PERF_COUNTER_100NS_QUEUELEN_TYPE

    Average length of a queue to a resource over time in 100 nanosecond units.

    https://msdn.microsoft.com/en-us/library/aa392905(v=vs.85).aspx

    Formula (n1 - n0) / (d1 - d0)

def calculate_perf_counter_100ns_queuelen_type(previous, current, property_name):
    """
    PERF_COUNTER_100NS_QUEUELEN_TYPE

    Average length of a queue to a resource over time in 100 nanosecond units.

    https://msdn.microsoft.com/en-us/library/aa392905(v=vs.85).aspx

    Formula (n1 - n0) / (d1 - d0)
    """
    n0 = previous[property_name]
    n1 = current[property_name]
    d0 = previous["Timestamp_Sys100NS"]
    d1 = current["Timestamp_Sys100NS"]
    if n0 is None or n1 is None:
        return

    return (n1 - n0) / (d1 - d0)