On Sat, 27 Nov 1999, Oliver Xymoron wrote:
>I'd like to take a look at this, I've been looking at putting some more
>uniform tree structures in the kernel (post 2.4).
This patch will add btree support to linux. I extracted it from my old
patches. I think it could be added also in the stock kernel so if somebody
needs rbtrees, he won't have to reinvent the wheel each time ;). The patch
is against 2.3.30pre3.
diff -urN 2.3.30pre3/include/linux/rbtree.h 2.3.30pre3-rbtree/include/linux/rbtree.h
--- 2.3.30pre3/include/linux/rbtree.h Thu Jan 1 01:00:00 1970
+++ 2.3.30pre3-rbtree/include/linux/rbtree.h Mon Nov 29 16:33:26 1999
@@ -0,0 +1,128 @@
+/*
+ Red Black Trees
+ (C) 1999 Andrea Arcangeli <[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
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ linux/include/linux/rbtree.h
+
+ To use rbtrees you'll have to implement your own insert and search cores.
+ This will avoid us to use callbacks and to drop drammatically performances.
+ I know it's not the cleaner way, but in C (not in C++) to get
+ performances and genericity...
+
+ Some example of insert and search follows here. The search is a plain
+ normal search over an ordered tree. The insert instead must be implemented
+ int two steps: as first thing the code must insert the element in
+ order as a red leaf in the tree, then the support library function
+ rb_insert_color() must be called. Such function will do the
+ not trivial work to rebalance the rbtree if necessary.
+
+-----------------------------------------------------------------------
+static inline struct page * rb_search_page_cache(struct inode * inode,
+ unsigned long offset)
+{
+ rb_node_t * n = inode->i_rb_page_cache.rb_node;
+ struct page * page;
+
+ while (n)
+ {
+ page = rb_entry(n, struct page, rb_page_cache);
+
+ if (offset < page->offset)
+ n = n->rb_left;
+ else if (offset > page->offset)
+ n = n->rb_right;
+ else
+ return page;
+ }
+ return NULL;
+}
+
+static inline struct page * __rb_insert_page_cache(struct inode * inode,
+ unsigned long offset,
+ rb_node_t * node)
+{
+ rb_node_t ** p = &inode->i_rb_page_cache.rb_node;
+ rb_node_t * parent = NULL;
+ struct page * page;
+
+ while (*p)
+ {
+ parent = *p;
+ page = rb_entry(parent, struct page, rb_page_cache);
+
+ if (offset < page->offset)
+ p = &(*p)->rb_left;
+ else if (offset > page->offset)
+ p = &(*p)->rb_right;
+ else
+ return page;
+ }
+
+ node->rb_parent = parent;
+ node->rb_color = RB_RED;
+ node->rb_left = node->rb_right = NULL;
+
+ *p = node;
+
+ return NULL;
+}
+
+static inline struct page * rb_insert_page_cache(struct inode * inode,
+ unsigned long offset,
+ rb_node_t * node)
+{
+ struct page * ret;
+ if ((ret = __rb_insert_page_cache(inode, offset, node)))
+ goto out;
+ rb_insert_color(node, &inode->i_rb_page_cache);
+ out:
+ return ret;
+}
+-----------------------------------------------------------------------
+*/
+
+#ifndef _LINUX_RBTREE_H
+#define _LINUX_RBTREE_H
+
+#include <linux/kernel.h>
+#include <linux/stddef.h>
+
+typedef struct rb_node_s
+{
+ struct rb_node_s * rb_parent;
+ int rb_color;
+#define RB_RED 0
+#define RB_BLACK 1
+ struct rb_node_s * rb_right;
+ struct rb_node_s * rb_left;
+}
+rb_node_t;
+
+typedef struct rb_root_s
+{
+ struct rb_node_s * rb_node;
+}
+rb_root_t;
+
+#define RB_ROOT (rb_root_t) { NULL, }
