org.xerial.snappy

Class SnappyFramedOutputStream

java.lang.Object

java.io.OutputStream

org.xerial.snappy.SnappyFramedOutputStream

All Implemented Interfaces:

java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable, java.nio.channels.Channel, java.nio.channels.WritableByteChannel

public final class SnappyFramedOutputStream
extends java.io.OutputStream
implements java.nio.channels.WritableByteChannel

Implements the x-snappy-framed as an OutputStream and WritableByteChannel.

Since:

1.1.0

Field Summary

Fields

Modifier and Type	Field and Description
private java.nio.ByteBuffer	buffer
private boolean	closed
static int	DEFAULT_BLOCK_SIZE The default block size to use.
static double	DEFAULT_MIN_COMPRESSION_RATIO The default min compression ratio to use.
private java.nio.ByteBuffer	directInputBuffer
private java.nio.ByteBuffer	headerBuffer
static int	MAX_BLOCK_SIZE The x-snappy-framed specification allows for a chunk size up to 16,777,211 bytes in length.
private double	minCompressionRatio
private java.nio.channels.WritableByteChannel	out
private java.nio.ByteBuffer	outputBuffer

Constructor Summary

Constructors

Constructor and Description
SnappyFramedOutputStream(java.io.OutputStream out) Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.
SnappyFramedOutputStream(java.io.OutputStream out, int blockSize, double minCompressionRatio) Creates a new SnappyFramedOutputStream instance.
SnappyFramedOutputStream(java.nio.channels.WritableByteChannel out) Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.
SnappyFramedOutputStream(java.nio.channels.WritableByteChannel out, int blockSize, double minCompressionRatio) Creates a new SnappyFramedOutputStream instance.

Method Summary

Modifier and Type	Method and Description
void	close()
void	flush()
private void	flushBuffer() Compresses and writes out any buffered data.
boolean	isOpen()
long	transferFrom(java.io.InputStream is) Transfers all the content from is to this OutputStream.
long	transferFrom(java.nio.channels.ReadableByteChannel rbc) Transfers all the content from rbc to this WritableByteChannel.
void	write(byte[] input, int offset, int length)
int	write(java.nio.ByteBuffer src)
void	write(int b)
private void	writeBlock(java.nio.channels.WritableByteChannel out, java.nio.ByteBuffer data, boolean compressed, int crc32c) Write a frame (block) to out.
private void	writeCompressed(java.nio.ByteBuffer buffer) SnappyFramed.maskedCrc32c(byte[], int, int) the crc, compresses the data, determines if the compression ratio is acceptable and calls writeBlock(java.nio.channels.WritableByteChannel, java.nio.ByteBuffer, boolean, int) to actually write the frame.
private void	writeHeader(java.nio.channels.WritableByteChannel out) Writes the implementation specific header or "marker bytes" to out.

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

MAX_BLOCK_SIZE

public static final int MAX_BLOCK_SIZE

The x-snappy-framed specification allows for a chunk size up to 16,777,211 bytes in length. However, it also goes on to state:

We place an additional restriction that the uncompressed data in a chunk must be no longer than 65536 bytes. This allows consumers to easily use small fixed-size buffers.

See Also:

Constant Field Values

DEFAULT_BLOCK_SIZE

public static final int DEFAULT_BLOCK_SIZE

The default block size to use.

See Also:

Constant Field Values

DEFAULT_MIN_COMPRESSION_RATIO

public static final double DEFAULT_MIN_COMPRESSION_RATIO

The default min compression ratio to use.

See Also:

Constant Field Values

headerBuffer

private final java.nio.ByteBuffer headerBuffer

buffer

private final java.nio.ByteBuffer buffer

directInputBuffer

private final java.nio.ByteBuffer directInputBuffer

outputBuffer

private final java.nio.ByteBuffer outputBuffer

minCompressionRatio

private final double minCompressionRatio

out

private final java.nio.channels.WritableByteChannel out

closed

private boolean closed

Constructor Detail

SnappyFramedOutputStream

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

Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.

Parameters:

out - The underlying OutputStream to write to. Must not be null.

