batch_get_items_soft

def batch_get_items_soft(keys: list, db_connection, table_name) -> list:
    result = []
    base_backoff_ms = 50
    step = 100
    current_attempt = 0
    max_attempt_qty = 3
    upper_limit = len(keys)

    for first_limit in range(0, upper_limit, step):
        second_limit = first_limit + step
        bunch_keys = keys[first_limit: second_limit]
        last_item = second_limit >= upper_limit
        last_attempt = current_attempt == max_attempt_qty

        try:
            response = batch_get_item(bunch_keys, db_connection, table_name)
        except ClientError as e:
            raise db_exceptions.DbSelectException(str(e))

        result.extend(response)

        if last_attempt or last_item:
            if last_attempt and not last_item:
                logger.error(f"Too many items for 'batch_get_item' {upper_limit}. Processed {second_limit}.")
            break

        sleep_time_ms = base_backoff_ms * 2 ** current_attempt  # calculate exponential backoff
        sleep_time_secs = sleep_time_ms / 1000  # convert milliseconds to seconds
        current_attempt += 1
        time.sleep(sleep_time_secs)

    return result