欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  后端开发

Nginx之红黑树

程序员文章站 2022-04-23 14:31:32
...
Nginx之红黑树
/*
* Copyright (C) Igor Sysoev
* Copyright (C) Nginx, Inc.
*/
#ifndef _NGX_RBTREE_H_INCLUDED_
#define _NGX_RBTREE_H_INCLUDED_
#include <ngx_config.h>
#include <ngx_core.h>
typedef ngx_uint_t ngx_rbtree_key_t;
typedef ngx_int_t ngx_rbtree_key_int_t;
typedef struct ngx_rbtree_node_s ngx_rbtree_node_t;
// 红黑树
struct ngx_rbtree_node_s {
// 无符号整形的关键字
ngx_rbtree_key_t key;
// 左子节点
ngx_rbtree_node_t *left;
// 右子节点
ngx_rbtree_node_t *right;
// 父节点
ngx_rbtree_node_t *parent;
// 节点的颜色,0表示黑色,1表示红色
u_char color;
// 仅1个字节的节点数据。由于表示的空间太小,所以一般很少使用。
u_char data;
};
typedef struct ngx_rbtree_s ngx_rbtree_t;
typedef void (*ngx_rbtree_insert_pt) (ngx_rbtree_node_t *root,
ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel);
struct ngx_rbtree_s {
// 指向树的根节点。
ngx_rbtree_node_t *root;
// 指向NIL哨兵节点
ngx_rbtree_node_t *sentinel;
// 表示红黑树添加元素的函数指针,它决定在添加新节点时的行为究竟是替换还是新增
ngx_rbtree_insert_pt insert;
};
#define ngx_rbtree_init(tree, s, i) \
ngx_rbtree_sentinel_init(s); \
(tree)->root = s; \
(tree)->sentinel = s; \
(tree)->insert = i
void ngx_rbtree_insert(ngx_thread_volatile ngx_rbtree_t *tree,
ngx_rbtree_node_t *node);
void ngx_rbtree_delete(ngx_thread_volatile ngx_rbtree_t *tree,
ngx_rbtree_node_t *node);
void ngx_rbtree_insert_value(ngx_rbtree_node_t *root, ngx_rbtree_node_t *node,
ngx_rbtree_node_t *sentinel);
void ngx_rbtree_insert_timer_value(ngx_rbtree_node_t *root,
ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel);
#define ngx_rbt_red(node) ((node)->color = 1)
#define ngx_rbt_black(node) ((node)->color = 0)
#define ngx_rbt_is_red(node) ((node)->color)
#define ngx_rbt_is_black(node) (!ngx_rbt_is_red(node))
#define ngx_rbt_copy_color(n1, n2) (n1->color = n2->color)
/* a sentinel must be black */
#define ngx_rbtree_sentinel_init(node) ngx_rbt_black(node)
static ngx_inline ngx_rbtree_node_t *
ngx_rbtree_min(ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel)
{
while (node->left != sentinel) {
node = node->left;
}
return node;
}
#endif /* _NGX_RBTREE_H_INCLUDED_ */
/*
* Copyright (C) Igor Sysoev
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
/*
* The red-black tree code is based on the algorithm described in
* the "Introduction to Algorithms" by Cormen, Leiserson and Rivest.
