Subrequest是由HTTP框架提供的一种分解复杂请求的设计模式,它可以把原始请求分解为许多子请求,由多个子请求协同完成一个用户请求。原理:子请求使用upstream机制访问上游服务器,由父请求根据上游响应重新构响应造返回下游客户端。主要流程如下:
1. 在nginx.conf配置文件中配置子请求处理方式
2.构造子请求并启动
3. 子请求执行结束处理
4. 父请求被激活时处理
在学习过程中发现,网上关于sub request的介绍都是基于“访问上证股市行情”的例子,不得不说,该程序对于入门学习非常好。可是对于进一步学习并应用该技术,则没有过多的例子可以参考。本文通过“运用子请求和drizzles模块访问mysql”例子再次诠释sub request的使用。
本例程涉及应用:
1. 后端访问配置方式(drizzle 访问mysql配置)
2.子请求基于upstream机制的处理配置
3. Cjson解析消息体(编译上述模块时,请安装Cjson)
本例子程序的处理逻辑:
1. 命令行通过curl(POST方式)发送请求数据(JSON格式)到服务器
2.nginx收到消息体后,解析并打印,构造子请求( URL:/mysql_query)访问Mysql数据库后端
3.nginx处理子请求:通过upstream机制访问数据库,URL(/mysql)
4.nginx通过drizzle模块访问数据库,读取数据,并通过upstream模块返回数据
5.子请求回调函数解析、保存查询到数据
6.主请求回调函数构造应答数据,返回给客户端
处理流程:nginx 主请求 -->nginx 子请求-->/mysql_query-->/mysql-->drizzle->mysql数据库
配置:
upstream backend { drizzle_server localhost:3306 dbname=test password=xxxx user=root protocol=mysql; } location /mysql_test{ client_body_in_single_buffer on; sub_request_mysql test;//test为参数,此例程未使用 } location /mysql { set $my_sql 'select * from student limit 3'; drizzle_query $my_sql; drizzle_pass backend; drizzle_connect_timeout 500ms; # default 60s drizzle_send_query_timeout 2s; # default 60s drizzle_recv_cols_timeout 1s; # default 60s drizzle_recv_rows_timeout 1s; # default 60s rds_json on; } //子请求查询数据库,此处使用upstream机制 location /mysql_query { proxy_pass http://localhost/mysql; #return 200; #return 200 '{"status":"success","result":"nginx json"}'; }
root@iZ2ze3uk97m2bfv681kyx4Z:~# curl -i -X POST -H "'Content-type':'application/json'" -d '{"name":"test"}' http://localhost:80/nestle HTTP/1.1 200 OK Server: openresty/1.13.6.1 Date: Tue, 01 May 2018 06:10:24 GMT Content-Type: text/plain; charset=GBK Content-Length: 104 Connection: keep-alive [{"id":1,"name":"zhang1","age":0},{"id":3,"name":"zhang-02","age":0},{"id":5,"name":"zhang-03","age":0}]
源码:
ngx_http_sub_request_mysql_module.c: #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> #include "cJSON.h" typedef struct { ngx_str_t output_words; ngx_uint_t flag; } ngx_http_sub_request_mysql_loc_conf_t; static char* ngx_http_sub_request_mysql(ngx_conf_t* cf, ngx_command_t* cmd, void* conf); static void* ngx_http_sub_request_mysql_create_loc_conf(ngx_conf_t* cf); static char* ngx_http_sub_request_mysql_merge_loc_conf(ngx_conf_t* cf, void* parent, void* child); static ngx_command_t ngx_http_sub_request_mysql_commands[] = { { ngx_string("sub_request_mysql"), // The command name NGX_HTTP_LOC_CONF | NGX_CONF_TAKE1, ngx_http_sub_request_mysql, // The command handler NGX_HTTP_LOC_CONF_OFFSET, offsetof(ngx_http_sub_request_mysql_loc_conf_t, output_words), NULL }, ngx_null_command }; // Structure for the HelloWorld context static ngx_http_module_t ngx_http_sub_request_mysql_module_ctx = { NULL, NULL, NULL, NULL, NULL, NULL, ngx_http_sub_request_mysql_create_loc_conf, ngx_http_sub_request_mysql_merge_loc_conf }; // Structure for the HelloWorld module, the most important thing ngx_module_t ngx_http_sub_request_mysql_module = { NGX_MODULE_V1, &ngx_http_sub_request_mysql_module_ctx, ngx_http_sub_request_mysql_commands, NGX_HTTP_MODULE, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NGX_MODULE_V1_PADDING }; typedef struct { ngx_str_t name; ngx_str_t db_request_data; } ngx_http_extern_request_mysql_ctx_t; static void extern_db_request_post_handler(ngx_http_request_t *r) { ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "%s: status[%d]",__FUNCTION__, r->headers_out.status); if (r->headers_out.status != NGX_HTTP_OK) { ngx_http_finalize_request(r, r->headers_out.status); return; } ngx_http_extern_request_mysql_ctx_t *my_ctx = ngx_http_get_module_ctx(r, ngx_http_sub_request_mysql_module); int