.

wcfs/δbtail.go

@@ -210,6 +210,29 @@ type δtrackIndex struct {
 	Add trackIndex
 }
 
+// gc1 garbage-collects oid and cleans up its parent down-up.
+func (tidx trackIndex) gc1(oid zodb.Oid) {
+	t, present := tidx[oid]
+	if !present {
+		return // already not there
+	}
+	if t.nchild != 0 {
+		panicf("gc %v  (nchild != 0)", t)
+	}
+
+	delete(tidx, oid)
+	parent := t.parent
+	for parent != zodb.InvalidOid {
+		t := tidx[parent]
+		t.nchild--
+		if t.nchild > 0 {
+			break
+		}
+		delete(tidx, parent)
+		parent = t.parent
+	}
+}
+
 // ApplyΔ applies δ to trackIdx.	XXX
 func (tidx trackIndex) ApplyΔ(δ *δtrackIndex) {
 	fmt.Printf("\n\nApplyΔ\n")
@@ -218,22 +241,7 @@ func (tidx trackIndex) ApplyΔ(δ *δtrackIndex) {
 
 	// remove leafs and thier parents
 	for leaf := range δ.DelLeaf {
-		t, present := tidx[leaf]
-		if !present {
-			continue // leaf already not there
-		}
-
-		delete(tidx, leaf)
-		parent := t.parent
-		for parent != zodb.InvalidOid {
-			t := tidx[parent]
-			t.nchild--
-			if t.nchild > 0 {
-				break
-			}
-			delete(tidx, parent)
-			parent = t.parent
-		}
+		tidx.gc1(leaf)
 	}
 
 	// process adds
@@ -254,9 +262,16 @@ func (tidx trackIndex) ApplyΔ(δ *δtrackIndex) {
 			δnchild[t.parent] += 1 // remeber to nchild++ in parent
 		}
 	}
+	gcq := []zodb.Oid{}
 	for parent, δnc := range δnchild {
-		tidx[parent].nchild += δnc
-		// XXX .nchild == 0 - remove ?
+		t := tidx[parent]
+		t.nchild += δnc
+		if t.nchild == 0 {
+			gcq = append(gcq, t.parent)
+		}
+	}
+	for _, oid := range gcq {
+		tidx.gc1(oid)
 	}
 }