RFR: 8368856: Add methods for saturating Duration arithmetic to Instant [v7]

[Pavel Rappo]

On Wed, 8 Oct 2025 19:05:50 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>>> Omit minusSaturating, I think subtraction is much less common and even more so to exceed the negative range.
>>> The caller can negate their argument and use plus if that's needed.
>> 
>> On the one hand, I also don't think we need `minusSaturating` as far as the typical use case is concerned. On the other hand, negating durations is a tricky business. Although, it's not a real use case, negating the minimum duration will cause `ArithmeticException`:
>> 
>> 
>> jshell> Duration.ofSeconds(Long.MIN_VALUE, 0).negated()
>> |  Exception java.lang.ArithmeticException: Exceeds capacity of Duration: 9223372036854775808000000000
>> |        at Duration.create (Duration.java:1056)
>> |        at Duration.multipliedBy (Duration.java:995)
>> |        at Duration.negated (Duration.java:1074)
>> |        at (#2:1)
>> 
>> 
>> So one cannot implement `i.minusSaturaring(Duration.ofSeconds(Long.MIN_VALUE, 0))` as `i.plusSaturating(Duration.ofSeconds(Long.MIN_VALUE, 0).negated())`.
>
> We're defining the values of MIN and MAX and they *could* be defined to be the negation of the other.
> The defined use case is a sentinels and the exact value is less significant.
> It just a different kind of oddity compared to twos-complement numbers that have their own asymmetry.

Hm... I imagine it would be confusing if we did that. Should we ask about it on that recent core-libs-dev discussion thread?

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PR Review Comment: https://git.openjdk.org/jdk/pull/27549#discussion_r2414897705