ngx_http_cmp_locations

1 定义

ngx_http_cmp_locations 函数 定义在 ./nginx-1.24.0/src/http/ngx_http.c

staticngx_int_tngx_http_cmp_locations(constngx_queue_t*one,constngx_queue_t*two){ngx_int_trc;ngx_http_core_loc_conf_t*first,*second;ngx_http_location_queue_t*lq1,*lq2;lq1=(ngx_http_location_queue_t*)one;lq2=(ngx_http_location_queue_t*)two;first=lq1->exact?lq1->exact:lq1->inclusive;second=lq2->exact?lq2->exact:lq2->inclusive;if(first->noname&&!second->noname){/* shift no named locations to the end */return1;}if(!first->noname&&second->noname){/* shift no named locations to the end */return-1;}if(first->noname||second->noname){/* do not sort no named locations */return0;}if(first->named&&!second->named){/* shift named locations to the end */return1;}if(!first->named&&second->named){/* shift named locations to the end */return-1;}if(first->named&&second->named){returnngx_strcmp(first->name.data,second->name.data);}#if(NGX_PCRE)if(first->regex&&!second->regex){/* shift the regex matches to the end */return1;}if(!first->regex&&second->regex){/* shift the regex matches to the end */return-1;}if(first->regex||second->regex){/* do not sort the regex matches */return0;}#endifrc=ngx_filename_cmp(first->name.data,second->name.data,ngx_min(first->name.len,second->name.len)+1);if(rc==0&&!first->exact_match&&second->exact_match){/* an exact match must be before the same inclusive one */return1;}returnrc;}

`ngx_http_cmp_locations` 是 nginx 中用于对配置文件中所有 `location` 进行排序的比较函数。 其作用是将不同类型的 `location` 按照 匹配优先级 排列成固定顺序： 1. 普通前缀匹配（精确匹配在前） 2. 正则匹配 location 3. 命名 location 4. 无名（noname）location 排序后的列表用于构建后续高效查找的位置树，确保运行时能按正确顺序匹配请求。

2 详解

1 函数签名

staticngx_int_tngx_http_cmp_locations(constngx_queue_t*one,constngx_queue_t*two)

返回值 < 0 表示 one 大于 two 第一个元素应该排在第二个之前。 == 0 表示 one 等于 two 两个元素排序位置相同（相对顺序不变）。 > 0 表示 one 小于 two 第一个元素应该排在第二个之后。

参数 const ngx_queue_t *one, const ngx_queue_t *two 需要比较排序的 2 个链表节点

2 逻辑流程

1 局部变量 2 比较 2-1 noname 排最后 2-2 named 排倒数第二 2-3 正则 排倒数第三 2-4 普通前缀匹配

1 局部变量

{ngx_int_trc;ngx_http_core_loc_conf_t*first,*second;ngx_http_location_queue_t*lq1,*lq2;lq1=(ngx_http_location_queue_t*)one;lq2=(ngx_http_location_queue_t*)two;first=lq1->exact?lq1->exact:lq1->inclusive;second=lq2->exact?lq2->exact:lq2->inclusive;

2 比较

2-1 noname 排最后

if(first->noname&&!second->noname){/* shift no named locations to the end */return1;}if(!first->noname&&second->noname){/* shift no named locations to the end */return-1;}if(first->noname||second->noname){/* do not sort no named locations */return0;}

确保有明确 URI 名称的 location 排在没有名称的 location 之前

2-2 named 排倒数第二

if(first->named&&!second->named){/* shift named locations to the end */return1;}if(!first->named&&second->named){/* shift named locations to the end */return-1;}if(first->named&&second->named){returnngx_strcmp(first->name.data,second->name.data);}

2-3 正则 排倒数第三

#if(NGX_PCRE)if(first->regex&&!second->regex){/* shift the regex matches to the end */return1;}if(!first->regex&&second->regex){/* shift the regex matches to the end */return-1;}if(first->regex||second->regex){/* do not sort the regex matches */return0;}#endif

2-4 普通前缀匹配

rc=ngx_filename_cmp(first->name.data,second->name.data,ngx_min(first->name.len,second->name.len)+1);if(rc==0&&!first->exact_match&&second->exact_match){/* an exact match must be before the same inclusive one */return1;}returnrc;}

精确匹配在前