Package org.apache.hadoop.io.compress.zlib

Class ZlibCompressor

java.lang.Object
org.apache.hadoop.io.compress.zlib.ZlibCompressor
All Implemented Interfaces:
Compressor
public class ZlibCompressor extends Object implements Compressor
A Compressor based on the popular zlib compression algorithm. http://www.zlib.net/

  • Constructor Details

    • ZlibCompressor

      public ZlibCompressor()
      Creates a new compressor with the default compression level. Compressed data will be generated in ZLIB format.

    • ZlibCompressor

      public ZlibCompressor(Configuration conf)
      Creates a new compressor, taking settings from the configuration.
      Parameters:
      conf - configuration.

    • ZlibCompressor

      public ZlibCompressor(ZlibCompressor.CompressionLevel level, ZlibCompressor.CompressionStrategy strategy, ZlibCompressor.CompressionHeader header, int directBufferSize)
      Creates a new compressor using the specified compression level. Compressed data will be generated in ZLIB format.
      Parameters:
      level - Compression level #CompressionLevel
      strategy - Compression strategy #CompressionStrategy
      header - Compression header #CompressionHeader
      directBufferSize - Size of the direct buffer to be used.

  • Method Details

    • construct

      protected final void construct(ZlibCompressor.CompressionLevel level, ZlibCompressor.CompressionStrategy strategy, ZlibCompressor.CompressionHeader header, int directBufferSize)

    • reinit

      public void reinit(Configuration conf)
      Prepare the compressor to be used in a new stream with settings defined in the given Configuration. It will reset the compressor's compression level and compression strategy.
      Specified by:
      reinit in interface Compressor
      Parameters:
      conf - Configuration storing new settings

    • setInput

      public void setInput(byte[] b, int off, int len)
      Description copied from interface: Compressor
      Sets input data for compression. This should be called whenever #needsInput() returns true indicating that more input data is required.
      Specified by:
      setInput in interface Compressor
      Parameters:
      b - Input data
      off - Start offset
      len - Length

    • setDictionary

      public void setDictionary(byte[] b, int off, int len)
      Description copied from interface: Compressor
      Sets preset dictionary for compression. A preset dictionary is used when the history buffer can be predetermined.
      Specified by:
      setDictionary in interface Compressor
      Parameters:
      b - Dictionary data bytes
      off - Start offset
      len - Length

    • needsInput

      public boolean needsInput()
      Description copied from interface: Compressor
      Returns true if the input data buffer is empty and #setInput() should be called to provide more input.
      Specified by:
      needsInput in interface Compressor
      Returns:
      true if the input data buffer is empty and #setInput() should be called in order to provide more input.

    • finish

      public void finish()
      Description copied from interface: Compressor
      When called, indicates that compression should end with the current contents of the input buffer.
      Specified by:
      finish in interface Compressor

    • finished

      public boolean finished()
      Description copied from interface: Compressor
      Returns true if the end of the compressed data output stream has been reached.
      Specified by:
      finished in interface Compressor
      Returns:
      true if the end of the compressed data output stream has been reached.

    • compress

      public int compress(byte[] b, int off, int len) throws IOException
      Description copied from interface: Compressor
      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.
      Specified by:
      compress in interface Compressor
      Parameters:
      b - Buffer for the compressed data
      off - Start offset of the data
      len - Size of the buffer
      Returns:
      The actual number of bytes of compressed data.
      Throws:
      IOException - raised on errors performing I/O.

    • getBytesWritten

      public long getBytesWritten()
      Returns the total number of compressed bytes output so far.
      Specified by:
      getBytesWritten in interface Compressor
      Returns:
      the total (non-negative) number of compressed bytes output so far

    • getBytesRead

      public long getBytesRead()
      Returns the total number of uncompressed bytes input so far.
      Specified by:
      getBytesRead in interface Compressor
      Returns:
      the total (non-negative) number of uncompressed bytes input so far

    • reset

      public void reset()
      Description copied from interface: Compressor
      Resets compressor so that a new set of input data can be processed.
      Specified by:
      reset in interface Compressor

    • end

      public void end()
      Description copied from interface: Compressor
      Closes the compressor and discards any unprocessed input.
      Specified by:
      end in interface Compressor

    • getLibraryName

      public static String getLibraryName()