def get_provisioned_gsi_read_units(table_name, gsi_name):
    """ Returns the number of provisioned read units for the table

    :type table_name: str
    :param table_name: Name of the DynamoDB table
    :type gsi_name: str
    :param gsi_name: Name of the GSI
    :returns: int -- Number of read units
    """
    try:
        desc = DYNAMODB_CONNECTION.describe_table(table_name)
    except JSONResponseError:
        raise

    for gsi in desc[u'Table'][u'GlobalSecondaryIndexes']:
        if gsi[u'IndexName'] == gsi_name:
            read_units = int(
                gsi[u'ProvisionedThroughput'][u'ReadCapacityUnits'])
            break

    logger.debug(
        '{0} - GSI: {1} - Currently provisioned read units: {2:d}'.format(
            table_name, gsi_name, read_units))
    return read_units