On Tue, 2 Mar 2021 06:29:07 GMT, Stuart Marks <sma...@openjdk.org> wrote:
>> This rewrites the doc of ArraysSupport.newLength, adds detail to the
>> exception message, and adds a test. In addition to some renaming and a bit
>> of refactoring of the actual code, I also made two changes of substance to
>> the code:
>>
>> 1. I fixed a problem with overflow checking. In the original code, if
>> oldLength and prefGrowth were both very large (say, Integer.MAX_VALUE), this
>> method could return a negative value. It turns out that writing tests helps
>> find bugs!
>>
>> 2. Under the old policy, if oldLength and minGrowth required a length above
>> SOFT_MAX_ARRAY_LENGTH but not above Integer.MAX_VALUE, this method would
>> return Integer.MAX_VALUE. That doesn't make any sense, because attempting to
>> allocate an array of that length will almost certainly cause the Hotspot to
>> throw OOME because its implementation limit was exceeded. Instead, if the
>> required length is in this range, this method returns that required length.
>>
>> Separately, I'll work on retrofitting various call sites around the JDK to
>> use this method.
>
> Stuart Marks has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Update copyright year.
Overall this looks good.
src/java.base/share/classes/jdk/internal/util/ArraysSupport.java line 579:
> 577: /**
> 578: * A soft maximum array length imposed by array growth computations.
> 579: * Some JVMs (such as Hotspot) have an implementation limit that
> will cause
The numbers of spellings "HotSpot" to that of "Hotspot" in the JDK codebase is
10 to 1 respectively. Also, on my machine I can see this:
$ java --version
java 15 2020-09-15
Java(TM) SE Runtime Environment (build 15+36-1562)
Java HotSpot(TM) 64-Bit Server VM (build 15+36-1562, mixed mode, sharing)
test/jdk/jdk/internal/util/ArraysSupport/NewLength.java line 100:
> 98: int r = ArraysSupport.newLength(old, min, pref);
> 99: fail("expected OutOfMemoryError, got normal return value of "
> + r);
> 100: } catch (OutOfMemoryError success) { }
Consider using `expectThrows` or `assertThrows` from `org.testng.Assert`.
-------------
Marked as reviewed by prappo (Reviewer).
PR: https://git.openjdk.java.net/jdk/pull/1617
