RFR: 8244202: Implementation of JEP 418: Internet-Address Resolution SPI [v3]

[Mark Sheppard]

On Tue, 12 Oct 2021 15:43:24 GMT, Aleksei Efimov <aefimov at openjdk.org> wrote:

>> This change implements a new service provider interface for host name and address resolution, so that java.net.InetAddress API can make use of resolvers other than the platform's built-in resolver.
>> 
>> The following API classes are added to `java.net.spi` package to facilitate this:
>> - `InetAddressResolverProvider` -  abstract class defining a service, and is, essentially, a factory for `InetAddressResolver` resolvers.
>> - `InetAddressResolverProvider.Configuration ` - an interface describing the platform's built-in configuration for resolution operations that could be used to bootstrap a resolver construction, or to implement partial delegation of lookup operations.
>> - `InetAddressResolver` - an interface that defines methods for the fundamental forward and reverse lookup operations.
>> - `InetAddressResolver.LookupPolicy` - a class whose instances describe the characteristics of one forward lookup operation.  
>> 
>> More details in [JEP-418](https://openjdk.java.net/jeps/418).
>> 
>> Testing: new and existing `tier1:tier3` tests
>
> Aleksei Efimov has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Add @since tags to new API classes
>  - Add checks and test for empty stream resolver results

What’s in a name?
I find the method names of the InetAddressResolver interface a bit ambiguous. Typically in this DNS problem space
one speaks of lookup to resolve a hostname to its associated addresses and reverse lookup
to resolve an IP address to a hostname (or names) associated with it.

For the method names lookupHostname, and lookupAddresses,
and the semantics conveyed in those names, 
I would expect lookupHostname to resolve a hostname, that is, take a hostname as parameter and
the return value the addresses, while lookupAddresses I would expect to resolve an address to its hostname,
that is, take an address and return a hostname.
However, the current pair of methods names convey the opposite, lookupHostname resolves an address and
lookupAddresses resolves a hostname.

I would proffer a method name change to use lookup and reverseLookup
OR to use resolvesHostname and resolveAddress, to resolve a hostname and address
respectively.

Thus, lookupHostname should be renamed to reverseLookup and
lookupAddresses to lookup OR
lookupHostname renamed to resolveAddress and lookupAddresses renamed to resolveHostname.

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PR: https://git.openjdk.java.net/jdk/pull/5822