jun0315 commented on code in PR #8619: URL: https://github.com/apache/iotdb/pull/8619#discussion_r1059437174
########## schema-engine-tag/src/main/java/org/apache/iotdb/lsm/util/BloomFilter.java: ########## @@ -0,0 +1,238 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ +package org.apache.iotdb.lsm.util; + +import org.apache.iotdb.lsm.sstable.bplustree.entry.IEntry; +import org.apache.iotdb.tsfile.common.conf.TSFileConfig; +import org.apache.iotdb.tsfile.utils.Murmur128Hash; +import org.apache.iotdb.tsfile.utils.ReadWriteForEncodingUtils; +import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils; + +import java.io.DataInputStream; +import java.io.DataOutputStream; +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.Arrays; +import java.util.BitSet; +import java.util.Objects; + +public class BloomFilter implements IEntry { + + private static final int MINIMAL_SIZE = 256; + private static final int MAXIMAL_HASH_FUNCTION_SIZE = 8; + private static final int[] SEEDS = new int[] {5, 7, 11, 19, 31, 37, 43, 59}; + private int size; + private int hashFunctionSize; + private BitSet bits; + private HashFunction[] func; + + // do not try to initialize the filter by construction method + public BloomFilter() {} + + // do not try to initialize the filter by construction method + private BloomFilter(byte[] bytes, int size, int hashFunctionSize) { + this.size = size; + this.hashFunctionSize = hashFunctionSize; + func = new HashFunction[hashFunctionSize]; + for (int i = 0; i < hashFunctionSize; i++) { + func[i] = new HashFunction(size, SEEDS[i]); + } + + bits = BitSet.valueOf(bytes); + } + + private BloomFilter(int size, int hashFunctionSize) { + this.size = size; + this.hashFunctionSize = hashFunctionSize; + func = new HashFunction[hashFunctionSize]; + for (int i = 0; i < hashFunctionSize; i++) { + func[i] = new HashFunction(size, SEEDS[i]); + } + + bits = new BitSet(size); + } + + /** + * get empty bloom filter + * + * @param errorPercent the tolerant percent of error of the bloom filter + * @param numOfString the number of string want to store in the bloom filter + * @return empty bloom + */ + public static BloomFilter getEmptyBloomFilter(double errorPercent, int numOfString) { + errorPercent = Math.max(errorPercent, TSFileConfig.MIN_BLOOM_FILTER_ERROR_RATE); + errorPercent = Math.min(errorPercent, TSFileConfig.MAX_BLOOM_FILTER_ERROR_RATE); + + double ln2 = Math.log(2); + int size = (int) (-numOfString * Math.log(errorPercent) / ln2 / ln2) + 1; + int hashFunctionSize = (int) (-Math.log(errorPercent) / ln2) + 1; + return new BloomFilter( + Math.max(MINIMAL_SIZE, size), Math.min(MAXIMAL_HASH_FUNCTION_SIZE, hashFunctionSize)); + } + + /** + * build bloom filter by bytes + * + * @param bytes bytes of bits + * @return bloom filter + */ + public static BloomFilter buildBloomFilter(byte[] bytes, int size, int hashFunctionSize) { + return new BloomFilter(bytes, size, Math.min(MAXIMAL_HASH_FUNCTION_SIZE, hashFunctionSize)); + } + + public int getHashFunctionSize() { + return hashFunctionSize; + } + + public int getSize() { + return size; + } + + public void setSize(int size) { + this.size = size; + } + + public void add(String value) { + for (HashFunction f : func) { + bits.set(f.hash(value), true); + } + } + + public boolean contains(String value) { + if (value == null) { + return false; + } + boolean ret = true; + int index = 0; + while (ret && index < hashFunctionSize) { + ret = bits.get(func[index++].hash(value)); + } + + return ret; + } + + public int getBitCount() { + int res = 0; + for (int i = 0; i < size; i++) { + res += bits.get(i) ? 1 : 0; + } + + return res; + } + + @Override + public boolean equals(Object o) { + if (this == o) { + return true; + } + if (o == null || getClass() != o.getClass()) { + return false; + } + BloomFilter that = (BloomFilter) o; + return size == that.size + && hashFunctionSize == that.hashFunctionSize + && Objects.equals(bits, that.bits) + && Arrays.equals(func, that.func); + } + + @Override + public int hashCode() { + return Objects.hash(size, hashFunctionSize, bits, func); + } + + private class HashFunction { + + private int cap; + private int seed; + + HashFunction(int cap, int seed) { + this.cap = cap; + this.seed = seed; + } + + public int hash(String value) { + int res = Murmur128Hash.hash(value, seed); + if (res == Integer.MIN_VALUE) { + res = 0; + } + + return Math.abs(res) % cap; + } Review Comment: done -- This is an automated message from the Apache Git Service. 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