+#define rb_entry(ptr, type, member) \
+ ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
+
+extern void rb_insert_color(rb_node_t *, rb_root_t *);
+extern void rb_erase(rb_node_t *, rb_root_t *);
+
+#endif /* _LINUX_RBTREE_H */
diff -urN 2.3.30pre3/lib/Makefile 2.3.30pre3-rbtree/lib/Makefile
--- 2.3.30pre3/lib/Makefile Mon Jan 18 02:27:00 1999
+++ 2.3.30pre3-rbtree/lib/Makefile Mon Nov 29 16:22:36 1999
@@ -7,6 +7,6 @@
#
L_TARGET := lib.a
-L_OBJS := errno.o ctype.o string.o vsprintf.o
+L_OBJS := errno.o ctype.o string.o vsprintf.o rbtree.o
include $(TOPDIR)/Rules.make
diff -urN 2.3.30pre3/lib/rbtree.c 2.3.30pre3-rbtree/lib/rbtree.c
--- 2.3.30pre3/lib/rbtree.c Thu Jan 1 01:00:00 1970
+++ 2.3.30pre3-rbtree/lib/rbtree.c Mon Nov 29 16:31:37 1999
@@ -0,0 +1,293 @@
+/*
+ Red Black Trees
+ (C) 1999 Andrea Arcangeli <[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
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ linux/lib/rbtree.c
+*/
+
+#include <linux/rbtree.h>
+
+static void __rb_rotate_left(rb_node_t * node, rb_root_t * root)
+{
+ rb_node_t * right = node->rb_right;
+
+ if ((node->rb_right = right->rb_left))
+ right->rb_left->rb_parent = node;
+ right->rb_left = node;
+
+ if ((right->rb_parent = node->rb_parent))
+ {
+ if (node == node->rb_parent->rb_left)
+ node->rb_parent->rb_left = right;
+ else
+ node->rb_parent->rb_right = right;
+ }
+ else
+ root->rb_node = right;
+ node->rb_parent = right;
+}
+
+static void __rb_rotate_right(rb_node_t * node, rb_root_t * root)
+{
+ rb_node_t * left = node->rb_left;
+
+ if ((node->rb_left = left->rb_right))
+ left->rb_right->rb_parent = node;
+ left->rb_right = node;
+
+ if ((left->rb_parent = node->rb_parent))
+ {
+ if (node == node->rb_parent->rb_right)
+ node->rb_parent->rb_right = left;
+ else
+ node->rb_parent->rb_left = left;
+ }
+ else
+ root->rb_node = left;
+ node->rb_parent = left;
+}
+
+void rb_insert_color(rb_node_t * node, rb_root_t * root)
+{
+ rb_node_t * parent, * gparent;
+
+ while ((parent = node->rb_parent) && parent->rb_color == RB_RED)
+ {
+ gparent = parent->rb_parent;
+
+ if (parent == gparent->rb_left)
+ {
+ {
+ register rb_node_t * uncle = gparent->rb_right;
+ if (uncle && uncle->rb_color == RB_RED)
+ {
+ uncle->rb_color = RB_BLACK;
+ parent->rb_color = RB_BLACK;
+ gparent->rb_color = RB_RED;
+ node = gparent;
+ continue;
+ }
+ }
+
+ if (parent->rb_right == node)
+ {
+ register rb_node_t * tmp;
+ __rb_rotate_left(parent, root);
+ tmp = parent;
+ parent = node;
+ node = tmp;
+ }
+
+ parent->rb_color = RB_BLACK;
+ gparent->rb_color = RB_RED;
+ __rb_rotate_right(gparent, root);
+ } else {
+ {
+ register rb_node_t * uncle = gparent->rb_left;
+ if (uncle && uncle->rb_color == RB_RED)
+ {
+ uncle->rb_color = RB_BLACK;
+ parent->rb_color = RB_BLACK;
+ gparent->rb_color = RB_RED;
+ node = gparent;
+ continue;
+ }
+ }
+
+ if (parent->rb_left == node)
+ {
+ register rb_node_t * tmp;
+ __rb_rotate_right(parent, root);
+ tmp = parent;
+ parent = node;
+ node = tmp;
+ }
+
+ parent->rb_color = RB_BLACK;
+ gparent->rb_color = RB_RED;
+ __rb_rotate_left(gparent, root);
+ }
+ }
+
+ root->rb_node->rb_color = RB_BLACK;
+}
+
+static void __rb_erase_color(rb_node_t * node, rb_node_t * parent,
+ rb_root_t * root)
+{
+ rb_node_t * other;
+
+ while ((!node || node->rb_color == RB_BLACK) && node != root->rb_node)
+ {
+ if (parent->rb_left == node)
