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Alting barriers: synchronisation with choice in Java using JCSP

Welch, Peter; Brown, Neil; Moores, James; Chalmers, Kevin; Sputh, Bernhard

Authors

Peter Welch

Neil Brown

James Moores

Kevin Chalmers

Bernhard Sputh



Abstract

Communicating Sequential Processes for Java (JCSP) is a mature library that implements CSP-derived concurrency primitives in Java. A JCSP system is a hierarchical network of autonomous processes communicating over synchronous (optionally buffered) channels, and multiway synchronising through barriers. This paper presents a significant extension to the barrier mechanism: the fast resolution of choice between any number of barrier events, channel communications (in either direction) and timeouts. Previously, and in line with all currently released libraries and languages offering the CSP concurrency model, choice was restricted to channel inputs and timeouts. The paper demonstrates an application of alting barriers and explains the mechanisms used in their implementation that enables their use as guards in a choice. It also shows how choice over channel outputs becomes possible, as a simple consequence of having choice over barriers. Finally, an efficient implementation of CSP's broadcasting channels is presented (using a phased barrier synchronisation pattern) and a mechanism for allowing choice over these is discussed. With this extended JCSP, almost all CSP-specified systems can now be directly implemented. The new library is available under LGPL open source

Journal Article Type Article
Online Publication Date Mar 1, 2010
Publication Date Jun 10, 2010
Deposit Date Aug 31, 2010
Print ISSN 1532-0626
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 22
Issue 8
Pages 1049-1062
DOI https://doi.org/10.1002/cpe.1471
Keywords Theoretical Computer Science; Computer Networks and Communications; Computational Theory and Mathematics; Software; Computer Science Applications
Public URL http://researchrepository.napier.ac.uk/id/eprint/3822
Publisher URL http://dx.doi.org/10.1002/cpe.1471