private boolean isNewState(Activity callPath) {
        if (state == null) {
            return true;
        } else if (callPath == state.activity) {
            return false;
        } else {
            return true;
        }
    }
A container for storing time stamps throughout the lifetime of an Execution instance.

<p>Check state both when entering and exiting, to allow for arbitrary
new queries anywhere inside a search chain.

@author Steinar Knutsen
container-search/src/main/java/com/yahoo/search/statistics/TimeTracker.java