.

wcfs/δbtail.go

@@ -52,6 +52,12 @@ const VDEL  = zodb.InvalidOid
 type Oid    = zodb.Oid
 type SetKey = SetI64
 
+// ΔValue represents change in value.
+type ΔValue struct {
+	Vold Value
+	Vnew Value
+}
+
 
 // ΔBtail represents tail of revisional changes to BTrees.
 //
@@ -431,13 +437,15 @@ func diffX(ctx context.Context, a, b Node, δZTC SetOid) (δ map[Key]Value, err
 //
 // a, b point to top of the subtree @old and @new revisions.
 // δZTC is connected set of objects covering δZT (objects changed in this tree in old..new).
-func diffT(ctx context.Context, a, b *Tree, δZTC SetOid) (δ map[Key]Value, err error) {
+func diffT(ctx context.Context, a, b *Tree, δZTC SetOid) (δ map[Key]ΔValue, 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 != nil && b != nil) && (a.POid() != b.POid()) {
-		panic("different trees")	// XXX wrong - tree object can be changed completely
+		panic("different trees")	// XXX wrong - tree object can be changed completely ?
 	}
+*/
 
 	var av []TreeEntry
 	var bv []TreeEntry
@@ -499,7 +507,7 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid) (δ map[Key]Value, err
 					return nil, fmt.Errorf("BUG or btree corrupt: [%v] has " +
 							"duplicate entries: %v, %v", k, vprev, v)
 				}
-				delete(δ, k)
+				delete(δ, k)	// FIXME does not notice change in v on reflow
 			}
 		}
 
@@ -522,13 +530,15 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid) (δ map[Key]Value, err
 
 // diffB computes difference in between two revisions of a bucket.
 // see diffX for details.
-func diffB(ctx context.Context, a, b *Bucket) (δ map[Key]Value, err error) {
+func diffB(ctx context.Context, a, b *Bucket) (δ map[Key]ΔValue, 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 != nil && b != nil) && (a.POid() != b.POid()) {
-		panic("different buckets") // XXX wrong - bucket object can be changed completely
+		panic("different buckets") // XXX wrong - bucket object can be changed completely ?
 	}
+*/
 
 
 	var av []BucketEntry
@@ -572,17 +582,17 @@ func diffB(ctx context.Context, a, b *Bucket) (δ map[Key]Value, err error) {
 
 		switch {
 		case ka < kb: // -a[0]
-			δ[ka] = VDEL
+			δ[ka] = ΔValue{va, VDEL}
 			av = av[1:]
 
 		case ka > kb: // +b[0]
-			δ[kb] = vb
+			δ[kb] = ΔValue{VDEL, vb}
 			bv = bv[1:]
 
 		// ka == kb   // va->vb
 		default:
 			if va != vb {
-				δ[ka] = vb
+				δ[ka] = ΔValue{va, vb}
 			}
 			av = av[1:]
 			bv = bv[1:]