Object Usage Models. Andrzej Wasylkowski Saarland University

Transcription

1 Object Usage Models Andrzej Wasylkowski Saarland University

2 A bug in AspectJ 2

3 A bug in AspectJ /** * This method looks through the type hierarchy for some target type - it is attempting to * find an existing parameterization that clashes with the new parent that the user * wants to apply to the type. If it finds an existing parameterization that matches the * new one, it silently completes, if it finds one that clashes (e.g. a type already has * A<String> when the user wants to add A<Number>) then it will produce an error. * * It uses recursion and exits recursion on hitting 'jlobject' * * Related bugzilla entries: pr */ private boolean verifynoinheritedalternateparameterization(resolvedtype typetoverify,resolvedtype newparent,world world) { if (typetoverify.equals(resolvedtype.object)) return true; ResolvedType newparentgenerictype = newparent.getgenerictype(); Iterator iter = typetoverify.getdirectsupertypes(); while (iter.hasnext()) { ResolvedType supertype = (ResolvedType)iter.next(); if ( ((supertype.israwtype() && newparent.isparameterizedtype()) (supertype.isparameterizedtype() && newparent.israwtype())) && newparentgenerictype.equals(supertype.getgenerictype())) { // new parent is a parameterized type, but this is a raw type world.getmessagehandler().handlemessage(new Message( WeaverMessages.format(WeaverMessages.CANT_DECP_MULTIPLE_PARAMETERIZATIONS,newParent.getName(),typeToVerify.getName(),supertype.getName()), getsourcelocation(), true, new ISourceLocation[]{typeToVerify.getSourceLocation())); return false; if (supertype.isparameterizedtype()) { ResolvedType generictype = supertype.getgenerictype(); // If the generic types are compatible but the parameterizations aren't then we have a problem if (generictype.isassignablefrom(newparentgenerictype) &&!supertype.isassignablefrom(newparent)) { world.getmessagehandler().handlemessage(new Message( WeaverMessages.format(WeaverMessages.CANT_DECP_MULTIPLE_PARAMETERIZATIONS,newParent.getName(),typeToVerify.getName(),supertype.getName()), getsourcelocation(), true, new ISourceLocation[]{typeToVerify.getSourceLocation())); return false; return verifynoinheritedalternateparameterization(supertype,newparent,world); return true; 3

4 A bug in AspectJ private boolean verify () { Iterator iter = ; while (iter.hasnext()) { = iter.next(); return verify (); return true; How can we find such a bug automatically? 4

5 The approach a b b Program Smart tool a a!!! c a d e f c d!!! Modeling objects behavior using finite state automata 5

6 How to create models? q = new Queue (); (); while () { e = (); (); Use method calls as transitions How to define states?

7 How to define states? I. Anonymous states via grammar inference q = new Queue (); (); while () { e = (); (); 7

8 How to define states? I. Anonymous states via grammar inference q = new Queue (); (); while () { Execution e = (); (); q = new 7

9 How to define states? I. Anonymous states via grammar inference q = new Queue (); (); while () { Execution e = (); (); q = new Grammar inference q = new 7

10 How to define states? I. Anonymous states via grammar inference q = new Grammar inference q = new 8

11 How to define states? I. Anonymous states via grammar inference q = new Grammar inference q = new Grammar inference q = new 8

12 How to define states? I. Anonymous states via grammar inference q = new Grammar inference q = new Grammar inference q = new Which model represents actual behavior? 8

13 How to define states? I. Anonymous states via grammar inference q = new Grammar inference q = new Can uncover hidden structure! Difficult to assign meaning! NP-hard Grammar inference! Does not handle ambiguity well q = new Which model represents actual behavior? 9

14 How to define states? II. Based on object s state q = new Queue (); (); while () { e = (); (); 10

15 How to define states? II. Based on object s state q = new Queue (); (); while () { e = (); (); Execution q = new size() == 0 size() == 1 10

16 How to define states? II. Based on object s state q = new Queue (); (); while () { e = (); (); q = new Expresses the true meaning of the state Execution size() == 0! Needs abstraction to keep models small size() == 1 11

17 How to define states? III.Based on the way the object is used q = new Queue (); (); while () { e = (); (); 12

18 How to define states? III.Based on the way the object is used q = new Queue (); (); while () { e = (); (); Static analysis q = new Queue (); (...);... (...); e = ();...

19 How to define states? III.Based on the way the object is used q = new Queue (); (); while () { e = (); (); Static analysis q = new!!!!!! 12!!!

