ngx_queue_t

/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */#include <ngx_config.h>#include <ngx_core.h>#ifndef _NGX_QUEUE_H_INCLUDED_#define _NGX_QUEUE_H_INCLUDED_typedef struct ngx_queue_s  ngx_queue_t;struct ngx_queue_s {    ngx_queue_t  *prev;    ngx_queue_t  *next;};//初始化一个已有的链表#define ngx_queue_init(q)                                                     \    (q)->prev = q;                                                            \    (q)->next = q//判断链表是否为空#define ngx_queue_empty(h)                                                    \    (h == (h)->prev)//在链表的头部插入元素 x#define ngx_queue_insert_head(h, x)                                           \    (x)->next = (h)->next;                                                    \    (x)->next->prev = x;                                                      \    (x)->prev = h;                                                            \    (h)->next = x//在链表的头部插入#define ngx_queue_insert_after   ngx_queue_insert_head//在链表的尾部插入#define ngx_queue_insert_tail(h, x)                                           \    (x)->prev = (h)->prev;                                                    \    (x)->prev->next = x;                                                      \    (x)->next = h;                                                            \    (h)->prev = x//访问链表的第一个元素#define ngx_queue_head(h)                                                     \    (h)->next//访问链表的最后一个元素#define ngx_queue_last(h)                                                     \    (h)->prev//获取链表的头#define ngx_queue_sentinel(h)                                                 \    (h)//访问q的下一个元素#define ngx_queue_next(q)                                                     \    (q)->next//访问q的前一个节点#define ngx_queue_prev(q)                                                     \    (q)->prev#if (NGX_DEBUG)#define ngx_queue_remove(x)                                                   \    (x)->next->prev = (x)->prev;                                              \    (x)->prev->next = (x)->next;                                              \    (x)->prev = NULL;                                                         \    (x)->next = NULL#else//删除连表中的x节点  这里只有调试版本才制空 //nginx真心是做的一个多余的操作都不要#define ngx_queue_remove(x)                                                   \    (x)->next->prev = (x)->prev;                                              \    (x)->prev->next = (x)->next#endif//把链表h 拆分成 h、n 两个链表 //其中 h：q元素之前的元素（不含q） n：q开始之后的元素（包含q）#define ngx_queue_split(h, q, n)                                              \    (n)->prev = (h)->prev;                                                    \    (n)->prev->next = n;                                                      \    (n)->next = q;                                                            \    (h)->prev = (q)->prev;                                                    \    (h)->prev->next = h;                                                      \    (q)->prev = n;//把n链表拼接到h链表的后面s#define ngx_queue_add(h, n)                                                   \    (h)->prev->next = (n)->next;                                              \    (n)->next->prev = (h)->prev;                                              \    (h)->prev = (n)->prev;                                                    \    (h)->prev->next = h;//获取q所在对象的地址，这种写法真心牛X，长知识了#define ngx_queue_data(q, type, link)                                         \    (type *) ((u_char *) q - offsetof(type, link))//取连表中的中间节点 (size/2 + 1)ngx_queue_t *ngx_queue_middle(ngx_queue_t *queue);//按照cmp函数对链表进行排序  //这里用的是插入排序，数据两大的情况下不建议使用void ngx_queue_sort(ngx_queue_t *queue,    ngx_int_t (*cmp)(const ngx_queue_t *, const ngx_queue_t *));#endif /* _NGX_QUEUE_H_INCLUDED_ */