bodylen = my_ctx->db_request_data.len; r->headers_out.content_length_n = bodylen; ngx_buf_t *b = ngx_create_temp_buf(r->pool,bodylen); ngx_snprintf(b->pos, bodylen, (char *)my_ctx->db_request_data.data); b->last = b->pos + bodylen; b->last_buf = 1; ngx_chain_t out; out.buf = b; out.next = NULL; static ngx_str_t type = ngx_string("text/plain; charset=GBK"); r->headers_out.content_type= type; r->headers_out.status =NGX_HTTP_OK; r->connection->buffered |= NGX_HTTP_WRITE_BUFFERED; ngx_int_t ret = ngx_http_send_header(r); ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "%s: send header ret[%d]", __FUNCTION__, ret); ret = ngx_http_output_filter(r,&out); ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "%s: send body ret[%d]", __FUNCTION__, ret); ngx_http_finalize_request(r,ret); } static ngx_int_t extern_db_sub_req_post_handler(ngx_http_request_t *r, void *data, ngx_int_t rc) { ngx_str_t response_data; ngx_http_request_t *pr = r->parent; ngx_http_extern_request_mysql_ctx_t *my_ctx = ngx_http_get_module_ctx(pr, ngx_http_sub_request_mysql_module); pr->headers_out.status = r->headers_out.status; ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "%s: %d",__FUNCTION__, r->headers_out.status); if (r->headers_out.status == NGX_HTTP_OK) { int flag = 0; ngx_buf_t *sub_recv_buf = &r->upstream->buffer; response_data.data = sub_recv_buf->pos; response_data.len = ngx_buf_size(sub_recv_buf); ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "data: %d, %V", response_data.len, &response_data); my_ctx->db_request_data.len = response_data.len; my_ctx->db_request_data.data = response_data.data; } pr->write_event_handler = extern_db_request_post_handler; return NGX_OK; } static void ngx_http_sub_request_mysql_client_body_handler_pt(ngx_http_request_t *r) { ngx_int_t rc = NGX_OK; char log_buf[32] = {0}; u_char body_buf[256] = {0}; ngx_buf_t *p_body_buf = NULL; cJSON *root = NULL; cJSON *name = NULL; ngx_http_sub_request_mysql_loc_conf_t* hlcf = NULL; hlcf = ngx_http_get_module_loc_conf(r, ngx_http_sub_request_mysql_module); if (NULL == hlcf) { } ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "%s", log_buf); p_body_buf = r->request_body->bufs->buf; ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "length:%d", ngx_buf_size(p_body_buf)); ngx_snprintf(body_buf, sizeof(body_buf), "%*s", ngx_buf_size(p_body_buf), p_body_buf->pos); ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "main: receive body:%s", body_buf); root = cJSON_Parse((char *)body_buf); if (NULL == root) { return; } name = cJSON_GetObjectItemCaseSensitive(root, "name"); if (NULL == name) { return; } ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "name: %s", name->valuestring); ngx_http_extern_request_mysql_ctx_t *my_ctx = ngx_http_get_module_ctx(r, ngx_http_sub_request_mysql_module); if (NULL == my_ctx) { my_ctx = ngx_palloc(r->pool, sizeof(ngx_http_extern_request_mysql_ctx_t)); if (NULL == my_ctx) { return; } ngx_http_set_ctx(r, my_ctx, ngx_http_sub_request_mysql_module); } ngx_http_post_subrequest_t *my_sub_req = ngx_palloc(r->pool, sizeof(ngx_http_post_subrequest_t)); if (NULL == my_sub_req) { return; } my_sub_req->handler = extern_db_sub_req_post_handler; my_sub_req->data = my_ctx; ngx_str_t sub_prefix = ngx_string("/mysql_query?name=hello"); ngx_str_t sub_location; sub_location.len =sub_prefix.len; sub_location.data = ngx_palloc(r->pool,sub_location.len); ngx_snprintf(sub_location.data, sub_location.len, "%V", &sub_prefix); ngx_http_request_t *sr = NULL; rc = ngx_http_subrequest(r, &sub_location, NULL, &sr, my_sub_req, NGX_HTTP_SUBREQUEST_IN_MEMORY); if (rc != NGX_OK) { return; } return; } static int ngx_response_info(ngx_http_request_t* r) { ngx_int_t rc = NGX_OK; ngx_buf_t* b = NULL; ngx_chain_t out[2]; cJSON *root = NULL; char json_buf[256] = {0}; root = cJSON_CreateObject(); cJSON_AddItemToObject(root, "res-info", cJSON_CreateString("no account info in body")); r->headers_out.content_type.len = sizeof("application/json; charset=utf-8") - 1; r->headers_out.content_type.data = (u_char*)"application/json; charset=utf-8"; b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t)); out[0].buf = b; out[0].next = NULL; snprintf(json_buf, sizeof(json_buf), "%s", cJSON_Print(root)); ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "%s,length:%d", json_buf, strlen(json_buf)); b->pos = (u_char*)cJSON_Print(root); b->last = b->pos + strlen(json_buf); b->memory = 1; b->last_buf = 1; r->headers_out.status = NGX_HTTP_OK; r->headers_out.content_length_n = strlen(json_buf); rc = ngx_http_send_header(r); if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) { return rc; } rc = ngx_http_output_filter(r, &out[0]); ngx_http_finalize_request(r,rc); cJSON_Delete(root); return rc; } static ngx_int_t ngx_http_sub_request_mysql_handler(ngx_http_request_t* r) { ngx_int_t rc = NGX_OK; int no_content_flag = 0; if (r->headers_in.content_length) { ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "%s: content length is %d", __FUNCTION__, ngx_atoi(r->headers_in.content_length->value.data, r->headers_in.content_length->value.len)); } else { no_content_flag = 1; ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "no content"); } if (0 == no_content_flag && ngx_atoi(r->headers_in.content_length->value.data, r->headers_in.content_length->value.len) <= 0) { ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "in: content length is %d", ngx_atoi(r->headers_in.content_length->value.data, r->headers_in.content_length->value.len)); no_content_flag = 1; ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "no content"); } ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "no content flag:%d", no_content_flag); if (no_content_flag) { return ngx_response_info(r); } rc = ngx_http_read_client_request_body(r, ngx_http_sub_request_mysql_client_body_handler_pt); if (rc >= NGX_HTTP_SPECIAL_RESPONSE) { ngx_log_error(NGX_LOG_EMERG, r->connection->log, 0, "%s", "unknown respone"); return rc; } return NGX_DONE; } static void* ngx_http_sub_request_mysql_create_loc_conf(ngx_conf_t* cf) { ngx_http_sub_request_mysql_loc_conf_t* conf; conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_sub_request_mysql_loc_conf_t)); if (conf == NULL) { return NGX_CONF_ERROR; } conf->output_words.len = 0; conf->output_words.data = NULL; conf->flag = NGX_CONF_UNSET; return conf; } static char* ngx_http_sub_request_mysql_merge_loc_conf(ngx_conf_t* cf, void* parent, void* child) { ngx_http_sub_request_mysql_loc_conf_t* prev = parent; ngx_http_sub_request_mysql_loc_conf_t* conf = child; ngx_conf_merge_str_value(conf->output_words, prev->output_words, "Nginx"); ngx_conf_merge_uint_value(conf->flag, prev->flag, 1); return NGX_CONF_OK; } static char* ngx_http_sub_request_mysql(ngx_conf_t* cf, ngx_command_t* cmd, void* conf) { ngx_http_core_loc_conf_t* clcf; clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module); clcf->handler = ngx_http_sub_request_mysql_handler; ngx_conf_set_str_slot(cf, cmd, conf); return NGX_CONF_OK; }s
config: ngx_addon_name=ngx_http_sub_request_mysql_module HTTP_MODULES="$HTTP_MODULES ngx_http_sub_request_mysql_module" NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/ngx_http_sub_request_mysql_module.c"