linguistic symbiosis between actors and threads

Linguistic Symbiosis between Actors and Threads

Tom Van Cutsem Stijn Mostinckx Wolfgang De Meuter

Programming Technology LabVrije Universiteit Brussel

Brussels, Belgium

International Conference on Dynamic Languages, August 27th 2007, Lugano

Overview

• AmbientTalk: OO DSL for mobile ad hoc networks

• Pure event-driven con-currency model (actors [Agha86])

• How to do a safe linguistic symbiosis between actors and threads?

2

Actors vs. Threads

3

actor: { def obj := object: { def m() { ... } }

def button := Button.new(“Click Me”); button.addActionListener(object: { def actionPerformed(actionEvent) { obj.m(); } })

obj.m();}

Actors vs. Threads

3

actor: { def obj := object: { def m() { ... } }

def button := Button.new(“Click Me”); button.addActionListener(object: { def actionPerformed(actionEvent) { obj.m(); } })

obj.m();}

Event Loop Concurrency

• Events are executed serially

• Event notification is strictly asynchronous

• Event loops should have no shared state

4

Event Event Queue

Event Loop Event Handler

Event loop concurrency

5

Actor

Message queue Event loop

Based on E programming language [Miller05]

Event loop concurrency

5

Actor

Message queue Event loop

‘local’ object

Based on E programming language [Miller05]

Event loop concurrency

5

Actor

Message queue Event loop

‘local’ object

obj

obj.m()

Based on E programming language [Miller05]

Event loop concurrency

5

Actor

Message queue Event loop

‘local’ object ‘remote’ object

Based on E programming language [Miller05]

Event loop concurrency

5

Actor

Message queue Event loop

‘local’ object ‘remote’ object

obj

obj<-m()

Based on E programming language [Miller05]

Event loop concurrency

5

Actor

Message queue Event loop

‘local’ object ‘remote’ object

Actors cannot cause deadlock

No race conditions on objects

obj

obj<-m()

Based on E programming language [Miller05]

AmbientTalk/Java

• AmbientTalk is implemented in Java

• Data mapping: cfr. JRuby, Jython, JScheme, LuaJava, JPiccola, ...

• Tight integration at the syntactic level

6

Based on Inter-language Reflection [Gybels et al 05]

def Button := jlobby.java.awt.Button;def button := Button.new(“Click Me”);button.addActionListener(object: { def actionPerformed(actionEvent) { ... }});button.setVisible(true);

Actor/Thread Mapping

7

Actor/Thread Mapping

7

?

Actors as Threads

8

Actor

obj

def obj := object: { ... };

aJavaCollection.add(obj);

aJavaCollection

Actors as Threads

8

Actor

obj

def obj := object: { ... };

aJavaCollection.add(obj);

aJavaCollection

add(obj)

Actors as Threads

8

Actor

obj

def obj := object: { ... };

aJavaCollection.add(obj);

aJavaCollection

add(obj)

Actors as Threads

8

Actor

obj

def obj := object: { ... };

aJavaCollection.add(obj);

synchronizedCol

add(obj)

Actors as Threads

9

Actor

obj

def obj := object: { def compareTo(other) { ... }}

aJavaCollection.add(obj);

aJavaCollection

Actors as Threads

9

Actor

obj

def obj := object: { def compareTo(other) { ... }}

aJavaCollection.add(obj);

aJavaCollection

add(obj)

Actors as Threads

9

Actor

obj

def obj := object: { def compareTo(other) { ... }}

aJavaCollection.add(obj);

aJavaCollection

add(obj)

Actors as Threads

9

Actor

obj

def obj := object: { def compareTo(other) { ... }}

aJavaCollection.add(obj);

aJavaCollection

add(obj)

compareTo(obj2)

Actors as Threads

9

Actor

obj

def obj := object: { def compareTo(other) { ... }}

aJavaCollection.add(obj);

aJavaCollection

add(obj)

