[GitHub] [arrow] stczwd commented on a change in pull request #8949: ARROW-10880: [Java] Support compressing RecordBatch IPC buffers by LZ4

[GitBox <gi...@apache.org>]

stczwd commented on a change in pull request #8949:
URL: https://github.com/apache/arrow/pull/8949#discussion_r555746080



##########
File path: java/vector/src/main/java/org/apache/arrow/vector/compression/Lz4CompressionCodec.java
##########
@@ -0,0 +1,135 @@
+/*
+ * 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.vector.compression;
+
+import static org.apache.arrow.memory.util.MemoryUtil.LITTLE_ENDIAN;
+
+import java.nio.ByteBuffer;
+
+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 net.jpountz.lz4.LZ4Compressor;
+import net.jpountz.lz4.LZ4Factory;
+import net.jpountz.lz4.LZ4FastDecompressor;
+
+/**
+ * Compression codec for the LZ4 algorithm.
+ */
+public class Lz4CompressionCodec implements CompressionCodec {
+
+  private static final long SIZE_OF_MESSAGE_LENGTH = 8L;
+
+  private final LZ4Factory factory;
+
+  private LZ4Compressor compressor;
+
+  private LZ4FastDecompressor decompressor;
+
+  public Lz4CompressionCodec() {
+    factory = LZ4Factory.fastestInstance();
+  }
+
+  @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(SIZE_OF_MESSAGE_LENGTH);
+      compressedBuffer.setLong(0, 0);
+      compressedBuffer.writerIndex(SIZE_OF_MESSAGE_LENGTH);
+      uncompressedBuffer.close();
+      return compressedBuffer;
+    }
+
+    // create compressor lazily
+    if (compressor == null) {
+      compressor = factory.fastCompressor();
+    }
+
+    int maxCompressedLength = compressor.maxCompressedLength((int) uncompressedBuffer.writerIndex());
+
+    // first 8 bytes reserved for uncompressed length, to be consistent with the
+    // C++ implementation.
+    ArrowBuf compressedBuffer = allocator.buffer(maxCompressedLength + SIZE_OF_MESSAGE_LENGTH);
+    long uncompressedLength = uncompressedBuffer.writerIndex();
+    if (!LITTLE_ENDIAN) {
+      uncompressedLength = Long.reverseBytes(uncompressedLength);
+    }
+    compressedBuffer.setLong(0, uncompressedLength);
+
+    ByteBuffer uncompressed =
+        MemoryUtil.directBuffer(uncompressedBuffer.memoryAddress(), (int) uncompressedBuffer.writerIndex());
+    ByteBuffer compressed =
+        MemoryUtil.directBuffer(compressedBuffer.memoryAddress() + SIZE_OF_MESSAGE_LENGTH, maxCompressedLength);
+
+    int compressedLength = compressor.compress(
+        uncompressed, 0, (int) uncompressedBuffer.writerIndex(), compressed, 0, maxCompressedLength);
+    compressedBuffer.writerIndex(compressedLength + SIZE_OF_MESSAGE_LENGTH);
+
+    uncompressedBuffer.close();
+    return compressedBuffer;
+  }
+
+  @Override
+  public ArrowBuf decompress(BufferAllocator allocator, ArrowBuf compressedBuffer) {
+    Preconditions.checkArgument(compressedBuffer.writerIndex() <= Integer.MAX_VALUE,
+        "The compressed buffer size exceeds the integer limit");
+
+    Preconditions.checkArgument(compressedBuffer.writerIndex() >= SIZE_OF_MESSAGE_LENGTH,
+        "Not enough data to decompress.");
+
+    long decompressedLength = compressedBuffer.getLong(0);
+    if (!LITTLE_ENDIAN) {
+      decompressedLength = Long.reverseBytes(decompressedLength);
+    }
+
+    if (decompressedLength == 0L) {
+      // shortcut for empty buffer
+      compressedBuffer.close();
+      return allocator.getEmpty();
+    }
+
+    // create decompressor lazily
+    if (decompressor == null) {
+      decompressor = factory.fastDecompressor();
+    }
+
+    ByteBuffer compressed = MemoryUtil.directBuffer(
+        compressedBuffer.memoryAddress() + SIZE_OF_MESSAGE_LENGTH, (int) compressedBuffer.writerIndex());

Review comment:
       the capacity may be `(int) (compressedBuffer.writerIndex() - SIZE_OF_MESSAGE_LENGTH)`?




----------------------------------------------------------------
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:
users@infra.apache.org