RFR: 8304885: Reuse stale data to improve DNS resolver resiliency [v5]

[Sergey Bylokhov]

On Thu, 27 Apr 2023 13:55:21 GMT, Michael McMahon <michaelm at openjdk.org> wrote:

>> Sergey Bylokhov has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 10 additional commits since the last revision:
>> 
>>  - Merge branch 'master' into JDK-8304885
>>  - documentation
>>  - PR feedback
>>  - Merge remote-tracking branch 'upstream/master' into JDK-8304885
>>  - Use "maximum stale timer" instead of the extended timeout, and bump it on each successful lookup
>>  -  the suggested cap is 7 days
>>  - simplify
>>  - comments
>>  - Merge remote-tracking branch 'upstream/master' into JDK-8304885
>>  - 8304885: Reuse stale data to improve DNS resolver resiliency
>
> I think this is a very useful enhancement, and I like the approach. To aid understanding can I suggest renaming a couple of the implementation classes (one already existing) and adding some apidoc as follows. I'd like to spend some more time studying the change also.
> 
> 
> /**
>  * A cached result of a name service lookup. The result
>  * can be either valid addresses or invalid (ie a failed lookup) 
>  * containing no addresses
>  */
> CachedAddresses -> CachedLookup
> 
> /**
>  * A cached valid lookup containing addresses whose validity
>  * may be temporarily extended by an additional stale period
>  * pending the mapping being refreshed or updated
>  */
> ValidAddresses -> ValidCachedLookup

@Michael-Mc-Mahon @djelinski @dfuch do you have any other comments? The CSR was updated based on feedback, please take a look.

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PR Comment: https://git.openjdk.org/jdk/pull/13285#issuecomment-1556963916