Threads as Actors

10

def ambientTalkTest := object: { def countTestCases() { ... } def run(result) { ... }}

interface junit.framework.Test { public int countTestCases(); public void run(TestResult r);}

Threads as Actors

10

def ambientTalkTest := object: { def countTestCases() { ... } def run(result) { ... }}

TestSuite suite = new TestSuite();ATObject atUnitTest = /* load ambienttalk test */;suite.addTest((Test) wrap(atUnitTest, Test.class));suite.addTest(aJavaUnitTest);junit.textuit.TestRunner.run(suite);

interface junit.framework.Test { public int countTestCases(); public void run(TestResult r);}

Actor

ambientTalkTest

suite

Threads as Actors

10

Actor

ambientTalkTest

suite

Threads as Actors

10

run(result)

Actor

ambientTalkTest

suite

Threads as Actors

10

run(result)

Actor

ambientTalkTest

suite

Threads as Actors

10

Actor

ambientTalkTest

suite

Threads as Actors

10

wrapper

Actor

ambientTalkTest

suite

Threads as Actors

10

wrapper

barrier.get()

Actor

ambientTalkTest

suite

Threads as Actors

10

wrapper

barrier.get()

Actor

ambientTalkTest

suite

Threads as Actors

10

wrapper

barrier.get()

Threads as Actors

11

ActionListener l = ...;l.actionPerformed(actionEvent);

def button := Button.new(“Click Me”);button.addActionListener(object: { def actionPerformed(actionEvent) { ... }});

Actor

buttonListener

button

Threads as Actors

11

ActionListener l = ...;l.actionPerformed(actionEvent);

def button := Button.new(“Click Me”);button.addActionListener(object: { def actionPerformed(actionEvent) { ... }});

Actor

buttonListener

button

Threads as Actors

11

actionPerformed(ae)

ActionListener l = ...;l.actionPerformed(actionEvent);

def button := Button.new(“Click Me”);button.addActionListener(object: { def actionPerformed(actionEvent) { ... }});

Actor

buttonListener

button

Threads as Actors

11

ActionListener l = ...;l.actionPerformed(actionEvent);

wrapper

def button := Button.new(“Click Me”);button.addActionListener(object: { def actionPerformed(actionEvent) { ... }});

Actor

buttonListener

button

Threads as Actors

11

ActionListener l = ...;l.actionPerformed(actionEvent);

wrapper

def button := Button.new(“Click Me”);button.addActionListener(object: { def actionPerformed(actionEvent) { ... }});

Actor

buttonListener

button

Threads as Actors

11

ActionListener l = ...;l.actionPerformed(actionEvent);

wrapper

def button := Button.new(“Click Me”);button.addActionListener(object: { def actionPerformed(actionEvent) { ... }});

Actor

buttonListener

button

Threads as Actors

11

ActionListener l = ...;l.actionPerformed(actionEvent);

wrapper

def button := Button.new(“Click Me”);button.addActionListener(object: { def actionPerformed(actionEvent) { ... }});

Actor

buttonListener

button

Threads as Actors

11

wrapper

interface I extends java.util.EventListener { public void event(...);}

Summary

12

Summary

12

collection.add(obj)

Summary

12

obj.compareTo(obj2)

Summary

12

Summary

12

unitTest.run(reporter)

Summary

12

listener.actionPerformed(ae)

Experience

• AmbientTalk using Java: AWT and Swing for GUI construction

• Java using AmbientTalk: JEdit plugin for collaborative text editing

• Self/Squeak’s Morphic UI framework in AmbientTalk

13

Conclusions

• AmbientTalk: object-oriented (distributed) event-driven programming

• Symbiotic Thread/Actor mapping:

• AmbientTalk invocations proceed immediately

• Automatic synchronization of Java invocations

• Support for Java “event notifications” (listeners)

14

http://prog.vub.ac.be/amop