RFR 4641897: Faster string conversion of large integers (original) (raw)

Aleksey Shipilev aleksey.shipilev at oracle.com
Tue Jun 25 18:45:43 UTC 2013

On 06/25/2013 10:13 PM, Peter Levart wrote:

On 06/22/2013 12:54 PM, Aleksey Shipilev wrote: T get(int index1, index2) { T[][] lc = cache; if (index1 >= lc.length) { // needs resizing lc = <generatenewT[][]ofsize>((index1 << 1) + 1);_ _cache = lc;_ _}_ _T[] lt = lc[*index2*];_ _if (index2 >= lt.length) { // needs resizing lt = <generatenewT[]ofsize>((index2 << 1) + 1); lc[index1] = lt; cache = lc; // publish } return lt[index2]; }

-Aleksey. Hi Aleksey, 1st I think there's a typo in above bolded part. There should be index1 instead of index2 there, right?

Nope, lc is indexed with index2; lt is indexed with index1.

Then I think there's a data race in above code which can de-reference half-constructed array and an element within it:

Damn. Good point, let's discuss that in the appropriate RFR, see 8017540.

I have studied the constraints of powerCache and have observed:

So the caching could be performed with no synchronization (other than that provided by final fields descibed above).

Yeah, we can do that with finals. Too bad you can't have the final semantics with BigInteger[] array.

Here is a possible variant of such caching:

Seems overcomplicated. ;) Let's instead fix the code proposed in 8017540.

Thanks, Aleksey.

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