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[aspectj-users] Is @DeclareMixin + around advice supported?
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Hello,
I would like to know whether it is supported to use @DeclareMixin & around advice in the way like below:
public interface KeySetKeyLockHandler {
// method signatures
}
public static class KeySetKeyLockHandlerImpl implements KeySetKeyLockHandler {
// contents of class
}
@DeclareMixin( value="slingong.web.gae.TransactionalMemcacheServiceImpl")
public static KeySetKeyLockHandler addKeySetKeyLockHandlerInterface( Object instance) {
return new KeySetKeyLockHandlerImpl( (TransactionalMemcacheServiceImpl)instance);
}
@Around( value="execution( "
+ "public * slingong.web.gae.TransactionalMemcacheServiceBase+"
+ ".setKeySetKey( java.lang.String)) "
+ "&& this( keySetKeyLockHandler)"
)
public Object aroundAdvisedSetKeySetKeyMethodExecution(
ProceedingJoinPoint proceedingJoinPoint, KeySetKeyLockHandler keySetKeyLockHandler) {
// Do some works on keySetKeyLockHandler
// Invocation of actual target method -------------------------------------------------
try {
return proceedingJoinPoint.proceed( proceedingJoinPoint.getArgs());
}
catch( Throwable throwable) {
// Exception handling
}
// ------------------------------------------------------------------------------------
// Do some works on keySetKeyLockHandler
}
Note:
KeySetKeyLockHandler interface does not contain the definition of the setKeySetKey method.
TransactionalMemcacheServiceImpl class is extended from TransactionalMemcacheServiceBase abstract class
I abbreviated the details from the actual code for easier readability.
What I expected was that, of course, calling the proceed method in the code snippet above executes setKeySetKey method of TransactionalMemcacheServiceImpl instance.
However, it fails at that statement by the puzzling ClassCastException like:
slingong.web.gae.TransactionalMemcacheServiceException: java.lang.ClassCastException: java.lang.String cannot be cast to slingong.web.gae.TransactionalMemcacheServiceBase
at slingong.web.gae.TransactionalMemcacheServiceBase.setKeySetKey_aroundBody1$advice(TransactionalMemcacheServiceBase.java:456)
at slingong.web.gae.TransactionalMemcacheServiceBase.setKeySetKey_aroundBody2(TransactionalMemcacheServiceBase.java:1)
at slingong.web.gae.TransactionalMemcacheServiceBase.setKeySetKey_aroundBody3$advice(TransactionalMemcacheServiceBase.java:578)
at slingong.web.gae.TransactionalMemcacheServiceBase.setKeySetKey(TransactionalMemcacheServiceBase.java:132)
at slingong.web.gae.TransactionalMemcacheServiceFactory.getInstance(TransactionalMemcacheServiceFactory.java:180)
at slingong.web.gae.TransactionalMemcacheServiceFactoryTest.testGetInstance(TransactionalMemcacheServiceFactoryTest.java:93)
As you may notice from the stack trace above, I have 2 around-advices weaving at this join point, and as I said that I omitted the detail, that exception may not be caused of the usage of @DeclareMixin & around advice but from those omitted parts. However, I like to be sure about if it's supported usage before digging deeper to find the cause, since I do not feel so sure about calling ProceedingJoinPoint.proceed method after mixing even though I assumed that it would be OK because I could not have found any document to tell the restriction on such combination.
I ran the test code under debugger and found that it fails at the statement calling proceed method right after getArgs method returns before actually running target setKeySetKey method.
Just before throwing the exception, proceedingJoinPoint appeared as below in debugger (though I eliminated the info on TransactionalMemcacheServiceImpl fields because I thought those would just bloated lines of info without clue.) It appears to me that the proceedingJoinPoint seems to be expected...
proceedingJoinPoint JoinPointImpl (id=49)
_this TransactionalMemcacheServiceImpl (id=44)
$SWITCH_TABLE$com$google$appengine$api$memcache$MemcacheService$SetPolicy null
ajc$anno$0 null
ajc$aspectjutil_eventmanager_EventListenerInstanceTracker$ptwAspectInstance EventListenerInstanceTracker (id=55)
ajc$withinType "slingong.web.gae.TransactionalMemcacheServiceBase" (id=106)
listenerMap WeakHashMap<K,V> (id=107)
ajc$aspectjutil_eventmanager_EventListenerInstanceTracker$ptwAspectInstance EventListenerInstanceTracker (id=72)
ajc$withinType "slingong.web.gae.TransactionalMemcacheServiceImpl" (id=111)
listenerMap WeakHashMap<K,V> (id=112)
ajc$instance$slingong_web_gae_TransactionalMemcacheServiceBaseThreadSyncAspect$slingong_web_gae_TransactionalMemcacheServiceBaseThreadSyncAspect$KeySetKeyLockHandler TransactionalMemcacheServiceBaseThreadSyncAspect$KeySetKeyLockHandlerImpl (id=73)
transactionalMemcacheServiceImpl TransactionalMemcacheServiceImpl (id=44)
arc null
args Object[1] (id=101)
[0] "testGetInstance_keySetKey" (id=67)
staticPart JoinPointImpl$StaticPartImpl (id=103)
id 1
kind "method-execution" (id=115)
count 16
hash 0
offset 0
value (id=128)
signature MethodSignatureImpl (id=116)
EMPTY_CLASS_ARRAY Class<T>[0] (id=129)
EMPTY_STRING_ARRAY String[0] (id=131)
useCache true
declaringType Class<T> (slingong.web.gae.TransactionalMemcacheServiceBase) (id=43)
declaringTypeName "slingong.web.gae.TransactionalMemcacheServiceBase" (id=106)
exceptionTypes Class<T>[0] (id=137)
lookupClassLoader null
method null
modifiers 1
name "setKeySetKey" (id=138)
parameterNames String[1] (id=139)
[0] "newKeysSetKey" (id=141)
parameterTypes Class<T>[1] (id=140)
[0] Class<T> (java.lang.String) (id=68)
returnType Class<T> (void) (id=142)
stringCache SignatureImpl$CacheImpl (id=143)
toStringCacheRef SoftReference<T> (id=149)
clock 1326542103609
lock Reference$Lock (id=152)
pending null
discovered null
next null
queue ReferenceQueue$Null (id=154)
referent String[3] (id=157)
[0] "void slingong.web.gae.TransactionalMemcacheServiceBase.setKeySetKey(String)" (id=161)
[1] null
[2] null
timestamp 1326542103609
stringRep null
sourceLocation SourceLocationImpl (id=118)
fileName "TransactionalMemcacheServiceBase.java" (id=162)
line 130
withinType Class<T> (slingong.web.gae.TransactionalMemcacheServiceBase) (id=43)
target TransactionalMemcacheServiceImpl (id=44)
Regards,
Art
