RFR(JDK12/NIO) 8202285: (fs) Add a method to Files for comparing file contents

[Alan Bateman]

On 20/09/2018 01:34, Joe Wang wrote:
> :
>
> The purpose of toRealPath is so that we can do a quick Path comparison 
> by following symlinks if any, I'll add a test to compare a file and 
> its symbolic link. 
You don't need it. If two non-equals paths locate the same file then 
mismatch will do the right thing. By dropping it then you avoid a 
potentially expensive realpath (x2).


> ProviderMismatchExcepiton was added in one of the iterations when we 
> defined UOE, shall be removed in the next update (I'll have an update 
> after some performance work to compare with direct buffer is done).
Good.

>
> mismatchByAttrs cannot be replaced with isSameFile, it does one edge 
> case check more than isSameFile when the size of one of the files is 
> zero. mismatchByAttrs opens the files once vs twice if isSameFile and 
> size(path) are called.
Hmm, I think we make this a lot simpler.

-Alan