weijietong commented on a change in pull request #1334: DRILL-6385: Support JPPD feature URL: https://github.com/apache/drill/pull/1334#discussion_r206014664
########## File path: exec/java-exec/src/main/java/org/apache/drill/exec/work/filter/BloomFilter.java ########## @@ -0,0 +1,176 @@ +/* + * 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.drill.exec.work.filter; + +import io.netty.buffer.DrillBuf; +import java.util.Arrays; + + +/** + * According to Putze et al.'s "Cache-, Hash- and Space-Efficient BloomFilter + * Filters", the main theory is to construct tiny bucket bloom filters which + * benefit to the cpu cache and SIMD opcode. + */ + +public class BloomFilter { + // Bytes in a bucket. + private static final int BYTES_PER_BUCKET = 32; + // Minimum bloom filter data size. + private static final int MINIMUM_BLOOM_SIZE = 256; + + private static final int DEFAULT_MAXIMUM_BLOOM_FILTER_SIZE = 16 * 1024 * 1024; + + private DrillBuf byteBuf; + + private int numBytes; + + private int mask[] = new int[8]; + + private byte[] tempBucket = new byte[32]; Review comment: The `DrillBuf.getBytes(int index, byte[] dst)` will override the dst array's content. And we always invoke the getBytes method before usage the dst array. So there's no risk to use a polluted byte array. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
