name lookup benchmark

hostsbench.c

#define _POSIX_C_SOURCE 199309L

#include <stdio.h>
#include <time.h>
#include <string.h>
#include <memory.h>
#include <stdlib.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>

int resolv_once(const char *host)
{
    struct addrinfo hints;
    memset(&hints, 0, sizeof(struct addrinfo));
    hints.ai_family = AF_UNSPEC;

    struct addrinfo *result;    
    int s = getaddrinfo(host, NULL, &hints, &result);
    if (s != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(s));
        exit(EXIT_FAILURE);
    }
    freeaddrinfo(result);    
    return 0;
}

int main(int argc, char *argv[])
{
    if (argc <= 2) {
        fputs("usage: hostsbench [count] [host]\n", stderr);
        return 1;
    }
    int count = atoi(argv[1]);
    const char *host = argv[2];

    struct timespec start, end;
    clock_gettime(CLOCK_REALTIME, &start);
    for (int i = 0; i < count; ++i) {
        resolv_once(host);
    }
    clock_gettime(CLOCK_REALTIME, &end);

    if (start.tv_nsec > end.tv_nsec) {
        end.tv_sec--;
        end.tv_nsec += 1000000000;
    }
    double elapsed = (double)(end.tv_sec - start.tv_sec) + (end.tv_nsec - start.tv_nsec) / 1000000000.0;
    printf("Resolved %d times. Elapsed time = %.3f seconds, %.3f us per host.\n",
        count, elapsed, elapsed * 1000 / count);
    return 0;
}