Copyright 2001, Matt Dwyer, John Hatcliff, and Radu Iosif. The syllabus and all lectures for this course are copyrighted materials and may not be used in other course settings outside of Kansas State University in their current form or modified form without the express written permission of one of the copyright holders. During this course, students are prohibited from selling notes to or being paid for taking notes by any person or commercial firm without the express written permission of one of the copyright holders. CIS 842: Specification and Verification of Reactive Systems Lecture 7: Demonstration of Basic Aspects of the Bandera Tool Set

Notes Demo examples are chosen to be simple and to illustrate tool components For more examples with interesting specifications, see… –Bandera tutorial… –Extended version of SPIN’00 paper complete presentation of BoundedBuffer example Doug Lea’s Readers/Writers Publish/Subscribe framework from java.util

Outline Concept of a session –configuring Bandera for a run Simple deadlock example –illustrates session, code display, counterexample navigation, and slicing Pipeline example –illustrates creating a temporal specification, slicing, and abstraction

Configuring Bandera A run of Bandera is configured by a session specification A session specifies... which Java files to take as input which property to check which tool components (e.g., slicer, abstraction) to invoke which backend model-checker to use …other options A session file holds several related sessions sessions in session file can be executed in batch mode or individually selected in the BUI.

Simple Deadlock Example Lock 1 Lock 2 Process 1 Process 2 acquisition blocked acquisition blocked acquisition

Simple Deadlock Example class Process1 extends Thread { public void run() { Deadlock.state++; synchronized (Deadlock.lock1) { synchronized (Deadlock.lock2) { Deadlock.state++; }}}} class Process2 extends Thread { public void run() { Deadlock.state++; synchronized (Deadlock.lock2) { synchronized (Deadlock.lock1) { Deadlock.state++; }}}} public class Deadlock { static Lock lock1; static Lock lock2; static int state; public static void main(String[] args) { lock1 = new Lock(); lock2 = new Lock(); Process1 p1 = new Process1(); Process2 p2 = new Process2(); p1.start(); p2.start(); } class Lock {}

Deadlock Example Artifacts BIRC BIR Simulator Abstraction Engine Slicer Analyses Translators SPIN dSPIN SMV JPF Property Tool Java Jimple Parser Error Trace Display.trail Sliced Java Abstracted Java Point.java

Pipeline Example PipeInt Stage1Stage2Stage3Listener print >0: + 1 =0: stop …if stop received, send out 0 c1.stopc2.stop..send 0 c3.stopc4.stop..send 0 Shutdown Actions: Connectors c1 c2 c3c4 Requirements: If main in PipeInt signals shutdown (by calling the stop method of c1), then Stage x eventually shuts down.

Pipeline Example class PipeInt { /** predset1 * LOCATION[main1] mainStop; */ static public void main (String[] args) { Heap.c1 = new Connector(); Heap.c2 = new Connector(); Heap.c3 = new Connector(); Heap.c4 = new Connector(); (new Stage1()).start(); (new Stage2()).start(); (new Stage3()).start(); (new Listener()).start(); for (int i = 1; i < 100; i++) Heap.c1.add(i); main1: Heap.c1.stop(); } Observable

Pipeline Example final class Stage1 extends Thread { /** predset1 * LOCATION[run1] stage1Shutdown; */ public void run() { System.out.println("Stage1 startup"); int tmp = -1; while (tmp != 0) { if ((tmp = Heap.c1.take()) != 0) Heap.c2.add(tmp + 1); } Heap.c2.stop(); run1: System.out.println("Stage1 shutdown"); } Observable

Pipeline Example final class Connector { int queue = -1; /* represents empty queue */ public final synchronized int take() { int value; while (queue < 0) /* wait ‘til not empty */ try { wait(); } catch (InterruptedException ex) {} value = queue; /* get value to send out */ queue = -1; /* set queue to empty */ return value; /* send out value */ } public final synchronized void add(int value) { queue = value; notifyAll(); }

Pipeline Example Specification Requirements: If main in PipeInt signals shutdown (by calling the stop method of c1), then Stage x eventually shuts down. …an example of the response or leads to pattern with global scope For hints on how to construct the specification, a user might consult the Specification Patterns Webpage Specification Patterns Webpage BSL Specification (for first stage shutdown): forall[s:Stage1]. {stage1Shutdown(s)} responds to {mainStop} globally;