RFR: 8283335 : Add exists and readAttributesIfExists methods to FileSystemProvider

[Lance Andersen]

On Wed, 22 Jun 2022 19:22:50 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Hi,
>> 
>> Please review the following patch which will:
>> 
>> - Enhance the java.nio.file.spi.FileSystemProvider abstract class to include the methods
>> 
>>   - public boolean exists(Path path, LinkOption... options)
>>   - public <A extends BasicFileAttributes> A readAttributesIfExists(Path path, Class<A> type, LinkOption... options)
>> 
>> 
>> This change allows for providers to provide optimizations when the file's attributes are not needed.
>> 
>> Mach5 tiers 1 - 3  run clean with this change
>> 
>> The CSR may be viewed at [JDK-8283336](https://bugs.openjdk.org/browse/JDK-8283336)
>> 
>> 
>> Best,
>> Lance
>
> src/java.base/share/classes/java/nio/file/spi/FileSystemProvider.java line 1184:
> 
>> 1182:      * is present then symbolic links are not followed and the method
>> 1183:      *  {@link #readAttributes(Path, Class, LinkOption...)} is called
>> 1184:      *  to determine whether a file exists.
> 
> Indentation is off at lines 1183-1184.

Thanks for catching that.  Will be addressed in the next push

> src/java.base/share/classes/java/nio/file/spi/FileSystemProvider.java line 1218:
> 
>> 1216: 
>> 1217:     /**
>> 1218:      * Reads a file's attributes as a bulk operation if it exists.
> 
> Maybe instead "it" put "the file"?

I can if you think that is better.  I followed the wording for `FileSystemProvider::deleteIfExists` trying to be consistent

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PR: https://git.openjdk.org/jdk/pull/9249