源码阅读再来一发:解读RGW中request的处理流程

 #src/rgw/rgw_main.cc
 get_str_list(g_conf->rgw_enable_apis, apis); #获取接口类型列表

   map<string, bool> apis_map;
   for (list<string>::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
     ...

 #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<string, string> 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 */

#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<RGWMongooseEnv *>(req_info->user_data); 

{
// 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
 ...

 #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,
 };