Spliterator implementations

[Doug Lea]

On 01/02/13 18:58, Brian Goetz wrote:

>  From your list, there are a few that might benefit enough from a better
> implementation to be worth the effort, such as Enum{Set,Map},
> {Hash,Tree,LinkedHash}{Set,Map}.  For most of the rest (and some of these,
> probably), the Iterator version is probably good enough.

We'd need to document goodness (or good-enough-ness) in the
same way we document other algorithmic properties of JDK collections.
For anything hopelessly listy (almost all queues, LinkedList,
LinkedHashSet, etc) we'd want to clearly indicate O(n) splitting
that would be worthwhile only if each function application to each
element is very expensive. Not documenting these will surely lead
to justifiable bug reports.

Conversely most array-based ones (including most hash tables)
can document best-case O(n/p) performance (p is parallelism level)
because of constant split time. Others somewhere in the middle.
Of those others, there may be those that could in principle be
faster but might not be  for JDK8 ship?

-Doug