[threeten-dev] [threeten-develop] #176 Cnveret ZoneRules from interface to calss

[Xueming Shen]

I'm not sure if we want to have an extra public factory method of(ZoneOffset)
to simply for better memory performance when being created from
ZoneOffset.getRules(), which probably will not happen in normal scenario.

The webrev has been updated for your other comments.

I will try to see if we can have a better option.

-Sherman

On 12/20/2012 04:52 PM, Stephen Colebourne wrote:
> On 21 December 2012 00:22, Xueming Shen<xueming.shen at oracle.com>  wrote:
>> On 12/20/2012 04:07 PM, Stephen Colebourne wrote:
>>> The rules for offsets are created and thrown away rapidly, whereas
>>> ZoneId rules are cached. Thus I think we should keep the special
>>> implementation for offsets (as a hidden inner class). It is likely to
>>> have much better performance and garbage collection because it is
>>> simpler.
>> Agreed. But the problem is that we want to return a ZoneRules, which is
>> supposed to be final... There should be not too big impact to the memory
>> footprint, given those a singleton empty list or zero-length array, but yes,
>> ideally we can have a simple representation for this special case.
> A non-final class with a package-scoped construcor can be considered
> to be immutable if all the fields it holds are declared final.
>
> We're talking about 16 extra bytes per instance created, which isn't
> ideal. If the other fields were null it may help the gc more than
> having empty arrays.
>
> Perhaps we could invert the internal hierarchy. Have the simple
> implementation as ZoneRules and the complex implementation as the
> subclass? A little weird, but effective in memory usage, and hidden
> from most users.
>
> I'd suggest you start by adding the extra factory method, and maybe
> push that. The internal optimisation can then come later.
>
> Stephen
>
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