Periodic summary of asynchronous RPC under Linux-non-blocking socket client

2. Use non-blocking sockets whenever possible

   int flags, S;
   Flags = FCNTL (FD, F_GETFL, 0);
   if (flags = =-1) {
   Close (FD);
   return-1;
   }
   
   Flags |= O_nonblock;
   s = fcntl (FD, F_SETFL, flags);
   if (s = =-1) {
   Close (FD);
   return-1;
   }
   

4. Get In/out events on multiple sockets using an efficient epoll mechanism

6. A non-blocking socket connection server is not necessarily immediately connected to the servers

   for further tracking by judging the return value and error number of the Connect function

   INT ret =:: Connect (THIS->FD, ( struct sockaddr*) & (SERVER_ADDR), sizeof (SERVER_ADDR));
               if (ret = = 0) {
           & nbsp;       this->on_connected ();
               }else if (Ret < 0 && errno! = einprogress) {
   & nbsp;              //error
                }else{
                   on_connecting ();
               }

1. In/out event If connecting needs to determine the socket status, the socket reset will also generate an event before entering a valid read and write
   

   if (this->connect_ Status = = 1) {//connecting
           int status = 0;
           socklen_t Slen;
           if (getsockopt (THIS->FD, Sol_socket, So_error, (void*) &status, & Slen) < 0) {
               this->on_epollhup ();
               return;
           }
           if (status! = 0) {
               this->on_epollhup ();
               return;
           }
         
           on_connected ();
       }
   

8. Read-write error, error code to determine whether it is an error or the data read or the buffer is full, an error occurs according to the socket disconnect

   Error codes include: Sigpip, Eagain, etc., eagain means reading or buffer full, Wait for the next event handler to read or write
   

10. In order to achieve higher performance, Epoll uses the Epollet (edge trigger) mechanism, but when an event occurs, when there is no data to write, the next time there is an out-of-date

    will not have an out event, so you can record a write-idling identity write_nil_loop, Epoll_wait event before determining if there is data sent and occurs Write_nil_loop, if any, re-enlist Epoll event

                 if (Worker->is_write_nil_loop () && (Events & Epollout)) {
                        epoll->remove (worker);
                        epoll->add ( Worker, events);
                    }else if (worker->get_events_mask ()! = events) {
                         Epoll->modify (worker, events);
                    }
    

Also, when reading the data, read the data as much as possible until the recv return value -1,errno== eagain, and other errors follow error handling

Periodic summary of asynchronous RPC under Linux-non-blocking socket client