HADOOP-7657. Add support for LZ4 compression. Contributed by Binglin Chang.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1220312 13f79535-47bb-0310-9956-ffa450edef68

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -9,6 +9,8 @@ Release 0.23.1 - Unreleased
     HADOOP-7777 Implement a base class for DNSToSwitchMapping implementations 
     that can offer extra topology information. (stevel)
 
+    HADOOP-7657. Add support for LZ4 compression. (Binglin Chang via todd)
+
   IMPROVEMENTS
 
     HADOOP-7801. HADOOP_PREFIX cannot be overriden. (Bruno Mahé via tomwhite)

hadoop-common-project/hadoop-common/LICENSE.txt

@@ -251,3 +251,34 @@ in src/main/native/src/org/apache/hadoop/util:
  *   All rights reserved. Use of this source code is governed by a
  *   BSD-style license that can be found in the LICENSE file.
  */
+
+ For src/main/native/src/org/apache/hadoop/io/compress/lz4/lz4.c:
+
+/*
+   LZ4 - Fast LZ compression algorithm
+   Copyright (C) 2011, Yann Collet.
+   BSD License
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+  
+       * Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+   copyright notice, this list of conditions and the following disclaimer
+   in the documentation and/or other materials provided with the
+   distribution.
+  
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/

hadoop-common-project/hadoop-common/pom.xml

@@ -542,6 +542,8 @@
                     <javahClassName>org.apache.hadoop.security.JniBasedUnixGroupsNetgroupMapping</javahClassName>
                     <javahClassName>org.apache.hadoop.io.compress.snappy.SnappyCompressor</javahClassName>
                     <javahClassName>org.apache.hadoop.io.compress.snappy.SnappyDecompressor</javahClassName>
+                    <javahClassName>org.apache.hadoop.io.compress.lz4.Lz4Compressor</javahClassName>
+                    <javahClassName>org.apache.hadoop.io.compress.lz4.Lz4Decompressor</javahClassName>
                     <javahClassName>org.apache.hadoop.util.NativeCrc32</javahClassName>
                   </javahClassNames>
                   <javahOutputDirectory>${project.build.directory}/native/javah</javahOutputDirectory>

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/CommonConfigurationKeys.java

@@ -93,7 +93,15 @@ public class CommonConfigurationKeys extends CommonConfigurationKeysPublic {
   /** Default value for IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY */
   public static final int IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_DEFAULT =
       256 * 1024;
-  
+
+  /** Internal buffer size for Snappy compressor/decompressors */
+  public static final String IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY =
+      "io.compression.codec.lz4.buffersize";
+
+  /** Default value for IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY */
+  public static final int IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT =
+      256 * 1024;
+
   /**
    * Service Authorization
    */

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/Lz4Codec.java

@@ -0,0 +1,217 @@
+/*
+ * 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;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import org.apache.hadoop.conf.Configurable;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.io.compress.lz4.Lz4Compressor;
+import org.apache.hadoop.io.compress.lz4.Lz4Decompressor;
+import org.apache.hadoop.fs.CommonConfigurationKeys;
+import org.apache.hadoop.util.NativeCodeLoader;
+
+/**
+ * This class creates lz4 compressors/decompressors.
+ */
+public class Lz4Codec implements Configurable, CompressionCodec {
+
+  static {
+    NativeCodeLoader.isNativeCodeLoaded();
+  }
+
+  Configuration conf;
+
+  /**
+   * Set the configuration to be used by this object.
+   *
+   * @param conf the configuration object.
+   */
+  @Override
+  public void setConf(Configuration conf) {
+    this.conf = conf;
+  }
+
+  /**
+   * Return the configuration used by this object.
+   *
+   * @return the configuration object used by this objec.
+   */
+  @Override
+  public Configuration getConf() {
+    return conf;
+  }
+
+  /**
+   * Are the native lz4 libraries loaded & initialized?
+   *
+   * @return true if loaded & initialized, otherwise false
+   */
+  public static boolean isNativeCodeLoaded() {
+    return NativeCodeLoader.isNativeCodeLoaded();
+  }
+
+  /**
+   * Create a {@link CompressionOutputStream} that will write to the given
+   * {@link OutputStream}.
+   *
+   * @param out the location for the final output stream
+   * @return a stream the user can write uncompressed data to have it compressed
+   * @throws IOException
+   */
+  @Override
+  public CompressionOutputStream createOutputStream(OutputStream out)
+      throws IOException {
+    return createOutputStream(out, createCompressor());
+  }
+
+  /**
+   * Create a {@link CompressionOutputStream} that will write to the given
+   * {@link OutputStream} with the given {@link Compressor}.
+   *
+   * @param out        the location for the final output stream
+   * @param compressor compressor to use
+   * @return a stream the user can write uncompressed data to have it compressed
+   * @throws IOException
+   */
+  @Override
+  public CompressionOutputStream createOutputStream(OutputStream out,
+                                                    Compressor compressor)
+      throws IOException {
+    if (!isNativeCodeLoaded()) {
+      throw new RuntimeException("native lz4 library not available");
+    }
+    int bufferSize = conf.getInt(
+        CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY,
+        CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT);
+
+    int compressionOverhead = Math.max((int)(bufferSize * 0.01), 10);
+
+    return new BlockCompressorStream(out, compressor, bufferSize,
+        compressionOverhead);
+  }
+
+  /**
+   * Get the type of {@link Compressor} needed by this {@link CompressionCodec}.
+   *
+   * @return the type of compressor needed by this codec.
+   */
+  @Override
+  public Class<? extends Compressor> getCompressorType() {
+    if (!isNativeCodeLoaded()) {
+      throw new RuntimeException("native lz4 library not available");
+    }
+
+    return Lz4Compressor.class;
+  }
+
+  /**
+   * Create a new {@link Compressor} for use by this {@link CompressionCodec}.
+   *
+   * @return a new compressor for use by this codec
+   */
+  @Override
+  public Compressor createCompressor() {
+    if (!isNativeCodeLoaded()) {
+      throw new RuntimeException("native lz4 library not available");
+    }
+    int bufferSize = conf.getInt(
+        CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY,
+        CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT);
+    return new Lz4Compressor(bufferSize);
+  }
+
+  /**
+   * Create a {@link CompressionInputStream} that will read from the given
+   * input stream.
+   *
+   * @param in the stream to read compressed bytes from
+   * @return a stream to read uncompressed bytes from
+   * @throws IOException
+   */
+  @Override
+  public CompressionInputStream createInputStream(InputStream in)
+      throws IOException {
+    return createInputStream(in, createDecompressor());
+  }
+
+  /**
+   * Create a {@link CompressionInputStream} that will read from the given
+   * {@link InputStream} with the given {@link Decompressor}.
+   *
+   * @param in           the stream to read compressed bytes from
+   * @param decompressor decompressor to use
+   * @return a stream to read uncompressed bytes from
+   * @throws IOException
+   */
+  @Override
+  public CompressionInputStream createInputStream(InputStream in,
+                                                  Decompressor decompressor)
+      throws IOException {
+    if (!isNativeCodeLoaded()) {
+      throw new RuntimeException("native lz4 library not available");
+    }
+
+    return new BlockDecompressorStream(in, decompressor, conf.getInt(
+        CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY,
+        CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT));
+  }
+
+  /**
+   * Get the type of {@link Decompressor} needed by this {@link CompressionCodec}.
+   *
+   * @return the type of decompressor needed by this codec.
+   */
+  @Override
+  public Class<? extends Decompressor> getDecompressorType() {
+    if (!isNativeCodeLoaded()) {
+      throw new RuntimeException("native lz4 library not available");
+    }
+
+    return Lz4Decompressor.class;
+  }
+
+  /**
+   * Create a new {@link Decompressor} for use by this {@link CompressionCodec}.
+   *
+   * @return a new decompressor for use by this codec
+   */
+  @Override
+  public Decompressor createDecompressor() {
+    if (!isNativeCodeLoaded()) {
+      throw new RuntimeException("native lz4 library not available");
+    }
+    int bufferSize = conf.getInt(
+        CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY,
+        CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT);
+    return new Lz4Decompressor(bufferSize);
+  }
+
+  /**
+   * Get the default filename extension for this kind of compression.
+   *
+   * @return <code>.lz4</code>.
+   */
+  @Override
+  public String getDefaultExtension() {
+    return ".lz4";
+  }
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/lz4/Lz4Compressor.java

