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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 ./diningTo run examples use:
run ./calc Main run ./dining Main run ./dining Main fast run ./sort Main run ./sort SortingBenchmark
import javax.swing.*;
import org.taj.ajava.lang.*;
public class NumberBox extends AComponent
{
protected JTextField textField;
private boolean reset = false;
private boolean donePoint = false;
public final Event OnOperation = new Event();
public NumberBox()
{
super(new JTextField(15));
textField = ((JTextField)component);
textField.setHorizontalAlignment(JTextField.RIGHT);
textField.setText("0");
}
private void react_0(char c)
{
if (Character.isDigit(c)) {
if (reset) {
textField.setText("" + c);
reset = false;
}
else if (textField.getText().equals("0")) {
if (c != '0') textField.setText("" + c);
}
else {
textField.setText(textField.getText() + "" + c);
}
}
else if (c == '.' && !donePoint) {
textField.setText(textField.getText() + '.');
donePoint = true;
}
}
public void deliver(char c)
{
bufferMessage(new org.taj.ajava.runtime.ActorMessage(new Character(c), 0));
}
protected void react(char c)
{
react_0(c);
}
private void react_1(Calculator.Operation op)
{
op.operand = Double.parseDouble(textField.getText());
OnOperation.deliver(op);
}
public void deliver(Calculator.Operation op)
{
bufferMessage(new org.taj.ajava.runtime.ActorMessage(op, 1));
}
protected void react(Calculator.Operation op)
{
react_1(op);
}
private void react_2(double v)
{
textField.setText(Double.toString(v));
reset = true;
donePoint = false;
}
public void deliver(double v)
{
bufferMessage(new org.taj.ajava.runtime.ActorMessage(new Double(v), 2));
}
protected void react(double v)
{
react_2(v);
}
protected void processMessage(org.taj.ajava.runtime.ActorMessage msg)
{
switch (msg.reactorId) {
case 0:
{
react_0(((Character)msg.payload).charValue());
return;
}
case 1:
{
react_1(((Calculator.Operation)msg.payload));
return;
}
case 2:
{
react_2(((Double)msg.payload).doubleValue());
return;
}
default:
{
super.processMessage(msg);
return;
}
}
}
}