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List:       openjdk-serviceability-dev
Subject:    Re: 15 RFR(XS): 8165276: Spec states that invoke the premain method in an agent class if it's public
From:       "serguei.spitsyn () oracle ! com" <serguei ! spitsyn () oracle ! com>
Date:       2020-06-29 17:46:45
Message-ID: f14a9293-fc6b-207a-f3ae-97576ad5c252 () oracle ! com
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Thanks a lot for review, Mandy!
I also, asked Leonid to look if the test changes can be simplified

Thanks,
Serguei


On 6/29/20 09:46, Mandy Chung wrote:
>
>
> On 6/27/20 12:23 AM, Alan Bateman wrote:
>> On 27/06/2020 01:40, serguei.spitsyn@oracle.com wrote:
>>>
>>> The implementation has this order of lookup:
>>>
>>>         // The agent class must have a premain or agentmain method that
>>>         // has 1 or 2 arguments. We check in the following order:
>>>         //
>>>         // 1) declared with a signature of (String, Instrumentation)
>>>         // 2) declared with a signature of (String)
>>>         // 3) inherited with a signature of (String, Instrumentation)
>>>         // 4) inherited with a signature of (String)
>>>
>>> The declared methods are gotten with the getDeclaredMethod and 
>>> inherited with the getMethod.
>>> This works for both 1-arg and 2-arg premain methods, so I'm not sure 
>>> what is inconsistent.
>>> Or you have a concern there can be a non-nice NoSuchMethodException?
>>>
>>> In fact, I don't understand why there is a need to use the 
>>> getDeclaredMethod.
>>> As I see, the getMethod should return a declared method first, and 
>>> only if it is absent then it checks for a inherited one.
>> The JPLIS agent used getMethod when it was originally created in JDK 
>> 5 so it would only find public methods. I haven't studied the 
>> intervening history too closely but I assume JDK-6289149 (in JDK 7) 
>> created the inconsistency between the spec and implementation when it 
>> explored the scenario of premain declared in a super class with 
>> different arity and/or modifiers to the premain in the sub-class. I 
>> assume the tests that you've been forced to change are related to 
>> this same issue.
>>
>
> Thanks for digging up the history.
>
>> So given where we are, and given the statement "The JVM first 
>> attempts to invoke the following method on the agent class" in the 
>> spec then I guess it's okay to keep the getDeclaredMethod to deal 
>> with "whacky" case where a super class of the agent class has a 
>> public premain method.
>>
>
> I also think it's okay to get a different exception message in this case.
>
> Serguie - I reviewed this version.  It looks okay.
>> New wevrev version is:
>> http://cr.openjdk.java.net/~sspitsyn/webrevs/2020/instr-setAccessible.2/
>
> Mandy
>
>
>

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