RFR: 8304885: Reuse stale data to improve DNS resolver resiliency [v6]

[Michael McMahon]

On Fri, 28 Apr 2023 15:13:35 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> src/java.base/share/classes/sun/net/InetAddressCachePolicy.java line 130:
>> 
>>> 128:                 staleCachePolicy = (int) Math.max(tmp, max);
>>> 129:             }
>>> 130:         }
>> 
>> Maybe there was discussion of this which I missed, but this seems to be saying if the cache policy is less than seven days, then the stale policy is set no less than seven days. What is the reason for that? I think it would need to be documented if we stick with it.
>
> It is come from the recommendation in the "RFC 8767" see the notion about "cap of 7 days":
> https://www.rfc-editor.org/rfc/rfc8767
> Depending on the final implementation I can document this, or delete it in the code.

>From what I can see RFC8767 recommends a cap of 7 days for the TTL itself - that is a maximum value for `cachePolicy` rather than `staleCachePolicy`. It seems to say the the stale timer should be configurable with the text: "The suggested value is between 1 and 3 days".  Personally, I would drop this part of the change. Such suggestions can be adopted (or not) by end users in my opinion.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13285#discussion_r1183726891