org.iq80.snappy

Class SnappyOutputStream

java.lang.Object

java.io.OutputStream

org.iq80.snappy.AbstractSnappyOutputStream

org.iq80.snappy.SnappyOutputStream

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable

Deprecated.

Use SnappyFramedOutputStream which implements the standard x-snappy-framed specification.

@Deprecated
public class SnappyOutputStream
extends AbstractSnappyOutputStream

This class implements an output stream for writing Snappy compressed data. The output format is the stream header "snappy\0" followed by one or more compressed blocks of data, each of which is preceded by a seven byte header.

The first byte of the header is a flag indicating if the block is compressed or not. A value of 0x00 means uncompressed, and 0x01 means compressed.

The second and third bytes are the size of the block in the stream as a big endian number. This value is never zero as empty blocks are never written. The maximum allowed length is 32k (1 << 15).

The remaining four byes are crc32c checksum of the user input data masked with the following function: ((crc >>> 15) | (crc << 17)) + 0xa282ead8

An uncompressed block is simply copied from the input, thus guaranteeing that the output is never larger than the input (not including the header).

NOTE:This data produced by this class is not compatible with the x-snappy-framed specification. It can only be read by SnappyInputStream.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	calculateChecksum Deprecated.
(package private) static int	MAX_BLOCK_SIZE Deprecated.
static double	MIN_COMPRESSION_RATIO Deprecated. Write out the uncompressed content if the compression ratio (compressed length / raw length) exceeds this value.
(package private) static byte[]	STREAM_HEADER Deprecated.

Constructor Summary

Constructors

Modifier	Constructor and Description
	SnappyOutputStream(java.io.OutputStream out) Deprecated. Creates a Snappy output stream to write data to the specified underlying output stream.
private	SnappyOutputStream(java.io.OutputStream out, boolean calculateChecksum) Deprecated.

Method Summary

Modifier and Type	Method and Description
protected int	calculateCRC32C(byte[] data, int offset, int length) Deprecated. Calculates a CRC32C checksum over the data.
static SnappyOutputStream	newChecksumFreeBenchmarkOutputStream(java.io.OutputStream out) Deprecated. Creates a Snappy output stream with block checksums disabled.
protected void	writeBlock(java.io.OutputStream out, byte[] data, int offset, int length, boolean compressed, int crc32c) Deprecated. Write a frame (block) to out.
protected void	writeHeader(java.io.OutputStream out) Deprecated. Writes the implementation specific header or "marker bytes" to out.

Methods inherited from class org.iq80.snappy.AbstractSnappyOutputStream

close, flush, write, write

Methods inherited from class java.io.OutputStream

write

Methods inherited from class java.lang.Object

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

Field Detail

STREAM_HEADER

static final byte[] STREAM_HEADER

Deprecated.

MAX_BLOCK_SIZE

static final int MAX_BLOCK_SIZE

Deprecated.

See Also:

Constant Field Values

MIN_COMPRESSION_RATIO

public static final double MIN_COMPRESSION_RATIO

Deprecated.

Write out the uncompressed content if the compression ratio (compressed length / raw length) exceeds this value.

See Also:

Constant Field Values

calculateChecksum

private final boolean calculateChecksum

Deprecated.

Constructor Detail

SnappyOutputStream

public SnappyOutputStream(java.io.OutputStream out)
                   throws java.io.IOException

Deprecated.

Creates a Snappy output stream to write data to the specified underlying output stream.

Parameters:

out - the underlying output stream

Throws:

java.io.IOException

SnappyOutputStream

private SnappyOutputStream(java.io.OutputStream out,
                           boolean calculateChecksum)
                    throws java.io.IOException

Deprecated.

Throws:

java.io.IOException

Method Detail

newChecksumFreeBenchmarkOutputStream

public static SnappyOutputStream newChecksumFreeBenchmarkOutputStream(java.io.OutputStream out)
                                                               throws java.io.IOException

Deprecated.

Creates a Snappy output stream with block checksums disabled. This is only useful for apples-to-apples benchmarks with other compressors that do not perform block checksums.

Parameters:

out - the underlying output stream

Throws:

java.io.IOException

writeHeader

protected void writeHeader(java.io.OutputStream out)
                    throws java.io.IOException

Deprecated.

Description copied from class: AbstractSnappyOutputStream

Writes the implementation specific header or "marker bytes" to out.

Specified by:

writeHeader in class AbstractSnappyOutputStream

Parameters:

out - The underlying OutputStream.

Throws:

java.io.IOException

calculateCRC32C

protected int calculateCRC32C(byte[] data,
                              int offset,
                              int length)

Deprecated.

Description copied from class: AbstractSnappyOutputStream

Calculates a CRC32C checksum over the data.

This can be overridden to provider alternative implementations (such as returning 0 if checksums are not desired).

Overrides:

calculateCRC32C in class AbstractSnappyOutputStream

Returns:

The CRC32 checksum.

writeBlock

protected void writeBlock(java.io.OutputStream out,
                          byte[] data,
                          int offset,
                          int length,
                          boolean compressed,
                          int crc32c)
                   throws java.io.IOException

Deprecated.

Description copied from class: AbstractSnappyOutputStream

Write a frame (block) to out.

Specified by:

writeBlock in class AbstractSnappyOutputStream

Parameters:

out - The OutputStream to write to.

data - The data to write.

offset - The offset in data to start at.

length - The length of data to use.

compressed - Indicates if data is the compressed or raw content. This is based on whether the compression ratio desired is reached.

crc32c - The calculated checksum.

Throws:

java.io.IOException