红黑树(三)之 Linux内核中红黑树的经典实现

概要

前面分别介绍了红黑树的理论知识 以及 通过C语言实现了红黑树。本章继续会红黑树进行介绍，下面将Linux 内核中的红黑树单独移植出来进行测试验证。若读者对红黑树的理论知识不熟悉，建立先学习红黑树的理论知识，再来学习本章。

转载请注明出处：http://www.cnblogs.com/skywang12345/p/3624202.html

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更多内容：数据结构与算法系列 目录

(01) 红黑树(一)之 原理和算法详细介绍
(02) 红黑树(二)之 C语言的实现
(03) 红黑树(三)之 Linux内核中红黑树的经典实现(04) 红黑树(四)之 C++的实现(05) 红黑树(五)之 Java的实现(06) 红黑树(六)之 参考资料

Linux内核中红黑树(完整源码)

红黑树的实现文件(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    _SLINUX_RBTREE_H
 #define    _SLINUX_RBTREE_H

 #include <stdio.h>
 //#include <linux/kernel.h>
 //#include <linux/stddef.h>

 struct rb_node
 {
     unsigned long  rb_parent_color;
 #define    RB_RED        0
 #define    RB_BLACK    1
     struct rb_node *rb_right;
     struct rb_node *rb_left;
 } /*  __attribute__((aligned(sizeof(long))))*/;
     /* The alignment might seem pointless, but allegedly CRIS needs it */

 struct rb_root
 {
     struct rb_node *rb_node;
 };

 #define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
 #define rb_color(r)   ((r)->rb_parent_color & 1)
 #define rb_is_red(r)   (!rb_color(r))
 #define rb_is_black(r) rb_color(r)
 #define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
 #define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)

 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
 {
     rb->rb_parent_color = (rb->rb_parent_color & ) | (unsigned long)p;
 }
 static inline void rb_set_color(struct rb_node *rb, int color)
 {
     rb->rb_parent_color = (rb->rb_parent_color & ~) | color;
 }

 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)

 #define container_of(ptr, type, member) ({          \
     const typeof( ((type *))->member ) *__mptr = (ptr);    \
     (type *)( (char *)__mptr - offsetof(type,member) );})

 #define RB_ROOT    (struct rb_root) { NULL, }
 #define    rb_entry(ptr, type, member) container_of(ptr, type, member)

 #define RB_EMPTY_ROOT(root)    ((root)->rb_node == NULL)
 #define RB_EMPTY_NODE(node)    (rb_parent(node) == node)
 #define RB_CLEAR_NODE(node)    (rb_set_parent(node, node))

 static inline void rb_init_node(struct rb_node *rb)
 {
     rb->rb_parent_color = ;
     rb->rb_right = NULL;
     rb->rb_left = NULL;
     RB_CLEAR_NODE(rb);
 }

 extern void rb_insert_color(struct rb_node *, struct rb_root *);
 extern void rb_erase(struct rb_node *, struct rb_root *);

 typedef void (*rb_augment_f)(struct rb_node *node, void *data);

 extern void rb_augment_insert(struct rb_node *node,
                   rb_augment_f func, void *data);
 extern struct rb_node *rb_augment_erase_begin(struct rb_node *node);
 extern void rb_augment_erase_end(struct rb_node *node,
                  rb_augment_f func, void *data);

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

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

 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
                 struct rb_node ** rb_link)
 {
     node->rb_parent_color = (unsigned long )parent;
     node->rb_left = node->rb_right = NULL;

     *rb_link = node;
 }

 #endif    /* _LINUX_RBTREE_H */

红黑树的实现文件(rbtree.c)

 /*
   Red Black Trees
   (C) 1999  Andrea Arcangeli <andrea@suse.de>
   (C) 2002  David Woodhouse <dwmw2@infradead.org>

   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 "rbtree.h"

 static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
 {
     struct rb_node *right = node->rb_right;
     struct rb_node *parent = rb_parent(node);

     if ((node->rb_right = right->rb_left))
         rb_set_parent(right->rb_left, node);
     right->rb_left = node;

     rb_set_parent(right, parent);

     if (parent)
     {
         if (node == parent->rb_left)
             parent->rb_left = right;
         else
             parent->rb_right = right;
     }
     else
         root->rb_node = right;
     rb_set_parent(node, right);
 }

 static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
 {
     struct rb_node *left = node->rb_left;
     struct rb_node *parent = rb_parent(node);

