RFR: 8196340: (coll) Examine overriding inherited methods in ArrayList and ArrayList.SubList

[Martin Buchholz]

On Mon, May 14, 2018 at 7:33 AM, Claes Redestad <claes.redestad at oracle.com>
wrote:

>
>> I would prefer having only one comodification check for a bulk operation,
>> but I understand that checking at each step is more compatible with the
>> default implementation.
>>
>>  594         for (int i = 0; i < s; i++) {
>>  595             if (!Objects.equals(es[i], otherEs[i])) {
>>  596  other.checkForComodification(otherModCount);
>>  597  checkForComodification(expectedModCount);
>>  598                 return false;
>>  599             }
>>  600         }
>>
>>
> Perhaps you misread as I think the patch does what I think you're
> suggesting and only checks once. True, this is subtly
> different in behavior from the current implementation
> which is fail-fast.
>

Oh right, I did miss that.  I would probably micro-refactor that into

boolean result = true;
...

+        other.checkForComodification(otherModCount);
+        checkForComodification(expectedModCount);
+        return result;

if only to save bytecode.



> While it shouldn't matter semantically, it could in theory mean a
> measurable delay in throwing a CME when dealing
> with large lists.  As CMEs in ArrayLists could be considered a coding
> error - and the speedup of only checking once
> for a bulk operation like equal is significant - I think it's a reasonable
> trade-off to go ahead with this.


Completely agree.