RFR 8198997: Cache normalized/resolved user.dir property

[Paul Sandoz]

> On Mar 12, 2018, at 11:42 AM, Claes Redestad <claes.redestad at oracle.com> wrote:
> 
> Hi,
> 
> mixing volatiles and non-volatiles fields that are read and written to outside of
> synchronized makes me somewhat queasy…
> 

Synchronizing on a string also makes me queasy, especially given that string can be input by the user, i dunno if there is any interning going on…

It's a little dirty but you might be able to piggyback off another field e.g. those of ExpiringCache.

Paul.

> Instead of a volatile boolean and a mutable userDir field, couldn't this just
> as well be modelled as:
> 
> - keep userDir final (always the not normalized value of System.getProperty("user.dir"))
> - replace volatile boolean isUserDirNormal with volatile String normalizedUserDir
> - then implement the DCL in getUserPath like:
> 
> String normalizedUserDir = this.normalizedUserDir;
> if (normalizedUserDir == null) {
>     synchronized(userDir) {
>         if (normalizedUserDir == null) {
>             normalizedUserDir = this.normalizedUserDir = normalize(userDir);
>         }
>     }
> }
> return normalizedUserDir;
> 
> WDYT?
> 
> /Claes
> 
> On 2018-03-12 19:32, Brian Burkhalter wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8198997
>> http://cr.openjdk.java.net/~bpb/8198997/webrev.00/
>> 
>> Lazily cache the value of the user.dir property on first access. This change is for Windows only as there does not appear to be any percentage in doing something similar on Unix.
>> 
>> Thanks,
>> 
>> Brian
>