On 06/04/2015 09:37 AM, Paul Sandoz wrote:
On Jun 4, 2015, at 9:04 AM, Remi Forax <fo...@univ-mlv.fr> wrote:
Thinking a little more about dropWhile(),
it can be written using filter() more or less like this:
default Stream<T> dropWhile(Predicate<? super T> predicate) {
return filter(new Predicate<>() {
private boolean noDropAnymore;
public boolean test(T t) {
return noDropAnymore || (noDropAnymore = !predicate.test(t));
}
});
}
and i maybe wrong but implementing dropWhile with an op is not better than that
in term of perf so for me dropWhile() doesn't pull its own weight.
Try running that in parallel.
I'm not sure it's a good idea if you want good perf, the cost of
checking a volatile flag inside the loop for each thread (I don't see
how to have something more lightweight) will cost more than just keeping
the stream sequential, no ?
(Stream.parallel() affects the whole pipeline, so it's not possible to
implement the default with sequential().filter(p) where p is a stateful
predicate.)
it's possible,
the default should return a proxy in front of the result of
sequential().filter(p) that return this if parallel() is called.
Paul.
Rémi