     if ((node->rb_left = left->rb_right))
         rb_set_parent(left->rb_right, node);
     left->rb_right = node;

     rb_set_parent(left, parent);

     if (parent)
     {
         if (node == parent->rb_right)
             parent->rb_right = left;
         else
             parent->rb_left = left;
     }
     else
         root->rb_node = left;
     rb_set_parent(node, left);
 }

 void rb_insert_color(struct rb_node *node, struct rb_root *root)
 {
     struct rb_node *parent, *gparent;

     while ((parent = rb_parent(node)) && rb_is_red(parent))
     {
         gparent = rb_parent(parent);

         if (parent == gparent->rb_left)
         {
             {
                 register struct rb_node *uncle = gparent->rb_right;
                 if (uncle && rb_is_red(uncle))
                 {
                     rb_set_black(uncle);
                     rb_set_black(parent);
                     rb_set_red(gparent);
                     node = gparent;
                     continue;
                 }
             }

             if (parent->rb_right == node)
             {
                 register struct rb_node *tmp;
                 __rb_rotate_left(parent, root);
                 tmp = parent;
                 parent = node;
                 node = tmp;
             }

             rb_set_black(parent);
             rb_set_red(gparent);
             __rb_rotate_right(gparent, root);
         } else {
             {
                 register struct rb_node *uncle = gparent->rb_left;
                 if (uncle && rb_is_red(uncle))
                 {
                     rb_set_black(uncle);
                     rb_set_black(parent);
                     rb_set_red(gparent);
                     node = gparent;
                     continue;
                 }
             }

             if (parent->rb_left == node)
             {
                 register struct rb_node *tmp;
                 __rb_rotate_right(parent, root);
                 tmp = parent;
                 parent = node;
                 node = tmp;
             }

             rb_set_black(parent);
             rb_set_red(gparent);
             __rb_rotate_left(gparent, root);
         }
     }

     rb_set_black(root->rb_node);
 }

 static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
                  struct rb_root *root)
 {
     struct rb_node *other;

     while ((!node || rb_is_black(node)) && node != root->rb_node)
     {
         if (parent->rb_left == node)
         {
             other = parent->rb_right;
             if (rb_is_red(other))
             {
                 rb_set_black(other);
                 rb_set_red(parent);
                 __rb_rotate_left(parent, root);
                 other = parent->rb_right;
             }
             if ((!other->rb_left || rb_is_black(other->rb_left)) &&
                 (!other->rb_right || rb_is_black(other->rb_right)))
             {
                 rb_set_red(other);
                 node = parent;
                 parent = rb_parent(node);
             }
             else
             {
                 if (!other->rb_right || rb_is_black(other->rb_right))
                 {
                     rb_set_black(other->rb_left);
                     rb_set_red(other);
                     __rb_rotate_right(other, root);
                     other = parent->rb_right;
                 }
                 rb_set_color(other, rb_color(parent));
                 rb_set_black(parent);
                 rb_set_black(other->rb_right);
                 __rb_rotate_left(parent, root);
                 node = root->rb_node;
                 break;
             }
         }
         else
         {
             other = parent->rb_left;
             if (rb_is_red(other))
             {
                 rb_set_black(other);
                 rb_set_red(parent);
                 __rb_rotate_right(parent, root);
                 other = parent->rb_left;
             }
             if ((!other->rb_left || rb_is_black(other->rb_left)) &&
                 (!other->rb_right || rb_is_black(other->rb_right)))
             {
                 rb_set_red(other);
                 node = parent;
                 parent = rb_parent(node);
             }
             else
             {
                 if (!other->rb_left || rb_is_black(other->rb_left))
                 {
                     rb_set_black(other->rb_right);
                     rb_set_red(other);
                     __rb_rotate_left(other, root);
                     other = parent->rb_left;
                 }
                 rb_set_color(other, rb_color(parent));
                 rb_set_black(parent);
                 rb_set_black(other->rb_left);
                 __rb_rotate_right(parent, root);
                 node = root->rb_node;
                 break;
             }
         }
     }
     if (node)
         rb_set_black(node);
 }

 void rb_erase(struct rb_node *node, struct rb_root *root)
 {
     struct rb_node *child, *parent;
     int color;

     if (!node->rb_left)
         child = node->rb_right;
     else if (!node->rb_right)
         child = node->rb_left;
     else
     {
         struct rb_node *old = node, *left;

         node = node->rb_right;
         while ((left = node->rb_left) != NULL)
             node = left;

