/**
    * 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.compress;
  
  import java.io.BufferedInputStream;
  import java.io.BufferedOutputStream;
  import java.io.FilterOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.conf.Configurable;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.io.IOUtils;
  import org.apache.hadoop.io.compress.CodecPool;
  import org.apache.hadoop.io.compress.CompressionCodec;
  import org.apache.hadoop.io.compress.CompressionInputStream;
  import org.apache.hadoop.io.compress.CompressionOutputStream;
  import org.apache.hadoop.io.compress.Compressor;
  import org.apache.hadoop.io.compress.Decompressor;
  import org.apache.hadoop.io.compress.DefaultCodec;
  import org.apache.hadoop.io.compress.DoNotPool;
  import org.apache.hadoop.io.compress.GzipCodec;
  import org.apache.hadoop.util.ReflectionUtils;
  
  /**
   * Compression related stuff.
   * Copied from hadoop-3315 tfile.
   */
  @InterfaceAudience.Private
  public final class Compression {
    static final Log LOG = LogFactory.getLog(Compression.class);
  
    /**
     * Prevent the instantiation of class.
     */
    private Compression() {
      super();
    }
  
    static class FinishOnFlushCompressionStream extends FilterOutputStream {
      public FinishOnFlushCompressionStream(CompressionOutputStream cout) {
        super(cout);
      }
  
      @Override
      public void write(byte b[], int off, int len) throws IOException {
        out.write(b, off, len);
      }
  
      @Override
      public void flush() throws IOException {
        CompressionOutputStream cout = (CompressionOutputStream) out;
        cout.finish();
        cout.flush();
        cout.resetState();
      }
    }
  
    /**
     * Returns the classloader to load the Codec class from.
     */
    private static ClassLoader getClassLoaderForCodec() {
      ClassLoader cl = Thread.currentThread().getContextClassLoader();
      if (cl == null) {
        cl = Compression.class.getClassLoader();
      }
      if (cl == null) {
        cl = ClassLoader.getSystemClassLoader();
      }
      if (cl == null) {
        throw new RuntimeException("A ClassLoader to load the Codec could not be determined");
      }
      return cl;
    }
  
    /**
     * Compression algorithms. The ordinal of these cannot change or else you
     * risk breaking all existing HFiles out there.  Even the ones that are
     * not compressed! (They use the NONE algorithm)
     */
   @edu.umd.cs.findbugs.annotations.SuppressWarnings(
       value="SE_TRANSIENT_FIELD_NOT_RESTORED",
       justification="We are not serializing so doesn't apply (not sure why transient though)")
   @InterfaceAudience.Public
   @InterfaceStability.Evolving
   public static enum Algorithm {
     LZO("lzo") {
       // Use base type to avoid compile-time dependencies.
       private volatile transient CompressionCodec lzoCodec;
       private transient Object lock = new Object();
 
       @Override
       CompressionCodec getCodec(Configuration conf) {
         if (lzoCodec == null) {
           synchronized (lock) {
             if (lzoCodec == null) {
               lzoCodec = buildCodec(conf);
             }
           }
         }
         return lzoCodec;
       }
 
       private CompressionCodec buildCodec(Configuration conf) {
         try {
           Class<?> externalCodec =
               getClassLoaderForCodec().loadClass("com.hadoop.compression.lzo.LzoCodec");
           return (CompressionCodec) ReflectionUtils.newInstance(externalCodec,
               new Configuration(conf));
         } catch (ClassNotFoundException e) {
           throw new RuntimeException(e);
         }
       }
     },
     GZ("gz") {
       private volatile transient GzipCodec codec;
       private transient Object lock = new Object();
 
       @Override
       DefaultCodec getCodec(Configuration conf) {
         if (codec == null) {
           synchronized (lock) {
             if (codec == null) {
               codec = buildCodec(conf);
             }
           }
         }
 
         return codec;
       }
 
       private GzipCodec buildCodec(Configuration conf) {
         GzipCodec gzcodec = new ReusableStreamGzipCodec();
         gzcodec.setConf(new Configuration(conf));
         return gzcodec;
       }
     },
 
     NONE("none") {
       @Override
       DefaultCodec getCodec(Configuration conf) {
         return null;
       }
 
