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https://issues.apache.org/jira/browse/LUCENE-2213?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12801160#action_12801160
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Dawid Weiss commented on LUCENE-2213:
-------------------------------------
Not to be picky, Michael, but is long promotion required here? Would it be
easier to see if you overflow into negative integers and if so, set to
MAX_VALUE?
Another thing -- given the fact that the parameter is an int, you'll never be
able to grow beyond Integer.MAX_VALUE (because no int value exists). I'd change
the contract to reflect this fact -- if the signature takes two parameters (int
currentSize, int expectedAdditions) then it's easy to throw an unchecked
exception if you simply can't meet the contract:
if (currentSize + expectedAdditions < 0)
throw new RuntimeException("Cannot allocate array larger than: " +
Integer.MAX_VALUE);
When reallocating, you can call it with grow(currentSize, 1), just to make sure
the array will be at least one element larger than previously; the method can
then make its best effort in estimating the growth ratio, but have a cap on
MAX_SIZE before overflowing into negative integers (and avoid looping endlessly
when Integer.MAX_VALUE is passed as an input argument).
These are just thoughts of course -- I've just finished implementing something
like this for another project...
> Small improvements to ArrayUtil.getNextSize
> -------------------------------------------
>
> Key: LUCENE-2213
> URL: https://issues.apache.org/jira/browse/LUCENE-2213
> Project: Lucene - Java
> Issue Type: Improvement
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Priority: Minor
> Fix For: 3.1
>
> Attachments: LUCENE-2213.patch, LUCENE-2213.patch
>
>
> Spinoff from java-dev thread "Dynamic array reallocation algorithms" started
> on Jan 12, 2010.
> Here's what I did:
> * Keep the +3 for small sizes
> * Added 2nd arg = number of bytes per element.
> * Round up to 4 or 8 byte boundary (if it's 32 or 64 bit JRE respectively)
> * Still grow by 1/8th
> * If 0 is passed in, return 0 back
> I also had to remove some asserts in tests that were checking the actual
> values returned by this method -- I don't think we should test that (it's an
> impl. detail).
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