RFR: 8062771: Core reflection should use final fields whenever possible

[Martin Buchholz]

Hi Aleksey,

On Tue, Nov 4, 2014 at 11:55 AM, Aleksey Shipilev
<aleksey.shipilev at oracle.com> wrote:
> On 04.11.2014 20:53, Martin Buchholz wrote:
>> On Tue, Nov 4, 2014 at 2:13 AM, Paul Sandoz <paul.sandoz at oracle.com> wrote:
>>> On Nov 3, 2014, at 11:18 PM, Martin Buchholz <martinrb at google.com> wrote:
> If you do this:
>
>>      // Generic info repository; lazily initialized
>> -    private transient ClassRepository genericInfo;
>> +    private volatile transient ClassRepository genericInfo;
>
> ...you don't need to do this for correctness (but may do for performance
> -- avoidable volatile read for ARM/PPC):

It's just reflex to always read volatiles into locals - never hurts,
except the line-of-code count.

>>      // accessor for generic info repository
>>      private ClassRepository getGenericInfo() {
>> +        ClassRepository genericInfo = this.genericInfo;
>>          // lazily initialize repository if necessary
>>          if (genericInfo == null) {
>>              // create and cache generic info repository
>>              genericInfo = ClassRepository.make(getGenericSignature(),
>>                                                 getFactory());
>> +            this.genericInfo = genericInfo;
>>          }
>>          return genericInfo; //return cached repository
>>      }
>>
>
> Also, I wonder if we need a singleton ClassRepository instance, or we
> can tolerate two different ClassRepository-ies returned under concurrent
> init.

Yeah, me too.  But the existing code has this behavior as well.  One
could fix it if needed with double-checked-locking or whatever our
fancy new volatile unsafe-less cas ends up looking like.