lib/util/rbtree.h

   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 struct rb_node
  98 {
  99         unsigned long  rb_parent_color;
 100         struct rb_node *rb_right;
 101         struct rb_node *rb_left;
 102 };
 103
 104 struct rb_root
 105 {
 106         struct rb_node *rb_node;
 107 };
 108
 109
 110 #define RB_ROOT (struct rb_root) { NULL, }
 111
 112 #if 0
 113 #define rb_entry(ptr, type, member) container_of(ptr, type, member)
 114 #endif
 115
 116 void rb_insert_color(struct rb_node *, struct rb_root *);
 117 void rb_erase(struct rb_node *, struct rb_root *);
 118
 119 /* Find logical next and previous nodes in a tree */
 120 struct rb_node *rb_next(struct rb_node *);
 121 struct rb_node *rb_prev(struct rb_node *);
 122 struct rb_node *rb_first(struct rb_root *);
 123 struct rb_node *rb_last(struct rb_root *);
 124
 125 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
 126 extern void rb_replace_node(struct rb_node *victim, struct rb_node *new_node,
 127                             struct rb_root *root);
 128
 129 void rb_link_node(struct rb_node * node, struct rb_node * parent,
 130                   struct rb_node ** rb_link);
 131
 132 #endif  /* _LINUX_RBTREE_H */