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Re: [aspectj-users] Re: ReferenceType.isCoerceableFrom question
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If your EPR interface is the one defining the get method, you can
specify that as the declaring type restriction in the pointcut:
execution(* EPR.get*(..)) { }
Andy
2009/5/11 James Stangler <jastangler@xxxxxxxxx>:
> Ah, I think I see. The pointcut definition is just saying that as long as
> it's a getter and the class implements the interface, the advice applies to
> it, regardless of whether the getter is defined in the interface or not.
>
> Is there a way to restrict it to only implemented methods defined in the
> interface? I think I can work around it now that I know what's happening,
> but I'm curious.
>
> Pretty sneaky....
>
>> I suspect your problem is that EPR is an interface.
>>
>> > The class "com.sabre.liberty.web.RequestTypeRegistry" extends Object and
>> > implements no interfaces. The interface "com.sabre.liberty.user.EPR"
>> > extends no other interfaces.
>>
>> Suppose I wrote this (probably non-sensical but possible) code:
>>
>> class Foo extends RequestTypeRegistry implements EPR {
>> }
>>
>> Object o = new Foo().getRequestTypes();
>>
>> Should it be advised? Clearly it should as that is what you wrote in
>> the pointcut:
>>
>> execution (* *.get*()) && this(com.sabre.liberty.user.EPR)
>>
>> Although it is advised, you will see the '[with runtime test]' check
>> attached to the weaveinfo message, and I imagine if you looked in the
>> woven code you would see the runtime test is 'instanceof EPR' which
>> acts as a guard before the advise is called. So the code will do what
>> you asked, but it can be worrying when it advises so many places like
>> this.
>>
>> This is a well known gotcha with using an interface type as at runtime
>> the types flowing around could implement any old interface - so to do
>> the right thing we have to advised lots of places - but include
>> runtime checks to prevent advise running when it should not.
>>
>> just a note: if RequestTypeRegistry was 'final' (and so could not be
>> subclassed), the get method would not be advised in this case.
>>
>> Does it cause you a problem that the extra places are advised?
>>
>> Andy.
>>
>> 2009/5/11 James Stangler <jastangler@xxxxxxxxx>:
>> > I hope someone can help me understand what's going wrong (or let me know
>> > what additional information I need to provide). I have an aspect where
>> > the
>> > pointcut seems to be advising code that it shouldn't be advising and it
>> > seems to be getting the ok from the isCoerceableFrom method in
>> > ReferenceType. I'm using aspectJ 1.6.4 with LTW.
>> >
>> > My aspect is defined with:
>> >
>> > @Pointcut("(execution (* *.get*()) &&
>> > this(com.sabre.liberty.user.EPR))")
>> >
>> > @Pointcut("(execution (* *.is*()) &&
>> > this(com.sabre.liberty.user.EPR))")
>> >
>> > @Around(value = "monitorEprGetMethod() || monitorEprIsMethod()")
>> >
>> > The pointcut should only be applied to instances of
>> > "com.sabre.liberty.user.EPR" and its subclasses. Unfortunately it seems
>> > to
>> > be getting applied to almost any getter such as:
>> >
>> > [TomcatInstrumentableClassLoader@18346a3] weaveinfo Join point
>> > 'method-execution(java.util.List
>> > com.sabre.liberty.web.RequestTypeRegistry.getRequestTypes())' in Type
>> > 'com.sabre.liberty.web.RequestTypeRegistry'
>> > (RequestTypeRegistry.java:54)
>> > advised by around advice from
>> > 'com.sabre.liberty.modules.util.greenbeans.IceDebugAspect'
>> > (IceDebugAspect.java) [with runtime test]
>> > [TomcatInstrumentableClassLoader@18346a3] weaveinfo Join point
>> > 'method-execution(java.lang.Object
>> > com.sabre.liberty.web.RequestTypeRegistry.getDefaultRequestType())' in
>> > Type
>> > 'com.sabre.liberty.web.RequestTypeRegistry'
>> > (RequestTypeRegistry.java:58)
>> > advised by around advice from
>> > 'com.sabre.liberty.modules.util.greenbeans.IceDebugAspect'
>> > (IceDebugAspect.java) [with runtime test]
>> >
>> > The class "com.sabre.liberty.web.RequestTypeRegistry" extends Object and
>> > implements no interfaces. The interface "com.sabre.liberty.user.EPR"
>> > extends no other interfaces.