20 How to define states? III.Based on the way the object is used q = new Queue (); (); while () { e = (); (); Static analysis q = new 12

21 How to define states? III.Based on the way the object is used q = new Queue (); (); while () { e = (); (); Static analysis q = new User-centered view of the object! May be too specific 13

22 How to define states? I. Anonymous states via grammar inference II. Based on object s state III.Based on the way the object is used 14

23 How to define states? I. Anonymous states via grammar inference II. Based on object s state III.Based on the way the object is used 14

24 External method calls q = new Queue (); (); while () { e = (); refresh (q); 15

25 External method calls q = new Queue (); (); while () { e = (); refresh (q); Static analysis q = new refresh (q) 15

26 Inlining models q = new Queue (); (); while () { e = (); refresh (q); void refresh (Queue q) { if (!q.isempty ()) { e = (); (e); 16

27 Inlining models q = new refresh (q) void refresh (Queue q) { if (!q.isempty ()) { e = (); (e); 16

28 Inlining models q = new q.isempty!!!! refresh (q) 16

29 Inlining models q = new q = new q.isempty refresh (q)!!!! Inlining!!!! q.isempty 17

30 Subject: AspectJ jar file Size (kb) Classes Methods aspectjlib.jar aspectjrt.jar aspectjweaver.jar aspectjtools.jar

31 Time & Models jar file Classes Models Time aspectjlib.jar :01 aspectjrt.jar :04 aspectjweaver.jar :23 aspectjtools.jar :33 19

32 Stack s in ThreadStackImpl11.getThreadStack() s = new s.push s.elements 20

33 StringTokenizer st in AdviceSignatureImpl.toAdviceName() st = new st.hasmoretokens!!!! st.nexttoken!!!!!!!! 21

34 StringTokenizer st in Factory.makeConstructorSig() st = new st.counttokens st.nexttoken 22

35 Method m in AjTypeImpl.asPointcut() m.getdeclaringclass m.getname m.getannotation new PointcutImpl (...,..., m,...,...)!!!!!!!! 23

36 Class c in SignatureImpl.shortTypeName() c.isarray c.getname c.getcomponenttype!!!!!!!!!!!! 24

37 Class c in AjTypeSystem.getAjType() Map.containsKey (c) new AjTypeImpl (c) Map.get (c) new AjTypeImpl (c) Map.put (c,...)!!!! Map.put (c,...) 25

38 Infrequent models (1) Model 1 Model Occurrences of models: SystemColor 26

39 Infrequent models (2) Model 1 Model 2 Model 3 Model Occurrences of models: RuntimeException 27

40 Infrequent models (3) re = new RuntimeException thrown The most frequently occurring RuntimeException model 28

41 Infrequent models (3) re = new re = new RuntimeException thrown Tra ce.e xit (..., re ) List.add (re) RuntimeException thrown Anomalous RuntimeException models 29

42 Infrequent models statistics Total Anomalies jar file Classes Classes Models Time aspectjlib.jar :02 aspectjrt.jar :05 aspectjweaver.jar :16 aspectjtools.jar :06 30

43 Subsequences q = new 31

44 Subsequences q = new Subsequences extraction (new, offer) (new, poll) (offer, offer) (offer, poll) (poll, offer) (poll, poll) 31

45 Frequent subsequences Method Ids of subsequences Dump.println 28, 45, 46, 47, 48, 4386 ClassPathManager.<init> 45, 46, 47, 48 DeclareParents.verify 4, 48, BcelObjectType.get 45, 48,

46 Frequent subsequences Method Ids of subsequences Dump.println 28, 45, 46, 47, 48, 4386 ClassPathManager.<init> 45, 46, 47, 48 DeclareParents.verify 4, 48, BcelObjectType.get 45, 48, Subsequence 48 forms an itemset with support 4 33

47 Frequent subsequences Method Ids of subsequences Dump.println 28, 45, 46, 47, 48, 4386 ClassPathManager.<init> 45, 46, 47, 48 DeclareParents.verify 4, 48, BcelObjectType.get 45, 48,

48 Frequent subsequences Method Ids of subsequences Dump.println 28, 45, 46, 47, 48, 4386 ClassPathManager.<init> 45, 46, 47, 48 DeclareParents.verify 4, 48, BcelObjectType.get 45, 48, Subsequences 45 and 48 form an itemset with support 3 35

49 Missing subsequences Method Ids of subsequences Dump.println 28, 45, 46, 47, 48, 4386 ClassPathManager.<init> 45, 46, 47, 48 DeclareParents.verify 4, 48, BcelObjectType.get 45, 48,

50 Missing subsequences Method Ids of subsequences Dump.println 28, 45, 46, 47, 48, 4386 ClassPathManager.<init> 45, 46, 47, 48 DeclareParents.verify 4, 48, BcelObjectType.get 45, 48, Missing subsequences point to anomalies 36

51 Missing subsequences Method Ids of subsequences Dump.println 28, 45, 46, 47, 48, 4386 ClassPathManager.<init> 45, 46, 47, 48 DeclareParents.verify 4, 48, BcelObjectType.get 45, 48, Subsequence 45: (hasnext, hasnext) Subsequence 48: (hasnext, next) Missing subsequences point to anomalies 36