       @Override
       public synchronized InputStream createDecompressionStream(
           InputStream downStream, Decompressor decompressor,
           int downStreamBufferSize) throws IOException {
         if (downStreamBufferSize > 0) {
           return new BufferedInputStream(downStream, downStreamBufferSize);
         }
         return downStream;
       }
 
       @Override
       public synchronized OutputStream createCompressionStream(
           OutputStream downStream, Compressor compressor,
           int downStreamBufferSize) throws IOException {
         if (downStreamBufferSize > 0) {
           return new BufferedOutputStream(downStream, downStreamBufferSize);
         }
 
         return downStream;
       }
     },
     SNAPPY("snappy") {
       // Use base type to avoid compile-time dependencies.
       private volatile transient CompressionCodec snappyCodec;
       private transient Object lock = new Object();
 
       @Override
       CompressionCodec getCodec(Configuration conf) {
         if (snappyCodec == null) {
           synchronized (lock) {
             if (snappyCodec == null) {
               snappyCodec = buildCodec(conf);
             }
           }
         }
         return snappyCodec;
       }
 
       private CompressionCodec buildCodec(Configuration conf) {
         try {
           Class<?> externalCodec =
               getClassLoaderForCodec().loadClass("org.apache.hadoop.io.compress.SnappyCodec");
           return (CompressionCodec) ReflectionUtils.newInstance(externalCodec, conf);
         } catch (ClassNotFoundException e) {
           throw new RuntimeException(e);
         }
       }
     },
     LZ4("lz4") {
       // Use base type to avoid compile-time dependencies.
       private volatile transient CompressionCodec lz4Codec;
       private transient Object lock = new Object();
 
       @Override
       CompressionCodec getCodec(Configuration conf) {
         if (lz4Codec == null) {
           synchronized (lock) {
             if (lz4Codec == null) {
               lz4Codec = buildCodec(conf);
             }
           }
         }
         return lz4Codec;
       }
 
       private CompressionCodec buildCodec(Configuration conf) {
         try {
           Class<?> externalCodec =
               getClassLoaderForCodec().loadClass("org.apache.hadoop.io.compress.Lz4Codec");
           return (CompressionCodec) ReflectionUtils.newInstance(externalCodec, conf);
         } catch (ClassNotFoundException e) {
           throw new RuntimeException(e);
         }
       }
   };
 
     private final Configuration conf;
     private final String compressName;
     /** data input buffer size to absorb small reads from application. */
     private static final int DATA_IBUF_SIZE = 1 * 1024;
     /** data output buffer size to absorb small writes from application. */
     private static final int DATA_OBUF_SIZE = 4 * 1024;
 
     Algorithm(String name) {
       this.conf = new Configuration();
       this.conf.setBoolean("io.native.lib.available", true);
       this.compressName = name;
     }
 
     abstract CompressionCodec getCodec(Configuration conf);
 
     public InputStream createDecompressionStream(
         InputStream downStream, Decompressor decompressor,
         int downStreamBufferSize) throws IOException {
       CompressionCodec codec = getCodec(conf);
       // Set the internal buffer size to read from down stream.
       if (downStreamBufferSize > 0) {
         ((Configurable)codec).getConf().setInt("io.file.buffer.size",
             downStreamBufferSize);
       }
       CompressionInputStream cis =
           codec.createInputStream(downStream, decompressor);
       BufferedInputStream bis2 = new BufferedInputStream(cis, DATA_IBUF_SIZE);
       return bis2;
 
     }
 
     public OutputStream createCompressionStream(
         OutputStream downStream, Compressor compressor, int downStreamBufferSize)
         throws IOException {
       OutputStream bos1 = null;
       if (downStreamBufferSize > 0) {
         bos1 = new BufferedOutputStream(downStream, downStreamBufferSize);
       }
       else {
         bos1 = downStream;
       }
       CompressionOutputStream cos =
           createPlainCompressionStream(bos1, compressor);
       BufferedOutputStream bos2 =
           new BufferedOutputStream(new FinishOnFlushCompressionStream(cos),
               DATA_OBUF_SIZE);
       return bos2;
     }
 