@@ -0,0 +1,299 @@
+/*
+ * 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.lz4;
+
+import java.io.IOException;
+import java.nio.Buffer;
+import java.nio.ByteBuffer;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.io.compress.Compressor;
+import org.apache.hadoop.util.NativeCodeLoader;
+
+/**
+ * A {@link Compressor} based on the lz4 compression algorithm.
+ * http://code.google.com/p/lz4/
+ */
+public class Lz4Compressor implements Compressor {
+  private static final Log LOG =
+      LogFactory.getLog(Lz4Compressor.class.getName());
+  private static final int DEFAULT_DIRECT_BUFFER_SIZE = 64 * 1024;
+
+  // HACK - Use this as a global lock in the JNI layer
+  @SuppressWarnings({"unchecked", "unused"})
+  private static Class clazz = Lz4Compressor.class;
+
+  private int directBufferSize;
+  private Buffer compressedDirectBuf = null;
+  private int uncompressedDirectBufLen;
+  private Buffer uncompressedDirectBuf = null;
+  private byte[] userBuf = null;
+  private int userBufOff = 0, userBufLen = 0;
+  private boolean finish, finished;
+
+  private long bytesRead = 0L;
+  private long bytesWritten = 0L;
+
+
+  static {
+    if (NativeCodeLoader.isNativeCodeLoaded()) {
+      // Initialize the native library
+      try {
+        initIDs();
+      } catch (Throwable t) {
+        // Ignore failure to load/initialize lz4
+        LOG.warn(t.toString());
+      }
+    } else {
+      LOG.error("Cannot load " + Lz4Compressor.class.getName() +
+          " without native hadoop library!");
+    }
+  }
+
+  /**
+   * Creates a new compressor.
+   *
+   * @param directBufferSize size of the direct buffer to be used.
+   */
+  public Lz4Compressor(int directBufferSize) {
+    this.directBufferSize = directBufferSize;
+
+    uncompressedDirectBuf = ByteBuffer.allocateDirect(directBufferSize);
+    compressedDirectBuf = ByteBuffer.allocateDirect(directBufferSize);
+    compressedDirectBuf.position(directBufferSize);
+  }
+
+  /**
+   * Creates a new compressor with the default buffer size.
+   */
+  public Lz4Compressor() {
+    this(DEFAULT_DIRECT_BUFFER_SIZE);
+  }
+
+  /**
+   * Sets input data for compression.
+   * This should be called whenever #needsInput() returns
+   * <code>true</code> indicating that more input data is required.
+   *
+   * @param b   Input data
+   * @param off Start offset
+   * @param len Length
+   */
+  @Override
+  public synchronized 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();
+    }
+    finished = false;
+
+    if (len > uncompressedDirectBuf.remaining()) {
+      // save data; now !needsInput
+      this.userBuf = b;
+      this.userBufOff = off;
+      this.userBufLen = len;
+    } else {
+      ((ByteBuffer) uncompressedDirectBuf).put(b, off, len);
+      uncompressedDirectBufLen = uncompressedDirectBuf.position();
+    }
+
+    bytesRead += len;
+  }
+
+  /**
+   * If a write would exceed the capacity of the direct buffers, it is set
+   * aside to be loaded by this function while the compressed data are
+   * consumed.
+   */
+  synchronized void setInputFromSavedData() {
+    if (0 >= userBufLen) {
+      return;
+    }
+    finished = false;
+
+    uncompressedDirectBufLen = Math.min(userBufLen, directBufferSize);
+    ((ByteBuffer) uncompressedDirectBuf).put(userBuf, userBufOff,
+        uncompressedDirectBufLen);
+
+    // Note how much data is being fed to lz4
+    userBufOff += uncompressedDirectBufLen;
+    userBufLen -= uncompressedDirectBufLen;
+  }
+
+  /**
+   * Does nothing.
+   */
+  @Override
+  public synchronized void setDictionary(byte[] b, int off, int len) {
+    // do nothing
+  }
+
+  /**
+   * Returns true if the input data buffer is empty and
+   * #setInput() should be called to provide more input.
+   *
+   * @return <code>true</code> if the input data buffer is empty and
+   *         #setInput() should be called in order to provide more input.
+   */
+  @Override
+  public synchronized boolean needsInput() {
+    return !(compressedDirectBuf.remaining() > 0
+        || uncompressedDirectBuf.remaining() == 0 || userBufLen > 0);
+  }
+
+  /**
+   * When called, indicates that compression should end
+   * with the current contents of the input buffer.
+   */
+  @Override
+  public synchronized void finish() {
+    finish = true;
+  }
+
+  /**
+   * Returns true if the end of the compressed
+   * data output stream has been reached.
+   *
+   * @return <code>true</code> if the end of the compressed
+   *         data output stream has been reached.
+   */
+  @Override
+  public synchronized boolean finished() {
+    // Check if all uncompressed data has been consumed
+    return (finish && finished && compressedDirectBuf.remaining() == 0);
+  }
+
+  /**
+   * Fills specified buffer with compressed data. Returns actual number
+   * of bytes of compressed data. A return value of 0 indicates that
+   * needsInput() should be called in order to determine if more input
+   * data is required.
+   *
+   * @param b   Buffer for the compressed data
+   * @param off Start offset of the data
+   * @param len Size of the buffer
+   * @return The actual number of bytes of compressed data.
+   */
+  @Override
+  public synchronized int compress(byte[] b, int off, int len)
+      throws IOException {
+    if (b == null) {
+      throw new NullPointerException();
+    }
+    if (off < 0 || len < 0 || off > b.length - len) {
+      throw new ArrayIndexOutOfBoundsException();
+    }
+
+    // Check if there is compressed data
+    int n = compressedDirectBuf.remaining();
+    if (n > 0) {
+      n = Math.min(n, len);
+      ((ByteBuffer) compressedDirectBuf).get(b, off, n);
+      bytesWritten += n;
+      return n;
+    }
+
+    // Re-initialize the lz4's output direct-buffer
+    compressedDirectBuf.clear();
+    compressedDirectBuf.limit(0);
+    if (0 == uncompressedDirectBuf.position()) {
+      // No compressed data, so we should have !needsInput or !finished
+      setInputFromSavedData();
+      if (0 == uncompressedDirectBuf.position()) {
+        // Called without data; write nothing
+        finished = true;
+        return 0;
+      }
+    }
+
+    // Compress data
+    n = compressBytesDirect();
+    compressedDirectBuf.limit(n);
+    uncompressedDirectBuf.clear(); // lz4 consumes all buffer input
+
+    // Set 'finished' if snapy has consumed all user-data
+    if (0 == userBufLen) {
+      finished = true;
+    }
+
+    // Get atmost 'len' bytes
+    n = Math.min(n, len);
+    bytesWritten += n;
+    ((ByteBuffer) compressedDirectBuf).get(b, off, n);
+
+    return n;
+  }
+
+  /**
+   * Resets compressor so that a new set of input data can be processed.
+   */
+  @Override
+  public synchronized void reset() {
+    finish = false;
+    finished = false;
+    uncompressedDirectBuf.clear();
+    uncompressedDirectBufLen = 0;
+    compressedDirectBuf.clear();
+    compressedDirectBuf.limit(0);
+    userBufOff = userBufLen = 0;
+    bytesRead = bytesWritten = 0L;
+  }
+
+  /**
+   * Prepare the compressor to be used in a new stream with settings defined in
+   * the given Configuration
+   *
+   * @param conf Configuration from which new setting are fetched
+   */
+  @Override
+  public synchronized void reinit(Configuration conf) {
+    reset();
+  }
+
+  /**
+   * Return number of bytes given to this compressor since last reset.
+   */
+  @Override
+  public synchronized long getBytesRead() {
+    return bytesRead;
+  }
+
+  /**
+   * Return number of bytes consumed by callers of compress since last reset.
+   */
+  @Override
+  public synchronized long getBytesWritten() {
+    return bytesWritten;
+  }
+
+  /**
+   * Closes the compressor and discards any unprocessed input.
+   */
+  @Override
+  public synchronized void end() {
+  }
+
+  private native static void initIDs();
+
+  private native int compressBytesDirect();
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/lz4/Lz4Decompressor.java

