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https://issues.apache.org/jira/browse/HADOOP-17825?focusedWorklogId=635474&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-635474
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ASF GitHub Bot logged work on HADOOP-17825:
-------------------------------------------
Author: ASF GitHub Bot
Created on: 06/Aug/21 20:18
Start Date: 06/Aug/21 20:18
Worklog Time Spent: 10m
Work Description: viirya commented on a change in pull request #3250:
URL: https://github.com/apache/hadoop/pull/3250#discussion_r684483080
##########
File path:
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/zlib/BuiltInGzipCompressor.java
##########
@@ -0,0 +1,251 @@
+/*
+ * 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.io.compress.zlib;
+
+import java.io.IOException;
+import java.util.zip.Checksum;
+import java.util.zip.Deflater;
+import java.util.zip.GZIPOutputStream;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.io.compress.Compressor;
+import org.apache.hadoop.io.compress.DoNotPool;
+import org.apache.hadoop.util.DataChecksum;
+
+/**
+ * A {@link Compressor} based on the popular gzip compressed file format.
+ * http://www.gzip.org/
+ */
+@DoNotPool
+public class BuiltInGzipCompressor implements Compressor {
+
+ /**
+ * Fixed ten-byte gzip header. See {@link GZIPOutputStream}'s source for
+ * details.
+ */
+ private static final byte[] GZIP_HEADER = new byte[]{
+ 0x1f, (byte) 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
+
+ // The trailer will be overwritten based on crc and output size.
+ private static final byte[] GZIP_TRAILER = new byte[]{0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00};
+
+ private static final int GZIP_HEADER_LEN = GZIP_HEADER.length;
+ private static final int GZIP_TRAILER_LEN = GZIP_TRAILER.length;
+
+ private Deflater deflater;
+
+ private int headerOff = 0;
+ private int trailerOff = 0;
+
+ private int numExtraBytesWritten = 0;
+
+ private int currentBufLen = 0;
+
+ private final Checksum crc = DataChecksum.newCrc32();
+
+ private BuiltInGzipDecompressor.GzipStateLabel state;
+
+ public BuiltInGzipCompressor(Configuration conf) { init(conf); }
+
+ @Override
+ public boolean finished() {
+ // Only if the trailer is also written, it is thought as finished.
+ return deflater.finished() && state ==
BuiltInGzipDecompressor.GzipStateLabel.FINISHED;
+ }
+
+ @Override
+ public boolean needsInput() {
+ if (state == BuiltInGzipDecompressor.GzipStateLabel.INFLATE_STREAM) {
+ return deflater.needsInput();
+ }
+
+ return false;
+ }
+
+ @Override
+ public int compress(byte[] b, int off, int len) throws IOException {
+ int compressedBytesWritten = 0;
+
+ if (currentBufLen <= 0) {
+ return compressedBytesWritten;
+ }
+
+ // If we are not within uncompressed data yet, output the header.
+ if (state != BuiltInGzipDecompressor.GzipStateLabel.INFLATE_STREAM &&
+ state != BuiltInGzipDecompressor.GzipStateLabel.TRAILER_CRC) {
+ int outputHeaderSize = writeHeader(b, off, len);
+ numExtraBytesWritten += outputHeaderSize;
+
+ compressedBytesWritten += outputHeaderSize;
+
+ if (outputHeaderSize == len) {
+ return compressedBytesWritten;
+ }
+
+ off += outputHeaderSize;
+ len -= outputHeaderSize;
+ }
+
+ if (state == BuiltInGzipDecompressor.GzipStateLabel.INFLATE_STREAM) {
+ // now compress it into b[]
+ int deflated = deflater.deflate(b, off, len);
+
+ compressedBytesWritten += deflated;
+ off += deflated;
+ len -= deflated;
+
+ // All current input are processed. Going to output trailer.
