基于改进乐观两阶段锁的移动事务处理模型

Mobile Transaction Processing Model Based on Improved Optimistic Two-phase Lock

在移动计算环境中,由于无线网络具有弱连接性、不稳定性及频繁断接等缺点,传统的乐观两阶段锁事务处理机制已经不能满足移动数据库系统的事务处理要求。因此,系统地分析了乐观两阶段锁协议,找到了该模型存在的问题,结合移动事务的特点,提出了一种基于改进乐观两阶段锁的移动事务处理模型。在原模型的基础上,引入移动事务处理机制和移动事务协调机制,移动事务处理机制允许移动端将整个事务操作序列分成若干个子序列,移动事务协调机制实时对移动网络进行监测,根据移动网络情况选择一次发送或者分多次发送,有效降低了长事务和频繁断接事务对移动数据库系统的影响。实验结果表明,与乐观两阶段锁事务处理机制相比,改进后的模型提高了移动事务的成活率,改善了系统的总体性能,更加适合移动计算环境。

In the mobile computing environment,the traditional optimistic two-phase locking transaction processing mechanism can no longer meet the transaction processing requirements of the mobile database system due to the disadvantages of wireless network such as weak connectivity,instability and frequent disconnection.Therefore,we systematically analyze the optimistic two-phase lock protocol,find out the problems of the model,and according to the characteristics of mobile transactions,propose a mobile transaction processing model based on improved optimistic two-phase lock.Based on the original model,the MTPM(mobile transaction processing mechanism)and MTCM(mobile transaction coordination mechanism)are introduced.MTPM allows the mobile terminal to divide the whole transaction operation sequence into several sub-sequences,and MTCM monitors the mobile network in real time,and chooses to send once or multiple times according to the mobile network situation,which effectively reduces the impact of long transactions and frequent interruptions transactions to the mobile database systems.The experiment shows that compared with the optimistic two-stage lock transaction processing mechanism,the improved model increases the survival rate of mobile transactions,improves the overall performance of the system,and is more suitable for mobile computing environment.