Using accept() and select() at the same time?

Question

I\'ve got an event-driven network server program. This program accepts connections from other processes on other hosts. There may be many short-lived connections from diff

Answer 1

you could use listen then use select or poll then accept

if (listen(socket_fd, Number_connection) < 0 )
{
    perror("listen");
    return 1;
}
fd_set set;
struct timeval timeout;
int rv;
FD_ZERO(&set); /* clear the set */
FD_SET(socket_fd, &set); /* add our file descriptor to the set */

timeout.tv_sec = 20;
timeout.tv_usec = 0;

rv = select(socket_fd + 1, &set, NULL, NULL, &timeout);
if (rv == -1)
{
    perror("select"); /* an error occurred */
    return 1;
}
else if (rv == 0)
{
    printf("timeout occurred (20 second) \n"); /* a timeout occurred */
    return 1;
}
else
{
    client_socket_fd = accept (socket_fd,(struct sockaddr *) &client_name, &client_name_len);
}

Answer 2

I'd put a listener in separate process(thread) not to mess things up. And run a worker process on another to handle existing sockets. There's no need for non-blocking listener really. And no thread overhead running 2 threads.

It should work like that: you accept on your listener thread till it returns you a descriptor of client socket and pass it to worker which is doing all dirty read/write job on it.

If you want to listen several ports and don't want to hold one process per listener I suggest you set your socket in O_NONBLOCK and do someth like:

// loop through listeners here and poll'em for read
// when read is successful call accept, get descriptor,
// pass it to worker and continue listen
while(1){
    foreach( serverSocket in ServerSockets ){
         if( serverSocket.Poll( 10, SelectRead ) ){
              clientSocket = serverSocket.Accept();
              // pass to worker here and release
         }
    }
}

Answer 3

Last time I checked, you could just listen on a socket and then select or poll to see if a connection came in. If so, accept it; it will not block (but you may want to really should set O_NONBLOCK just to be sure)