.

wcfs/δbtail.go

@@ -40,6 +40,7 @@ type Tree   = btree.LOBTree
 type Bucket = btree.LOBucket
 type Node   = btree.LONode
 
+type TreeEntry   = btree.LOEntry
 type BucketEntry = btree.LOBucketEntry
 
 type Key    = int64
@@ -417,20 +418,25 @@ func diffX(ctx context.Context, a, b Node, δZTC SetOid) (δ map[Key]Value, err
 func diffT(ctx context.Context, a, b *Tree, δZTC SetOid) (δ map[Key]Value, err error) {
 	fmt.Printf("  T %s %s\n", xidOf(a), xidOf(b))
 	defer xerr.Contextf(&err, "diffT %s %s", xidOf(a), xidOf(b))
-	if a.POid() != b.POid() {
+
+	if (a != nil && b != nil) && (a.POid() != b.POid()) {
 		panic("different trees")
 	}
 
-	// XXX a/b = nil - means del/add -> handle
-
-	err = a.PActivate(ctx);  if err != nil { return nil, err }
-	defer a.PDeactivate()
-	err = b.PActivate(ctx);  if err != nil { return nil, err }
-	defer b.PDeactivate()
+	var av []TreeEntry
+	var bv []TreeEntry
+	if a != nil {
+		err = a.PActivate(ctx);  if err != nil { return nil, err }
+		defer a.PDeactivate()
+		av  = a.Entryv() // key↑
+	}
+	if b != nil {
+		err = b.PActivate(ctx);  if err != nil { return nil, err }
+		defer b.PDeactivate()
+		bv  = b.Entryv() // key↑
+	}
 
-	av := a.Entryv() // key↑
-	bv := b.Entryv() // key↑
-	δ   = map[Key]Value{}
+	δ = map[Key]Value{}
 
 	// [i].Key ≤ [i].Child.*.Key < [i+1].Key  i ∈ [0, len([]))
 	//
@@ -494,11 +500,10 @@ func diffB(ctx context.Context, a, b *Bucket) (δ map[Key]Value, err error) {
 	fmt.Printf("  B %s %s\n", xidOf(a), xidOf(b))
 	defer xerr.Contextf(&err, "diffB %s %s", xidOf(a), xidOf(b))
 	// XXX oid can be InvalidOid for T/B... (i.e. B is part of T and is not yet committed separately)
-	if a.POid() != b.POid() {
+	if (a != nil && b != nil) && (a.POid() != b.POid()) {
 		panic("different buckets")
 	}
 
-	// XXX a/b = nil - means del/add -> handle
 
 	var av []BucketEntry
 	var bv []BucketEntry