ros::Rate::sleep() equivalent in rosserial

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I am building a rosserial application.

I would like to use a construct such as the following

ros::Rate loop_rate(30);

while (ros::ok())
{
    update();
    ros::spinOnce();
    loop_rate.sleep();
}

rate.h does not appear to be included in rosserial. With ros, I can effectively achieve the same thing using ros::Duration, which also has a sleep function. While duration.h exists in rosserial, it does not appear to have a sleep function...

Is there an equivalent of ros::Rate or ros::Duration in rosserial which allows me to set a looping frequency in this way?

The best equivalent I can find is something like the following:

while (1)
{
    update();
    nh.spinOnce();
    sleep(1./30.);
}

This is not exactly equivalent, though, as it sleeps for a constant time, whereas ros::Rate::sleep and ros::Duration::sleep only sleep for the remaining time in the cycle.