.

wcfs/δbtail.go

@@ -877,7 +877,6 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 		Aqueue = SetKey{}
 		for k := range Bqueue {
 			fmt.Printf("  B [%v]\n", k)
-			Bdone.Add(k)
 			bnode, ok, err := bv.GetToLeaf(ctx, k)
 			if err != nil {
 				return nil, err
@@ -889,8 +888,7 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 
 			// XXX check for bnode.node.(*Tree)   (ø tree case)
 
-			// + bucket if not already done
-			// XXX update track.hole if k not in bbucket
+			// +bucket if that bucket is reached for the first time
 			if !bnode.done {
 				δB, err := diffB(ctx, nil, bnode.node.(*Bucket))
 				if err != nil {
@@ -903,16 +901,25 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 					return nil, err
 				}
 
+				// Bdone  <- δB
 				// Aqueue <- δB
-				for k := range δB {
-					if !Adone.Has(k) {
-						Aqueue.Add(k)
+				for k_ := range δB {
+					Bdone.Add(k_)
+					if !Adone.Has(k_) {
+						Aqueue.Add(k_)
 					}
 				}
 
 				bnode.done = true
 			}
 
+			// add k as hole if k is not there
+			if !Bdone.Has(k) {
+				δB := map[Key]ΔValue{k: {VDEL, VDEL}} // hole
+				err = δMerge(δ, δB);  if err != nil { return nil, err }
+				Bdone.Add(k)
+			}
+
 			fmt.Printf("  bv: %s\n", bv)
 		}
 
@@ -1000,7 +1007,7 @@ func δMerge(δ, δ2 map[Key]ΔValue) error {
 		if δv.Old != δv.New {
 			δ[k] = δv
 		} else {
-			delete(δ, k)
+			delete(δ, k) // NOTE also annihilates hole migration
 		}
 	}