/// <summary>
        /// Adds the specified amount to the count of the provided index. Also increments the <see cref="HistogramBase.TotalCount"/> by the same amount.
        /// </summary>
        /// <param name="index">The index to increment.</param>
        /// <param name="addend">The amount to increment by.</param>
        protected override void AddToCountAtIndex(int index, long addend)
        {
            long criticalValue = _wrp.WriterCriticalSectionEnter();

            try
            {
                _counts.AddAndGet(index, addend);
                Interlocked.Add(ref _totalCount, addend);
            }
            finally
            {
                _wrp.WriterCriticalSectionExit(criticalValue);
            }
        }