Un-OK. Sometimes when microbenchmarking, we stumble upon a code sequence
that hotspot likes. I observed 20% improvement with the below, so
switching to that:
public boolean tryAdvance(Consumer<? super E> action) {
Objects.requireNonNull(action);
final Object[] es = elements;
if (fence < 0) { fence = tail; cursor = head; } // late-binding
final int i;
if ((i = cursor) == fence)
return false;
E e = nonNullElementAt(es, i);
cursor = inc(i, es.length);
action.accept(e);
return true;
}
On Thu, Nov 17, 2016 at 7:41 PM, Martin Buchholz <marti...@google.com>
wrote:
>
>
> On Thu, Nov 17, 2016 at 12:03 PM, Paul Sandoz <paul.san...@oracle.com>
> wrote:
>
>>
>> 843 public boolean tryAdvance(Consumer<? super E> action) {
>> 844 if (action == null)
>> 845 throw new NullPointerException();
>> 846 int t, i;
>> 847 if ((t = fence) < 0) t = getFence();
>>
>> Is that for optimisation purposes, since the same check is also performed
>> in getFence? If so that seems like overkill
>>
>>
> OK:
>
> --- src/main/java/util/ArrayDeque.java 18 Nov 2016 03:22:20 -0000 1.114
> +++ src/main/java/util/ArrayDeque.java 18 Nov 2016 03:38:23 -0000
> @@ -866,9 +866,8 @@
> public boolean tryAdvance(Consumer<? super E> action) {
> if (action == null)
> throw new NullPointerException();
> - int t, i;
> - if ((t = fence) < 0) t = getFence();
> - if (t == (i = cursor))
> + final int t, i;
> + if ((t = getFence()) == (i = cursor))
> return false;
> final Object[] es = elements;
> cursor = inc(i, es.length);
>
>
>
>>
>> 848 if (t == (i = cursor))
>> 849 return false;
>> 850 final Object[] es;
>> 851 action.accept(nonNullElementAt(es = elements, i));
>> 852 cursor = inc(i, es.length);
>>
>
