RFR [16/java.xml] 8246816: XMLGregorianCalendar.hashCode() produces far too many identical hashes

[Joe Wang]

Thanks Naoto, Roger!  I'll prepare push based on version 01.

Best,
Joe

On 8/6/20 1:29 PM, Roger Riggs wrote:
> +1
>
> On 8/6/20 4:18 PM, naoto.sato at oracle.com wrote:
>> Hi Joe, thank you for looking it into further.
>>
>> Yes, I agree the chances of collision is very rare, as 
>> sub-millisecond difference in two objects. So fine with the version 01.
>>
>> Naoto
>>
>> On 8/6/20 12:18 PM, Joe Wang wrote:
>>> Thanks Naoto, Roger for the review!
>>>
>>> For Naoto's concern about the equals method using EonAndYear and 
>>> FractionalSecond, I did cut corners using the all int getXXX method. 
>>> The rational was: it fulfills the equals-hashcode contract just 
>>> fine, is consistent with the existing implementation, and concise. 
>>> This API was introduced since 1.5, but I have yet to see any usage 
>>> of EonAndYear, and very rarely FractionalSecond. The chances 
>>> collisions occur due to these differences are very low.
>>>
>>> But I understand your concern. To be precise or exact as equals(), 
>>> we would need to call getFractionalSecond and EonAndYear. Here's 
>>> what that would look like:
>>> http://cr.openjdk.java.net/~joehw/jdk16/8246816/webrev_02/
>>>
>>> To me, I like version 1 for the reasons above:
>>> http://cr.openjdk.java.net/~joehw/jdk16/8246816/webrev_01/
>>>
>>> What would you think?
>>>
>>> Regards,
>>> Joe
>>>
>>> On 8/5/20 6:13 PM, naoto.sato at oracle.com wrote:
>>>> Hi Joe,
>>>>
>>>> For the consistency with equals(), just wondering if the sub-second 
>>>> element should be obtained with getFractionalSecond() instead of 
>>>> getMillisecond(), as the equals() subsequently calls it in 
>>>> internalCompare() method. Also should it call getEonAndYear() 
>>>> appropriately for the year?
>>>>
>>>> Naoto
>>>>
>>>> On 8/5/20 4:37 PM, Joe Wang wrote:
>>>>> Hello,
>>>>>
>>>>> Please review a fix for the hashCode generation.
>>>>>
>>>>> JBS: https://bugs.openjdk.java.net/browse/JDK-8246816
>>>>>
>>>>> webrev: http://cr.openjdk.java.net/~joehw/jdk16/8246816/webrev/
>>>>>
>>>>> Thanks,
>>>>> Joe
>>>>>
>>>
>