[Mono-list] Hashtable bucket growth

[Jeffrey Stedfast]

Since the table is so easily created, I wonder if it wouldn't be best to
just generate it on the fly.

Then again, it's not that large so having a static table isn't gonna
bloat it too much I guess.

Jeff

On 14 Jul 2001 15:13:49 -0600, John Barnette wrote:
> Hey kids,
> 
> This is what I'm currently using to generate the new available bucket count
> during a rehash.  Any comments?
> 
> 
> ~ j.
> 
> --- CUT CUT CUT ---
> 
> // Max entries in a Hashtable == Int32.MaxValue == 2,147,483,647
> private static int[] PRIMES = {
> 	2, 5, 11, 23, 47, 97, 197, 397, 797, 1597, 3203, 6421, 12853,
> 	25717, 51437, 102877, 205759, 411527, 823117, 1646237, 3292489,
> 	6584983, 13169977, 26339969, 52679969, 105359939, 210719881,
> 	421439783, 842879579, 1685759167 };
> private static int NUMBER_OF_PRIMES = 30;
> 
> 
> private int GetNewBucketSize(int oldBucketSize) {
> 	int target = oldBucketSize * 2;
> 	int first = 0, last = NUMBER_OF_PRIMES - 1;
> 
> 	while (first < last) {
> 		int mid = (first + last) / 2;
> 		if      (target < PRIMES[mid]) last = mid;
> 		else if (target > PRIMES[mid]) first = mid + 1;
> 		else {
> 			// can't happen
> 			throw new Exception("Can't happen in prime search");
> 		}
> 	}
> 
> 	return PRIMES[last];
> }
> 
> 
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