Automated Software Engineering with Concurrent Class

MachinesRadu Grosu

SUNY at Stony Brook

joint work with

Y. Liu, S. Smolka, S.Stoller, J. Yan

SUNY at Stony Brook

Motivation (ASE) Automated OO software development method:

• OO language for req.specification/modeling/implem,

• transition semantics capturing OO constructs,

• trace semantics supporting compositional refinement,

• analysis exploiting OO structure,

• generation of optimized (and monitored) code.

Close the gap between:

• object oriented methods (UML,OMT,…),

• formal methods (Model Checking, Static Analysis,…).

Concurrent Class Machines (CCM) 1. Modeling language for concurrent OO

systems• classes, inheritance, objects, object

creation• methods, exceptions, multithreading,• abstract collection types,

nondeterminism.2. Observational trace semantics • class machine refinement,• modular reasoning.

3. Code generation and analysis• prototype code generation.

• exploits the hierarchy information (in progress),

Readers/Writers Problem

Resource

Monitor

Client WrCapThread

RdCapm

m

1

*

res

1 *

Class Diagram

Classes

+Monitor(r:Resource)

+acqRd(): void

res: Resource; -free: boolean; ar: int;

+acqWr(): void

+relRd(): void

+relWr(): void

attributes

Call entry point

Method signature methods

return exit point

Monitor

Transitions

+Monitor(r:Resource)

+acqRd() free | ar > 0 -> free := false; ar := ar+1

res: Resource; -free: boolean; ar: int;

+acqWr()

+relRd()

+relWr()

transition (atomic)

assignments(parallel)

guard(blocking)

Monitor

method can bedeclared atomic

Call Hierarchy (Boxes)

+RdCap(m:Monitor)

-m: Monitor; -inCS: boolean;

+acq():void throws MonExc

+rel():void throws MonExc

new MonExc! inCS e

+read():int throws MonExc v: int; e:MonExc

inCs m.res.read()v

e

v

choice point(nondeterminism)

objectcreation box

return variable

methodinvocation box

return expression

exceptionexit point

local variables

RdCap

Concurrency

+main(): void r: Resource; c: Client

-m: Monitor

+run(): void

Client extends Thread

new Resourcer

new Monitor(r)m

new Client(m)

c.start

new Client(m)

c.start

c

threadstart box

threadrun method

c

Operational Semantics

Transition system A* = (S, s0, )

b0k0

…

b01

n0

f0k0-1

…

f00

f0k0

Ctrl Stack

Frame

Stack

t0:Thread

Attrt0

Object Pool

biki

…

bi1

ni

fiki-1

…

fi0

fiki

Ctrl Stack

Frame

Stack

…

ti:Thread

Attrti

…

…

b0k0

…

b01

n’0

f0k0-1

…

f00

f’0k0

Ctrl Stack

Frame

Stack

t0:Thread

Attr’t0

Object Pool

biki

…

bi1

ni

fiki-1

…

fi0

fiki

Ctrl Stack

Frame

Stack

…

ti:Thread

Attrti

…

…

t0

Method Invocation Box

+run(): int r: Resource; i: int

-m: Monitor

Client

r.read()i

+read(): int

Resource

+read(): int

RResource

v

v

b

b.c

…

f

…

Ctrl Stack

Frame

Stack

Method Invocation Box (Call)

+run(): int r: Resource; i: int

-m: Monitor

Client

r.read()i

+read(): int

Resource

+read(): int

RResource

v

v

b

b.c

…

f

…

Ctrl Stack

Frame

Stack

b

…

f

…

Ctrl Stack

Frame

Stack

c fb

Method Invocation Box (Return)

+run(): int r: Resource; i: int

-m: Monitor

Client

r.read()i

+read(): int

Resource

+read(): int

RResource

v

v

b

b.r

…

f[v/i]

…

Ctrl Stack

Frame

Stack

b

…

f

…

Ctrl Stack

Frame

Stack

r fb

Environment (Interface) Objects

b.r

…

f[v/i]

…

Ctrl Stack

Frame

Stack

• Their body is not known and not part of

• Allow any update of public objects. The latter are determined via an escape analysis.

Allow compositional modeling & reasoning:

Static vars, streams…

+run(): int r: Resource; i: int

-m: Monitor

Client

r.read()i

+read(): int

Resourcev

b

Denotational Semantics

Execution of CCM m

• s0-> s1-> s2->… -> sn

• si-> si+1 is a CCM transition in or

• si-> si+1 is an environment transition.

Set of Traces Lm of m

• Projection of executions on global variables.

• Object escape analysis is necessary.

Refinement m < n

• Inclusion of the sets of traces Lm Ln

• Compositional w.r.t. beh/arch hierarchies.

Modular Reasoning

N N’<

NM

N’M<

Sub-CCM refinement

NM < N

M’

Super-CCM refinement

M M’<N

M’

N N<

M < N

M’M =

lfp

Fixpoint induction

M

Wrap Up 1. Modeling language for concurrent OO

systems• classes, inheritance, objects, object

creation• methods, exceptions, multithreading,• abstract collection types,

nondeterminism.2. Observational trace semantics • class machine refinement,• modular reasoning.

3. Code generation and analysis• prototype code generation.

• exploits the hierarchy information (in progress),