On Mon, 11 Mar 2024 20:41:25 GMT, Shaojin Wen <[email protected]> wrote:
>> The current BigDecimal(String) constructor calls String#toCharArray, which
>> has a memory allocation.
>>
>>
>> public BigDecimal(String val) {
>> this(val.toCharArray(), 0, val.length()); // allocate char[]
>> }
>>
>>
>> When the length is greater than 18, create a char[]
>>
>>
>> boolean isCompact = (len <= MAX_COMPACT_DIGITS); // 18
>> if (!isCompact) {
>> // ...
>> } else {
>> char[] coeff = new char[len]; // allocate char[]
>> // ...
>> }
>>
>>
>> This PR eliminates the two memory allocations mentioned above, resulting in
>> an approximate 60% increase in performance..
>
> Shaojin Wen has updated the pull request incrementally with one additional
> commit since the last revision:
>
> 1. bug fix for CharBuffer catch IndexOutOfBoundsException
> 2. reorder if statement
> 3. Improve the performance of !isCompact branch
src/java.base/share/classes/java/math/BigDecimal.java line 762:
> 760: }
> 761:
> 762: private BigDecimal(CharSequence val, MathContext mc) {
Can we move this constructor to before `parseExp`? This way there will be less
diff and it will be easier to compare old and new code side-by-side.
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PR Review Comment: https://git.openjdk.org/jdk/pull/18177#discussion_r1520792359