         if (rb_parent(old)) {
             if (rb_parent(old)->rb_left == old)
                 rb_parent(old)->rb_left = node;
             else
                 rb_parent(old)->rb_right = node;
         } else
             root->rb_node = node;

         child = node->rb_right;
         parent = rb_parent(node);
         color = rb_color(node);

         if (parent == old) {
             parent = node;
         } else {
             if (child)
                 rb_set_parent(child, parent);
             parent->rb_left = child;

             node->rb_right = old->rb_right;
             rb_set_parent(old->rb_right, node);
         }

         node->rb_parent_color = old->rb_parent_color;
         node->rb_left = old->rb_left;
         rb_set_parent(old->rb_left, node);

         goto color;
     }

     parent = rb_parent(node);
     color = rb_color(node);

     if (child)
         rb_set_parent(child, 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);
 }

 static void rb_augment_path(struct rb_node *node, rb_augment_f func, void *data)
 {
     struct rb_node *parent;

 up:
     func(node, data);
     parent = rb_parent(node);
     if (!parent)
         return;

     if (node == parent->rb_left && parent->rb_right)
         func(parent->rb_right, data);
     else if (parent->rb_left)
         func(parent->rb_left, data);

     node = parent;
     goto up;
 }

 /*
  * after inserting @node into the tree, update the tree to account for
  * both the new entry and any damage done by rebalance
  */
 void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data)
 {
     if (node->rb_left)
         node = node->rb_left;
     else if (node->rb_right)
         node = node->rb_right;

     rb_augment_path(node, func, data);
 }

 /*
  * before removing the node, find the deepest node on the rebalance path
  * that will still be there after @node gets removed
  */
 struct rb_node *rb_augment_erase_begin(struct rb_node *node)
 {
     struct rb_node *deepest;

     if (!node->rb_right && !node->rb_left)
         deepest = rb_parent(node);
     else if (!node->rb_right)
         deepest = node->rb_left;
     else if (!node->rb_left)
         deepest = node->rb_right;
     else {
         deepest = rb_next(node);
         if (deepest->rb_right)
             deepest = deepest->rb_right;
         else if (rb_parent(deepest) != node)
             deepest = rb_parent(deepest);
     }

     return deepest;
 }

 /*
  * after removal, update the tree to account for the removed entry
  * and any rebalance damage.
  */
 void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data)
 {
     if (node)
         rb_augment_path(node, func, data);
 }

 /*
  * This function returns the first node (in sort order) of the tree.
  */
 struct rb_node *rb_first(const struct rb_root *root)
 {
     struct rb_node    *n;

     n = root->rb_node;
     if (!n)
         return NULL;
     while (n->rb_left)
         n = n->rb_left;
     return n;
 }

 struct rb_node *rb_last(const struct rb_root *root)
 {
     struct rb_node    *n;

     n = root->rb_node;
     if (!n)
         return NULL;
     while (n->rb_right)
         n = n->rb_right;
     return n;
 }

 struct rb_node *rb_next(const struct rb_node *node)
 {
     struct rb_node *parent;

     if (rb_parent(node) == node)
         return NULL;

     /* 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 (struct rb_node *)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 ((parent = rb_parent(node)) && node == parent->rb_right)
         node = parent;

     return parent;
 }

 struct rb_node *rb_prev(const struct rb_node *node)
 {
     struct rb_node *parent;

     if (rb_parent(node) == node)
         return NULL;

     /* 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 (struct rb_node *)node;
     }

     /* No left-hand children. Go up till we find an ancestor which
        is a right-hand child of its parent */
     while ((parent = rb_parent(node)) && node == parent->rb_left)
         node = parent;

     return parent;
 }

 void rb_replace_node(struct rb_node *victim, struct rb_node *new,
              struct rb_root *root)
 {
     struct rb_node *parent = rb_parent(victim);

     /* 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)
         rb_set_parent(victim->rb_left, new);
     if (victim->rb_right)
         rb_set_parent(victim->rb_right, new);

     /* Copy the pointers/colour from the victim to the replacement */
     *new = *victim;
 }

红黑树的测试文件(test.c)

 /**
  * 根据Linux Kernel定义的红黑树(Red Black Tree)
  *
  * @author skywang
  * @date 2013/11/18
  */

 #include <stdio.h>
 #include <stdlib.h>
 #include "rbtree.h"

