ActiveJava

Copyright Tristan Aubrey-Jones May 2008.

Abstract: A project investigating and developing an implicitly concurrent programming language, based on a metaphor taken from the physical world is reported. Uses a programming paradigm where programs consist of systems of autonomous agents, or active objects which communicate via message passing. A language enhancing Java with actors and linear types is presented. Example programs are written, compiled, and executed to evaluate the usefulness of the language. The language found to provide a familiar notation for implicit parallelism, and a compelling new model for concurrency, combining the performance of shared variables with the elegance of message passing.

Introductory Slides (PDF), Report (PDF),
ActiveJava compiler prototype (ajavac), ActiveJava runtime library (ajava_lang).

Examples:

calc - pocket calculator actor program
dining - dining philosophers actor program (never deadlocks)
sort - parallel quicksort implementation ("SortBenchmark" sorts 10,000 random integers using actors, java threads, and sequentially and compares)
To compile examples use:
compile.bat ./calc
compile.bat ./sort
compile.bat ./dining
To run examples use:
run ./calc Main
run ./dining Main
run ./dining Main fast
run ./sort Main
run ./sort SortingBenchmark

ListIterator.ajava

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import java.util.List; /** list iterator iterates over all * values in the list when receives run * to use extend from this and override * reaction to Object, which is called * for every iteration. */ public aclass ListIterator { private List list; public ListIterator(List list) { this.list = list; } public static class Run {} public react(Run r) { if (list.size() > 0) this(list.size()-1); } public react(Object v) {} private react(int it) { this(list.get(it)); if (it > 0) this <-- it - 1; } }