     /**
      * Creates a compression stream without any additional wrapping into
      * buffering streams.
      */
     public CompressionOutputStream createPlainCompressionStream(
         OutputStream downStream, Compressor compressor) throws IOException {
       CompressionCodec codec = getCodec(conf);
       ((Configurable)codec).getConf().setInt("io.file.buffer.size", 32 * 1024);
       return codec.createOutputStream(downStream, compressor);
     }
 
     public Compressor getCompressor() {
       CompressionCodec codec = getCodec(conf);
       if (codec != null) {
         Compressor compressor = CodecPool.getCompressor(codec);
         if (LOG.isTraceEnabled()) LOG.trace("Retrieved compressor " + compressor + " from pool.");
         if (compressor != null) {
           if (compressor.finished()) {
             // Somebody returns the compressor to CodecPool but is still using it.
             LOG.warn("Compressor obtained from CodecPool is already finished()");
           }
           compressor.reset();
         }
         return compressor;
       }
       return null;
     }
 
     public void returnCompressor(Compressor compressor) {
       if (compressor != null) {
         if (LOG.isTraceEnabled()) LOG.trace("Returning compressor " + compressor + " to pool.");
         CodecPool.returnCompressor(compressor);
       }
     }
 
     public Decompressor getDecompressor() {
       CompressionCodec codec = getCodec(conf);
       if (codec != null) {
         Decompressor decompressor = CodecPool.getDecompressor(codec);
         if (LOG.isTraceEnabled()) LOG.trace("Retrieved decompressor " + decompressor + " from pool.");
         if (decompressor != null) {
           if (decompressor.finished()) {
             // Somebody returns the decompressor to CodecPool but is still using it.
             LOG.warn("Deompressor obtained from CodecPool is already finished()");
           }
           decompressor.reset();
         }
         return decompressor;
       }
 
       return null;
     }
 
     public void returnDecompressor(Decompressor decompressor) {
       if (decompressor != null) {
         if (LOG.isTraceEnabled()) LOG.trace("Returning decompressor " + decompressor + " to pool.");
         CodecPool.returnDecompressor(decompressor);
         if (decompressor.getClass().isAnnotationPresent(DoNotPool.class)) {
           if (LOG.isTraceEnabled()) LOG.trace("Ending decompressor " + decompressor);
           decompressor.end();
         }
       }
     }
 
     public String getName() {
       return compressName;
     }
   }
 
   public static Algorithm getCompressionAlgorithmByName(String compressName) {
     Algorithm[] algos = Algorithm.class.getEnumConstants();
 
     for (Algorithm a : algos) {
       if (a.getName().equals(compressName)) {
         return a;
       }
     }
 
     throw new IllegalArgumentException("Unsupported compression algorithm name: " + compressName);
   }
 
   /**
    * Get names of supported compression algorithms.
    *
    * @return Array of strings, each represents a supported compression
    * algorithm. Currently, the following compression algorithms are supported.
    */
   public static String[] getSupportedAlgorithms() {
     Algorithm[] algos = Algorithm.class.getEnumConstants();
 
     String[] ret = new String[algos.length];
     int i = 0;
     for (Algorithm a : algos) {
       ret[i++] = a.getName();
     }
 
     return ret;
   }
 
   /**
    * Decompresses data from the given stream using the configured compression
    * algorithm. It will throw an exception if the dest buffer does not have
    * enough space to hold the decompressed data.
    *
    * @param dest
    *          the output bytes buffer
    * @param destOffset
    *          start writing position of the output buffer
    * @param bufferedBoundedStream
    *          a stream to read compressed data from, bounded to the exact amount
    *          of compressed data
    * @param compressedSize
    *          compressed data size, header not included
    * @param uncompressedSize
    *          uncompressed data size, header not included
    * @param compressAlgo
    *          compression algorithm used
    * @throws IOException
    */
   public static void decompress(byte[] dest, int destOffset,
       InputStream bufferedBoundedStream, int compressedSize,
       int uncompressedSize, Compression.Algorithm compressAlgo)
       throws IOException {
 
     if (dest.length - destOffset < uncompressedSize) {
       throw new IllegalArgumentException(
           "Output buffer does not have enough space to hold "
               + uncompressedSize + " decompressed bytes, available: "
               + (dest.length - destOffset));
     }
 
     Decompressor decompressor = null;
     try {
       decompressor = compressAlgo.getDecompressor();
       InputStream is = compressAlgo.createDecompressionStream(
           bufferedBoundedStream, decompressor, 0);
 
       IOUtils.readFully(is, dest, destOffset, uncompressedSize);
       is.close();
     } finally {
       if (decompressor != null) {
         compressAlgo.returnDecompressor(decompressor);
       }
     }
   }
 }