A Formal Approach for Flexible Modeling and Analysis of Transaction Timeliness and Isolation

Traditional Concurrency Control (CC) mechanisms ensure absence of undesired interference in transaction-based systems and enforce isolation. However, CC may introduce unpredictable delays that could lead to breached timeliness, which is unwanted for real-time transactions. To avoid deadline misses, some CC algorithms relax isolation in favor of timeliness, whereas others limit possible interleavings by leveraging real-time constraints and preserve isolation. Selecting an appropriate CC algorithm that can guarantee timeliness at an acceptable level of isolation thus becomes an essential concern for system designers. However, trading-off isolation for timeliness is not easy with existing analysis techniques in database and real-time communities. In this paper, we propose to use model checking of a timed automata model of the transaction system, in order to check the traded-off timeliness and isolation. Our solution provides modularization for the basic transactional constituents, which enables flexible modeling and composition of various candidate CC algorithms, and thus reduces the effort of selecting the appropriate CC algorithm.