.

wcfs/δbtail.go

@@ -542,7 +542,7 @@ func (rs rangeSplit) Get_(k Key) (rnode *nodeInRange, ok bool) {
 // rnode.node must be tree.
 // rnode.node must be aleady activated.
 //
-// inserted children is also return for convenience.
+// inserted children is also returned for convenience.
 func (prs *rangeSplit) Expand(rnode *nodeInRange) (children rangeSplit) {
 	rs := *prs
 	i := sort.Search(len(rs), func(i int) bool {
@@ -577,6 +577,33 @@ func (prs *rangeSplit) Expand(rnode *nodeInRange) (children rangeSplit) {
 	return children
 }
 
+// GetToBucket returns bucket corresponding to key k.
+// While reaching to that bucket, it expands step-by-step trees that are leading to that bucket.
+// XXX also return path?
+func (prs *rangeSplit) GetToBucket(ctx, k) (rbucket *nodeInRange, bool ok, err error) {
+	rnode, ok := prs.Get_(k)
+	if !ok {
+		return nil, false, nil // key not covered
+	}
+
+	for {
+		switch rnode.node.(type) {
+		case *Bucket:
+			return rnode, true, nil
+		}
+
+		// it's tree
+		err = rnode.node.PActivate(ctx)
+		if err != nil {
+			return nil, false, err
+		}
+		defer rnode.node.PDeactivate()
+
+		children := prs.Expand(rnode)
+		rnode = children.Get(k) // k must be there
+	}
+}
+
 func (rs rangeSplit) String() string {
 	s := ""
 	for _, rn := range rs {
@@ -749,21 +776,21 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 		btop := &nodeInRange{lo: KeyMin, hi_: KeyMax, node: b} // [-∞, ∞)
 		bv   = rangeSplit{btop}
 	}
-	bq := []*nodeInRange{...}
 	for k := range Bkeysq {
-		bnode, ok := bv.Get_(k)
+		bbucket, ok, err := bv.GetToBucket(ctx, k)
 		if !ok {
 			continue // key not covered
 		}
 
-		for {
-			switch bnode.node.(type) {
-			case *Tree:
-				err := bnode.node.PActivate(ctx); X(err)
-				defer bnode.node.PDeactivate()
+		bbucket.node.(*Bucket)
+		δB, err := diffB(ctx, nil, bbucket.node.(*Bucket))
+		if err != nil {
+			return nil, err
+		}
 
-			case *Bucket:
-			btree, ok := bnode.node.(*Tree
+		// XXX δ <- δB
+		for k, δv := range δ {
+			// 
 		}
 
 	}