details: http://hg.nginx.org/njs/rev/7156ba123eae
branches:
changeset: 343:7156ba123eae
user: Igor Sysoev <igor@sysoev.ru>
date: Fri May 26 20:10:22 2017 +0300
description:
A small rbtree insert fixup optimization.

Thanks to ??? (Hong Zhi Dao).

diffstat:

nxt/nxt_rbtree.c | 13 +++++++++----
1 files changed, 9 insertions(+), 4 deletions(-)

diffs (36 lines):

diff -r be8d68d4b8b5 -r 7156ba123eae nxt/nxt_rbtree.c
--- a/nxt/nxt_rbtree.c Fri May 26 20:07:24 2017 +0300
+++ b/nxt/nxt_rbtree.c Fri May 26 20:10:22 2017 +0300
@@ -129,11 +129,15 @@ nxt_rbtree_insert_fixup(nxt_rbtree_node_
nxt_rbtree_left_rotate(node);
}

+ /*
+ * nxt_rbtree_left_rotate() swaps parent and
+ * child whilst keeps grandparent the same.
+ */
parent = node->parent;
+
parent->color = NXT_RBTREE_BLACK;
+ grandparent->color = NXT_RBTREE_RED;

- grandparent = parent->parent;
- grandparent->color = NXT_RBTREE_RED;
nxt_rbtree_right_rotate(grandparent);
/*
* nxt_rbtree_right_rotate() does not change node->parent
@@ -153,11 +157,12 @@ nxt_rbtree_insert_fixup(nxt_rbtree_node_
nxt_rbtree_right_rotate(node);
}

+ /* See the comment in the symmetric branch above. */
parent = node->parent;
+
parent->color = NXT_RBTREE_BLACK;
+ grandparent->color = NXT_RBTREE_RED;

- grandparent = parent->parent;
- grandparent->color = NXT_RBTREE_RED;
nxt_rbtree_left_rotate(grandparent);

/* See the comment in the symmetric branch above. */
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