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

Aleksey Shipilev aleksey.shipilev at oracle.com
Sat Jun 22 10:54:26 UTC 2013

On 06/22/2013 02:50 PM, Aleksey Shipilev wrote:

On 06/22/2013 08:06 AM, Dmitry Nadezhin wrote:

Alexey,

Each possible radix has its cacheLine in the cache. Cache contents looks like BigInteger[][] powerCache = new BigInteger[37] { /0/ null, /1/ null, /2/ new BigInteger[] { 2, 4, 16, 256, 32768, ... }, /3/ new BigInteger[] { 3, 9, 81, ... }, /4/ new BigInteger[] { 4, 16, 256, ... } /5/ new BigInteger[] { 5, 25, 625, ... }, /6/ new BigInteger[] { 6 }, /7/ new BigInteger[] { 7 }, . . . /36/ new BigInteger[] { 36 } }; Is there an idiom for a list/array of volatile references ? AtomicReferenceArray is your friend there. Although I'm not sure why you need the list of volatile references in this case. Placing volatile to the root reference resolves the race. I am not sure that such naive code works: volatile BigInteger[][] powerCache = .., Why wouldn't it work? volatile T[][] cache; T[] get(int index) { T[][] lc = cache; if (index >= lc.length) { // need resizing lc = generateNew(index << 1);_ _cache = lc;_ _}_ _return lc[index];_ _}_ _If you need to populate the 2nd level, then you have to have the final_ _volatile write to the cache.Thecorrespondingcache. The corresponding cache.Thecorrespondingcache volatile read makes the update on 2nd level visible. T get(int index1, index2) { T[][] lc = cache; if (index1 >= lc.length) { // needs resizing lc = generateNewT2(index1 << 1);_ _cache = lc;_ _}_ _T[] lt = lc[index2];_ _if (index2 >= lt.length) { // needs resizing lt = generateNewT1(index2 << 1); lc[index2] = lt; cache = lc; // publish } return lt[index2]; }

Of course, there is a series of typos. Should instead be:

T get(int index1, index2) { T[][] lc = cache; if (index1 >= lc.length) { // needs resizing lc = <generate_new_T[][]_of_size>((index1 << 1) + 1); cache = lc; } T[] lt = lc[index2]; if (index2 >= lt.length) { // needs resizing lt = <generate_new_T[]_of_size>((index2 << 1) + 1); lc[index1] = lt; cache = lc; // publish } return lt[index2]; }

-Aleksey.

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