RFR: 8244202: Implementation of JEP 418: Internet-Address Resolution SPI [v9]

[Michael McMahon]

On Tue, 26 Oct 2021 16:24:48 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 one additional commit since the last revision:
> 
>   Add @ throws NPE to hosts file resolver javadoc

src/java.base/share/classes/java/net/InetAddress.java line 841:

> 839:         // 'resolver.lookupByAddress' and 'InetAddress.getAllByName0' delegate to the system-wide resolver,
> 840:         // which could be a custom one. At that point we treat any unexpected RuntimeException thrown by
> 841:         // the resolver as we would treat an UnknownHostException or an unmatched host name.

indentation issue in comment above

src/java.base/share/classes/java/net/InetAddress.java line 1308:

> 1306:      * Creates an InetAddress based on the provided host name and IP address.
> 1307:      * System {@linkplain InetAddressResolver resolver} is not used to check
> 1308:      * the validity of the address.

Is this term "system resolver" defined somewhere? I think it means the configured resolver for the current VM. Previously, it really was the system resolver. So, I think it's potentially confusing, as there is also reference to the java.net.preferIPv6Addresses system property as having a possible value "system" which refers to the operating system. Since the CSR is approved, I'm happy to discuss this point post integration.

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