A distributed locking algorithm for a transactions system in flat concurrent prolog

Abstract

This paper reports on the design and the implementation of a distributed transactions-system for a Universal File Server. The system maintains consistency in a general purpose file-system by means of concurrency control and crash recovery. Both the distributivity of a transaction and the intra-transaction concurrency, are depicted by a single model which describes the transaction as a partially ordered set of operations. The main concurrency control algorithm described in this paper is a novel distributed locking management algorithm based on the two-phase-locking (2pl) protocol. The system is implemented in Flat Concurrent Prolog (FCP), a concurrent logic programming language. FCP lends itself to the development of new distributed algorithms which utilize the fine-grained concurrency and the powerful communication and synchronization mechanisms supplied by the language. The features of concurrent logic languages, which are useful for implementing file and database systems are demonstrated in this paper.