>> >
>> > It appears that the method ReferenceType.isCoerceableFrom is the one
>> > that
>> > allows the methods to be advised. The command in the method
>> > isCoerceableFrom has the comment "true iff the statement "this =
>> > (ThisType)
>> > other" would compile" which would never be the case since none of the
>> > methods overlap (I guess a subclass could implement the interface and
>> > define
>> > the methods, but the advice would always be applied to the subclass and
>> > never this class). Why would this method decide that one was coerceable
>> > to
>> > the other? The stacktrace below was while seeing if the advice
>> > "@Around(value = "monitorEprGetMethod() || monitorEprIsMethod()")"
>> > should be
>> > applied to
>> > "com.sabre.liberty.web.RequestTypeRegistry.getRequestTypes()".
>> > The method returns true.
>> >
>> > Thread [main] (Suspended)
>> > ReferenceType.isCoerceableFrom(ResolvedType) line: 298
>> > ExactTypePattern.matchesInstanceof(ResolvedType) line: 177
>> > ExactTypePattern(TypePattern).matches(ResolvedType,
>> > TypePattern$MatchKind) line: 150
>> > ThisOrTargetPointcut.matchInternal(Shadow) line: 113
>> > ThisOrTargetPointcut(Pointcut).match(Shadow) line: 146
>> > AndPointcut.matchInternal(Shadow) line: 54
>> > AndPointcut(Pointcut).match(Shadow) line: 146
>> > AndPointcut.matchInternal(Shadow) line: 52
>> > AndPointcut(Pointcut).match(Shadow) line: 146
>> > OrPointcut.matchInternal(Shadow) line: 53
>> > OrPointcut(Pointcut).match(Shadow) line: 146
>> > BcelAdvice(ShadowMunger).match(Shadow, World) line: 79
>> > BcelAdvice(Advice).match(Shadow, World) line: 112
>> > BcelAdvice.match(Shadow, World) line: 145
>> > BcelClassWeaver.match(BcelShadow, List) line: 3025
>> > BcelClassWeaver.match(LazyMethodGen) line: 2499
>> > BcelClassWeaver.weave() line: 480
>> > BcelClassWeaver.weave(BcelWorld, LazyClassGen, List, List, List,
>> > boolean) line: 103
>> > BcelWeaver.weave(UnwovenClassFile, BcelObjectType, boolean) line:
>> > 1735
>> > BcelWeaver.weaveWithoutDump(UnwovenClassFile, BcelObjectType) line:
>> > 1696
>> > BcelWeaver.weaveAndNotify(UnwovenClassFile, BcelObjectType,
>> > IWeaveRequestor) line: 1458
>> > BcelWeaver.weave(IClassFileProvider) line: 1272
>> > ClassLoaderWeavingAdaptor(WeavingAdaptor).getWovenBytes(String,
>> > byte[])
>> > line: 423
>> > ClassLoaderWeavingAdaptor(WeavingAdaptor).weaveClass(String, byte[],
>> > boolean) line: 286
>> > Aj.preProcess(String, byte[], ClassLoader) line: 95
>> > ClassPreProcessorAgentAdapter.transform(ClassLoader, String,
>> > Class<?>,
>> > ProtectionDomain, byte[]) line: 52
>> >
>> >
>> > AspectJWeavingEnabler$AspectJClassBypassingClassFileTransformer.transform(ClassLoader,
>> > String, Class<?>, ProtectionDomain, byte[]) line: 92
>> >
>> >
>> > InstrumentationLoadTimeWeaver$FilteringClassFileTransformer.transform(ClassLoader,
>> > String, Class<?>, ProtectionDomain, byte[]) line: 181
>> > TransformerManager.transform(ClassLoader, String, Class,
>> > ProtectionDomain, byte[]) line: not available
>> > InstrumentationImpl.transform(ClassLoader, String, Class,
>> > ProtectionDomain, byte[], boolean) line: not available
>> > ClassLoader.defineClass1(String, byte[], int, int, ProtectionDomain,
>> > String) line: not available [native method]
>> > TomcatInstrumentableClassLoader(ClassLoader).defineClass(String,
>> > byte[],
>> > int, int, ProtectionDomain) line: not available
>> >
>> > TomcatInstrumentableClassLoader(SecureClassLoader).defineClass(String,
>> > byte[], int, int, CodeSource) line: not available
>> > <snip>
>
>
>
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