hs25 review request (2nd round): 8008511 JSR 292: MemberName vmtarget refs to methods must be updated at class redefinition

[serguei.spitsyn at oracle.com]

On 4/15/13 4:48 PM, David Holmes wrote:
> On 16/04/2013 3:59 AM, serguei.spitsyn at oracle.com wrote:
>> Hi David,
>>
>>
>> Thank you for the comments!
>>
>>
>> On 4/14/13 10:12 PM, David Holmes wrote:
>>> Hi Serguei,
>>>
>>> Not a full review ...
>>>
>>> In instanceKlass.cpp:
>>>
>>> +   MemberNameTable* mnt = member_names();
>>> +   if (mnt != NULL) {
>>> +     delete mnt;
>>> +   }
>>>
>>> a) do we need to call set_member_names(null) ?
>>
>> Fixed, thanks.
>>
>>
>>> b) do we need to use the MemberNameTable_lock to guard this?
>>
>> I don't think so.
>> This deallocation must be done at a safepoint.
>> We can't grab locks at safepoints.
>
> Okay but that is only one side of things. We also have to verify that 
> any code that does grab the lock can't enter a safepoint while holding 
> the lock.

Thank you for checking this.
I did a check that the code that grabs the lock does not need a safepoint.
I can place a No_Safepoint_Verifier, if you think, it makes sense to do.

Currently, this is the only place that grabs the lock:

void InstanceKlass::add_member_name(Handle mem_name) {
   jweak mem_name_wref = JNIHandles::make_weak_global(mem_name);
   MutexLocker ml(MemberNameTable_lock);
   DEBUG_ONLY(No_Safepoint_Verifier nsv);  // <= We can add this check

   if (_member_names == NULL) {
     _member_names = new (ResourceObj::C_HEAP, mtClass) MemberNameTable();
   }
   _member_names->add_member_name(mem_name_wref);
}


Thanks,
Serguei

>
> David
> ------

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