Value type sorting

[Doug Lea]

I've been exploring sorting algorithms (mainly parallel but also
sequential) that should apply well to value types. Even though Valhalla
is not yet at a state where you can use generic by-value Comparables,
I've been trying things out by manually plugging in various types, in
part to scope out future issues. Sorting is the most famous example of a
problem for which no algorithm is always best. Among other things,
performance varies with element comparison vs copying cost, parallelism
support, workspace overhead, and trade-offs of average vs worst case
behavior. I placed a snapshot of the current Goldilocks candidate
balancing these for value types at:
  http://gee.cs.oswego.edu/dl/wwwtmp/CVSorter.java
The internal documentation describes some of the algorithmic choices.
As the instruction near the top indicate, for now you need to plug in
any __ByValue class named "CVal". This compiles and runs using current
(build zero) early access (http://jdk.java.net/valhalla/).

Just for comparison, there's also an otherwise identical version for
long[] arrays at:
  http://gee.cs.oswego.edu/dl/wwwtmp/LongSorter.java
When using a __ByValue type just emulating a single long, CVSorter seems
to be only 5% or so slower than LongSorter sorting 100 million elements,
which is pretty good for using something labeled build zero. But
CVSorter also works well with various small or medium-sized value types.

Any feedback would be welcome. It would be especially nice to hear from
anyone who has actual data and types that need sorting. There are a lot
of synthetic loads available (it does well on most), but having some
actual cases that anyone might be dealing with in the future would be
helpful.

-Doug