RFR (XS) 8209802: JFR failed to build when certain garbage collectors are disabled

[Thomas Schatzl]

Hi Derek,

  some comment in JIRA I accidentally came across that may be helfpul:

On Thu, 2018-11-01 at 16:05 -0700, Derek Thomson wrote:
> > 

[...]
> Thanks for the review! Comments inline. And new webrev at 
> http://cr.openjdk.java.net/~jcbeyler/8209802/webrev.01/
> 
[...]
> >   - in jfr.cpp, I would prefer the ifdef's completely removed the
> > TRACE_REQUEST_FUNC(G1HeapRegionInformation), if possible.
> > Otherwise, I think it is better to remove starting from the body of
> > this method.
> 
> Sorry, did you mean jfrPeriodic.cpp? In which case not sure what
> method you mean here. Can you clarify for me please?
>  
> >   - in jfrType.cpp the question is if compiling without g1 could 

Yes.

> > remove the entire declaration of G1HeapRegionTypeConstant.
> > 
> > Cc'ing hotspot-jfr-dev at openjdk.java.net as the jfr devs might have
> > an idea how to accomplish that.
> 
> Sure.

There has been an answer how to do this (I believe :)) in the comment
for this CR at 
https://bugs.openjdk.java.net/browse/JDK-8209802?focusedCommentId=14221326&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14221326

"The preferred way is to have the JFR type constant registrations
repatriated to their natural origin. 
The registration mechanism now supports dynamic registrations, where it
originally only had static means to register. 

The ZGC JFR type constants can be referred to as precedents, see: 

ZStatisticsCounterTypeConstant 
ZStatisticsSamplerTypeConstant "

Hth (and does not confuse too much),
  Thomas