gistfile1.d

// Save the time a request comes in
rack*:::request_start
{
        self->start = timestamp;
        self->flip = 1;
}

// Save the request's path
rack*:::path
/ self->flip == 1 /
{
  self->path = copyinstr((int) arg0);
}

// Save the difference between the request's start and finish for its path
rack*:::request_finish
{
        @length[self->path] = quantize(timestamp - self->start);
        self->flip = 0;
}