*/
static ngx_inline void ngx_rbtree_left_rotate(ngx_rbtree_node_t **root,
ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node);
static ngx_inline void ngx_rbtree_right_rotate(ngx_rbtree_node_t **root,
ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node);
void ngx_rbtree_insert(ngx_thread_volatile ngx_rbtree_t *tree,
ngx_rbtree_node_t *node) {
ngx_rbtree_node_t **root, *temp, *sentinel;
/* a binary tree insert */
root = (ngx_rbtree_node_t **) &tree->root;
sentinel = tree->sentinel;
if (*root == sentinel) { //空树
node->parent = NULL;
node->left = sentinel;
node->right = sentinel;
ngx_rbt_black(node);
*root = node;
return;
}
tree->insert(*root, node, sentinel);
/* re-balance tree */
while (node != *root && ngx_rbt_is_red(node->parent)) {
if (node->parent == node->parent->parent->left) {
temp = node->parent->parent->right;
if (ngx_rbt_is_red(temp)) {
ngx_rbt_black(node->parent);
ngx_rbt_black(temp);
ngx_rbt_red(node->parent->parent);
node = node->parent->parent;
} else {
if (node == node->parent->right) {
node = node->parent;
ngx_rbtree_left_rotate(root, sentinel, node);
}
ngx_rbt_black(node->parent);
ngx_rbt_red(node->parent->parent);
ngx_rbtree_right_rotate(root, sentinel, node->parent->parent);
}
} else {
temp = node->parent->parent->left;
if (ngx_rbt_is_red(temp)) {
ngx_rbt_black(node->parent);
ngx_rbt_black(temp);
ngx_rbt_red(node->parent->parent);
node = node->parent->parent;
} else {
if (node == node->parent->left) {
node = node->parent;
ngx_rbtree_right_rotate(root, sentinel, node);
}
ngx_rbt_black(node->parent);
ngx_rbt_red(node->parent->parent);
ngx_rbtree_left_rotate(root, sentinel, node->parent->parent);
}
}
}
ngx_rbt_black(*root);
}
void ngx_rbtree_insert_value(ngx_rbtree_node_t *temp, ngx_rbtree_node_t *node,
ngx_rbtree_node_t *sentinel) {
ngx_rbtree_node_t **p;
for (;;) {
p = (node->key < temp->key) ? &temp->left : &temp->right;
if (*p == sentinel) {
break;
}
temp = *p;
}
*p = node;
node->parent = temp;
node->left = sentinel;
node->right = sentinel;
ngx_rbt_red(node);
}
void ngx_rbtree_insert_timer_value(ngx_rbtree_node_t *temp,
ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel) {
ngx_rbtree_node_t **p;
for (;;) {
/*
* Timer values
* 1) are spread in small range, usually several minutes,
* 2) and overflow each 49 days, if milliseconds are stored in 32 bits.
* The comparison takes into account that overflow.
*/
/* node->key < temp->key */
p = ((ngx_rbtree_key_int_t) node->key - (ngx_rbtree_key_int_t) temp->key
< 0) ? &temp->left : &temp->right;
if (*p == sentinel) {
break;
}
temp = *p;
}
*p = node;
node->parent = temp;
node->left = sentinel;
node->right = sentinel;
ngx_rbt_red(node);
}
void ngx_rbtree_delete(ngx_thread_volatile ngx_rbtree_t *tree,
ngx_rbtree_node_t *node) {
ngx_uint_t red;
ngx_rbtree_node_t **root, *sentinel, *subst, *temp, *w;
/* a binary tree delete */
root = (ngx_rbtree_node_t **) &tree->root;
sentinel = tree->sentinel;
//找到y和x节点
if (node->left == sentinel) {
temp = node->right;
subst = node;
} else if (node->right == sentinel) {
temp = node->left;
subst = node;
} else {
subst = ngx_rbtree_min(node->right, sentinel);
if (subst->left != sentinel) {
temp = subst->left;
} else {
temp = subst->right;
}
}
//y节点为root节点
if (subst == *root) {
*root = temp;
ngx_rbt_black(temp);
/* DEBUG stuff */
node->left = NULL;
node->right = NULL;
