Package org.apache.hadoop.io.compress

Interface Compressor

@Public @Evolving public interface Compressor
Specification of a stream-based 'compressor' which can be plugged into a CompressionOutputStream to compress data. This is modelled after Deflater

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    compress(byte[] b, int off, int len)
    Fills specified buffer with compressed data.
    void
    end()
    Closes the compressor and discards any unprocessed input.
    void
    finish()
    When called, indicates that compression should end with the current contents of the input buffer.
    boolean
    finished()
    Returns true if the end of the compressed data output stream has been reached.
    long
    getBytesRead()
    Return number of uncompressed bytes input so far.
    long
    getBytesWritten()
    Return number of compressed bytes output so far.
    boolean
    needsInput()
    Returns true if the input data buffer is empty and #setInput() should be called to provide more input.
    void
    reinit(Configuration conf)
    Prepare the compressor to be used in a new stream with settings defined in the given Configuration
    void
    reset()
    Resets compressor so that a new set of input data can be processed.
    void
    setDictionary(byte[] b, int off, int len)
    Sets preset dictionary for compression.
    void
    setInput(byte[] b, int off, int len)
    Sets input data for compression.

  • Method Details

    • setInput

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

    • needsInput

      boolean needsInput()
      Returns true if the input data buffer is empty and #setInput() should be called to provide more input.
      Returns:
      true if the input data buffer is empty and #setInput() should be called in order to provide more input.

    • setDictionary

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

    • getBytesRead

      long getBytesRead()
      Return number of uncompressed bytes input so far.
      Returns:
      bytes read.

    • getBytesWritten

      long getBytesWritten()
      Return number of compressed bytes output so far.
      Returns:
      bytes written.

    • finish

      void finish()
      When called, indicates that compression should end with the current contents of the input buffer.

    • finished

      boolean finished()
      Returns true if the end of the compressed data output stream has been reached.
      Returns:
      true if the end of the compressed data output stream has been reached.

    • compress

      int compress(byte[] b, int off, int len) throws IOException
      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.
      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.

    • reset

      void reset()
      Resets compressor so that a new set of input data can be processed.

    • end

      void end()
      Closes the compressor and discards any unprocessed input.

    • reinit

      void reinit(Configuration conf)
      Prepare the compressor to be used in a new stream with settings defined in the given Configuration
      Parameters:
      conf - Configuration from which new setting are fetched