@@ -0,0 +1,281 @@
+/*
+ * 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.lz4;
+
+import java.io.IOException;
+import java.nio.Buffer;
+import java.nio.ByteBuffer;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.io.compress.Decompressor;
+import org.apache.hadoop.util.NativeCodeLoader;
+
+/**
+ * A {@link Decompressor} based on the lz4 compression algorithm.
+ * http://code.google.com/p/lz4/
+ */
+public class Lz4Decompressor implements Decompressor {
+  private static final Log LOG =
+      LogFactory.getLog(Lz4Compressor.class.getName());
+  private static final int DEFAULT_DIRECT_BUFFER_SIZE = 64 * 1024;
+
+  // HACK - Use this as a global lock in the JNI layer
+  @SuppressWarnings({"unchecked", "unused"})
+  private static Class clazz = Lz4Decompressor.class;
+
+  private int directBufferSize;
+  private Buffer compressedDirectBuf = null;
+  private int compressedDirectBufLen;
+  private Buffer uncompressedDirectBuf = null;
+  private byte[] userBuf = null;
+  private int userBufOff = 0, userBufLen = 0;
+  private boolean finished;
+
+  static {
+    if (NativeCodeLoader.isNativeCodeLoaded()) {
+      // Initialize the native library
+      try {
+        initIDs();
+      } catch (Throwable t) {
+        // Ignore failure to load/initialize lz4
+        LOG.warn(t.toString());
+      }
+    } else {
+      LOG.error("Cannot load " + Lz4Compressor.class.getName() +
+          " without native hadoop library!");
+    }
+  }
+
+  /**
+   * Creates a new compressor.
+   *
+   * @param directBufferSize size of the direct buffer to be used.
+   */
+  public Lz4Decompressor(int directBufferSize) {
+    this.directBufferSize = directBufferSize;
+
+    compressedDirectBuf = ByteBuffer.allocateDirect(directBufferSize);
+    uncompressedDirectBuf = ByteBuffer.allocateDirect(directBufferSize);
+    uncompressedDirectBuf.position(directBufferSize);
+
+  }
+
+  /**
+   * Creates a new decompressor with the default buffer size.
+   */
+  public Lz4Decompressor() {
+    this(DEFAULT_DIRECT_BUFFER_SIZE);
+  }
+
+  /**
+   * Sets input data for decompression.
+   * This should be called if and only if {@link #needsInput()} returns
+   * <code>true</code> indicating that more input data is required.
+   * (Both native and non-native versions of various Decompressors require
+   * that the data passed in via <code>b[]</code> remain unmodified until
+   * the caller is explicitly notified--via {@link #needsInput()}--that the
+   * buffer may be safely modified.  With this requirement, an extra
+   * buffer-copy can be avoided.)
+   *
+   * @param b   Input data
+   * @param off Start offset
+   * @param len Length
+   */
+  @Override
+  public synchronized 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();
+    }
+
+    this.userBuf = b;
+    this.userBufOff = off;
+    this.userBufLen = len;
+
+    setInputFromSavedData();
+
+    // Reinitialize lz4's output direct-buffer
+    uncompressedDirectBuf.limit(directBufferSize);
+    uncompressedDirectBuf.position(directBufferSize);
+  }
+
+  /**
+   * If a write would exceed the capacity of the direct buffers, it is set
+   * aside to be loaded by this function while the compressed data are
+   * consumed.
+   */
+  synchronized void setInputFromSavedData() {
+    compressedDirectBufLen = Math.min(userBufLen, directBufferSize);
+
+    // Reinitialize lz4's input direct buffer
+    compressedDirectBuf.rewind();
+    ((ByteBuffer) compressedDirectBuf).put(userBuf, userBufOff,
+        compressedDirectBufLen);
+
+    // Note how much data is being fed to lz4
+    userBufOff += compressedDirectBufLen;
+    userBufLen -= compressedDirectBufLen;
+  }
+
+  /**
+   * Does nothing.
+   */
+  @Override
+  public synchronized void setDictionary(byte[] b, int off, int len) {
+    // do nothing
+  }
+
+  /**
+   * Returns true if the input data buffer is empty and
+   * {@link #setInput(byte[], int, int)} should be called to
+   * provide more input.
+   *
+   * @return <code>true</code> if the input data buffer is empty and
+   *         {@link #setInput(byte[], int, int)} should be called in
+   *         order to provide more input.
+   */
+  @Override
+  public synchronized boolean needsInput() {
+    // Consume remaining compressed data?
+    if (uncompressedDirectBuf.remaining() > 0) {
+      return false;
+    }
+
+    // Check if lz4 has consumed all input
+    if (compressedDirectBufLen <= 0) {
+      // Check if we have consumed all user-input
+      if (userBufLen <= 0) {
+        return true;
+      } else {
+        setInputFromSavedData();
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Returns <code>false</code>.
+   *
+   * @return <code>false</code>.
+   */
+  @Override
+  public synchronized boolean needsDictionary() {
+    return false;
+  }
+
+  /**
+   * Returns true if the end of the decompressed
+   * data output stream has been reached.
+   *
+   * @return <code>true</code> if the end of the decompressed
+   *         data output stream has been reached.
+   */
+  @Override
+  public synchronized boolean finished() {
+    return (finished && uncompressedDirectBuf.remaining() == 0);
+  }
+
+  /**
+   * Fills specified buffer with uncompressed data. Returns actual number
+   * of bytes of uncompressed data. A return value of 0 indicates that
+   * {@link #needsInput()} should be called in order to determine if more
+   * input data is required.
+   *
+   * @param b   Buffer for the compressed data
+   * @param off Start offset of the data
+   * @param len Size of the buffer
+   * @return The actual number of bytes of compressed data.
+   * @throws IOException
+   */
+  @Override
+  public synchronized int decompress(byte[] b, int off, int len)
+      throws IOException {
+    if (b == null) {
+      throw new NullPointerException();
+    }
+    if (off < 0 || len < 0 || off > b.length - len) {
+      throw new ArrayIndexOutOfBoundsException();
+    }
+
+    int n = 0;
+
+    // Check if there is uncompressed data
+    n = uncompressedDirectBuf.remaining();
+    if (n > 0) {
+      n = Math.min(n, len);
+      ((ByteBuffer) uncompressedDirectBuf).get(b, off, n);
+      return n;
+    }
+    if (compressedDirectBufLen > 0) {
+      // Re-initialize the lz4's output direct buffer
+      uncompressedDirectBuf.rewind();
+      uncompressedDirectBuf.limit(directBufferSize);
+
+      // Decompress data
+      n = decompressBytesDirect();
+      uncompressedDirectBuf.limit(n);
+
+      if (userBufLen <= 0) {
+        finished = true;
+      }
+
+      // Get atmost 'len' bytes
+      n = Math.min(n, len);
+      ((ByteBuffer) uncompressedDirectBuf).get(b, off, n);
+    }
+
+    return n;
+  }
+
+  /**
+   * Returns <code>0</code>.
+   *
+   * @return <code>0</code>.
+   */
+  @Override
+  public synchronized int getRemaining() {
+    // Never use this function in BlockDecompressorStream.
+    return 0;
+  }
+
+  public synchronized void reset() {
+    finished = false;
+    compressedDirectBufLen = 0;
+    uncompressedDirectBuf.limit(directBufferSize);
+    uncompressedDirectBuf.position(directBufferSize);
+    userBufOff = userBufLen = 0;
+  }
+
+  /**
+   * Resets decompressor and input and output buffers so that a new set of
+   * input data can be processed.
+   */
+  @Override
+  public synchronized void end() {
+    // do nothing
+  }
+
+  private native static void initIDs();
+
+  private native int decompressBytesDirect();
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/compress/lz4/package-info.java

