part: Mark newly created nodes as mutated

We can mark the node4 created when splitting and the nodes
created when demoted as mutated so we don't need to clone them
on further modifications.

Signed-off-by: Jussi Maki <[email protected]>

Author: joamaki

part/txn.go

@@ -360,6 +360,7 @@ func (txn *Txn[T]) modify(root *header[T], key []byte, mod func(T) T) (oldValue
 		newNode.setSize(2)
 	}
 	*thisp = newNode.self()
+	nodeMutatedSet(txn.mutated, newNode.self())
 
 	return
 }
@@ -511,6 +512,7 @@ func (txn *Txn[T]) removeChild(parent *header[T], index int) *header[T] {
 		childClone := child.clone(false)
 		childClone.watch = child.watch
 		childClone.setPrefix(slices.Concat(parent.prefix(), childClone.prefix()))
+		nodeMutatedSet(txn.mutated, childClone)
 		return childClone
 
 	case parent.kind() == nodeKind256 && size <= 49:
@@ -526,6 +528,7 @@ func (txn *Txn[T]) removeChild(parent *header[T], index int) *header[T] {
 				children = append(children, n)
 			}
 		}
+		nodeMutatedSet(txn.mutated, demoted)
 		return demoted
 	case parent.kind() == nodeKind48 && size <= 17:
 		demoted := (&node16[T]{header: *parent}).self()
@@ -541,6 +544,7 @@ func (txn *Txn[T]) removeChild(parent *header[T], index int) *header[T] {
 				idx++
 			}
 		}
+		nodeMutatedSet(txn.mutated, demoted)
 		return demoted
 	case parent.kind() == nodeKind16 && size <= 5:
 		demoted := (&node4[T]{header: *parent}).self()
@@ -557,6 +561,7 @@ func (txn *Txn[T]) removeChild(parent *header[T], index int) *header[T] {
 				idx++
 			}
 		}
+		nodeMutatedSet(txn.mutated, demoted)
 		return demoted
 	default:
 		parent = txn.cloneNode(parent)