.

wcfs/δbtail.go

@@ -379,7 +379,23 @@ func (δBtail *ΔBtail) treediff(ctx context.Context, root zodb.Oid, δZT SetOid
 	return δT, nil
 }
 
-// diffT computes difference in between two revisions of a tree's substree.
+// diffX computes difference in between two revisions of a tree's subtree.
+//
+// a, b point to top of the subtree @old and @new revisions and must be of the
+// same type - tree or bucket.
+//
+// δZTC is connected set of objects covering δZT (objects changed in this tree in old..new).
+//
+// a/b can be = nil; a=nil means addition, b=nil means deletion.
+func diffX(ctx context.Context, a, b Node, δZTC SetOid) (δ map[Key]Value, err error) {
+	if (a==nil && b==nil) {
+		panic("BUG: both a & b == nil")
+	}
+
+	panic("TODO")
+}
+
+// diffT computes difference in between two revisions of a tree's subtree.
 //
 // 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).
@@ -389,6 +405,8 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid) (δ map[Key]Value, err
 		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 }
@@ -402,48 +420,60 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid) (δ map[Key]Value, err
 	//
 	// [0].Key       = -∞ ; always returned so
 	// [len(ev)].Key = +∞ ; should be assumed so
-	aChildren := SetOid{}
-	bChildren := SetOid{}
-	for _, __ := range av { aChildren.Add(__.Child().POid()) } // InvalidOid = embedded bucket
-	for _, __ := range bv { bChildren.Add(__.Child().POid()) } // ----//----
-	allChildren := SetOid{}; allChildren.Update(aChildren); allChildren.Update(bChildren)
-
-	del := SetOid{}
-	add := SetOid{}
-	mod := SetOid{}
+	aChildren := map[zodb.Oid]Node{}
+	bChildren := map[zodb.Oid]Node{}
+	allChildren := SetOid{}
+	for _, __ := range av {
+		child := __.Child()
+		aChildren[child.POid()] = child // InvalidOid = embedded bucket
+		allChildren.Add(child.POid())
+	}
+	for _, __ := range bv {
+		child := __.Child()
+		bChildren[child.POid()] = child // ----//----
+		allChildren.Add(child.POid())
+	}
 
-	for child := range allChildren {
+	for child := range allChildren { // XXX -> sorted?
 		// add/del/modify, but child is not tracked - ignore
 		if !δZTC.Has(child) {
 			continue
 		}
 
-		ina := aChildren.Has(child)
-		inb := bChildren.Has(child)
-		switch {
-		case ina && inb:	mod.Add(child)
-		case ina:		del.Add(child)
-		case inb:		add.Add(child)
-		default:		panic("unreachable")
+		ca := aChildren[child]
+		cb := bChildren[child]
+
+		δc, err := diffX(ctx, ca, cb, δZTC)
+		if err != nil {
+			return nil, err
 		}
-	}
 
-	for child := range del { // XXX sorted ?
-		δc, err := delChild(ctx, child, δZTC) // -> removal + remove child and its children from tracked
-		// XXX err
-	}
-	for child := range add { // XXX sorted ?
-		δc, err := addChild(ctx, child, δZTC) // -> addd + add child and its children into tracked
-	}
-	for child := range mod { // XXX sorted ?
+		// merge δ <- δc
+		for k, v := range δc {
+			vprev, already := δ[k]
+			if !already {
+				δ[k] = v
+			} else {
+				// both δ and δc has [k] - it can be that key
+				// entry migrated from one bucket into another.
+				if (vprev == VDEL && v == VDEL) || (vprev != VDEL && v != VDEL) {
+					return nil, fmt.Errorf("BUG or btree corrupt: [%v] has " +
+							"duplicate entries: %v, %v", k, vprev, v)
+				}
+				if v != VDEL {
+					δ[k] =v
+				}
+			}
+		}
 
+		// XXX process keys from δ outside of already tracked nodes
 	}
 
-
 	return δ, nil
 }
 
 // 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) {
 	defer xerr.Contextf(&err, "diffB %s", a.POid())
 	// XXX oid can be InvalidOid for T/B... (i.e. B is part of T and is not yet committed separately)
@@ -451,6 +481,8 @@ func diffB(ctx context.Context, a, b *Bucket) (δ map[Key]Value, err error) {
 		panic("different buckets")
 	}
 
+	// 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 }