private SearcherTimer getPreviouslyRunSearcher(int searcherIndex, boolean calledAsInvoking) {
        if (calledAsInvoking) {
            searcherIndex -= 1;
            if (searcherIndex < entryIndex) {
                return null;
            } else {
                return searcherTracking[searcherIndex];
            }
        } else {
            return searcherTracking[searcherIndex];
        }
    }
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