Polyphonic JR

1
Polyphonic JR

• Ludwik Ejsmont
• www.mdstud.chalmers.se/ludwik/

2
Polyphonic C - overview

• Asynchronous Methods
• async postEvent(EventInfo data)
• // large method body
• Chords
• public class Buffer
• public string Get() public async Put(string
  s)
• return s

3
JR - overview

• Semaphores

4
Transformation - Single synchronous method in a
chord

• // Polyphonic version
• ...
• f()
• ...
• public void f(..)
• //body
• // JR version
• public op void f(..) //declaration not necessary
• ...
• call f() // call keyword not necessary
• ...
• public void f(..) // if without declaration we
  have
• //body add op to definition header

5
Transformation- Single asynchronous method in a
chord

• // Polyphonic version
• ...
• f()
• ...
• public async f(..)
• //body
• // JR version
• public op void f(..) //declaration not necessary
• ...
• send f() // send keyword necessary
• ...
• public void f(..) // if without declaration we
  have
• //body add op to definition header

6
Transformation- No the same method used more than
once in different chord headers
public class Test1 public op void
sendTest1(String) public op void
sendTest2(String) public op String getTest()
String st1, st2 receive
sendTest2(st2) receive sendTest1(st1) return
st1 st2 public static void main(String
args) Test1 test new Test1()
send test.sendTest1("Hello ") send
test.sendTest2("World ") System.out.println(te
st.getTest())

• public class Test1
• public async sendTest1(string st1)
• public async sendTest2(string st2)
• public string getTest() sendTest1(string st1)
• sendTest2(string st2)
• return st1 st2
• public static void Main()
• Test1 test new Test1()
• test.sendTest1("Hello ")
• test.sendTest2("World ")
• Console.Write(test.getTest())

7
Transformation - One synchronous, one
asynchronous methods, possibly the same in
different chord headers
class Room public Room (int size)
hasspaces(size) private async
hasspaces(int n) public void enter()
hasspaces(int n) if (n gt 1)
hasspaces(n-1) else isfull() private
async isfull() public void leave()
hasspaces(int n) hasspaces(n1)
isfull() hasspaces(1)
class Room public Room (int size) send
hasspaces(size) private op void
hasspaces(int n) public void enter()
int n receive hasspaces(n) if (n gt 1)
send hasspaces(n-1) else send isfull()
private op void isfull() public void
leave() inni void hasspaces(int n) send
hasspaces(n1) void isfull() send
hasspaces(1)
8
Transformation - One synchronous, an arbitrary
number of asynchronous methods, possibly the same
in different chord headers
class santa ... static void
waittobewoken() elvesready()
reindeernotready() reindeernotready()
reindeerready() reindeernotrea
dy() ... static void
clearreindeernotready() reindeernotready()
elvesready() reindeernotready()
9
Transformation - One synchronous, an arbitrary
number of asynchronous methods, possibly the same
in different chord headers

• class ElvesReady
• class ReindeerNotReady
• public class Santa
• private static ArrayList er new
  ArrayList()
• private static ArrayList rnr new
  ArrayList()
• private static sem mutex 1
• private static void waitToBeWoken()
• while(true)
• inni void elvesReady()
• P(mutex)
• if (rnr.isEmpty())
• er.add(new ElvesReady())
• V(mutex)
• else
• rnr.remove(0)
• V(mutex)
• send reindeerNotReady()
• break
• void reindeerNotReady()

void reindeerReady() send
reindeerNotReady() send reinWaiting(0)
delay() unharness.acceptn(9,"all ")
rcount break private
static void clearReindeerNotReady()
P(mutex) if (!rnr.isEmpty())
rnr.remove(0) V(mutex) else
V(mutex) receive reindeerNotReady()
10
Transformation - Only asynchronous messages (more
than one) in a chord
public class Test3 public op void
m1() public op void m2() public op void
m3() String s "Hello World" public void
m1() receive m2() receive m3()
System.out.println(s) public static void
main(String args) Test3 t3 new
Test3() send t3.m1() send t3.m2() send
t3.m3()

• class Test3
• public async m1()
• public async m2()
• public async m3()
• string s "I am Test3"
• when m1() m2() m3()
• Console.WriteLine(s)
• public static void Main()
• T t3 new Test3()
• t3.m1()
• t3.m2()
• t3.m3()

11
Other issues

• Inheritance
• Exception handling
• Problems with JR

12
Conclusions

• JR more extensive, more familiar
• Polyphonic C - a different approach but treated
  more seriously
• Transformation JR Polyphonic C seems much
  harder
• Why no popular programming language treats
  concurrency seriously ?

13
Sources

• http//research.microsoft.com/nick/polyphony/
• http//research.microsoft.com/comega/
• http//www.cs.ucdavis.edu/olsson/research/jr/
• R. A. Ollson, A. W. Keen, The JR Programming
  Language, Kulwer Academic Publishers 2004
• www.mdstud.chalmers.se/ludwik/polyphonicjr.html

14
Questions

• ?

15
Thank You!!