liyafan82 commented on a change in pull request #8949: URL: https://github.com/apache/arrow/pull/8949#discussion_r589202945
########## File path: java/compression/src/main/java/org/apache/arrow/compression/Lz4CompressionCodec.java ########## @@ -0,0 +1,159 @@ +/* + * 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.arrow.compression; + +import java.io.ByteArrayInputStream; +import java.io.ByteArrayOutputStream; +import java.io.IOException; +import java.io.InputStream; +import java.io.OutputStream; + +import org.apache.arrow.flatbuf.CompressionType; +import org.apache.arrow.memory.ArrowBuf; +import org.apache.arrow.memory.BufferAllocator; +import org.apache.arrow.memory.util.MemoryUtil; +import org.apache.arrow.util.Preconditions; +import org.apache.arrow.vector.compression.CompressionCodec; +import org.apache.arrow.vector.compression.CompressionUtil; +import org.apache.commons.compress.compressors.lz4.FramedLZ4CompressorInputStream; +import org.apache.commons.compress.compressors.lz4.FramedLZ4CompressorOutputStream; +import org.apache.commons.compress.utils.IOUtils; + +import io.netty.util.internal.PlatformDependent; + +/** + * Compression codec for the LZ4 algorithm. + */ +public class Lz4CompressionCodec implements CompressionCodec { + + @Override + public ArrowBuf compress(BufferAllocator allocator, ArrowBuf uncompressedBuffer) { + Preconditions.checkArgument(uncompressedBuffer.writerIndex() <= Integer.MAX_VALUE, + "The uncompressed buffer size exceeds the integer limit"); + + if (uncompressedBuffer.writerIndex() == 0L) { + // shortcut for empty buffer + ArrowBuf compressedBuffer = allocator.buffer(CompressionUtil.SIZE_OF_UNCOMPRESSED_LENGTH); + compressedBuffer.setLong(0, 0); + compressedBuffer.writerIndex(CompressionUtil.SIZE_OF_UNCOMPRESSED_LENGTH); + uncompressedBuffer.close(); + return compressedBuffer; + } + + try { + ArrowBuf compressedBuffer = doCompress(allocator, uncompressedBuffer); + long compressedLength = compressedBuffer.writerIndex() - CompressionUtil.SIZE_OF_UNCOMPRESSED_LENGTH; + if (compressedLength > uncompressedBuffer.writerIndex()) { + // compressed buffer is larger, send the raw buffer + compressedBuffer.close(); + compressedBuffer = CompressionUtil.compressRawBuffer(allocator, uncompressedBuffer); + } + + uncompressedBuffer.close(); + return compressedBuffer; + } catch (IOException e) { + throw new RuntimeException(e); + } + } + + private ArrowBuf doCompress(BufferAllocator allocator, ArrowBuf uncompressedBuffer) throws IOException { + byte[] inBytes = new byte[(int) uncompressedBuffer.writerIndex()]; Review comment: Sure. I have opened ARROW-11901 to track it. I also want to share some thoughts briefly: to use the native memory directly, we need a way to wrap `ByteBuffers` as input/output streams (In Java, the only "standard" way to access the off-heap memory is through the `DirectByteBuffer`). We need some third party library to achieve that. We also need to evaluate the performance thereafter, because the Commons-compress library also uses on-heap data extensively, the copy between on-heap and off-heap data can be difficult to avoid. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: us...@infra.apache.org