@@ -0,0 +1,23 @@
+/*
+ * 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.
+ */
+@InterfaceAudience.Private
+@InterfaceStability.Unstable
+package org.apache.hadoop.io.compress.lz4;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+

hadoop-common-project/hadoop-common/src/main/native/Makefile.am

@@ -46,6 +46,9 @@ libhadoop_la_SOURCES = src/org/apache/hadoop/io/compress/zlib/ZlibCompressor.c \
                        src/org/apache/hadoop/io/compress/zlib/ZlibDecompressor.c \
                        src/org/apache/hadoop/io/compress/snappy/SnappyCompressor.c \
                        src/org/apache/hadoop/io/compress/snappy/SnappyDecompressor.c \
+                       src/org/apache/hadoop/io/compress/lz4/lz4.c \
+                       src/org/apache/hadoop/io/compress/lz4/Lz4Compressor.c \
+                       src/org/apache/hadoop/io/compress/lz4/Lz4Decompressor.c \
                        src/org/apache/hadoop/security/getGroup.c \
                        src/org/apache/hadoop/security/JniBasedUnixGroupsMapping.c \
                        src/org/apache/hadoop/security/JniBasedUnixGroupsNetgroupMapping.c \

hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/compress/lz4/Lz4Compressor.c

@@ -0,0 +1,101 @@
+/*
+ * 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.
+ */
+
+#if defined HAVE_CONFIG_H
+  #include <config.h>
+#endif
+
+#include "org_apache_hadoop.h"
+#include "org_apache_hadoop_io_compress_lz4_Lz4Compressor.h"
+
+//****************************
+// Simple Functions
+//****************************
+
+extern int LZ4_compress   (char* source, char* dest, int isize);
+
+/*
+LZ4_compress() :
+ return : the number of bytes in compressed buffer dest
+ note : destination buffer must be already allocated.
+  To avoid any problem, size it to handle worst cases situations (input data not compressible)
+  Worst case size is : "inputsize + 0.4%", with "0.4%" being at least 8 bytes.
+
+*/
+
+static jfieldID Lz4Compressor_clazz;
+static jfieldID Lz4Compressor_uncompressedDirectBuf;
+static jfieldID Lz4Compressor_uncompressedDirectBufLen;
+static jfieldID Lz4Compressor_compressedDirectBuf;
+static jfieldID Lz4Compressor_directBufferSize;
+
+
+JNIEXPORT void JNICALL Java_org_apache_hadoop_io_compress_lz4_Lz4Compressor_initIDs
+(JNIEnv *env, jclass clazz){
+
+  Lz4Compressor_clazz = (*env)->GetStaticFieldID(env, clazz, "clazz",
+                                                 "Ljava/lang/Class;");
+  Lz4Compressor_uncompressedDirectBuf = (*env)->GetFieldID(env, clazz,
+                                                           "uncompressedDirectBuf",
+                                                           "Ljava/nio/Buffer;");
+  Lz4Compressor_uncompressedDirectBufLen = (*env)->GetFieldID(env, clazz,
+                                                              "uncompressedDirectBufLen", "I");
+  Lz4Compressor_compressedDirectBuf = (*env)->GetFieldID(env, clazz,
+                                                         "compressedDirectBuf",
+                                                         "Ljava/nio/Buffer;");
+  Lz4Compressor_directBufferSize = (*env)->GetFieldID(env, clazz,
+                                                       "directBufferSize", "I");
+}
+
+JNIEXPORT jint JNICALL Java_org_apache_hadoop_io_compress_lz4_Lz4Compressor_compressBytesDirect
+(JNIEnv *env, jobject thisj){
+  // Get members of Lz4Compressor
+  jobject clazz = (*env)->GetStaticObjectField(env, thisj, Lz4Compressor_clazz);
+  jobject uncompressed_direct_buf = (*env)->GetObjectField(env, thisj, Lz4Compressor_uncompressedDirectBuf);
+  jint uncompressed_direct_buf_len = (*env)->GetIntField(env, thisj, Lz4Compressor_uncompressedDirectBufLen);
+  jobject compressed_direct_buf = (*env)->GetObjectField(env, thisj, Lz4Compressor_compressedDirectBuf);
+  jint compressed_direct_buf_len = (*env)->GetIntField(env, thisj, Lz4Compressor_directBufferSize);
+
+  // Get the input direct buffer
+  LOCK_CLASS(env, clazz, "Lz4Compressor");
+  const char* uncompressed_bytes = (const char*)(*env)->GetDirectBufferAddress(env, uncompressed_direct_buf);
+  UNLOCK_CLASS(env, clazz, "Lz4Compressor");
+
+  if (uncompressed_bytes == 0) {
+    return (jint)0;
+  }
+
+  // Get the output direct buffer
+  LOCK_CLASS(env, clazz, "Lz4Compressor");
+  char* compressed_bytes = (char *)(*env)->GetDirectBufferAddress(env, compressed_direct_buf);
+  UNLOCK_CLASS(env, clazz, "Lz4Compressor");
+
+  if (compressed_bytes == 0) {
+    return (jint)0;
+  }
+
+  compressed_direct_buf_len = LZ4_compress(uncompressed_bytes, compressed_bytes, uncompressed_direct_buf_len);
+  if (compressed_direct_buf_len < 0){
+    THROW(env, "Ljava/lang/InternalError", "LZ4_compress failed");
+  }
+
+  (*env)->SetIntField(env, thisj, Lz4Compressor_uncompressedDirectBufLen, 0);
+
+  return (jint)compressed_direct_buf_len;
+}
+

hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/compress/lz4/Lz4Decompressor.c

