Add X-Request-Start header so we can track queue times in New Relic RPM beginning at Varnish.

default.vcl

C{
  #include </etc/varnish/newrelic.h>
}C


sub vcl_recv {

  C{
    set_x_request_start(sp);
  }C

}

newrelic.h

/*
 * Add X-Request-Start header so we can track queue times in New Relic RPM beginning at Varnish.
 * Taken from https://gist.github.com/494265 & modified to compile on OSX.
 */

#include <sys/time.h>

void set_x_request_start(const struct sess *sp) {
  struct timeval detail_time;
  gettimeofday(&detail_time,NULL);
  char start[20]; 
  sprintf(start, "t=%lu%06lu", detail_time.tv_sec, detail_time.tv_usec);
  VRT_SetHdr(sp, HDR_REQ, "\020X-Request-Start:", start, vrt_magic_string_end);
}

Had to wrap it in a function - original Gist wont compile on OSX due to disabled support for -fnested-functions CFLAG/