RFR (XS) CR 8014509: @Contended: explicit default value behaves differently from the implicit value

[Aleksey Shipilev]

Thanks!

On 05/15/2013 08:34 PM, Vladimir Kozlov wrote:
> Why you need to test 2 fields but not class annotation?

The tags are only meaningful on fields, tags are inducing the
equivalence class over the fields. The tags are plainly ignored on
class-level @Contended.

> It would be nice to have a comment in parse_annotations() explaining
> what formats of Contended are expected.

I think I really, really need to push the proper Javadoc to @Contended,
and not push the explanation about this to VM code.

> And the code could be rearranged to simplify it a little:
> 
>      if (id == AnnotationCollector::_sun_misc_Contended) {
>        u2 group_index = 0; // default contended group
>        if (count == 1
>            && s_size == (index - index0)  // match size
>            && s_tag_val == *(abase + tag_off)
>            && member == vmSymbols::value_name()) {
>          u2 group_index = Bytes::get_Java_u2(abase + s_con_off);
>          if (_cp->symbol_at(group_index)->utf8_length() == 0) {
>            group_index = 0; // empty tag => default contended group
>          }
>        }
>        coll->set_contended_group(group_index);
>      }

Good, I'll fix this and re-spin JPRT.

-Aleksey.