Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | Red Black Trees |
| 3 | (C) 1999 Andrea Arcangeli <andrea@suse.de> |
| 4 | |
| 5 | This program is free software; you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by |
| 7 | the Free Software Foundation; either version 2 of the License, or |
| 8 | (at your option) any later version. |
| 9 | |
| 10 | This program is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | GNU General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU General Public License |
| 16 | along with this program; if not, write to the Free Software |
| 17 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 18 | |
| 19 | linux/include/linux/rbtree.h |
| 20 | |
| 21 | To use rbtrees you'll have to implement your own insert and search cores. |
| 22 | This will avoid us to use callbacks and to drop drammatically performances. |
| 23 | I know it's not the cleaner way, but in C (not in C++) to get |
| 24 | performances and genericity... |
| 25 | |
| 26 | Some example of insert and search follows here. The search is a plain |
| 27 | normal search over an ordered tree. The insert instead must be implemented |
| 28 | int two steps: as first thing the code must insert the element in |
| 29 | order as a red leaf in the tree, then the support library function |
| 30 | rb_insert_color() must be called. Such function will do the |
| 31 | not trivial work to rebalance the rbtree if necessary. |
| 32 | |
| 33 | ----------------------------------------------------------------------- |
| 34 | static inline struct page * rb_search_page_cache(struct inode * inode, |
| 35 | unsigned long offset) |
| 36 | { |
| 37 | struct rb_node * n = inode->i_rb_page_cache.rb_node; |
| 38 | struct page * page; |
| 39 | |
| 40 | while (n) |
| 41 | { |
| 42 | page = rb_entry(n, struct page, rb_page_cache); |
| 43 | |
| 44 | if (offset < page->offset) |
| 45 | n = n->rb_left; |
| 46 | else if (offset > page->offset) |
| 47 | n = n->rb_right; |
| 48 | else |
| 49 | return page; |
| 50 | } |
| 51 | return NULL; |
| 52 | } |
| 53 | |
| 54 | static inline struct page * __rb_insert_page_cache(struct inode * inode, |
| 55 | unsigned long offset, |
| 56 | struct rb_node * node) |
| 57 | { |
| 58 | struct rb_node ** p = &inode->i_rb_page_cache.rb_node; |
| 59 | struct rb_node * parent = NULL; |
| 60 | struct page * page; |
| 61 | |
| 62 | while (*p) |
| 63 | { |
| 64 | parent = *p; |
| 65 | page = rb_entry(parent, struct page, rb_page_cache); |
| 66 | |
| 67 | if (offset < page->offset) |
| 68 | p = &(*p)->rb_left; |
| 69 | else if (offset > page->offset) |
| 70 | p = &(*p)->rb_right; |
| 71 | else |
| 72 | return page; |
| 73 | } |
| 74 | |
| 75 | rb_link_node(node, parent, p); |
| 76 | |
| 77 | return NULL; |
| 78 | } |
| 79 | |
| 80 | static inline struct page * rb_insert_page_cache(struct inode * inode, |
| 81 | unsigned long offset, |
| 82 | struct rb_node * node) |
| 83 | { |
| 84 | struct page * ret; |
| 85 | if ((ret = __rb_insert_page_cache(inode, offset, node))) |
| 86 | goto out; |
| 87 | rb_insert_color(node, &inode->i_rb_page_cache); |
| 88 | out: |
| 89 | return ret; |
| 90 | } |
| 91 | ----------------------------------------------------------------------- |
| 92 | */ |
| 93 | |
| 94 | #ifndef _LINUX_RBTREE_H |
| 95 | #define _LINUX_RBTREE_H |
| 96 | |
| 97 | #include <linux/kernel.h> |
| 98 | #include <linux/stddef.h> |
| 99 | |
| 100 | struct rb_node |
| 101 | { |
David Woodhouse | 55a9810 | 2006-04-21 13:35:51 +0100 | [diff] [blame^] | 102 | unsigned long rb_parent_colour; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | #define RB_RED 0 |
| 104 | #define RB_BLACK 1 |
| 105 | struct rb_node *rb_right; |
| 106 | struct rb_node *rb_left; |
| 107 | }; |
| 108 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 109 | struct rb_root |
| 110 | { |
| 111 | struct rb_node *rb_node; |
| 112 | }; |
| 113 | |
David Woodhouse | 55a9810 | 2006-04-21 13:35:51 +0100 | [diff] [blame^] | 114 | |
| 115 | #define rb_parent(r) ((struct rb_node *)((r)->rb_parent_colour & ~3)) |
| 116 | #define rb_colour(r) ((r)->rb_parent_colour & 1) |
| 117 | #define rb_is_red(r) (!rb_colour(r)) |
| 118 | #define rb_is_black(r) rb_colour(r) |
| 119 | #define rb_set_red(r) do { (r)->rb_parent_colour &= ~1; } while (0) |
| 120 | #define rb_set_black(r) do { (r)->rb_parent_colour |= 1; } while (0) |
| 121 | |
| 122 | static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) |
| 123 | { |
| 124 | rb->rb_parent_colour = (rb->rb_parent_colour & 3) | (unsigned long)p; |
| 125 | } |
| 126 | static inline void rb_set_colour(struct rb_node *rb, int colour) |
| 127 | { |
| 128 | rb->rb_parent_colour = (rb->rb_parent_colour & ~1) | colour; |
| 129 | } |
| 130 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | #define RB_ROOT (struct rb_root) { NULL, } |
| 132 | #define rb_entry(ptr, type, member) container_of(ptr, type, member) |
| 133 | |
| 134 | extern void rb_insert_color(struct rb_node *, struct rb_root *); |
| 135 | extern void rb_erase(struct rb_node *, struct rb_root *); |
| 136 | |
| 137 | /* Find logical next and previous nodes in a tree */ |
| 138 | extern struct rb_node *rb_next(struct rb_node *); |
| 139 | extern struct rb_node *rb_prev(struct rb_node *); |
| 140 | extern struct rb_node *rb_first(struct rb_root *); |
| 141 | extern struct rb_node *rb_last(struct rb_root *); |
| 142 | |
| 143 | /* Fast replacement of a single node without remove/rebalance/add/rebalance */ |
| 144 | extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, |
| 145 | struct rb_root *root); |
| 146 | |
| 147 | static inline void rb_link_node(struct rb_node * node, struct rb_node * parent, |
| 148 | struct rb_node ** rb_link) |
| 149 | { |
David Woodhouse | 55a9810 | 2006-04-21 13:35:51 +0100 | [diff] [blame^] | 150 | node->rb_parent_colour = (unsigned long )parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | node->rb_left = node->rb_right = NULL; |
| 152 | |
| 153 | *rb_link = node; |
| 154 | } |
| 155 | |
| 156 | #endif /* _LINUX_RBTREE_H */ |