From 30f52202775155c1d301af3634d0122c3d7851f8 Mon Sep 17 00:00:00 2001
From: Matt Armstrong <matt@rfc20.org>
Date: Sat, 8 Oct 2022 09:15:26 -0700
Subject: [PATCH] Comment change: explain inheriting "dirty" offsets
; * src/itree.c (interval_generator_next): explain why the code
handles inheriting offsets from dirty nodes.
---
src/itree.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/src/itree.c b/src/itree.c
index de16af5b0c2..05851007f5a 100644
--- a/src/itree.c
+++ b/src/itree.c
@@ -1086,8 +1086,17 @@ interval_tree_inherit_offset (uintmax_t otick, struct interval_node *node)
node->right->offset += node->offset;
node->offset = 0;
}
- /* FIXME: I wonder when/why this condition can be false, and more generally
- why we'd want to propagate offsets that may not be fully up-to-date. */
+ /* FIXME: I wonder when/why this condition can be false, and more
+ generally why we'd want to propagate offsets that may not be
+ fully up-to-date. --stef
+
+ Offsets can be inherited from dirty nodes (with out of date
+ otick) during insert and remove. Offsets aren't inherited
+ downward from the root for these operations so rotations are
+ performed on potentially "dirty" nodes. We could fix this by
+ always inheriting offsets downward from the root for every insert
+ and remove. --matt
+ */
if (node->parent == ITREE_NULL || node->parent->otick == otick)
node->otick = otick;
}
--
2.39.5