RFR 8198997: Cache normalized/resolved user.dir property

[Claes Redestad]

Hi Brian,

I expect the original user.dir property to be kept resident in memory by 
System.properties
(thus no memory loss), and going from a boolean field to an Object 
reference field on an
object that I expect to be a singleton(?) is unlikely to be a footprint 
concern[1].

/Claes

[1] Chances are the two approaches are footprint neutral on most archs 
due to padding.


On 2018-03-12 19:46, Brian Burkhalter wrote:
> Hi Claes,
>
> That was what I had originally but did not post as I did not like the 
> extra String variable increasing the memory footprint. Of course this 
> would only be true were the user.dir accessed at all.
>
> Thanks,
>
> Brian
>
> On Mar 12, 2018, at 11:42 AM, Claes Redestad 
> <claes.redestad at oracle.com <mailto:claes.redestad at oracle.com>> wrote:
>
>> 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;
>