Re: Class load order

Hi tim and Remi,

Thanks for help, it saved me a lot of time.

It sounds like a though problem to crack using an agent. But i wanted  
to add a compiletime instrumenter for quite some time, so perhaps i  
should pull that issue in the comming release. It also solves another  
similar problem; subclassing ( that also relies on not yet existing  
classes)

Ps the stm implementation is called multiverse and can be found here:
http://multiverse.googlecode.com

I hope to do a release at the end of the month.



On 12 jan 2010, at 20:32, "Tim Eck" <[email protected]> wrote:

> I don't know if there is a magic answer to this quandary  
> unfortunately.
> Giving the lazy class load behavior in most (all?) VMs you can't  
> really make
> any assumptions here, especially for types not directly connected in  
> the
> inheritance chain.
>
> My quick thought is that you can either produce your instrumentation  
> to be
> dynamic (have both paths) or to eagerly load all referenced types.  
> Although,
> starting more class loads in the path in the path of loadClass() is  
> a lovely
> way to produce deadlocks, and if you're doing this in a  
> ClassFileTransformer
> you'll likely be disappointed since they are not re-entrant.
>
> You’d have to benchmark it of course but hotspot might be able to ma 
> ke the
> dynamic case plenty fast enough.
>
>> -----Original Message-----
>> From: Peter Veentjer [mailto:[email protected]]
>> Sent: Tuesday, January 12, 2010 9:32 AM
>> To: [email protected]
>> Subject: [asm] Class load order
>>
>>
>> Hi guys,
>>
>> I'm struggling with an issue that is caused by the order of loading
>> classes.
>>
>> I add additional methods to classes and this works great. If enhanced
>> class A is loaded before enhanced class B, B is allowed to call these
>> extra methods of A. But if class B is loaded before class A is
>> loaded,  i get à verify error that i'm calling a non existing method
>> on A.
>>
>> If i manually force loading A before B everything is allright.
>>
>> I would like to learn an approach to deal with this problem so that
>> the instrumentation process gets more predictable.
>>
>> More info about the transformation. I'm building an stm and i add
>> transactions to classes. This is done by creating an extra method  
>> with
>> an extra argument of type transaction. All the original Logic is  
>> moved
>> to this method. The code in the original method is replaced by
>> transaction management code that forwards the call inclusive the
>> transaction to the added method.
>>
>> The optimization i want to add is that if transactional methods are
>> called from the original code, that the method calls are replaced by
>> the version that acceps à transaction. There is no need to go thro 
>> ugh
>> the transaction management and access à threadlocal to get the
>> transaction.
>

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