.

wcfs/δbtail.go

@@ -375,6 +375,11 @@ func (A trackIndex) DifferenceInplace(B trackIndex) {
 }
 
 func (A trackIndex) xDifferenceInplace(B trackIndex, δnchild map[zodb.Oid]int) {
+	fmt.Printf("\n\n  xDifferenceInplace:\n")
+	fmt.Printf("    a: %s\n", A)
+	fmt.Printf("    b: %s\n", B)
+	defer fmt.Printf("  ->d: %s\n", A)
+
 	// remove B.leafs and thier parents
 	for oid, t2 := range B {
 		if t2.nchild != 0 {
@@ -386,7 +391,14 @@ func (A trackIndex) xDifferenceInplace(B trackIndex, δnchild map[zodb.Oid]int)
 			continue // already not there
 		}
 
-		// XXX assert t.parent == t2.parent ?
+		if t2.parent != t.parent {
+			// XXX or verify this at Track time and require
+			// that update is passed only entries with the
+			// same .parent? (then it would be ok to panic here)
+			// XXX -> error (e.g. due to corrupt data in ZODB)
+			panicf("node %s is reachable from multiple parents: %s %s",
+				oid, t.parent, t2.parent)
+		}
 
 		delete(A, oid)
 		if t.parent != zodb.InvalidOid {
@@ -396,21 +408,29 @@ func (A trackIndex) xDifferenceInplace(B trackIndex, δnchild map[zodb.Oid]int)
 }
 
 func (A trackIndex) xUnionInplace(B trackIndex, δnchild map[zodb.Oid]int) {
-	// process additions
+	fmt.Printf("\n\n  xUnionInplace:\n")
+	fmt.Printf("    a: %s\n", A)
+	fmt.Printf("    b: %s\n", B)
+	defer fmt.Printf("  ->u: %s\n", A)
+
 	for oid, t2 := range B {
 		t, already := A[oid]
-		if already {
+		if !already {
+			t = &nodeTrack{parent: t2.parent, nchild: 0}
+			A[oid] = t
+			// remeber to nchild++ in parent
 			if t.parent != zodb.InvalidOid {
-				δnchild[t.parent] -= 1
-				t.parent = t2.parent
+				δnchild[t.parent] += 1
 			}
 		} else {
-			t = &nodeTrack{parent: t2.parent, nchild: 0}
-			A[oid] = t
-		}
-
-		if t.parent != zodb.InvalidOid {
-			δnchild[t.parent] += 1 // remeber to nchild++ in parent
+			if t2.parent != t.parent {
+				// XXX or verify this at Track time and require
+				// that update is passed only entries with the
+				// same .parent? (then it would be ok to panic here)
+				// XXX -> error (e.g. due to corrupt data in ZODB)
+				panicf("node %s is reachable from multiple parents: %s %s",
+					oid, t.parent, t2.parent)
+			}
 		}
 	}
 }