RFR JDK-8066709 Make some JDK system properties read only

[Roger Riggs]

Hi Max,

On 6/4/2018 11:41 AM, Wang Weijun wrote:
> Not a native English speaker, so my feeling might be incorrect.
>
> Will someone interpret this as that System.getProperty() will return a cached value?
I don't think so, it should be clear that the values are cached at 
initialization or first use.
>
> I would say “Although getProperty() always returns the last value set by setProperty() (I assume this is the current behavior), it is not uncommon that consumers of a system property may read it once and cache the value it for later use, which means setting the property <strong>may not have the desired effect</strong>”.
The purpose of the change is to clarify the behavior of the java.base 
module internal access to the properties.
How applications handle properties is beyond the intended scope.
>
> I also don’t think it’s worth listing the 4 property names in the spec. Quite some other system properties are also cached. Listing them there could further suggests that calling getProperty() on them will return the cached value.
It seemed worthwhile to highlight the specific properties affected and 
the release note should be specific.
I moved them to an implNote as Alan suggested.

Thanks, Roger

>
> Thanks
> Max
>
>> 在 2018年6月4日，下午9:32，Roger Riggs <Roger.Riggs at oracle.com> 写道：
>>
>> Please review a change to make the values of java.home, user.home, user.dir, and user.name
>> effectively read-only for internal use.  The values are cached during initialization and the
>> cached values are used.
>>
>> Webrev:
>>    http://cr.openjdk.java.net/~rriggs/webrev-static-property-8066709/
>>
>> Issue:
>>    https://bugs.openjdk.java.net/browse/JDK-8066709
>>
>> CSR:
>>    https://bugs.openjdk.java.net/browse/JDK-8204235
>>
>> Thanks, Roger
>>
>>