@@ -0,0 +1,97 @@
+/*
+ * 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.
+ */
+
+#if defined HAVE_CONFIG_H
+  #include <config.h>
+#endif
+
+#include "org_apache_hadoop.h"
+#include "org_apache_hadoop_io_compress_lz4_Lz4Decompressor.h"
+
+int LZ4_uncompress_unknownOutputSize (char* source, char* dest, int isize, int maxOutputSize);
+
+/*
+LZ4_uncompress_unknownOutputSize() :
+ isize  : is the input size, therefore the compressed size
+ maxOutputSize : is the size of the destination buffer (which must be already allocated)
+ return : the number of bytes decoded in the destination buffer (necessarily <= maxOutputSize)
+    If the source stream is malformed, the function will stop decoding and return a negative result, indicating the byte position of the faulty instruction
+    This version never writes beyond dest + maxOutputSize, and is therefore protected against malicious data packets
+ note   : This version is a bit slower than LZ4_uncompress
+*/
+
+
+static jfieldID Lz4Decompressor_clazz;
+static jfieldID Lz4Decompressor_compressedDirectBuf;
+static jfieldID Lz4Decompressor_compressedDirectBufLen;
+static jfieldID Lz4Decompressor_uncompressedDirectBuf;
+static jfieldID Lz4Decompressor_directBufferSize;
+
+JNIEXPORT void JNICALL Java_org_apache_hadoop_io_compress_lz4_Lz4Decompressor_initIDs
+(JNIEnv *env, jclass clazz){
+
+  Lz4Decompressor_clazz = (*env)->GetStaticFieldID(env, clazz, "clazz",
+                                                   "Ljava/lang/Class;");
+  Lz4Decompressor_compressedDirectBuf = (*env)->GetFieldID(env,clazz,
+                                                           "compressedDirectBuf",
+                                                           "Ljava/nio/Buffer;");
+  Lz4Decompressor_compressedDirectBufLen = (*env)->GetFieldID(env,clazz,
+                                                              "compressedDirectBufLen", "I");
+  Lz4Decompressor_uncompressedDirectBuf = (*env)->GetFieldID(env,clazz,
+                                                             "uncompressedDirectBuf",
+                                                             "Ljava/nio/Buffer;");
+  Lz4Decompressor_directBufferSize = (*env)->GetFieldID(env, clazz,
+                                                         "directBufferSize", "I");
+}
+
+JNIEXPORT jint JNICALL Java_org_apache_hadoop_io_compress_lz4_Lz4Decompressor_decompressBytesDirect
+(JNIEnv *env, jobject thisj){
+  // Get members of Lz4Decompressor
+  jobject clazz = (*env)->GetStaticObjectField(env,thisj, Lz4Decompressor_clazz);
+  jobject compressed_direct_buf = (*env)->GetObjectField(env,thisj, Lz4Decompressor_compressedDirectBuf);
+  jint compressed_direct_buf_len = (*env)->GetIntField(env,thisj, Lz4Decompressor_compressedDirectBufLen);
+  jobject uncompressed_direct_buf = (*env)->GetObjectField(env,thisj, Lz4Decompressor_uncompressedDirectBuf);
+  size_t uncompressed_direct_buf_len = (*env)->GetIntField(env, thisj, Lz4Decompressor_directBufferSize);
+
+  // Get the input direct buffer
+  LOCK_CLASS(env, clazz, "Lz4Decompressor");
+  const char* compressed_bytes = (const char*)(*env)->GetDirectBufferAddress(env, compressed_direct_buf);
+  UNLOCK_CLASS(env, clazz, "Lz4Decompressor");
+
+  if (compressed_bytes == 0) {
+    return (jint)0;
+  }
+
+  // Get the output direct buffer
+  LOCK_CLASS(env, clazz, "Lz4Decompressor");
+  char* uncompressed_bytes = (char *)(*env)->GetDirectBufferAddress(env, uncompressed_direct_buf);
+  UNLOCK_CLASS(env, clazz, "Lz4Decompressor");
+
+  if (uncompressed_bytes == 0) {
+    return (jint)0;
+  }
+
+  uncompressed_direct_buf_len = LZ4_uncompress_unknownOutputSize(compressed_bytes, uncompressed_bytes, compressed_direct_buf_len, uncompressed_direct_buf_len);
+  if (uncompressed_direct_buf_len < 0) {
+    THROW(env, "Ljava/lang/InternalError", "LZ4_uncompress_unknownOutputSize failed.");
+  }
+
+  (*env)->SetIntField(env, thisj, Lz4Decompressor_compressedDirectBufLen, 0);
+
+  return (jint)uncompressed_direct_buf_len;
+}

hadoop-common-project/hadoop-common/src/main/native/src/org/apache/hadoop/io/compress/lz4/lz4.c