+ if (deflater.finished()) {
+ state = BuiltInGzipDecompressor.GzipStateLabel.TRAILER_CRC;
+ fillTrailer();
+ } else {
+ return compressedBytesWritten;
+ }
+ }
+
+ int outputTrailerSize = writeTrailer(b, off, len);
+ numExtraBytesWritten += outputTrailerSize;
+
+ compressedBytesWritten += outputTrailerSize;
+
+ return compressedBytesWritten;
+ }
+
+ @Override
+ public long getBytesRead() {
+ return deflater.getTotalIn();
+ }
+
+ @Override
+ public long getBytesWritten() {
+ return numExtraBytesWritten + deflater.getTotalOut();
+ }
+
+ @Override
+ public void end() {
+ deflater.end();
+ }
+
+ @Override
+ public void finish() {
+ deflater.finish();
+ }
+
+ private void init(Configuration conf) {
+ ZlibCompressor.CompressionLevel level =
ZlibFactory.getCompressionLevel(conf);
+ ZlibCompressor.CompressionStrategy strategy =
ZlibFactory.getCompressionStrategy(conf);
+
+ // 'true' (nowrap) => Deflater will handle raw deflate stream only
+ deflater = new Deflater(level.compressionLevel(), true);
+ deflater.setStrategy(strategy.compressionStrategy());
+
+ state = BuiltInGzipDecompressor.GzipStateLabel.HEADER_BASIC;
+ }
+
+ @Override
+ public void reinit(Configuration conf) {
+ init(conf);
+ crc.reset();
+ numExtraBytesWritten = 0;
+ currentBufLen = 0;
+ headerOff = trailerOff = 0;
+ }
+
+ @Override
+ public void reset() {
+ deflater.reset();
+ state = BuiltInGzipDecompressor.GzipStateLabel.HEADER_BASIC;
+ crc.reset();
+ numExtraBytesWritten = 0;
+ currentBufLen = 0;
+ headerOff = trailerOff = 0;
+ }
+
+ @Override
+ public void setDictionary(byte[] b, int off, int len) {
+ deflater.setDictionary(b, off, len);
+ }
+
+ @Override
+ public void setInput(byte[] b, int off, int len) {
+ if (b == null) {
+ throw new NullPointerException();
+ }
+ if (off < 0 || len < 0 || off > b.length - len) {
+ throw new ArrayIndexOutOfBoundsException();
+ }
+
+ deflater.reset();
+ crc.reset();
+
+ deflater.setInput(b, off, len);
+ crc.update(b, off, len); // CRC-32 is on uncompressed data
+ currentBufLen = len;
+ }
+
+ private int writeHeader(byte[] b, int off, int len) {
+ if (len <= 0) {
+ return 0;
+ }
+
+ int n = Math.min(len, GZIP_HEADER_LEN - headerOff);
+ System.arraycopy(GZIP_HEADER, headerOff, b, off, n);
+ headerOff += n;
+
+ // Completes header output.
+ if (headerOff == GZIP_HEADER_LEN) {
+ state = BuiltInGzipDecompressor.GzipStateLabel.INFLATE_STREAM;
+ }
+
+ return n;
+ }
+
+ private void fillTrailer() {
+ if (state == BuiltInGzipDecompressor.GzipStateLabel.TRAILER_CRC) {
+ int streamCrc = (int) crc.getValue();
+ GZIP_TRAILER[0] = (byte) (streamCrc & 0x000000ff);
+ GZIP_TRAILER[1] = (byte) ((streamCrc & 0x0000ff00) >> 8);
+ GZIP_TRAILER[2] = (byte) ((streamCrc & 0x00ff0000) >> 16);
+ GZIP_TRAILER[3] = (byte) ((streamCrc & 0xff000000) >> 24);
+
+ GZIP_TRAILER[4] = (byte) (currentBufLen & 0x000000ff);
Review comment:
Because we don't know when the caller will end the compressed output, so
every input (coming from `setInput`), we write out a trailer and so the size
here is just for the input for current run.
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Issue Time Tracking
-------------------
Worklog Id: (was: 635474)
Time Spent: 15h 40m (was: 15.5h)
> Add BuiltInGzipCompressor
> -------------------------
>
> Key: HADOOP-17825
> URL: https://issues.apache.org/jira/browse/HADOOP-17825
> Project: Hadoop Common
> Issue Type: Improvement
> Reporter: L. C. Hsieh
> Priority: Major
> Labels: pull-request-available
> Time Spent: 15h 40m
> Remaining Estimate: 0h
>
> Currently, GzipCodec only supports BuiltInGzipDecompressor, if native zlib is
> not loaded. So, without Hadoop native codec installed, saving SequenceFile
> using GzipCodec will throw exception like "SequenceFile doesn't work with
> GzipCodec without native-hadoop code!"
> Same as other codecs which we migrated to using prepared packages (lz4,
> snappy), it will be better if we support GzipCodec generally without Hadoop
> native codec installed. Similar to BuiltInGzipDecompressor, we can use Java
> Deflater to support BuiltInGzipCompressor.
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