Fastest way to send multiple char array over TCP

Question

I'm working on a webserver framework in C++ mostly for my own understanding, but I want to optimize it as well.

My question is is it faster to write multiple char arrays to the TCP connection for every html response or to spend the time to concatenate up front and only write to the TCP connection once. I was thinking about benchmarking it, but I am not quite sure how to go about it.

This is my first post on stackoverflow, although I have benefitted from the website very often!

Thanks!

Here is what I am talking about for sending many char arrays individually. The alternate would be concatenate all of these char arrays into one char array then sending that.

int main() {
    sockaddr_in address;
    int server_handle;
    int addrlen = sizeof(address);
    if ((server_handle = socket(AF_INET, SOCK_STREAM, 0)) < 0) 
    {
        perror("cannot create socket");  
        exit(0);
    }
    memset((char *) &address, 0, sizeof(address)); 
    address.sin_family = AF_INET; 
    address.sin_addr.s_addr = htonl(INADDR_ANY); 
    address.sin_port = htons(PORT); 
    if (bind(server_handle, (sockaddr *) &address, (socklen_t) addrlen) < 0) 
    { 
        perror("bind failed"); 
        exit(0); 
    }

    if (listen(server_handle, 3) < 0) 
    { 
        perror("In listen");  
        exit(EXIT_FAILURE); 
    } 
    while(1) {
        std::cout << "\n+++++++ Waiting for new connection ++++++++\n\n"; 
        int client_handle;
        if ((client_handle = accept(server_handle, (struct sockaddr *)&address, (socklen_t *) &addrlen))<0)
        { 
            perror("In accept");            
            exit(EXIT_FAILURE);        
        }

        // read and respond to client request 
        char buffer[30000] = {0};
        int bytesRead = read(client_handle, buffer, 30000); 

        char * httptype = "HTTP/1.1 ";
        char * status = "200 \n";
        char * contenttype = "Content-Type: text/html \n";
        char * contentlength = "Content-Length: 21\n\n";
        char * body = "<h1>hello world!</h1>";


        write(client_handle, httptype, 9);
        write(client_handle, status, 5);
        write(client_handle, contenttype, 26);
        write(client_handle, contentlength, 20);
        write(client_handle, body, 21);

        std::cout << "------------------Response sent-------------------\n";

        close(client_handle);
    }
}

Answer 1

If you want to send multiple buffers with a single write call you can use vectored IO (aka scatter/gather IO) as the manual suggests:

char *str0 = "hello ";
char *str1 = "world\n";
struct iovec iov[2];
ssize_t nwritten;

iov[0].iov_base = str0;
iov[0].iov_len = strlen(str0);
iov[1].iov_base = str1;
iov[1].iov_len = strlen(str1);

nwritten = writev(STDOUT_FILENO, iov, 2);