RFR(S): 8227255: Switchable helpful NullPointerExceptions

[Lindenmaier, Goetz]

Hi David, 

the implementation of the JEP is to be found here:
https://bugs.openjdk.java.net/browse/JDK-8218628
http://cr.openjdk.java.net/~goetz/wr19/8218628-exMsg-NPE/12/

I thought it's good to keep different aspects in changes of their 
own, also as I need two CSRs: one to mention there are new messages
and one to mention there is a new flag.

It also simplifies reviews a lot.

Best regards,
  Goetz.

> -----Original Message-----
> From: David Holmes <david.holmes at oracle.com>
> Sent: Donnerstag, 4. Juli 2019 12:52
> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>; hotspot-runtime-
> dev at openjdk.java.net
> Cc: Coleen Phillimore (coleen.phillimore at oracle.com)
> <coleen.phillimore at oracle.com>
> Subject: Re: RFR(S): 8227255: Switchable helpful NullPointerExceptions
> 
> Sorry Goetz but I am confused by this. You have a JEP that is still in
> draft but here you have a RFR for a change related to that JEP but not
> the implementation of that JEP ??? I only expect to see one issue filed
> to implement that JEP including the creation of the flag to
> enable/disable it.  The introduction of the flag should be part of the
> JEP as well.
> 
> That said you may as well get the CSR going in parallel with the JEP.
> 
> David
> 
> On 4/07/2019 8:35 pm, Lindenmaier, Goetz wrote:
> > Hi,
> >
> > please review this small change.
> >
> > http://cr.openjdk.java.net/~goetz/wr19/8227255-NPE-switchable/01/
> >
> > It will be part of JEP 8220715.
> >
> > https://bugs.openjdk.java.net/browse/JDK-8220715
> >
> > The exception messages proposed there will first be
> >
> > off per default. After gathering experience, they
> >
> > will be turned on per default.
> >
> > I was asked to use a manageable flag so it can be switched
> >
> > by jcmd.
> >
> > The flag: SuppressCodeDetailsInExceptionMessages
> >
> >    "Suppress"  because the feature is meant to be on per
> >
> >                         default in the long run. Then you'll have to
> >
> >                         use -XX:_+_ if using the switch.
> >
> >    "CodeDetails" tries to summarize the concerns with
> >
> >    the message.
> >
> > The flag does not mention NPE so it can  be used in
> >
> > other, similar cases.
> >
> > If there are not objections to the flag name, I'll file a
> >
> > CSR.  Or should I wait with the CSR until the JEP is
> >
> > targeted?
> >
> > Best regards,
> >
> >    Goetz.
> >