RFR(s): JDK-8214687 Optimize Collections.nCopies().hashCode()

[Ivan Gerasimov]

Also, I believe it makes sense to override CopiesList.equals() to at 
least optimize the case when the other list is a CopiesList too.

With kind regards,

Ivan


On 12/2/18 11:23 PM, Ivan Gerasimov wrote:
> Thank you Tagir!
>
> I think your solution is quite clever, and the fix looks good.
>
> While we are here:  Would it make sense to use CopiesList only for n > 
> 0, and make nCopies() and nCopies().subList() return 
> Collection.emptyList() otherwise?
>
> This would allow to remove the check for n == 0 in a couple of places.
> Also an unnecessary reference to the `element` wouldn't be kept.
>
> With kind regards,
> Ivan
>
>
> On 12/2/18 9:27 PM, Tagir Valeev wrote:
>> Hello!
>>
>> Please review and sponsor the optimized implementation of
>> Collections.nCopies().hashCode():
>> https://bugs.openjdk.java.net/browse/JDK-8214687
>> http://cr.openjdk.java.net/~tvaleev/webrev/8214687/r1/
>>
>> Previous discussion thread:
>> http://mail.openjdk.java.net/pipermail/core-libs-dev/2018-November/056843.html 
>>
>>
>> Thanks to Zheka Kozlov for the original proposal. Also thanks to Ivan
>> Gerasimov for the simplification idea: (x & 0x8000_0000) != 0 => x <
>> 0.
>>
>> With best regards,
>> Tagir Valeev
>>
>

-- 
With kind regards,
Ivan Gerasimov