Package com.github.luben.zstd

Class ZstdCompressCtx

java.lang.Object

com.github.luben.zstd.ZstdCompressCtx

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class ZstdCompressCtx
extends java.lang.Object

Constructor Summary

Constructors

Constructor	Description
ZstdCompressCtx()	Create a context for faster compress operations One such context is required for each thread - put this in a ThreadLocal.

Method Summary

Modifier and Type	Method	Description
void	close()
byte[]	compress(byte[] src)
int	compress(byte[] dst, byte[] src)
java.nio.ByteBuffer	compress(java.nio.ByteBuffer srcBuf)	Compresses the data in buffer 'srcBuf'
int	compress(java.nio.ByteBuffer dstBuf, java.nio.ByteBuffer srcBuf)	Compresses the data in buffer 'srcBuf'
int	compressByteArray(byte[] dstBuff, int dstOffset, int dstSize, byte[] srcBuff, int srcOffset, int srcSize)	Compresses byte array 'srcBuff' into byte array 'dstBuff' reusing this ZstdCompressCtx.
int	compressDirectByteBuffer(java.nio.ByteBuffer dstBuff, int dstOffset, int dstSize, java.nio.ByteBuffer srcBuff, int srcOffset, int srcSize)	Compresses buffer 'srcBuff' into buffer 'dstBuff' reusing this ZstdCompressCtx.
boolean	compressDirectByteBufferStream(java.nio.ByteBuffer dst, java.nio.ByteBuffer src, EndDirective endOp)	Compress as much of the src ByteBuffer into the dst ByteBuffer as possible.
ZstdFrameProgression	getFrameProgression()	Tells how much data has been ingested (read from input), consumed (input actually compressed) and produced (output) for current frame.
ZstdCompressCtx	loadDict(byte[] dict)	Load compression dictionary to be used for subsequently compressed frames.
ZstdCompressCtx	loadDict(ZstdDictCompress dict)	Load compression dictionary to be used for subsequently compressed frames.
void	reset()	Clear all state and parameters from the compression context.
ZstdCompressCtx	setChainLog(int chainLog)
ZstdCompressCtx	setChecksum(boolean checksumFlag)	Enable or disable compression checksums
ZstdCompressCtx	setContentSize(boolean contentSizeFlag)	Enable or disable content size
ZstdCompressCtx	setDictID(boolean dictIDFlag)	Enable or disable dictID
ZstdCompressCtx	setHashLog(int hashLog)
ZstdCompressCtx	setJobSize(int jobSize)
ZstdCompressCtx	setLevel(int level)	Set compression level
ZstdCompressCtx	setLong(int windowLog)	Enable or disable LongDistanceMatching and set the window size
ZstdCompressCtx	setMagicless(boolean magiclessFlag)	Enable or disable magicless frames
ZstdCompressCtx	setMinMatch(int minMatch)
ZstdCompressCtx	setOverlapLog(int overlapLog)
void	setPledgedSrcSize(long srcSize)	Promise to compress a certain number of source bytes.
ZstdCompressCtx	setSearchLog(int searchLog)
ZstdCompressCtx	setStrategy(int strategy)
ZstdCompressCtx	setTargetLength(int targetLength)
ZstdCompressCtx	setWindowLog(int windowLog)
ZstdCompressCtx	setWorkers(int workers)

Methods inherited from class java.lang.Object

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

Constructor Detail

ZstdCompressCtx

public ZstdCompressCtx()

Create a context for faster compress operations One such context is required for each thread - put this in a ThreadLocal.

Method Detail

setLevel

public ZstdCompressCtx setLevel(int level)

Set compression level

Parameters:

level - compression level, default: Zstd.defaultCompressionLevel()

setMagicless

public ZstdCompressCtx setMagicless(boolean magiclessFlag)

Enable or disable magicless frames

Parameters:

magiclessFlag - A 32-bits magic number is written at start of frame, default: false

setChecksum

public ZstdCompressCtx setChecksum(boolean checksumFlag)

Enable or disable compression checksums

Parameters:

checksumFlag - A 32-bits checksum of content is written at end of frame, default: false

setWorkers

public ZstdCompressCtx setWorkers(int workers)

setOverlapLog

public ZstdCompressCtx setOverlapLog(int overlapLog)

setJobSize

public ZstdCompressCtx setJobSize(int jobSize)

setTargetLength

public ZstdCompressCtx setTargetLength(int targetLength)

setMinMatch

public ZstdCompressCtx setMinMatch(int minMatch)

setSearchLog

public ZstdCompressCtx setSearchLog(int searchLog)

setChainLog

public ZstdCompressCtx setChainLog(int chainLog)

setHashLog

public ZstdCompressCtx setHashLog(int hashLog)

setWindowLog

public ZstdCompressCtx setWindowLog(int windowLog)

setStrategy

public ZstdCompressCtx setStrategy(int strategy)

setContentSize

public ZstdCompressCtx setContentSize(boolean contentSizeFlag)

