.

wcfs/internal/xbtree/δbtail.go

@@ -34,7 +34,7 @@ package xbtree
 //
 // Because it is very computationally expensive(+) to find out for an object to
 // which BTree it belongs, ΔBtail cannot provide full BTree-level history given
-// just ΔZtail with δZ changes. Because of this ΔBtail requires help from
+// just ΔZtail with δZ changes. Due to this ΔBtail requires help from
 // users, which are expected to call ΔBtail.Track(treepath) to let ΔBtail know
 // that such and such ZODB objects constitute a path from root of a tree to some
 // of its leaf. After Track call the objects from the path and tree keys, that
@@ -310,18 +310,15 @@ 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, for non-empty tree, must be Bucket.
+// path[-1] signifies leaf node.
+// keycov should be key range covered by the leaf node.
 //
-// Besides key (which might point to value or hole), δBtail will also track all		XXX
-// 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.
+// ΔBtail will start tracking provided tree nodes and keys ∈ keycov.
 //
-// Objects in path must be with .PJar().At() == .Head()
-func (δBtail *ΔBtail) Track(keycov KeyRange, nodePath []Node) {
-	// NOTE key not needed for anything besides tracing	XXX kill comment
-	// (tracking set will be added with all keys, covered by leaf keyrange)
-
+// All path elements must be Tree except last one which, for non-empty tree, must be Bucket.
+//
+// Objects in the path must be with .PJar().At() == .Head()
+func (δBtail *ΔBtail) Track(nodePath []Node, keycov KeyRange) {
 	if traceΔBtail {
 		pathv := []string{}
 		for _, node := range nodePath { pathv = append(pathv, vnode(node)) }
@@ -338,7 +335,7 @@ func (δBtail *ΔBtail) Track(keycov KeyRange, nodePath []Node) {
 	}
 
 	path := nodePathToPath(nodePath)
-	δBtail.track(keycov, path)
+	δBtail.track(path, keycov)
 }
 
 // nodePathToPath converts path from []Node to []Oid.
@@ -366,7 +363,7 @@ func nodePathToPath(nodePath []Node) (path []zodb.Oid) {
 	return path
 }
 
-func (δBtail *ΔBtail) track(keycov KeyRange, path []zodb.Oid) {
+func (δBtail *ΔBtail) track(path []zodb.Oid, keycov KeyRange) {
 	// XXX locking
 
 	// first normalize path: remove embedded bucket and check if it was an

wcfs/internal/xbtree/δbtail_test.go

@@ -1768,7 +1768,7 @@ func trackKeys(δbtail *ΔBtail, t *xbtreetest.Commit, keys setKey) {
 		// tracking set. By aligning initial state to the same as after
 		// T1->ø, we test what will happen on ø->T2.
 		b := t.Xkv.Get(k)
-		δbtail.track(b.Keycov, b.Path())
+		δbtail.track(b.Path(), b.Keycov)
 	}
 }
 

wcfs/internal/zdata/δftail.go

@@ -225,7 +225,7 @@ func (δFtail *ΔFtail) Track(file *ZBigFile, blk int64, path []btree.LONode, bl
 //	if blk == -1 {
 //		blk = xbtree.KeyMax
 //	}
-	δFtail.δBtail.Track(blkcov, path)
+	δFtail.δBtail.Track(path, blkcov)
 
 	rootObj := path[0].(*btree.LOBTree)
 	root    := rootObj.POid()