Throws:

java.io.IOException

SnappyFramedOutputStream

public SnappyFramedOutputStream(java.io.OutputStream out,
                                int blockSize,
                                double minCompressionRatio)
                         throws java.io.IOException

Creates a new SnappyFramedOutputStream instance.

Parameters:

out - The underlying OutputStream to write to. Must not be null.

blockSize - The block size (of raw data) to compress before writing frames to out. Must be in (0, 65536].

minCompressionRatio - Defines the minimum compression ratio ( compressedLength / rawLength) that must be achieved to write the compressed data. This must be in (0, 1.0].

Throws:

java.io.IOException

SnappyFramedOutputStream

public SnappyFramedOutputStream(java.nio.channels.WritableByteChannel out)
                         throws java.io.IOException

Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.

Parameters:

out - The underlying WritableByteChannel to write to. Must not be null.

Throws:

java.io.IOException

Since:

1.1.1

SnappyFramedOutputStream

public SnappyFramedOutputStream(java.nio.channels.WritableByteChannel out,
                                int blockSize,
                                double minCompressionRatio)
                         throws java.io.IOException

Creates a new SnappyFramedOutputStream instance.

Parameters:

out - The underlying WritableByteChannel to write to. Must not be null.

blockSize - The block size (of raw data) to compress before writing frames to out. Must be in (0, 65536].

minCompressionRatio - Defines the minimum compression ratio ( compressedLength / rawLength) that must be achieved to write the compressed data. This must be in (0, 1.0].

Throws:

java.io.IOException

Since:

1.1.1

Method Detail

writeHeader

private void writeHeader(java.nio.channels.WritableByteChannel out)
                  throws java.io.IOException

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

Parameters:

out - The underlying OutputStream.

Throws:

java.io.IOException

isOpen

public boolean isOpen()

Specified by:

isOpen in interface java.nio.channels.Channel

write

public void write(int b)
           throws java.io.IOException

Specified by:

write in class java.io.OutputStream

Throws:

java.io.IOException

write

public void write(byte[] input,
                  int offset,
                  int length)
           throws java.io.IOException

Overrides:

write in class java.io.OutputStream

Throws:

java.io.IOException

write

public int write(java.nio.ByteBuffer src)
          throws java.io.IOException

Specified by:

write in interface java.nio.channels.WritableByteChannel

Throws:

java.io.IOException

transferFrom

public long transferFrom(java.io.InputStream is)
                  throws java.io.IOException

Transfers all the content from is to this OutputStream. This potentially limits the amount of buffering required to compress content.

Parameters:

is - The source of data to compress.

Returns:

The number of bytes read from is.

Throws:

java.io.IOException

Since:

1.1.1

transferFrom

public long transferFrom(java.nio.channels.ReadableByteChannel rbc)
                  throws java.io.IOException

Transfers all the content from rbc to this WritableByteChannel. This potentially limits the amount of buffering required to compress content.

Parameters:

rbc - The source of data to compress.

Returns:

The number of bytes read from rbc.

Throws:

java.io.IOException

Since:

1.1.1

flush

public final void flush()
                 throws java.io.IOException

Specified by:

flush in interface java.io.Flushable

Overrides:

flush in class java.io.OutputStream

Throws:

java.io.IOException

close

public final void close()
                 throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.nio.channels.Channel

Overrides:

close in class java.io.OutputStream

Throws:

java.io.IOException

flushBuffer

private void flushBuffer()
                  throws java.io.IOException

Compresses and writes out any buffered data. This does nothing if there is no currently buffered data.

Throws:

java.io.IOException

writeCompressed

private void writeCompressed(java.nio.ByteBuffer buffer)
                      throws java.io.IOException

SnappyFramed.maskedCrc32c(byte[], int, int) the crc, compresses the data, determines if the compression ratio is acceptable and calls writeBlock(java.nio.channels.WritableByteChannel, java.nio.ByteBuffer, boolean, int) to actually write the frame.

Parameters:

buffer -

Throws:

java.io.IOException

writeBlock

private void writeBlock(java.nio.channels.WritableByteChannel out,
                        java.nio.ByteBuffer data,
                        boolean compressed,
                        int crc32c)
                 throws java.io.IOException

Write a frame (block) to out.

Parameters:

out - The OutputStream to write to.

data - The data to write.

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