JDK-8259873: (fs) Add java.nio.file.attribute.BasicWithKeyFileAttributeView interface

[Alan Bateman]

On 20/01/2021 07:55, Martin Buchholz wrote:
> I'm mostly cheerleading here, and haven't developed for Windows in 
> many years, but ... I agree with the strategy here.  More use of file 
> keys would benefit performance on all platforms.  OTOH I worry that 
> filekeys are inconsistently implemented on different OSes and filesystems.
>
The recent thread with subject line "Files.isSameFile(Path,Path)" may be 
useful to re-read. The JDK has been using the volume serial number and 
file indexes but they are problematic on some volumes (not guarantee to 
be unique, maybe be zero). The Microsoft folks here have been looking to 
replace the usage with the "full path" (the approximate equivalent to 
realpath).

We did a lot work in JDK 7 to make the default case (not following sym 
links) be efficient on Windows. This is the reason for the internal 
BasicFileAttribuetHolder that FileTreeWalker uses to avoid needing to 
read the file attributes. Maybe we could lean on that internal interface 
and try to find options there before adding to the standard API.

Switching from FindFirstFile/FindNextFile to NtQueryDirectoryInformation 
is definitely worth exploring, it will just take significant time to 
review and will likely go through a few review iterations.

-Alan