@@ -0,0 +1,646 @@
+/*
+   LZ4 - Fast LZ compression algorithm
+   Copyright (C) 2011, Yann Collet.
+   BSD License
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+  
+       * Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+   copyright notice, this list of conditions and the following disclaimer
+   in the documentation and/or other materials provided with the
+   distribution.
+  
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+//**************************************
+//  Copy from:
+// URL: http://lz4.googlecode.com/svn/trunk/lz4.c
+// Repository Root: http://lz4.googlecode.com/svn
+// Repository UUID: 650e7d94-2a16-8b24-b05c-7c0b3f6821cd
+// Revision: 43
+// Node Kind: file
+// Last Changed Author: yann.collet.73@gmail.com
+// Last Changed Rev: 43
+// Last Changed Date: 2011-12-16 15:41:46 -0800 (Fri, 16 Dec 2011)
+// Sha1: 9db7b2c57698c528d79572e6bce2e7dc33fa5998
+//**************************************
+
+//**************************************
+// Compilation Directives
+//**************************************
+#if __STDC_VERSION__ >= 199901L
+  /* "restrict" is a known keyword */
+#else
+#define restrict  // Disable restrict
+#endif
+
+
+//**************************************
+// Includes
+//**************************************
+#include <stdlib.h>   // for malloc
+#include <string.h>   // for memset
+#include "lz4.h"
+
+
+//**************************************
+// Performance parameter               
+//**************************************
+// Increasing this value improves compression ratio
+// Lowering this value reduces memory usage
+// Lowering may also improve speed, typically on reaching cache size limits (L1 32KB for Intel, 64KB for AMD)
+// Memory usage formula for 32 bits systems : N->2^(N+2) Bytes (examples : 17 -> 512KB ; 12 -> 16KB)
+#define HASH_LOG 12
+
+
+//**************************************
+// Basic Types
+//**************************************
+#if defined(_MSC_VER)    // Visual Studio does not support 'stdint' natively
+#define BYTE	unsigned __int8
+#define U16		unsigned __int16
+#define U32		unsigned __int32
+#define S32		__int32
+#else
+#include <stdint.h>
+#define BYTE	uint8_t
+#define U16		uint16_t
+#define U32		uint32_t
+#define S32		int32_t
+#endif
+
+
+//**************************************
+// Constants
+//**************************************
+#define MINMATCH 4
+#define SKIPSTRENGTH 6
+#define STACKLIMIT 13
+#define HEAPMODE (HASH_LOG>STACKLIMIT)  // Defines if memory is allocated into the stack (local variable), or into the heap (malloc()).
+#define COPYTOKEN 4
+#define COPYLENGTH 8
+#define LASTLITERALS 5
+#define MFLIMIT (COPYLENGTH+MINMATCH)
+#define MINLENGTH (MFLIMIT+1)
+
+#define MAXD_LOG 16
+#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
+
+#define HASHTABLESIZE (1 << HASH_LOG)
+#define HASH_MASK (HASHTABLESIZE - 1)
+
+#define ML_BITS 4
+#define ML_MASK ((1U<<ML_BITS)-1)
+#define RUN_BITS (8-ML_BITS)
+#define RUN_MASK ((1U<<RUN_BITS)-1)
+
+
+//**************************************
+// Local structures
+//**************************************
+struct refTables
+{
+	const BYTE* hashTable[HASHTABLESIZE];
+};
+
+#ifdef __GNUC__
+#  define _PACKED __attribute__ ((packed))
+#else
+#  define _PACKED
+#endif
+
+typedef struct _U32_S
+{
+	U32 v;
+} _PACKED U32_S;
+
+typedef struct _U16_S
+{
+	U16 v;
+} _PACKED U16_S;
+
+#define A32(x) (((U32_S *)(x))->v)
+#define A16(x) (((U16_S *)(x))->v)
+
+
+//**************************************
+// Macros
+//**************************************
+#define LZ4_HASH_FUNCTION(i)	(((i) * 2654435761U) >> ((MINMATCH*8)-HASH_LOG))
+#define LZ4_HASH_VALUE(p)		LZ4_HASH_FUNCTION(A32(p))
+#define LZ4_COPYPACKET(s,d)		A32(d) = A32(s); d+=4; s+=4; A32(d) = A32(s); d+=4; s+=4;
+#define LZ4_WILDCOPY(s,d,e)		do { LZ4_COPYPACKET(s,d) } while (d<e);
+#define LZ4_BLINDCOPY(s,d,l)	{ BYTE* e=d+l; LZ4_WILDCOPY(s,d,e); d=e; }
+
+
+
+//****************************
+// Compression CODE
+//****************************
+
+int LZ4_compressCtx(void** ctx,
+				 char* source, 
+				 char* dest,
+				 int isize)
+{	
+#if HEAPMODE
+	struct refTables *srt = (struct refTables *) (*ctx);
+	const BYTE** HashTable;
+#else
+	const BYTE* HashTable[HASHTABLESIZE] = {0};
+#endif
+
+	const BYTE* ip = (BYTE*) source;       
+	const BYTE* anchor = ip;
+	const BYTE* const iend = ip + isize;
+	const BYTE* const mflimit = iend - MFLIMIT;
+#define matchlimit (iend - LASTLITERALS)
+
+	BYTE* op = (BYTE*) dest;
+	
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	const size_t DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
+#endif
+	int len, length;
+	const int skipStrength = SKIPSTRENGTH;
+	U32 forwardH;
+
+
+	// Init 
+	if (isize<MINLENGTH) goto _last_literals;
+#if HEAPMODE
+	if (*ctx == NULL) 
+	{
+		srt = (struct refTables *) malloc ( sizeof(struct refTables) );
+		*ctx = (void*) srt;
+	}
+	HashTable = srt->hashTable;
+	memset((void*)HashTable, 0, sizeof(srt->hashTable));
+#else
+	(void) ctx;
+#endif
+
+
+	// First Byte
+	HashTable[LZ4_HASH_VALUE(ip)] = ip;
+	ip++; forwardH = LZ4_HASH_VALUE(ip);
+	
+	// Main Loop
+    for ( ; ; ) 
+	{
+		int findMatchAttempts = (1U << skipStrength) + 3;
+		const BYTE* forwardIp = ip;
+		const BYTE* ref;
+		BYTE* token;
+
+		// Find a match
+		do {
+			U32 h = forwardH;
+			int step = findMatchAttempts++ >> skipStrength;
+			ip = forwardIp;
+			forwardIp = ip + step;
+
+			if (forwardIp > mflimit) { goto _last_literals; }
+
+			forwardH = LZ4_HASH_VALUE(forwardIp);
+			ref = HashTable[h];
+			HashTable[h] = ip;
+
+		} while ((ref < ip - MAX_DISTANCE) || (A32(ref) != A32(ip)));
+
+		// Catch up
+		while ((ip>anchor) && (ref>(BYTE*)source) && (ip[-1]==ref[-1])) { ip--; ref--; }  
+
+		// Encode Literal length
+		length = ip - anchor;
+		token = op++;
+		if (length>=(int)RUN_MASK) { *token=(RUN_MASK<<ML_BITS); len = length-RUN_MASK; for(; len > 254 ; len-=255) *op++ = 255; *op++ = (BYTE)len; } 
+		else *token = (length<<ML_BITS);
