Master Thesis - Past Projects - Abstract

Concurrency Control in a Configurable Component-Based Real-Time Database

ID: LiTH-IDA-EX-04/069-SE

The increased demand for efficient data management in real-time systems and the increasing need for having configurable real-time software has lead to the development of a configurable COMponent-based Embedded real-Time database (COMET). COMET is designed using AspeCtual COmponent-based Real-time system Development (ACCORD), which supports decomposition of real-time software into aspects and components. Hence, COMET is designed to consist of aspects and components. COMET has a library of components that allow configuring a system with basic database functionality, without support for concurrency. The goal of this work is to extend the COMET library, with focus on enabling concurrency. We present the design and implementation of aspects that can be woven into the existing COMET components to produce COMET configurations that support concurrency. Three concurrency control algorithms have been designed and implemented: high priority 2-phase locking with similarity, optimistic divergence control and GUARD-link. High priority 2-phase locking with similarity and optimistic divergence control are concurrency control methods that control access to tuples in the database. Both methods are based on locks, which makes their design similar. They are implemented as aspects that crosscut large parts of the components in the COMET library. GUARD-link is an index concurrency control method. It consists of an admission controller and a B-link tree index structure. The admission controller is implemented as an aspect and the B-link tree as a replacement to the existing indexing component. By extending the COMET library with these aspects and the replacement indexing component, several new configurations of COMET become possible, all of which support concurrency.

Keywords: concurrency control, real-time databases, aspect-oriented software development, real-time systems, aspects, components, similarity- based concurrency control, index concurrency control

Author(s): Kristoffer Erlandsson

Contact: Jörgen Hansson