怎么理解RGW中request的处理流程
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源码解读RGW中request的处理流程
请求处理流程图
以civetweb为例
rgw_main.cc为整个radosgw服务的入口,main()函数中根据在ceph.conf的rgw frontends参数设置来选择不同的前端类型,之后执行相应的run()方法实现整个frontend服务的启动。注意这里会根据ceph.conf中rgw_enable_apis的设置,实现s3、swift、admin等多种类型的接口生成不同的handler,具体代码如下
#src/rgw/rgw_main.cc get_str_list(g_conf->rgw_enable_apis, apis); #获取接口类型列表 map
apis_map; for (list ::iterator li = apis.begin(); li != apis.end(); ++li) { apis_map[*li] = true; } ... if (apis_map.count("s3") > 0 || s3website_enabled) { if (! swift_at_root) { rest.register_default_mgr(set_logging(new RGWRESTMgr_S3(s3website_enabled))); #设置S3接口默认handler为RGWRESTMgr_S3 ... if (apis_map.count("swift") > 0) { do_swift = true; swift_init(g_ceph_context); RGWRESTMgr_SWIFT* const swift_resource = new RGWRESTMgr_SWIFT;#设置swift接口默认handler为RGWRESTMgr_SWIFT ... 之后在对应的rgw_civetweb_fronted.cc中,根据之前介绍的civetweb启动流程,设置相应启动参数,之后使用mg_start()完成civetweb的启动。(注意参数中callback设置的是civetweb_callback)
#src/rgw/rgw_civetweb_frontend.cc int RGWMongooseFrontend::run() { char thread_pool_buf[32]; snprintf(thread_pool_buf, sizeof(thread_pool_buf), "%d", (int)g_conf->rgw_thread_pool_size); string port_str; map
conf_map = conf->get_config_map(); conf->get_val("port", "80", &port_str); conf_map.erase("port"); std::replace(port_str.begin(), port_str.end(), '+', ','); conf_map["listening_ports"] = port_str; #civetweb默认启动监听端口 set_conf_default(conf_map, "enable_keep_alive", "yes"); #keep_alive参数设置 set_conf_default(conf_map, "num_threads", thread_pool_buf); #默认threads设置 set_conf_default(conf_map, "decode_url", "no"); ... struct mg_callbacks cb; memset((void *)&cb, 0, sizeof(cb)); cb.begin_request = civetweb_callback; #回调函数设置 cb.log_message = rgw_civetweb_log_callback; cb.log_access = rgw_civetweb_log_access_callback; ctx = mg_start(&cb, &env, (const char **)&options); #启动服务 if (!ctx) { return -EIO; } return 0; } /* RGWMongooseFrontend::run */ 经过上一步的设置,在civetweb_callback中每一个request请求都需要经过process_request()进行处理,注意每个request请求都会绑定一组RGWRados(负责底层Librados的数据读写)/RGWREST(对应request和Response的处理)/OpsLogSocket(日志消息记录)
#src/rgw/rgw_civetweb_frontend.cc
static int civetweb_callback(struct mg_connection* conn) { struct mg_request_info* req_info = mg_get_request_info(conn); RGWMongooseEnv* pe = static_cast
{ // hold a read lock over access to pe->store for reconfiguration RWLock::RLocker lock(pe->mutex);
RGWRados* store = pe->store; RGWREST* rest = pe->rest; OpsLogSocket* olog = pe->olog;
RGWRequest req(store->get_new_req_id()); RGWMongoose client_io(conn);
int ret = process_request(pe->store, rest, &req, &client_io, olog); #每个request请求绑定一组前面的RGWRados、RGWREST、OpsLogSocket ... ```
之后调用rgw_process.cc中的process_request(),其中rest->get_handler根据请求的URL是否包含bucket、object信息,获取到对应的handler类型,之后调用handler->get_op(store)根据前面取得的handler对应request_method获取到最终的handler,之后触发handler对应的pre_exec()、execute()、complete()完整整个request请求的处理,代码如下:
#src/rgw/rgw_process.cc int process_request(RGWRados* store, RGWREST* rest, RGWRequest* req,GWStreamIO* client_io, OpsLogSocket* olog) {int ret = 0; client_io->init(g_ceph_context); ... RGWHandler_REST *handler = rest->get_handler(store, s, client_io, &mgr,&init_error); #这里根据URL里面是否包含bucket、Object字段会进一步获取到对应的handler类型 if (init_error != 0) { abort_early(s, NULL, init_error, NULL); goto done; } dout(10) << "handler=" << typeid(*handler).name() << dendl; should_log = mgr->get_logging(); req->log_format(s, "getting op %d", s->op); op = handler->get_op(store); #这里根据request_method获取到最终处理request请求的handler类型 ... req->log(s, "pre-executing"); op->pre_exec(); #请求预处理 req->log(s, "executing"); op->execute(); #具体请求的具体实现 req->log(s, "completing"); op->complete(); #完成请求处理
#src/rgw/rgw_process.cc RGWHandler_REST* RGWRESTMgr_S3::get_handler(struct req_state *s) { bool is_s3website = enable_s3website && (s->prot_flags & RGW_REST_WEBSITE); int ret = RGWHandler_REST_S3::init_from_header(s, is_s3website ? RGW_FORMAT_HTML : RGW_FORMAT_XML, true); if (ret < 0) return NULL; RGWHandler_REST* handler; // TODO: Make this more readable if (is_s3website) { if (s->init_state.url_bucket.empty()) { handler = new RGWHandler_REST_Service_S3Website; } else if (s->object.empty()) { handler = new RGWHandler_REST_Bucket_S3Website; } else { handler = new RGWHandler_REST_Obj_S3Website; } } else { if (s->init_state.url_bucket.empty()) { handler = new RGWHandler_REST_Service_S3; #bucket为空则切换到RGWHandler_REST_Service_S3 } else if (s->object.empty()) { handler = new RGWHandler_REST_Bucket_S3; #obj为空则切换RGWHandler_REST_Bucket_S3 } else { handler = new RGWHandler_REST_Obj_S3; #bucket和Object都不为空,则切换到RGWHandler_REST_Obj_S3 } } ldout(s->cct, 20) << __func__ << " handler=" << typeid(*handler).name() << dendl; return handler; }
#src/rgw/rgw_rest.cc RGWOp* RGWHandler_REST::get_op(RGWRados* store) { RGWOp *op; switch (s->op) #这里s对应一个req_state的结构体 { rest->op case OP_GET: op = op_get(); break; case OP_PUT: op = op_put(); break; case OP_DELETE: op = op_delete(); break; case OP_HEAD: op = op_head(); break; case OP_POST: op = op_post(); break; case OP_COPY: op = op_copy(); break; case OP_OPTIONS: op = op_options(); break; default: return NULL; } if (op) { op->init(store, s, this); } return op; } /* get_op */
结构体定义 struct req_state { CephContext *cct; RGWClientIO *cio; RGWRequest *req; /// XXX: re-remove?? http_op op; #对应一个枚举类型,具体如下 RGWOpType op_type; ... enum http_op { OP_GET, OP_PUT, OP_DELETE, OP_HEAD, OP_POST, OP_COPY, OP_OPTIONS, OP_UNKNOWN, };
URL->handler过程
理解整个URL转换handler的过程,能够感觉request信息快速定位具体的op操作,方便debug,整个过程用下面一张图总结。
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