一种新型同步控制机制Guard-Trace及其实现技术研究  

On a New Synchronization Control Mechanism Guard-Trace and its Implementation Techniques

作　　者：廖宇[1] 杨大军[1] 唐宝[1] 张鸣[1] 吕建[1] 

机构地区：[1]南京大学计算机软件新技术国家重点实验室,南京210093

出　　处：《南京大学学报（自然科学版）》2001年第2期165-173,共9页Journal of Nanjing University（Natural Science）

基　　金：国家杰出青年科学基金! ( 61 52 50 4 );攀登计划项目

摘　　要：在并发面向对象环境中 ,对象需要同步控制机制来保证其内部状态的一致性 ,我们自行设计的Guard Trace机制是在传统的同步控制机制Trace之上的拓广 ,可较好地刻划被动对象的同步控制约束 ,具有简明、表达能力强、使用灵活等优点 .然而 ,Guard Trace机制对实现技术提出了更高的要求 ,在定义了Guard Trace的语法语义的基础上 ,阐述了它的模拟实现系统的设计决策 ,并深入讨论了GuardObject oriented methodology is proven useful in the design and reuse of software. Meantime, objects in real world are almost all behaving concurrently, and introducing concurrency into object oriented languages is a hot topic in modern computer research. In view of these facts, we designed a concurrent object oriented specification language — ND COOSL, whose synchronization control mechanism — Guard Trace is used to ensure the consistency of object's internal states. Our self designed Guard Trace, derived from extending traditional synchronization control mechanism-Trace, is expected to act as a synchronization mechanism for passive objects. By extending the atom of a Trace to a triple, including condition, method name and post processing, Guard Trace can be used effectively to describe the synchronization constraints related to an object's inner states; also by introducing several new operators, it provides the facility needed for allowing the concurrent execution of an object's methods. It has many distinguished advantages such as concision、rich expressiveness、flexibility for use. However Guard Trace puts a higher demand on implementation techniques. After precisely defining Guard Trace's syntax and semantics, this paper puts great emphasis on elaborating the important design decisions of its demo implementation system, such delicate control problems as how to start the parallel operator and when to address the stop of iterative operators. The tough nondeterminism problem brought by the flexibility of Guard Trace is discussed in detail, and three solutions from both static and dynamic aspects are given.

关 键 词：同步控制机制 同步控制树 同步控制线索 动态优化 Guard-Trace机制 面向对象 程序设计 

分 类 号：TP311.1[自动化与计算机技术—计算机软件与理论]