.

wcfs/δbtail.go

@@ -782,9 +782,14 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 	// corresponding nodes, and merge diff generated from them into δ.
 	// Each delve for A or B, potentially adds new keys to process on the
 	// other side.
+	//
+	// XXX inneficient: we process each key separately, while they can be
+	// processed in sorted batches.
 	for len(Aqueue) > 0 || len(Bqueue) > 0 {
+		// B queue
 		// expand keys in new δA -> in B till buckets;
 		// process B buckets that cover new keys into δ+
+		Aqueue = SetKey{}
 		for k := range Bqueue {
 			Bdone.Add(k)
 			bbucket, ok, err := bv.GetToBucket(ctx, k)
@@ -806,14 +811,42 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 			}
 
 			// Aqueue <- δB
-			for k, δv := range δ {
+			for k := range δB {
 				if !Adone.Has(k) {
 					Aqueue.Add(k)
 				}
+			}
 
-				_ = δv
+		}
+
+		// A queue
+		Bqueue = SetKey{}
+		for k := range Aqueue {
+			Adone.Add(k)
+			abucket, ok, err := av.GetToBucket(ctx, k)
+			if !ok {
+				continue // key not covered
 			}
 
+			// XXX check bucket for already "done"
+
+			δA, err := diffB(ctx, abucket.node.(*Bucket), nil)
+			if err != nil {
+				return nil, err
+			}
+
+			// δ <- δA
+			err = δMerge(δ, δA)
+			if err != nil {
+				return nil, err
+			}
+
+			// Bqueue <- δA
+			for k := range δA {
+				if !Bdone.Has(k) {
+					Bqueue.Add(k)
+				}
+			}
 		}
 
 	}