Nginx赤黒樹構造ngx_rbtree_t
概要
赤と黒の木の基礎知識については、前の文章で紹介しましたが、赤と黒の木をもっと詳しく知るためには、記事「データ構造-赤と黒の木」を参照してください.ここでは、単にNgixの中の赤と黒の木のソースコードを解析するだけです.
マホガニー構造
初期化操作
赤と黒の木の基礎知識については、前の文章で紹介しましたが、赤と黒の木をもっと詳しく知るためには、記事「データ構造-赤と黒の木」を参照してください.ここでは、単にNgixの中の赤と黒の木のソースコードを解析するだけです.
マホガニー構造
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;
struct ngx_rbtree_node_s {
ngx_rbtree_key_t key; /* */
ngx_rbtree_node_t *left; /* */
ngx_rbtree_node_t *right; /* */
ngx_rbtree_node_t *parent; /* */
u_char color; /* */
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 {
ngx_rbtree_node_t *root; /* */
ngx_rbtree_node_t *sentinel;/* NIL */
ngx_rbtree_insert_pt insert; /* , , ;
* */
};
マホガニーの操作初期化操作
/* ,1 ,0 */
#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)
/* , */
/* tree ,
* s NIL ,
* i ,
*/
#define ngx_rbtree_init(tree, s, i) \
ngx_rbtree_sentinel_init(s); \
(tree)->root = s; \
(tree)->sentinel = s; \
(tree)->insert = i
回転操作/* */
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;
temp = node->right;/* temp node */
node->right = temp->left;/* node temp */
if (temp->left != sentinel) {
temp->left->parent = node;
}
temp->parent = node->parent;
if (node == *root) {
*root = temp;
} else if (node == node->parent->left) {
node->parent->left = temp;
} else {
node->parent->right = temp;
}
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;
}
挿入操作/* */
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;
}
/* */
/* :
* 1、 ;
* 2、 ( 5);
* 3、 , ( ), ;
*/
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) {
node->parent = NULL;
node->left = sentinel;
node->right = sentinel;
ngx_rbt_black(node);
*root = node;
return;
}
/* ,
*
*/
tree->insert(*root, node, sentinel);
/* re-balance tree */
/* , ,
* 4: , ;
* 4, node node->parent ;
*/
while (node != *root && ngx_rbt_is_red(node->parent)) {
/* node */
if (node->parent == node->parent->parent->left) {
temp = node->parent->parent->right;/* temp node */
/* case1:node */
/* ,node ;
* : node , node ;
* ;
*/
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 {
/* case2:node node */
/* , node , case2 case3;
*/
if (node == node->parent->right) {
node = node->parent;
ngx_rbtree_left_rotate(root, sentinel, node);
}
/* case3:node node */
/* , node , ;
* ;
*/
ngx_rbt_black(node->parent);
ngx_rbt_red(node->parent->parent);
ngx_rbtree_right_rotate(root, sentinel, node->parent->parent);
}
} else {/* node */
/* ,
*/
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 ( ;; ) {
/* node temp , node temp */
p = (node->key < temp->key) ? &temp->left : &temp->right;
if (*p == sentinel) {
break;
}
temp = *p;
}
/* node , */
*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 - 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);
}
操作を削除/* */
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;
/* temp ,temp node ;
* subst ;
*/
/* case1: node ( )*/
if (node->left == sentinel) {
temp = node->right;
subst = node;
} else if (node->right == sentinel) {/* case2:node , */
temp = node->left;
subst = node;
} else {/* case3:node , */
subst = ngx_rbtree_min(node->right, sentinel);/* node */
if (subst->left != sentinel) {
temp = subst->left;
} else {
temp = subst->right;
}
}
/* subst , temp subst */
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 subst */
red = ngx_rbt_is_red(subst);
/* temp subst */
if (subst == subst->parent->left) {
subst->parent->left = temp;
} else {
subst->parent->right = temp;
}
/* subst node */
if (subst == node) {
temp->parent = subst->parent;
} else {
if (subst->parent == node) {
temp->parent = subst;
} else {
temp->parent = subst->parent;
}
/* node */
subst->left = node->left;
subst->right = node->right;
subst->parent = node->parent;
ngx_rbt_copy_color(subst, node);
if (node == *root) {
*root = subst;
} else {
if (node == node->parent->left) {
node->parent->left = subst;
} else {
node->parent->right = subst;
}
}
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 */
/* temp , temp */
while (temp != *root && ngx_rbt_is_black(temp)) {
/* temp */
if (temp == temp->parent->left) {
w = temp->parent->right;/* w temp */
/* case A:temp */
/* :
* 1、 w temp ;
* 2、 temp , ,temp w , ;
* 3、 ,case A case B、case C case D;
*/
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;
}
/* case B:temp w , w */
/* :
* 1、 w ;
* 2、 temp temp ;
*/
if (ngx_rbt_is_black(w->left) && ngx_rbt_is_black(w->right)) {
ngx_rbt_red(w);
temp = temp->parent;
} else {/* case C:temp , w , */
/* :
* 1、 w ;
* 2、 w ;
* 3、 ,temp w , case D;
*/
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;
}
/* case D:temp w , w */
/* :
* 1、 w temp ,temp ;
* 2、w ;
* 3、 temp ;
* 4、 root temp ;*/
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 {/* temp */
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);
}