Class SnappyFramedOutputStream

java.lang.Object

java.io.OutputStream

org.xerial.snappy.SnappyFramedOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable, Channel, WritableByteChannel

public final class SnappyFramedOutputStream
extends OutputStream
implements WritableByteChannel

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

Since:

1.1.0

Field Summary

Fields

Modifier and Type	Field	Description
private final int	blockSize
private final ByteBuffer	buffer
private final BufferPool	bufferPool
private boolean	closed
private final Checksum	crc32
static final int	DEFAULT_BLOCK_SIZE	The default block size to use.
static final double	DEFAULT_MIN_COMPRESSION_RATIO	The default min compression ratio to use.
private final ByteBuffer	directInputBuffer
private final ByteBuffer	headerBuffer
static final int	MAX_BLOCK_SIZE	The x-snappy-framed specification allows for a chunk size up to 16,777,211 bytes in length.
private final double	minCompressionRatio
private final WritableByteChannel	out
private final ByteBuffer	outputBuffer

Constructor Summary

Constructors

Constructor	Description
SnappyFramedOutputStream(OutputStream out)	Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.
SnappyFramedOutputStream(OutputStream out, int blockSize, double minCompressionRatio)	Creates a new SnappyFramedOutputStream instance.
SnappyFramedOutputStream(OutputStream out, int blockSize, double minCompressionRatio, BufferPool bufferPool)	Creates a new SnappyFramedOutputStream instance.
SnappyFramedOutputStream(OutputStream out, BufferPool bufferPool)	Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.
SnappyFramedOutputStream(WritableByteChannel out)	Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.
SnappyFramedOutputStream(WritableByteChannel out, int blockSize, double minCompressionRatio)	Creates a new SnappyFramedOutputStream instance.
SnappyFramedOutputStream(WritableByteChannel out, int blockSize, double minCompressionRatio, BufferPool bufferPool)	Creates a new SnappyFramedOutputStream instance.
SnappyFramedOutputStream(WritableByteChannel out, BufferPool bufferPool)	Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.

Method Summary

Modifier and Type	Method	Description
final void	close()
final void	flush()
private void	flushBuffer()	Compresses and writes out any buffered data.
boolean	isOpen()
long	transferFrom(InputStream is)	Transfers all the content from is to this OutputStream.
long	transferFrom(ReadableByteChannel rbc)	Transfers all the content from rbc to this WritableByteChannel.
void	write(byte[] input, int offset, int length)
void	write(int b)
int	write(ByteBuffer src)
private void	writeBlock(WritableByteChannel out, ByteBuffer data, boolean compressed, int crc32c)	Write a frame (block) to out.
private void	writeCompressed(ByteBuffer buffer)	invalid reference 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(WritableByteChannel out)	Writes the implementation specific header or "marker bytes" to out.

Methods inherited from class OutputStream

nullOutputStream, write

Methods inherited from class Object

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

Field Details

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

crc32

private final Checksum crc32

headerBuffer

private final ByteBuffer headerBuffer

bufferPool

private final BufferPool bufferPool

blockSize

private final int blockSize

buffer

private final ByteBuffer buffer

directInputBuffer

private final ByteBuffer directInputBuffer

outputBuffer

private final ByteBuffer outputBuffer

minCompressionRatio

private final double minCompressionRatio

out

private final WritableByteChannel out

closed

private boolean closed

Constructor Details

SnappyFramedOutputStream

public SnappyFramedOutputStream(OutputStream out)
                         throws IOException

Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.

Uses DefaultPoolFactory to obtain BufferPool for buffers.

Parameters:

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

Throws:

IOException

SnappyFramedOutputStream

public SnappyFramedOutputStream(OutputStream out,
 BufferPool bufferPool)
                         throws 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.

bufferPool - Used to obtain buffer instances. Must not be null.

Throws:

IOException

SnappyFramedOutputStream

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

Creates a new SnappyFramedOutputStream instance.

Uses DefaultPoolFactory to obtain BufferPool for buffers.

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:

IOException

SnappyFramedOutputStream

public SnappyFramedOutputStream(OutputStream out,
 int blockSize,
 double minCompressionRatio,
 BufferPool bufferPool)
                         throws 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].

bufferPool - Used to obtain buffer instances. Must not be null.

Throws:

IOException

SnappyFramedOutputStream

public SnappyFramedOutputStream(WritableByteChannel out)
                         throws IOException

Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.

Uses DefaultPoolFactory to obtain BufferPool for buffers.

Parameters:

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

Throws:

IOException

Since:

1.1.1

SnappyFramedOutputStream

public SnappyFramedOutputStream(WritableByteChannel out,
 BufferPool bufferPool)
                         throws IOException

Creates a new SnappyFramedOutputStream using the DEFAULT_BLOCK_SIZE and DEFAULT_MIN_COMPRESSION_RATIO.

Uses DefaultPoolFactory to obtain BufferPool for buffers.

Parameters:

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

bufferPool - Used to obtain buffer instances. Must not be null.

Throws:

IOException

SnappyFramedOutputStream

public SnappyFramedOutputStream(WritableByteChannel out,
 int blockSize,
 double minCompressionRatio)
                         throws 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:

IOException

Since:

1.1.1

SnappyFramedOutputStream

public SnappyFramedOutputStream(WritableByteChannel out,
 int blockSize,
 double minCompressionRatio,
 BufferPool bufferPool)
                         throws 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].

bufferPool - Used to obtain buffer instances. Must not be null.

Throws:

IOException

Since:

1.1.1

Method Details

writeHeader

private void writeHeader(WritableByteChannel out)
                  throws IOException

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

Parameters:

out - The underlying OutputStream.

Throws:

IOException

isOpen

public boolean isOpen()

Specified by:

isOpen in interface Channel

write

public void write(int b)
           throws IOException

Specified by:

write in class OutputStream

Throws:

IOException

write

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

Overrides:

write in class OutputStream

Throws:

IOException

write

public int write(ByteBuffer src)
          throws IOException

Specified by:

write in interface WritableByteChannel

Throws:

IOException

transferFrom

public long transferFrom(InputStream is)
                  throws 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:

IOException

Since:

1.1.1

transferFrom

public long transferFrom(ReadableByteChannel rbc)
                  throws 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:

IOException

Since:

1.1.1

flush

public final void flush()
                 throws IOException

Specified by:

flush in interface Flushable

Overrides:

flush in class OutputStream

Throws:

IOException

close

public final void close()
                 throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Channel

Specified by:

close in interface Closeable

Overrides:

close in class OutputStream

Throws:

IOException

flushBuffer

private void flushBuffer()
                  throws IOException

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

Throws:

IOException

writeCompressed

private void writeCompressed(ByteBuffer buffer)
                      throws IOException

invalid reference

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:

IOException

writeBlock

private void writeBlock(WritableByteChannel out,
 ByteBuffer data,
 boolean compressed,
 int crc32c)
                 throws 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:

IOException