+
+		// Copy Literals
+		LZ4_BLINDCOPY(anchor, op, length);
+
+
+_next_match:
+		// Encode Offset
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+		A16(op) = (ip-ref); op+=2;
+#else
+		{ int delta = ip-ref; *op++ = delta; *op++ = delta>>8; }
+#endif
+
+		// Start Counting
+		ip+=MINMATCH; ref+=MINMATCH;   // MinMatch verified
+		anchor = ip;
+		while (ip<matchlimit-3)
+		{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+			int diff = A32(ref) ^ A32(ip);
+			if (!diff) { ip+=4; ref+=4; continue; }
+			ip += DeBruijnBytePos[((U32)((diff & -diff) * 0x077CB531U)) >> 27];
+#else
+			if (A32(ref) == A32(ip)) { ip+=4; ref+=4; continue; }
+			if (A16(ref) == A16(ip)) { ip+=2; ref+=2; }
+			if (*ref == *ip) ip++;
+#endif
+			goto _endCount;
+		}
+		if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }
+		if ((ip<matchlimit) && (*ref == *ip)) ip++;
+_endCount:
+		len = (ip - anchor);
+		
+		// Encode MatchLength
+		if (len>=(int)ML_MASK) { *token+=ML_MASK; len-=ML_MASK; for(; len > 509 ; len-=510) { *op++ = 255; *op++ = 255; } if (len > 254) { len-=255; *op++ = 255; } *op++ = (BYTE)len; } 
+		else *token += len;	
+
+		// Test end of chunk
+		if (ip > mflimit) { anchor = ip;  break; }
+
+		// Fill table
+		HashTable[LZ4_HASH_VALUE(ip-2)] = ip-2;
+
+		// Test next position
+		ref = HashTable[LZ4_HASH_VALUE(ip)];
+		HashTable[LZ4_HASH_VALUE(ip)] = ip;
+		if ((ref > ip - (MAX_DISTANCE + 1)) && (A32(ref) == A32(ip))) { token = op++; *token=0; goto _next_match; }
+
+		// Prepare next loop
+		anchor = ip++; 
+		forwardH = LZ4_HASH_VALUE(ip);
+	}
+
+_last_literals:
+	// Encode Last Literals
+	{
+		int lastRun = iend - anchor;
+		if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun > 254 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; } 
+		else *op++ = (lastRun<<ML_BITS);
+		memcpy(op, anchor, iend - anchor);
+		op += iend-anchor;
+	} 
+
+	// End
+	return (int) (((char*)op)-dest);
+}
+
+
+
+// Note : this function is valid only if isize < LZ4_64KLIMIT
+#define LZ4_64KLIMIT ((1U<<16) + (MFLIMIT-1))
+#define HASHLOG64K (HASH_LOG+1)
+#define LZ4_HASH64K_FUNCTION(i)	(((i) * 2654435761U) >> ((MINMATCH*8)-HASHLOG64K))
+#define LZ4_HASH64K_VALUE(p)	LZ4_HASH64K_FUNCTION(A32(p))
+int LZ4_compress64kCtx(void** ctx,
+				 char* source, 
+				 char* dest,
+				 int isize)
+{	
+#if HEAPMODE
+	struct refTables *srt = (struct refTables *) (*ctx);
+	U16* HashTable;
+#else
+	U16 HashTable[HASHTABLESIZE<<1] = {0};
+#endif
+
+	const BYTE* ip = (BYTE*) source;       
+	const BYTE* anchor = ip;
+	const BYTE* const base = ip;
+	const BYTE* const iend = ip + isize;
+	const BYTE* const mflimit = iend - MFLIMIT;
+#define matchlimit (iend - LASTLITERALS)
+
+	BYTE* op = (BYTE*) dest;
+	
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	const size_t DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
+#endif
+	int len, length;
+	const int skipStrength = SKIPSTRENGTH;
+	U32 forwardH;
+
+
+	// Init 
+	if (isize<MINLENGTH) goto _last_literals;
+#if HEAPMODE
+	if (*ctx == NULL) 
+	{
+		srt = (struct refTables *) malloc ( sizeof(struct refTables) );
+		*ctx = (void*) srt;
+	}
+	HashTable = (U16*)(srt->hashTable);
+	memset((void*)HashTable, 0, sizeof(srt->hashTable));
+#else
+	(void) ctx;
+#endif
+
+
+	// First Byte
+	ip++; forwardH = LZ4_HASH64K_VALUE(ip);
+	
+	// Main Loop
+    for ( ; ; ) 
+	{
+		int findMatchAttempts = (1U << skipStrength) + 3;
+		const BYTE* forwardIp = ip;
+		const BYTE* ref;
+		BYTE* token;
+
+		// Find a match
+		do {
+			U32 h = forwardH;
+			int step = findMatchAttempts++ >> skipStrength;
+			ip = forwardIp;
+			forwardIp = ip + step;
+
+			if (forwardIp > mflimit) { goto _last_literals; }
+
+			forwardH = LZ4_HASH64K_VALUE(forwardIp);
+			ref = base + HashTable[h];
+			HashTable[h] = ip - base;
+
+		} while (A32(ref) != A32(ip));
+
+		// Catch up
+		while ((ip>anchor) && (ref>(BYTE*)source) && (ip[-1]==ref[-1])) { ip--; ref--; }  
+
+		// Encode Literal length
+		length = ip - anchor;
+		token = op++;
+		if (length>=(int)RUN_MASK) { *token=(RUN_MASK<<ML_BITS); len = length-RUN_MASK; for(; len > 254 ; len-=255) *op++ = 255; *op++ = (BYTE)len; } 
+		else *token = (length<<ML_BITS);
+
+		// Copy Literals
+		LZ4_BLINDCOPY(anchor, op, length);
+
+
+_next_match:
+		// Encode Offset
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+		A16(op) = (ip-ref); op+=2;
+#else
+		{ int delta = ip-ref; *op++ = delta; *op++ = delta>>8; }
+#endif
+
+		// Start Counting
+		ip+=MINMATCH; ref+=MINMATCH;   // MinMatch verified
+		anchor = ip;
+		while (ip<matchlimit-3)
+		{
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+			int diff = A32(ref) ^ A32(ip);
+			if (!diff) { ip+=4; ref+=4; continue; }
+			ip += DeBruijnBytePos[((U32)((diff & -diff) * 0x077CB531U)) >> 27];
+#else
+			if (A32(ref) == A32(ip)) { ip+=4; ref+=4; continue; }
+			if (A16(ref) == A16(ip)) { ip+=2; ref+=2; }
+			if (*ref == *ip) ip++;
+#endif
+			goto _endCount;
+		}
+		if ((ip<(matchlimit-1)) && (A16(ref) == A16(ip))) { ip+=2; ref+=2; }
+		if ((ip<matchlimit) && (*ref == *ip)) ip++;
+_endCount:
+		len = (ip - anchor);
+		
+		// Encode MatchLength
+		if (len>=(int)ML_MASK) { *token+=ML_MASK; len-=ML_MASK; for(; len > 509 ; len-=510) { *op++ = 255; *op++ = 255; } if (len > 254) { len-=255; *op++ = 255; } *op++ = (BYTE)len; } 
+		else *token += len;	
+
+		// Test end of chunk
+		if (ip > mflimit) { anchor = ip;  break; }
+
+		// Test next position
+		ref = base + HashTable[LZ4_HASH64K_VALUE(ip)];
+		HashTable[LZ4_HASH64K_VALUE(ip)] = ip - base;
+		if (A32(ref) == A32(ip)) { token = op++; *token=0; goto _next_match; }
+
+		// Prepare next loop
+		anchor = ip++; 
+		forwardH = LZ4_HASH64K_VALUE(ip);
+	}
+
+_last_literals:
+	// Encode Last Literals
+	{
+		int lastRun = iend - anchor;
+		if (lastRun>=(int)RUN_MASK) { *op++=(RUN_MASK<<ML_BITS); lastRun-=RUN_MASK; for(; lastRun > 254 ; lastRun-=255) *op++ = 255; *op++ = (BYTE) lastRun; } 
+		else *op++ = (lastRun<<ML_BITS);