 #define CHECK_INSERT 0    // "插入"动作的检测开关(0，关闭；1，打开)
 #define CHECK_DELETE 0    // "删除"动作的检测开关(0，关闭；1，打开)
 #define LENGTH(a) ( (sizeof(a)) / (sizeof(a[0])) )

 typedef int Type;

 struct my_node {
     struct rb_node rb_node;    // 红黑树节点
     Type key;                // 键值
     // ... 用户自定义的数据
 };

 /*
  * 查找"红黑树"中键值为key的节点。没找到的话，返回NULL。
  */
 struct my_node *my_search(struct rb_root *root, Type key)
 {
     struct rb_node *rbnode = root->rb_node;

     while (rbnode!=NULL)
     {
         struct my_node *mynode = container_of(rbnode, struct my_node, rb_node);

         if (key < mynode->key)
             rbnode = rbnode->rb_left;
         else if (key > mynode->key)
             rbnode = rbnode->rb_right;
         else
             return mynode;
     }

     return NULL;
 }

 /*
  * 将key插入到红黑树中。插入成功，返回0；失败返回-1。
  */
 int my_insert(struct rb_root *root, Type key)
 {
     struct my_node *mynode; // 新建结点
     struct rb_node **tmp = &(root->rb_node), *parent = NULL;

     /* Figure out where to put new node */
     while (*tmp)
     {
         struct my_node *my = container_of(*tmp, struct my_node, rb_node);

         parent = *tmp;
         if (key < my->key)
             tmp = &((*tmp)->rb_left);
         else if (key > my->key)
             tmp = &((*tmp)->rb_right);
         else
             return -;
     }

     // 如果新建结点失败，则返回。
     if ((mynode=malloc(sizeof(struct my_node))) == NULL)
         return -;
     mynode->key = key;

     /* Add new node and rebalance tree. */
     rb_link_node(&mynode->rb_node, parent, tmp);
     rb_insert_color(&mynode->rb_node, root);

     return ;
 }

 /*
  * 删除键值为key的结点
  */
 void my_delete(struct rb_root *root, Type key)
 {
     struct my_node *mynode;

     // 在红黑树中查找key对应的节点mynode
     if ((mynode = my_search(root, key)) == NULL)
         return ;

     // 从红黑树中删除节点mynode
     rb_erase(&mynode->rb_node, root);
     free(mynode);
 }

 /*
  * 打印"红黑树"
  */
 static void print_rbtree(struct rb_node *tree, Type key, int direction)
 {
     if(tree != NULL)
     {
         if(direction==)    // tree是根节点
             printf("%2d(B) is root\n", key);
         else                // tree是分支节点
             printf("%2d(%s) is %2d's %6s child\n", key, rb_is_black(tree)?"B":"R", key, direction==?"right" : "left");

         if (tree->rb_left)
             print_rbtree(tree->rb_left, rb_entry(tree->rb_left, struct my_node, rb_node)->key, -);
         if (tree->rb_right)
             print_rbtree(tree->rb_right,rb_entry(tree->rb_right, struct my_node, rb_node)->key,  );
     }
 }

 void my_print(struct rb_root *root)
 {
     if (root!=NULL && root->rb_node!=NULL)
         print_rbtree(root->rb_node, rb_entry(root->rb_node, struct my_node, rb_node)->key,  );
 }

 void main()
 {
     int a[] = {, , , , , , , , };
     int i, ilen=LENGTH(a);
     struct rb_root mytree = RB_ROOT;

     printf("== 原始数据: ");
     for(i=; i<ilen; i++)
         printf("%d ", a[i]);
     printf("\n");

     for (i=; i < ilen; i++)
     {
         my_insert(&mytree, a[i]);
 #if CHECK_INSERT
         printf("== 添加节点: %d\n", a[i]);
         printf("== 树的详细信息: \n");
         my_print(&mytree);
         printf("\n");
 #endif

     }

 #if CHECK_DELETE
     for (i=; i<ilen; i++) {
         my_delete(&mytree, a[i]);

         printf("== 删除节点: %d\n", a[i]);
         printf("== 树的详细信息: \n");
         my_print(&mytree);
         printf("\n");
     }
 #endif
 }

rbtree.h和rbtree.c基本上是从Linux 3.0的Kernel中移植出来的。仅仅只添加了offestof和container_of两个宏，这两个宏在文章"Linux内核中双向链表的经典实现"中已经介绍过了，这里就不再重复说明了。
test.c中包含了两部分内容：一是，基于内核红黑树接口，自定义的一个结构体，并提供了相应的接口(添加、删除、搜索、打印)。二是，包含了相应的测试程序。