Package org.apache.hadoop.io.compress.snappy

Class SnappyCompressor

java.lang.Object
org.apache.hadoop.io.compress.snappy.SnappyCompressor
All Implemented Interfaces:
Compressor
public class SnappyCompressor extends Object implements Compressor
A Compressor based on the snappy compression algorithm. http://code.google.com/p/snappy/

  • Constructor Summary

    Constructors
    Constructor
    Description
    SnappyCompressor()
    Creates a new compressor with the default buffer size.
    SnappyCompressor(int directBufferSize)
    Creates a new compressor.

  • 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 bytes given to this compressor since last reset.
    long
    getBytesWritten()
    Return number of bytes consumed by callers of compress since last reset.
    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)
    Does nothing.
    void
    setInput(byte[] b, int off, int len)
    Sets input data for compression.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • SnappyCompressor

      public SnappyCompressor(int directBufferSize)
      Creates a new compressor.
      Parameters:
      directBufferSize - size of the direct buffer to be used.

    • SnappyCompressor

      public SnappyCompressor()
      Creates a new compressor with the default buffer size.

  • Method Details

    • setInput

      public 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.
      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)
      Does nothing.
      Specified by:
      setDictionary in interface Compressor
      Parameters:
      b - Dictionary data bytes
      off - Start offset
      len - Length

    • needsInput

      public boolean needsInput()
      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()
      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()
      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
      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.

    • reset

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

    • reinit

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

    • getBytesRead

      public long getBytesRead()
      Return number of bytes given to this compressor since last reset.
      Specified by:
      getBytesRead in interface Compressor
      Returns:
      bytes read.

    • getBytesWritten

      public long getBytesWritten()
      Return number of bytes consumed by callers of compress since last reset.
      Specified by:
      getBytesWritten in interface Compressor
      Returns:
      bytes written.

    • end

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