node->parent = NULL;
node->key = 0;
return;
}
//
red = ngx_rbt_is_red(subst);//记录y节点颜色
//y父的孩子节点
if (subst == subst->parent->left) {
subst->parent->left = temp;
} else {
subst->parent->right = temp;
}
//y孩子的父节点
if (subst == node) {//只有一个孩子节点
temp->parent = subst->parent;
} else {
if (subst->parent == node) {
temp->parent = subst;
} else {
temp->parent = subst->parent;
}
//y节点copy z节点属性
subst->left = node->left;
subst->right = node->right;
subst->parent = node->parent;
ngx_rbt_copy_color(subst, node);
if (node == *root) {
*root = subst;
} else {//删除节点的父节点的孩子节点
if (node == node->parent->left) {
node->parent->left = subst;
} else {
node->parent->right = subst;
}
}
//y节点的父节点
if (subst->left != sentinel) {
subst->left->parent = subst;
}
if (subst->right != sentinel) {
subst->right->parent = subst;
}
}
/* DEBUG stuff */
node->left = NULL;
node->right = NULL;
node->parent = NULL;
node->key = 0;
if (red) {
return;
}
/* a delete fixup */
while (temp != *root && ngx_rbt_is_black(temp)) {
if (temp == temp->parent->left) {
w = temp->parent->right;
if (ngx_rbt_is_red(w)) {
ngx_rbt_black(w);
ngx_rbt_red(temp->parent);
ngx_rbtree_left_rotate(root, sentinel, temp->parent);
w = temp->parent->right;
}
if (ngx_rbt_is_black(w->left) && ngx_rbt_is_black(w->right)) {
ngx_rbt_red(w);
temp = temp->parent;
} else {
if (ngx_rbt_is_black(w->right)) {
ngx_rbt_black(w->left);
ngx_rbt_red(w);
ngx_rbtree_right_rotate(root, sentinel, w);
w = temp->parent->right;
}
ngx_rbt_copy_color(w, temp->parent);
ngx_rbt_black(temp->parent);
ngx_rbt_black(w->right);
ngx_rbtree_left_rotate(root, sentinel, temp->parent);
temp = *root;
}
} else {
w = temp->parent->left;
if (ngx_rbt_is_red(w)) {
ngx_rbt_black(w);
ngx_rbt_red(temp->parent);
ngx_rbtree_right_rotate(root, sentinel, temp->parent);
w = temp->parent->left;
}
if (ngx_rbt_is_black(w->left) && ngx_rbt_is_black(w->right)) {
ngx_rbt_red(w);
temp = temp->parent;
} else {
if (ngx_rbt_is_black(w->left)) {
ngx_rbt_black(w->right);
ngx_rbt_red(w);
ngx_rbtree_left_rotate(root, sentinel, w);
w = temp->parent->left;
}
ngx_rbt_copy_color(w, temp->parent);
ngx_rbt_black(temp->parent);
ngx_rbt_black(w->left);
ngx_rbtree_right_rotate(root, sentinel, temp->parent);
temp = *root;
}
}
}
ngx_rbt_black(temp);
}
static ngx_inline void ngx_rbtree_left_rotate(ngx_rbtree_node_t **root,
ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node) {
ngx_rbtree_node_t *temp;
//1、设置节点y
temp = node->right;
//2、将y的左子树作为x的右子树
node->right = temp->left;
if (temp->left != sentinel) {
temp->left->parent = node;
}
//3、链接y与x的父节点
temp->parent = node->parent;
if (node == *root) {
*root = temp;
} else if (node == node->parent->left) {
node->parent->left = temp;
} else {
node->parent->right = temp;
}
//4、x作为y的左子树
temp->left = node;
node->parent = temp;
}
static ngx_inline void ngx_rbtree_right_rotate(ngx_rbtree_node_t **root,
ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node) {
ngx_rbtree_node_t *temp;
temp = node->left;
node->left = temp->right;
if (temp->right != sentinel) {
temp->right->parent = node;
}
temp->parent = node->parent;
if (node == *root) {
*root = temp;
} else if (node == node->parent->right) {
node->parent->right = temp;
} else {
node->parent->left = temp;
}
temp->right = node;
node->parent = temp;
}

以上就是Nginx之红黑树的内容,更多相关内容请关注PHP中文网(www.php.cn)!

相关标签: Nginx,红黑树