btrfsutil: RebuiltForrest: Allow skipping the .AddedItem loop

3 files changed, 38 insertions, 24 deletions

diff --git a/lib/btrfsutil/rebuilt_callbacks.go b/lib/btrfsutil/rebuilt_callbacks.go
index fef16d4..3a7e6e6 100644
--- a/lib/btrfsutil/rebuilt_callbacks.go
+++ b/lib/btrfsutil/rebuilt_callbacks.go
@@ -14,17 +14,20 @@ import (
 )
 
 type RebuiltForrestCallbacks interface {
-	AddedItem(ctx context.Context, tree btrfsprim.ObjID, key btrfsprim.Key)
 	AddedRoot(ctx context.Context, tree btrfsprim.ObjID, root btrfsvol.LogicalAddr)
 	LookupRoot(ctx context.Context, tree btrfsprim.ObjID) (offset btrfsprim.Generation, item btrfsitem.Root, ok bool)
 	LookupUUID(ctx context.Context, uuid btrfsprim.UUID) (id btrfsprim.ObjID, ok bool)
 }
 
+type RebuiltForrestExtendedCallbacks interface {
+	RebuiltForrestCallbacks
+	AddedItem(ctx context.Context, tree btrfsprim.ObjID, key btrfsprim.Key)
+}
+
 type noopRebuiltForrestCallbacks struct {
 	forrest *RebuiltForrest
 }
 
-func (noopRebuiltForrestCallbacks) AddedItem(context.Context, btrfsprim.ObjID, btrfsprim.Key) {}
 func (noopRebuiltForrestCallbacks) AddedRoot(context.Context, btrfsprim.ObjID, btrfsvol.LogicalAddr) {
 }
 
diff --git a/lib/btrfsutil/rebuilt_forrest.go b/lib/btrfsutil/rebuilt_forrest.go
index 29a5210..4249396 100644
--- a/lib/btrfsutil/rebuilt_forrest.go
+++ b/lib/btrfsutil/rebuilt_forrest.go
@@ -73,8 +73,11 @@ type RebuiltForrest struct {
 	rebuiltSharedCache
 }
 
-// NewRebuiltForrest returns a new RebuiltForrest instance.  The
-// RebuiltForrestCallbacks may be nil.
+// NewRebuiltForrest returns a new RebuiltForrest instance.
+//
+// The `cb` RebuiltForrestCallbacks may be nil.  If `cb` also
+// implements RebuiltForrestExtendedCallbacks, then a series of
+// .AddedItem() calls will be made before each call to .AddedRoot().
 func NewRebuiltForrest(fs btrfs.ReadableFS, graph Graph, cb RebuiltForrestCallbacks) *RebuiltForrest {
 	ret := &RebuiltForrest{
 		inner: fs,
diff --git a/lib/btrfsutil/rebuilt_tree.go b/lib/btrfsutil/rebuilt_tree.go
index 31a31be..e4d5ddd 100644
--- a/lib/btrfsutil/rebuilt_tree.go
+++ b/lib/btrfsutil/rebuilt_tree.go
@@ -320,37 +320,45 @@ func (tree *RebuiltTree) RebuiltAddRoot(ctx context.Context, rootNode btrfsvol.L
 	ctx = dlog.WithField(ctx, "btrfs.util.rebuilt-tree.add-root", fmt.Sprintf("tree=%v rootNode=%v", tree.ID, rootNode))
 	dlog.Info(ctx, "adding root...")
 
-	var stats rebuiltRootStats
-	leafToRoots := tree.acquireLeafToRoots(ctx)
-	stats.Leafs.D = len(leafToRoots)
-	progressWriter := textui.NewProgress[rebuiltRootStats](ctx, dlog.LogLevelInfo, textui.Tunable(1*time.Second))
-	for i, leaf := range maps.SortedKeys(leafToRoots) {
-		stats.Leafs.N = i
-		progressWriter.Set(stats)
+	shouldFlush := tree.ID == btrfsprim.ROOT_TREE_OBJECTID || tree.ID == btrfsprim.UUID_TREE_OBJECTID
+
+	if extCB, ok := tree.forrest.cb.(RebuiltForrestExtendedCallbacks); ok {
+		var stats rebuiltRootStats
+		leafToRoots := tree.acquireLeafToRoots(ctx)
+		stats.Leafs.D = len(leafToRoots)
+		progressWriter := textui.NewProgress[rebuiltRootStats](ctx, dlog.LogLevelInfo, textui.Tunable(1*time.Second))
+		for i, leaf := range maps.SortedKeys(leafToRoots) {
+			stats.Leafs.N = i
+			progressWriter.Set(stats)
 
-		if tree.Roots.HasAny(leafToRoots[leaf]) || !leafToRoots[leaf].Has(rootNode) {
-			continue
-		}
+			if tree.Roots.HasAny(leafToRoots[leaf]) || !leafToRoots[leaf].Has(rootNode) {
+				continue
+			}
+
+			stats.AddedLeafs++
+			progressWriter.Set(stats)
 
-		stats.AddedLeafs++
+			for _, itemKey := range tree.forrest.graph.Nodes[leaf].Items {
+				extCB.AddedItem(ctx, tree.ID, itemKey)
+				stats.AddedItems++
+				progressWriter.Set(stats)
+			}
+		}
+		stats.Leafs.N = len(leafToRoots)
+		tree.releaseLeafToRoots()
 		progressWriter.Set(stats)
+		progressWriter.Done()
 
-		for _, itemKey := range tree.forrest.graph.Nodes[leaf].Items {
-			tree.forrest.cb.AddedItem(ctx, tree.ID, itemKey)
-			stats.AddedItems++
-			progressWriter.Set(stats)
+		if stats.AddedItems == 0 {
+			shouldFlush = false
 		}
 	}
-	stats.Leafs.N = len(leafToRoots)
-	tree.releaseLeafToRoots()
-	progressWriter.Set(stats)
-	progressWriter.Done()
 
 	tree.Roots.Insert(rootNode)
 	tree.forrest.incItems.Delete(tree.ID) // force re-gen
 	tree.forrest.excItems.Delete(tree.ID) // force re-gen
 
-	if (tree.ID == btrfsprim.ROOT_TREE_OBJECTID || tree.ID == btrfsprim.UUID_TREE_OBJECTID) && stats.AddedItems > 0 {
+	if shouldFlush {
 		tree.forrest.flushNegativeCache(ctx)
 	}
 	tree.forrest.cb.AddedRoot(ctx, tree.ID, rootNode)