Red Black Tree cleanups [1/2]
PATCH RESEND 1/1 Red Black Tree cleanups [1/2]
This is the first of two rbtree patches which can be pulled from
master.kernel.org:/home/dwmw2/BK/rbtree-2.5
This adds three new rbtree functions. rb_next() and rb_prev() are used for traversing a tree, and rb_replace_node() is for replacing a single node without having to erase, rebalance, insert the replacement and rebalance again.
# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or higher.
# This patch includes the following deltas:
# ChangeSet 1.621 -> 1.622
# lib/rbtree.c 1.2 -> 1.3
# include/linux/rbtree.h 1.1 -> 1.2
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/09/09 [email protected] 1.622
# Add three functions for rbtree manipulation -- rb_next(), rb_prev() and rb_replace_node() #
# rb_next() and rb_prev() return the next and previous nodes in the tree, respectively. #
# rb_replace_node() allows fast replacement of a single node without having to remove the # victim, rebalance the tree, insert the replacement and then rebalance again to the original
# topology. # -------------------------------------------- # diff -Nru a/include/linux/rbtree.h b/include/linux/rbtree.h --- a/include/linux/rbtree.h Thu Sep 12 13:49:39 2002 +++ b/include/linux/rbtree.h Thu Sep 12 13:49:39 2002 @@ -121,6 +121,13 @@ extern void rb_insert_color(rb_node_t *, rb_root_t *); extern void rb_erase(rb_node_t *, rb_root_t *);
+/* Find logical next and previous nodes in a tree */
+extern rb_node_t *rb_next(rb_node_t *);
+extern rb_node_t *rb_prev(rb_node_t *);
+
+/* Fast replacement of a single node without remove/rebalance/add/rebalance */ +extern void rb_replace_node(rb_node_t *victim, rb_node_t *new, rb_root_t *root); +
static inline void rb_link_node(rb_node_t * node, rb_node_t * parent, rb_node_t ** rb_link) {
node->rb_parent = parent;
lib/rbtree.c +68 -0
@@ -1,6 +1,7 @@/* Red Black Trees (C) 1999 Andrea Arcangeli <[email protected]> +(C) 2002 David Woodhouse <[email protected]> This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
@@ -294,3 +295,70 @@__rb_erase_color (child, parent, root); }EXPORT_SYMBOL (rb_erase); + +rb_node_t *rb_next (rb_node_t *node) +{ +/* If we have a right-hand child, go down and then left as far +as we can. */ +if (node->rb_right) { + node = node->rb_right; +while (node->rb_left) + node=node->rb_left; +return node; + } + +/* No right-hand children. Everything down and left is +smaller than us, so any 'next' node must be in the general +direction of our parent. Go up the tree; any time the +ancestor is a right-hand child of its parent, keep going +up. First time it's a left-hand child of its parent, said +parent is our 'next' node. */ +while (node->rb_parent && node == node->rb_parent->rb_right) + node = node->rb_parent; + +return node->rb_parent; +} +EXPORT_SYMBOL (rb_next); + +rb_node_t *rb_prev (rb_node_t *node) +{ +/* If we have a left-hand child, go down and then right as far +as we can. */ +if (node->rb_left) { + node = node->rb_left; +while (node->rb_right) + node=node->rb_right; +return node; + } + +/* No left-hand children. Go up till we find an ancestor which +is a right-hand child of its parent */ +while (node->rb_parent && node == node->rb_parent->rb_left) + node = node->rb_parent; + +return node->rb_parent; +} +EXPORT_SYMBOL (rb_prev); + +void rb_replace_node (rb_node_t *victim,rb_node_t *new,rb_root_t *root) +{ +rb_node_t *parent = victim->rb_parent; + +/* Set the surrounding nodes to point to the replacement */ +if (parent) { +if (victim == parent->rb_left) + parent->rb_left = new; +else + parent->rb_right = new; + }else { + root->rb_node = new; + } +if (victim->rb_left) + victim->rb_left->rb_parent = new; +if (victim->rb_right) + victim->rb_right->rb_parent = new; + +/* Copy the pointers/colour from the victim to the replacement */ + *new = *victim; +} +EXPORT_SYMBOL (rb_replace_node);
--
dwmw2