[PATCH] Docfix for Unsafe regarding fence methods

[Ian Graves]

Hello,

When reviewing some of the documentation in jdk.internal.misc.Unsafe, it appears that there is some dated information regarding the availability of “pure barrier” methods (i.e. pure StoreStoreFence sans a LoadStore barrier). When the storeFence() and loadFence() methods were implemented the pure variations (loadLoadFence(), storeStoreFence()) were not implemented and the documentation indicated as much. This is no longer the case. 

I’ve included a patch with this email that updates the docs to reflect the new state of affairs here as well as indicate some implementation details as to how the pure variants utilize the impure original methods.

Thanks!

Ian