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From Oliver Deakin <oliver.dea...@googlemail.com>
Subject Re: [classlib][jdwp] Use java 6 branch JDWP in java 5 builds?
Date Fri, 31 Jul 2009 13:58:32 GMT
Mark Hindess wrote:
> In message <4A7031F1.3020209@apache.org>, Gregory Shimansky writes:
>> Oliver Deakin said the following on 29.07.2009 15:20:
>>> Hi all,
>>> After determining the cause of HARMONY-6246 [1] I discovered that it has 
>>> already been fixed in the Java 6 branch, where I recently applied the 
>>> contribution in HARMONY-6187 [2]. This got me thinking - there have been 
>>> a number of bug fixes, performance improvements and portability changes 
>>> made which were applied in that contribution and it is likely we will 
>>> hit some of the same issues again in the Java 5 branch which have 
>>> already been fixed in Java 6.
>>> Is it possible for us just to use the updated Java 6 branch JDWP in our 
>>> Java 5 builds as well? Not only would we benefit from the code 
>>> improvements made there, we would have one unified code base for JDWP 
>>> (and possibly the whole of jdktools?).
>>> Any comments on this idea?
>> If JDWP agent with Java6 update doesn't demand that VM support new 
>> features of JVMTI (that is it can work with Java5 VM), I think it is a 
>> good idea. Backporting all of the bugfixes may be quite difficult since 
>> it is necessary to separate pure bugfixes from Java6 enhancements in [2].
>>> [1] https://issues.apache.org/jira/browse/HARMONY-6246
>>> [2] https://issues.apache.org/jira/browse/HARMONY-6187
> Does the current combination of DRLVM and java6 branch JDWP work
> consistently?  That is, do all of hardcoded (?) capabilities[0] that
> JDWP claims are supported work with DRLVM as expected?
> Does any of the Java 5 JDWP functionality require 6.0 JVMTI calls?

I need to do a bit more investigation on this - I would hope the Java 5 
functionality wouldn't require any JVMTI calls from Java 6, but will 
need to confirm that. When I get a chance Ill have a look at the new 
JVMTI functions introduced into Java 6 and where they are used in JDWP.


> Assuming the answers to the above are yes, yes and no, then I see no
> problem.  If anyone needs a JDWP for a Java 5 VM then we'd just need
> to #ifdef the reporting of the capabilities to stop 6.0 calls being
> invoked.
> Regards,
>  Mark.
> [0] particularly java 6 ones such as canGetInstanceInfo,
>     canRequestMonitorEvents, canGetMonitorFrameInfo,
>    canUseSourceNameFilters, canGetConstantPool, and canForceEarlyReturn

Oliver Deakin
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