+ {
+ other = parent->rb_right;
+ if (other->rb_color == RB_RED)
+ {
+ other->rb_color = RB_BLACK;
+ parent->rb_color = RB_RED;
+ __rb_rotate_left(parent, root);
+ other = parent->rb_right;
+ }
+ if ((!other->rb_left ||
+ other->rb_left->rb_color == RB_BLACK)
+ && (!other->rb_right ||
+ other->rb_right->rb_color == RB_BLACK))
+ {
+ other->rb_color = RB_RED;
+ node = parent;
+ parent = node->rb_parent;
+ }
+ else
+ {
+ if (!other->rb_right ||
+ other->rb_right->rb_color == RB_BLACK)
+ {
+ register rb_node_t * o_left;
+ if ((o_left = other->rb_left))
+ o_left->rb_color = RB_BLACK;
+ other->rb_color = RB_RED;
+ __rb_rotate_right(other, root);
+ other = parent->rb_right;
+ }
+ other->rb_color = parent->rb_color;
+ parent->rb_color = RB_BLACK;
+ if (other->rb_right)
+ other->rb_right->rb_color = RB_BLACK;
+ __rb_rotate_left(parent, root);
+ node = root->rb_node;
+ break;
+ }
+ }
+ else
+ {
+ other = parent->rb_left;
+ if (other->rb_color == RB_RED)
+ {
+ other->rb_color = RB_BLACK;
+ parent->rb_color = RB_RED;
+ __rb_rotate_right(parent, root);
+ other = parent->rb_left;
+ }
+ if ((!other->rb_left ||
+ other->rb_left->rb_color == RB_BLACK)
+ && (!other->rb_right ||
+ other->rb_right->rb_color == RB_BLACK))
+ {
+ other->rb_color = RB_RED;
+ node = parent;
+ parent = node->rb_parent;
+ }
+ else
+ {
+ if (!other->rb_left ||
+ other->rb_left->rb_color == RB_BLACK)
+ {
+ register rb_node_t * o_right;
+ if ((o_right = other->rb_right))
+ o_right->rb_color = RB_BLACK;
+ other->rb_color = RB_RED;
+ __rb_rotate_left(other, root);
+ other = parent->rb_left;
+ }
+ other->rb_color = parent->rb_color;
+ parent->rb_color = RB_BLACK;
+ if (other->rb_left)
+ other->rb_left->rb_color = RB_BLACK;
+ __rb_rotate_right(parent, root);
+ node = root->rb_node;
+ break;
+ }
+ }
+ }
+ if (node)
+ node->rb_color = RB_BLACK;
+}
+
+void rb_erase(rb_node_t * node, rb_root_t * root)
+{
+ rb_node_t * child, * parent;
+ int color;
+
+ if (!node->rb_left)
+ child = node->rb_right;
+ else if (!node->rb_right)
+ child = node->rb_left;
+ else
+ {
+ rb_node_t * old = node, * left;
+
+ node = node->rb_right;
+ while ((left = node->rb_left))
+ node = left;
+ child = node->rb_right;
+ parent = node->rb_parent;
+ color = node->rb_color;
+
+ if (child)
+ child->rb_parent = parent;
+ if (parent)
+ {
+ if (parent->rb_left == node)
+ parent->rb_left = child;
+ else
+ parent->rb_right = child;
+ }
+ else
+ root->rb_node = child;
+
+ if (node->rb_parent == old)
+ parent = node;
+ node->rb_parent = old->rb_parent;
+ node->rb_color = old->rb_color;
+ node->rb_right = old->rb_right;
+ node->rb_left = old->rb_left;
+
+ if (old->rb_parent)
+ {
+ if (old->rb_parent->rb_left == old)
+ old->rb_parent->rb_left = node;
+ else
+ old->rb_parent->rb_right = node;
+ } else
+ root->rb_node = node;
+
+ old->rb_left->rb_parent = node;
+ if (old->rb_right)
+ old->rb_right->rb_parent = node;
+ goto color;
+ }
+
+ parent = node->rb_parent;
+ color = node->rb_color;
+
+ if (child)
+ child->rb_parent = parent;
+ if (parent)
+ {
+ if (parent->rb_left == node)
+ parent->rb_left = child;
+ else
+ parent->rb_right = child;
+ }
+ else
+ root->rb_node = child;
+
+ color:
+ if (color == RB_BLACK)
+ __rb_erase_color(child, parent, root);
+}
Downloadable also from:
ftp://ftp.*.kernel.org/pub/linux/kernel/people/andrea/patches/v2.3/2.3.30pre3/rbtree-1.bz2
Andrea