Package org.apache.hadoop.io.compress.zstd

Class ZStandardDecompressor

java.lang.Object

org.apache.hadoop.io.compress.zstd.ZStandardDecompressor

All Implemented Interfaces:

Decompressor

Direct Known Subclasses:

ZStandardDecompressor.ZStandardDirectDecompressor

public class ZStandardDecompressor
extends java.lang.Object
implements Decompressor

A Decompressor based on the zStandard compression algorithm. https://github.com/facebook/zstd

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ZStandardDecompressor.ZStandardDirectDecompressor	A DirectDecompressor for ZStandard https://github.com/facebook/zstd.

Constructor Summary

Constructors

Constructor	Description
ZStandardDecompressor()
ZStandardDecompressor(int bufferSize)	Creates a new decompressor.

Method Summary

Modifier and Type	Method	Description
int	decompress(byte[] b, int off, int len)	Fills specified buffer with uncompressed data.
void	end()	Closes the decompressor and discards any unprocessed input.
protected void	finalize()
boolean	finished()	Returns true if the end of the decompressed data output stream has been reached.
static int	getRecommendedBufferSize()
int	getRemaining()	Returns the number of bytes remaining in the input buffers; normally called when finished() is true to determine amount of post-stream data.
static boolean	isNativeCodeLoaded()
boolean	needsDictionary()	Returns true if a preset dictionary is needed for decompression.
boolean	needsInput()	Returns true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called to provide more input.
void	reset()	Resets everything including the input buffers (user and direct).
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 decompression.

Methods inherited from class java.lang.Object

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

Constructor Detail

ZStandardDecompressor

public ZStandardDecompressor()

ZStandardDecompressor

public ZStandardDecompressor(int bufferSize)

Creates a new decompressor.

Parameters:

bufferSize - bufferSize.

Method Detail

isNativeCodeLoaded

public static boolean isNativeCodeLoaded()

getRecommendedBufferSize

public static int getRecommendedBufferSize()

setInput

public void setInput(byte[] b,
                     int off,
                     int len)

Description copied from interface: Decompressor

Sets input data for decompression. This should be called if and only if Decompressor.needsInput() returns true indicating that more input data is required. (Both native and non-native versions of various Decompressors require that the data passed in via b[] remain unmodified until the caller is explicitly notified--via Decompressor.needsInput()--that the buffer may be safely modified. With this requirement, an extra buffer-copy can be avoided.)

Specified by:

setInput in interface Decompressor

Parameters:

b - Input data

off - Start offset

len - Length

setDictionary

public void setDictionary(byte[] b,
                          int off,
                          int len)

Description copied from interface: Decompressor

Sets preset dictionary for compression. A preset dictionary is used when the history buffer can be predetermined.

Specified by:

setDictionary in interface Decompressor

Parameters:

b - Dictionary data bytes

off - Start offset

len - Length

needsInput

public boolean needsInput()

Description copied from interface: Decompressor

Returns true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called to provide more input.

Specified by:

needsInput in interface Decompressor

Returns:

true if the input data buffer is empty and Decompressor.setInput(byte[], int, int) should be called in order to provide more input.

needsDictionary

public boolean needsDictionary()

Description copied from interface: Decompressor

Returns true if a preset dictionary is needed for decompression.

Specified by:

needsDictionary in interface Decompressor

Returns:

true if a preset dictionary is needed for decompression

finished

public boolean finished()

Description copied from interface: Decompressor

Returns true if the end of the decompressed data output stream has been reached. Indicates a concatenated data stream when finished() returns true and Decompressor.getRemaining() returns a positive value. finished() will be reset with the Decompressor.reset() method.

Specified by:

finished in interface Decompressor

Returns:

true if the end of the decompressed data output stream has been reached.

decompress

public int decompress(byte[] b,
                      int off,
                      int len)
               throws java.io.IOException

Description copied from interface: Decompressor

Fills specified buffer with uncompressed data. Returns actual number of bytes of uncompressed data. A return value of 0 indicates that Decompressor.needsInput() should be called in order to determine if more input data is required.

Specified by:

decompress in interface Decompressor

Parameters:

b - Buffer for the uncompressed data

off - Start offset of the data

len - Size of the buffer

Returns:

The actual number of bytes of uncompressed data.

Throws:

java.io.IOException - raised on errors performing I/O.

getRemaining

public int getRemaining()

Returns the number of bytes remaining in the input buffers; normally called when finished() is true to determine amount of post-stream data.

Specified by:

getRemaining in interface Decompressor

Returns:

the total (non-negative) number of unprocessed bytes in input

reset

public void reset()

Resets everything including the input buffers (user and direct).

Specified by:

reset in interface Decompressor

end

public void end()

Description copied from interface: Decompressor

Closes the decompressor and discards any unprocessed input.

Specified by:

end in interface Decompressor

finalize

protected void finalize()

Overrides:

finalize in class java.lang.Object