-// XXX no need to pass in key?  (-> all keys, covered by leaf keyrange, will be added to tracking set of keys)
-func (δBtail *ΔBtail) Track(key Key, nodePath []Node) { // XXX Tree|Bucket; path[0] = root
+// Objects in path must be with .PJar().At() == .Head()
+func (δBtail *ΔBtail) Track(key Key, nodePath []Node) {
+	// NOTE key not needed for anything besides tracing
+	// (tracking set will be added with all keys, covered by leaf keyrange)
+
+	// XXX assert node.PJar().At() == .Head()
 
 	path := nodePathToPath(nodePath)