wchevreuil commented on code in PR #4675: URL: https://github.com/apache/hbase/pull/4675#discussion_r945204803
########## hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/PreviousBlockCompressionRatePredicator.java: ########## @@ -0,0 +1,63 @@ +/* + * 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.hadoop.hbase.io.hfile; + +import org.apache.hadoop.hbase.io.ByteArrayOutputStream; +import org.apache.hadoop.hbase.io.encoding.EncodedDataBlock; +import org.apache.yetus.audience.InterfaceAudience; + +import java.io.IOException; + +/** + * This BlockCompressedSizePredicator implementation adjusts the block size limit based on the + * compression rate of the block contents read so far. For the first block, adjusted size would be + * zero, so it performs a compression of current block contents and calculate compression rate and + * adjusted size. For subsequent blocks, it only performs this calculation once the previous block + * adjusted size has been reached, and the block is about to be closed. + */ +@InterfaceAudience.Private +public class PreviousBlockCompressionRatePredicator implements BlockCompressedSizePredicator { + + int adjustedBlockSize; + + /** + * Calculates an adjusted block size limit based on the compression rate of current block + * contents. This calculation is only performed if this is the first block, otherwise, if the + * adjusted size from previous block has been reached by the current one. + * @param context the meta file information for the current file. + * @param uncompressedBlockSize the total uncompressed size read for the block so far. + * @param contents The byte array containing the block content so far. + * @return the adjusted block size limit based on block compression rate. + * @throws IOException + */ + @Override + public int calculateCompressionSizeLimit(HFileContext context, int uncompressedBlockSize, + ByteArrayOutputStream contents) throws IOException { + // In order to avoid excessive compression size calculations, we do it only once when + // the uncompressed size has reached BLOCKSIZE. We then use this compression size to + // calculate the compression rate, and adjust the block size limit by this ratio. + if (adjustedBlockSize == 0 || uncompressedBlockSize >= adjustedBlockSize) { + int compressedSize = EncodedDataBlock.getCompressedSize(context.getCompression(), + context.getCompression().getCompressor(), contents.getBuffer(), 0, + contents.size()); + adjustedBlockSize = uncompressedBlockSize / compressedSize; + adjustedBlockSize *= context.getBlocksize(); Review Comment: Had pushed a new commit with this approach. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@hbase.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
