Re: [aspectj-users] Using cflowbelow to detect cycles in the call graph

[Andy Clement <andrew.clement@xxxxxxxxx>]

I modified the aspect and it does what I think you want, but requires that you handle the control flow yourself.  I think that is necessary because the method you are advising is 'equals()' which is likely to be used internally to the cflow implementation (although I haven't checked).

aspect A {

 pointcut inTest1(Test1 i): within(Test1) && execution(boolean Test1.equals(Object)) && target(i);

 Stack<Test1> t1Stack = new Stack<Test1>();

 

 boolean around(Test1 t): inTest1(t) {

 for (int i=0;i<t1Stack.size();i++) {

 if (t1Stack.get(i)==t) {

 return true;

 }

 }

 t1Stack.push(t);

 boolean b = proceed(t);

 t1Stack.pop();

 return b;

 }

 

 pointcut inTest2(Test2 i): within(Test2) && execution(boolean Test2.equals(Object)) && target(i);

 Stack<Test2> t2Stack = new Stack<Test2>();

 

 boolean around(Test2 t): inTest2(t) {

 for (int i=0;i<t2Stack.size();i++) {

 if (t2Stack.get(i)==t) {

 return true;

 }

 }

 t2Stack.push(t);

 boolean b = proceed(t);

 t2Stack.pop();

 return b;

 }

}

run:

3

4

1

2

4

1

2

3

haha, no more cycles!

2009/8/6 Neville Grech <nevillegrech@xxxxxxxxx>

Hi, I'm trying out the following simple example whereby I have two classes, which contain an object of the other class's type in each. I then proceed to construct four objects in such a way that a cycle is created. When I call the equals method, I should get an infinite cycle. I tried to create a pointcut descriptor that detects this. Unfortunately, this only works when the nesting level in the call stack is less than 4. I need to create a PCD which detects cycles when the same equals method in the same object is called in the same call stack. Here is the code (which doesn't work as it should):

import java.util.*;

class Launcher {
    public static void main(String[] args) {
        Test1 t1=new Test1(1);
        Test2 t2=new Test2(2);
        Test1 t3=new Test1(3);
        Test2 t4=new Test2(4);
        t1.myObject=t2;
        t2.myObject=t3;
        t3.myObject=t4;
        t4.myObject=t1;
        assert t3.equals(t1);
        System.out.println("haha, no more cycles!");
    }
}
class Test1 {
    public Test1(int c) { i=c; }
    int i;
    Test2 myObject;
    public boolean equals(Object o) {
        System.out.println(i);
        return myObject.equals(((Test1)o).myObject);
    }
}

class Test2 {
    public Test2(int c) { i=c; }
    int i;
    Test1 myObject;
   
    public boolean equals(Object o) {
        System.out.println(i);
        return myObject.equals(((Test2)o).myObject);
    }
}

aspect A {
    pointcut inTest1(Test1 i): call(boolean Test1.equals(Object)) && target(i);
    pointcut inTest2(Test2 i): call(boolean Test2.equals(Object)) && target(i);

    boolean around(Test1 up, Test1 now):
        inTest1(now) && cflowbelow(inTest1(up)) && if(up==now){
        return true;
    }
    boolean around(Test2 up, Test2 now):
        if(up==now) && cflowbelow(inTest2(up)) && inTest2(now) {
        return true;
    }

}


--
Regards,
Neville Grech

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