【摘要】 提出了初始化弧的概念,并将这一概念引入高级时间Petri网中,从而给出了扩展的高级时间Petri网(Extended High-Level Time Petri Nets-EHLTPN)。此外,在EHLTPN模型中,变迁所附加的常量时间区间扩展为变量时间区间。用EHLTPN对实时数据库系统的并发事务进行了建模,所建模型不仅可以描述并发事务在数据存取中所出现的各种现象,而且还可以实现2PL-LW协议所具有的可避免并发事务的无用重启、无用等待、无死锁的等功能。更多还原

【Abstract】 An initialization arc is proposed and introduced to high-level time Petri net in this paper. Accordingly an Extended High-Level Time Petri Net(EHLTPN) model is presented. The paper models concurrency transactions of real-time database with EHLTPN. The model not only well describe the phenomena occurring during the data access for concurrency transactions but also has some characteristics same as 2PL-LW protocol such as avoiding useless restarts and useless waits and constructing deadlock-free and serializable scheduling. It can be used to calculate the miss rate, restart rate and complete rate by analyzing reachability of the model.更多还原