52 The anomalous method /** * This method looks through the type hierarchy for some target type - it is attempting to * find an existing parameterization that clashes with the new parent that the user * wants to apply to the type. If it finds an existing parameterization that matches the * new one, it silently completes, if it finds one that clashes (e.g. a type already has * A<String> when the user wants to add A<Number>) then it will produce an error. * * It uses recursion and exits recursion on hitting 'jlobject' * * Related bugzilla entries: pr */ private boolean verifynoinheritedalternateparameterization(resolvedtype typetoverify,resolvedtype newparent,world world) { if (typetoverify.equals(resolvedtype.object)) return true; ResolvedType newparentgenerictype = newparent.getgenerictype(); Iterator iter = typetoverify.getdirectsupertypes(); while (iter.hasnext()) { ResolvedType supertype = (ResolvedType)iter.next(); if ( ((supertype.israwtype() && newparent.isparameterizedtype()) (supertype.isparameterizedtype() && newparent.israwtype())) && newparentgenerictype.equals(supertype.getgenerictype())) { // new parent is a parameterized type, but this is a raw type world.getmessagehandler().handlemessage(new Message( WeaverMessages.format(WeaverMessages.CANT_DECP_MULTIPLE_PARAMETERIZATIONS,newParent.getName(),typeToVerify.getName(),supertype.getName()), getsourcelocation(), true, new ISourceLocation[]{typeToVerify.getSourceLocation())); return false; if (supertype.isparameterizedtype()) { ResolvedType generictype = supertype.getgenerictype(); // If the generic types are compatible but the parameterizations aren't then we have a problem if (generictype.isassignablefrom(newparentgenerictype) &&!supertype.isassignablefrom(newparent)) { world.getmessagehandler().handlemessage(new Message( WeaverMessages.format(WeaverMessages.CANT_DECP_MULTIPLE_PARAMETERIZATIONS,newParent.getName(),typeToVerify.getName(),supertype.getName()), getsourcelocation(), true, new ISourceLocation[]{typeToVerify.getSourceLocation())); return false; return verifynoinheritedalternateparameterization(supertype,newparent,world); return true; 37

53 The anomalous method /** * This method looks through the type hierarchy for some target type - it is attempting to * find an existing parameterization that clashes with the new parent that the user * wants to apply to the type. If it finds an existing parameterization that matches the * new one, it silently completes, if it finds one that clashes (e.g. a type already has * A<String> when the user wants to add A<Number>) then it will produce an error. * * It uses recursion and exits recursion on hitting 'jlobject' * * Related bugzilla entries: pr */ private boolean verifynoinheritedalternateparameterization(resolvedtype typetoverify,resolvedtype newparent,world world) { if (typetoverify.equals(resolvedtype.object)) return true; ResolvedType newparentgenerictype = newparent.getgenerictype(); Iterator iter = typetoverify.getdirectsupertypes(); while (iter.hasnext()) { ResolvedType supertype = (ResolvedType)iter.next(); if ( ((supertype.israwtype() && newparent.isparameterizedtype()) (supertype.isparameterizedtype() && newparent.israwtype())) && newparentgenerictype.equals(supertype.getgenerictype())) { // new parent is a parameterized type, but this is a raw type world.getmessagehandler().handlemessage(new Message( WeaverMessages.format(WeaverMessages.CANT_DECP_MULTIPLE_PARAMETERIZATIONS,newParent.getName(),typeToVerify.getName(),supertype.getName()), getsourcelocation(), true, new ISourceLocation[]{typeToVerify.getSourceLocation())); return false; if (supertype.isparameterizedtype()) { ResolvedType generictype = supertype.getgenerictype(); // If the generic types are compatible but the parameterizations aren't then we have a problem if (generictype.isassignablefrom(newparentgenerictype) &&!supertype.isassignablefrom(newparent)) { world.getmessagehandler().handlemessage(new Message( WeaverMessages.format(WeaverMessages.CANT_DECP_MULTIPLE_PARAMETERIZATIONS,newParent.getName(),typeToVerify.getName(),supertype.getName()), getsourcelocation(), true, new ISourceLocation[]{typeToVerify.getSourceLocation())); return false; return verifynoinheritedalternateparameterization(supertype,newparent,world); return true; This method is in fact buggy 37

54 Another anomaly List values = ; for (Iterator it = values.iterator(); it.hasnext();) { return ; The list holds in fact at most one element 38

55 Frequent subsequences statistics jar file Classes Rules Flaws Time aspectjlib.jar :03 aspectjrt.jar :04 aspectjweaver.jar :06 aspectjtools.jar :50 39

56 Frequent subsequences statistics Fast enough to be practically useful jar file Classes Rules Flaws Time aspectjlib.jar :03 Found previously unknown bug in AspectJ aspectjrt.jar :04 Found violations of convention in AspectJ aspectjweaver.jar :06 aspectjtools.jar :50! Many false positives 40

57 Suggesting method calls In Eclipse 44

58 Suggesting method calls st = new st.hasmoretokens!!!! st.nexttoken!!!!!!!! Using models 48

59 Other ideas (1) Use conditions in code to enhance models st = new st = new st.hasmoretokens st.nexttoken!!!!!!!!!!!! st.hasmoretokens st.nexttoken!!!!!!!!!st.hasmoretokens 49

60 Other ideas (2) Suggest changes based on model s evolution Evolution of a model of class A originating from method B 50

61 Other ideas (2) Suggest changes based on model s evolution

62 Other ideas (2) Suggest changes based on model s evolution

63 Other ideas (2) Suggest changes based on model s evolution Suggest the change 52

64 Conclusion 53