/** * Creates a Bloom filter chunk of the given size. * * @param byteSizeHint the desired number of bytes for the Bloom filter bit * array. Will be increased so that folding is possible. * @param errorRate target false positive rate of the Bloom filter * @param hashType Bloom filter hash function type * @param foldFactor * @param bloomType * @return the new Bloom filter of the desired size */ public static BloomFilterChunk createBySize(int byteSizeHint, double errorRate, int hashType, int foldFactor, BloomType bloomType) { BloomFilterChunk bbf = new BloomFilterChunk(hashType, bloomType); bbf.byteSize = computeFoldableByteSize(byteSizeHint * 8L, foldFactor); long bitSize = bbf.byteSize * 8; bbf.maxKeys = (int) idealMaxKeys(bitSize, errorRate); bbf.hashCount = optimalFunctionCount(bbf.maxKeys, bitSize); // Adjust max keys to bring error rate closer to what was requested, // because byteSize was adjusted to allow for folding, and hashCount was // rounded. bbf.maxKeys = (int) computeMaxKeys(bitSize, errorRate, bbf.hashCount); return bbf; }