+		memcpy(op, anchor, iend - anchor);
+		op += iend-anchor;
+	} 
+
+	// End
+	return (int) (((char*)op)-dest);
+}
+
+
+
+int LZ4_compress(char* source, 
+				 char* dest,
+				 int isize)
+{
+#if HEAPMODE
+	void* ctx = malloc(sizeof(struct refTables));
+	int result;
+	if (isize < LZ4_64KLIMIT)
+		result = LZ4_compress64kCtx(&ctx, source, dest, isize);
+	else result = LZ4_compressCtx(&ctx, source, dest, isize);
+	free(ctx);
+	return result;
+#else
+	if (isize < (int)LZ4_64KLIMIT) return LZ4_compress64kCtx(NULL, source, dest, isize);
+	return LZ4_compressCtx(NULL, source, dest, isize);
+#endif
+}
+
+
+
+
+//****************************
+// Decompression CODE
+//****************************
+
+// Note : The decoding functions LZ4_uncompress() and LZ4_uncompress_unknownOutputSize() 
+//		are safe against "buffer overflow" attack type
+//		since they will *never* write outside of the provided output buffer :
+//		they both check this condition *before* writing anything.
+//		A corrupted packet however can make them *read* within the first 64K before the output buffer.
+
+int LZ4_uncompress(char* source, 
+				 char* dest,
+				 int osize)
+{	
+	// Local Variables
+	const BYTE* restrict ip = (const BYTE*) source;
+	const BYTE* restrict ref;
+
+	BYTE* restrict op = (BYTE*) dest;
+	BYTE* const oend = op + osize;
+	BYTE* cpy;
+
+	BYTE token;
+	
+	U32	dec[4]={0, 3, 2, 3};
+	int	len, length;
+
+
+	// Main Loop
+	while (1)
+	{
+		// get runlength
+		token = *ip++;
+		if ((length=(token>>ML_BITS)) == RUN_MASK)  { for (;(len=*ip++)==255;length+=255){} length += len; } 
+
+		// copy literals
+		cpy = op+length;
+		if (cpy>oend-COPYLENGTH) 
+		{ 
+			if (cpy > oend) goto _output_error;
+			memcpy(op, ip, length);
+			ip += length;
+			break;    // Necessarily EOF
+		}
+		LZ4_WILDCOPY(ip, op, cpy); ip -= (op-cpy); op = cpy;
+
+
+		// get offset
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+		ref = cpy - A16(ip); ip+=2;
+#else
+		{ int delta = *ip++; delta += *ip++ << 8; ref = cpy - delta; }
+#endif
+
+		// get matchlength
+		if ((length=(token&ML_MASK)) == ML_MASK) { for (;*ip==255;length+=255) {ip++;} length += *ip++; } 
+
+		// copy repeated sequence
+		if (op-ref<COPYTOKEN)
+		{
+			*op++ = *ref++;
+			*op++ = *ref++;
+			*op++ = *ref++;
+			*op++ = *ref++;
+			ref -= dec[op-ref];
+			A32(op)=A32(ref); 
+		} else { A32(op)=A32(ref); op+=4; ref+=4; }
+		cpy = op + length;
+		if (cpy > oend-COPYLENGTH)
+		{
+			if (cpy > oend) goto _output_error;	
+			LZ4_WILDCOPY(ref, op, (oend-COPYLENGTH));
+			while(op<cpy) *op++=*ref++;
+			op=cpy;
+			if (op == oend) break;    // Check EOF (should never happen, since last 5 bytes are supposed to be literals)
+			continue;
+		}
+		LZ4_WILDCOPY(ref, op, cpy);
+		op=cpy;		// correction
+	}
+
+	// end of decoding
+	return (int) (((char*)ip)-source);
+
+	// write overflow error detected
+_output_error:
+	return (int) (-(((char*)ip)-source));
+}
+
+
+int LZ4_uncompress_unknownOutputSize(
+				char* source, 
+				char* dest,
+				int isize,
+				int maxOutputSize)
+{	
+	// Local Variables
+	const BYTE* restrict ip = (const BYTE*) source;
+	const BYTE* const iend = ip + isize;
+	const BYTE* restrict ref;
+
+	BYTE* restrict op = (BYTE*) dest;
+	BYTE* const oend = op + maxOutputSize;
+	BYTE* cpy;
+
+	BYTE token;
+	
+	U32	dec[4]={0, 3, 2, 3};
+	int	len, length;
+
+
+	// Main Loop
+	while (ip<iend)
+	{
+		// get runlength
+		token = *ip++;
+		if ((length=(token>>ML_BITS)) == RUN_MASK)  { for (;(len=*ip++)==255;length+=255){} length += len; } 
+
+		// copy literals
+		cpy = op+length;
+		if (cpy>oend-COPYLENGTH) 
+		{ 
+			if (cpy > oend) goto _output_error;
+			memcpy(op, ip, length);
+			op += length;
+			break;    // Necessarily EOF
+		}
+		LZ4_WILDCOPY(ip, op, cpy); ip -= (op-cpy); op = cpy;
+		if (ip>=iend) break;    // check EOF
+
+		// get offset
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+		ref = cpy - A16(ip); ip+=2;
+#else
+		{ int delta = *ip++; delta += *ip++ << 8; ref = cpy - delta; }
+#endif
+
+		// get matchlength
+		if ((length=(token&ML_MASK)) == ML_MASK) { for (;(len=*ip++)==255;length+=255){} length += len; }
+
+		// copy repeated sequence
+		if (op-ref<COPYTOKEN)
+		{
+			*op++ = *ref++;
+			*op++ = *ref++;
+			*op++ = *ref++;
+			*op++ = *ref++;
+			ref -= dec[op-ref];
+			A32(op)=A32(ref); 
+		} else { A32(op)=A32(ref); op+=4; ref+=4; }
+		cpy = op + length;
+		if (cpy>oend-COPYLENGTH)
+		{
+			if (cpy > oend) goto _output_error;	
+			LZ4_WILDCOPY(ref, op, (oend-COPYLENGTH));
+			while(op<cpy) *op++=*ref++;
+			op=cpy;
+			if (op == oend) break;    // Check EOF (should never happen, since last 5 bytes are supposed to be literals)
+			continue;
+		}
+		LZ4_WILDCOPY(ref, op, cpy);
+		op=cpy;		// correction
+	}
+
+	// end of decoding
+	return (int) (((char*)op)-dest);
+
+	// write overflow error detected
+_output_error:
+	return (int) (-(((char*)ip)-source));
+}
+

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/io/compress/TestCodec.java

@@ -60,6 +60,7 @@ import org.apache.hadoop.io.compress.zlib.ZlibCompressor.CompressionLevel;
 import org.apache.hadoop.io.compress.zlib.ZlibCompressor.CompressionStrategy;
 import org.apache.hadoop.io.compress.zlib.ZlibFactory;
 import org.apache.hadoop.util.LineReader;
+import org.apache.hadoop.util.NativeCodeLoader;
 import org.apache.hadoop.util.ReflectionUtils;
 
 import org.apache.commons.codec.binary.Base64;
@@ -108,6 +109,18 @@ public class TestCodec {
       }
     }
   }
+  
+  @Test
+  public void testLz4Codec() throws IOException {
+    if (NativeCodeLoader.isNativeCodeLoaded()) {
+      if (Lz4Codec.isNativeCodeLoaded()) {
+        codecTest(conf, seed, 0, "org.apache.hadoop.io.compress.Lz4Codec");
+        codecTest(conf, seed, count, "org.apache.hadoop.io.compress.Lz4Codec");
+      } else {
+        Assert.fail("Native hadoop library available but lz4 not");
+      }
+    }
+  }
 
   @Test
   public void testDeflateCodec() throws IOException {