RFR 8017540: Improve multi-threaded contention behavior of BigInteger.toString() radix conversion cache

[Brian Burkhalter]

So do we have consensus on this version?

Thanks for the lively "conversation."

Brian

On Jun 26, 2013, at 12:05 AM, Aleksey Shipilev wrote:

> Yes, like that.
> 
> -Aleksey
> 
> On 26.06.2013, at 10:53, Dmitry Nadezhin <dmitry.nadezhin at gmail.com> wrote:
> 
>>> We could check for the existing cacheLine.length right before installing
>> the new one
>> 
>> Do you mean something like this ?
>> 
>> BigInteger getRadixConversionCache(int radix, int exponent) {
>> BigInteger[] cacheLine = powerCache[radix]; // volatile read
>> if (exponent < cacheLine.length)
>>    return cacheLine[exponent];
>> 
>> int oldLength = cacheLine.length;
>> cacheLine = Arrays.copyOf(cacheLine, exponent + 1);
>> for (int i = oldLength; i < exponent + 1; i++)
>>    cacheLine[i] = cacheLine[i - 1].square();
>> 
>> if (exponent >= powerCache[radix].length) { // volatile read again
>>   BigInteger[][] pc = Arrays.copyOf(powerCache);
>>   pc[radix] = cacheLine;
>>   powerCache = pc; // volatile write, publish
>> }
>> return cacheLine[exponent];
>> }