RFR: 8160000: Runtime.version() cause startup regressions in 9+119

[Paul Sandoz]

> On 26 Jun 2016, at 21:55, Claes Redestad <claes.redestad at oracle.com> wrote:
> 
> Hi,
> 
> 9+119 changed java.util.regex to initialize java.lang.invoke early, causing a number of easily reproducible startup regressions.
> 
> This patch uses the fact that we already maintain the version string constituents during build time to simplify creation of the java.lang.Runtime.version().
> 
> Webrev: http://cr.openjdk.java.net/~redestad/8160000/webrev.3/
> Bug: https://bugs.openjdk.java.net/browse/JDK-8160000
> 
> Since getting Runtime.version() now does not have to touch java.util.regex classes we end up slightly ahead of previous builds for applications which does not use regular expressions.
> 
> Thanks!
> 

Looks good.

- Perhaps it’s worth pre-sizing the array list exactly by counting the ‘.’ before processing? or is 4 always pre-sized exactly?

- add an assert to check Version produced by version() is the same as that produced the previous way parsing the sys prop

-
 957             if (!VersionProps.VERSION_PRE.isEmpty()) {
 958                 pre = Optional.of(VersionProps.VERSION_PRE);
 959             } else {
 960                 pre = Optional.empty();
 961             }

Encapsulate that and the other two into a separate method e.g. optionalOfEmpty then do:

  version = new Version(…
     optionalOfEmpty(VersionProps.VERSION_PRE),
     …
     );

Paul.