libhv/base/rbtree.h

/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>

  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
  in two steps: First, the code must insert the element in order as a red leaf
  in the tree, and 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)
{
    struct rb_node * 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,
                           struct rb_node * node)
{
    struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
    struct rb_node * 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;
    }

    rb_link_node(node, parent, p);

    return NULL;
}

static inline struct page * rb_insert_page_cache(struct inode * inode,
                         unsigned long offset,
                         struct rb_node * 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 <stdint.h> // for uintptr_t

struct rb_node
{
    struct rb_node *rb_parent;
    struct rb_node *rb_right;
    struct rb_node *rb_left;
    char            rb_color;
#define RB_RED      0
#define RB_BLACK    1
};

struct rb_root
{
    struct rb_node *rb_node;
};

#define RB_ROOT (struct rb_root){ (struct rb_node *)0, }
#define rb_entry(ptr, type, member) \
    ((type *)((char *)(ptr)-(uintptr_t)(&((type *)0)->member)))

#ifdef __cplusplus
extern "C"
{
#endif

void rb_insert_color(struct rb_node *node, struct rb_root *root);
void rb_erase(struct rb_node *node, struct rb_root *root);

/* Find logical next and previous nodes in a tree */
struct rb_node *rb_next(struct rb_node *);
struct rb_node *rb_prev(struct rb_node *);
struct rb_node *rb_first(struct rb_root *);
struct rb_node *rb_last(struct rb_root *);

/* Fast replacement of a single node without remove/rebalance/add/rebalance */
void rb_replace_node(struct rb_node *victim, struct rb_node *newnode,
                struct rb_root *root);

#ifdef __cplusplus
}
#endif

static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
                struct rb_node **link)
{
    node->rb_parent = parent;
    node->rb_color = RB_RED;
    node->rb_left = node->rb_right = (struct rb_node *)0;
    *link = node;
}

#endif  /* _LINUX_RBTREE_H */