Enable or disable content size

Parameters:

contentSizeFlag - Content size will be written into frame header _whenever known_, default: true

setDictID

public ZstdCompressCtx setDictID(boolean dictIDFlag)

Enable or disable dictID

Parameters:

dictIDFlag - When applicable, dictionary's ID is written into frame header, default: true

setLong

public ZstdCompressCtx setLong(int windowLog)

Enable or disable LongDistanceMatching and set the window size

Parameters:

windowLog - Maximum allowed back-reference distance, expressed as power of 2. This will set a memory budget for streaming decompression, with larger values requiring more memory and typically compressing more. Must be clamped between 10 and 32/64 but values greater than 27 may not be decompressable in all context as they require more memory. 0 disables LDM.

loadDict

public ZstdCompressCtx loadDict(ZstdDictCompress dict)

Load compression dictionary to be used for subsequently compressed frames.

Parameters:

dict - the dictionary or `null` to remove loaded dictionary

loadDict

public ZstdCompressCtx loadDict(byte[] dict)

Load compression dictionary to be used for subsequently compressed frames.

Parameters:

dict - the dictionary or `null` to remove loaded dictionary

getFrameProgression

public ZstdFrameProgression getFrameProgression()

Tells how much data has been ingested (read from input), consumed (input actually compressed) and produced (output) for current frame.

reset

public void reset()

Clear all state and parameters from the compression context. This leaves the object in a state identical to a newly created compression context.

setPledgedSrcSize

public void setPledgedSrcSize(long srcSize)

Promise to compress a certain number of source bytes. Knowing the number of bytes to compress up front helps to choose proper compression settings and size internal buffers. Additionally, the pledged size is stored in the header of the output stream, allowing decompressors to know how much uncompressed data to expect. Attempting to compress more or less than the pledged size will result in an error.

compressDirectByteBufferStream

public boolean compressDirectByteBufferStream(java.nio.ByteBuffer dst,
                                              java.nio.ByteBuffer src,
                                              EndDirective endOp)

Compress as much of the src ByteBuffer into the dst ByteBuffer as possible.

Parameters:

dst - destination of compressed data

src - buffer to compress

endOp - directive for handling the end of the stream

Returns:

true if all state has been flushed from internal buffers

compressDirectByteBuffer

public int compressDirectByteBuffer(java.nio.ByteBuffer dstBuff,
                                    int dstOffset,
                                    int dstSize,
                                    java.nio.ByteBuffer srcBuff,
                                    int srcOffset,
                                    int srcSize)

Compresses buffer 'srcBuff' into buffer 'dstBuff' reusing this ZstdCompressCtx. Destination buffer should be sized to handle worst cases situations (input data not compressible). Worst case size evaluation is provided by function ZSTD_compressBound(). This is a low-level function that does not take into account or affect the `limit` or `position` of source or destination buffers.

Parameters:

dstBuff - the destination buffer - must be direct

dstOffset - the start offset of 'dstBuff'

dstSize - the size of 'dstBuff' (after 'dstOffset')

srcBuff - the source buffer - must be direct

srcOffset - the start offset of 'srcBuff'

srcSize - the length of 'srcBuff' (after 'srcOffset')

Returns:

the number of bytes written into buffer 'dstBuff'.

compressByteArray

public int compressByteArray(byte[] dstBuff,
                             int dstOffset,
                             int dstSize,
                             byte[] srcBuff,
                             int srcOffset,
                             int srcSize)

Compresses byte array 'srcBuff' into byte array 'dstBuff' reusing this ZstdCompressCtx. Destination buffer should be sized to handle worst cases situations (input data not compressible). Worst case size evaluation is provided by function ZSTD_compressBound().

Parameters:

dstBuff - the destination buffer (byte array)

dstOffset - the start offset of 'dstBuff'

dstSize - the size of 'dstBuff' (after 'dstOffset')

srcBuff - the source buffer (byte array)

srcOffset - the start offset of 'srcBuff'

srcSize - the length of 'srcBuff' (after 'srcOffset')

Returns:

the number of bytes written into buffer 'dstBuff'.

compress

public int compress(java.nio.ByteBuffer dstBuf,
                    java.nio.ByteBuffer srcBuf)

Compresses the data in buffer 'srcBuf'

Parameters:

dstBuf - the destination buffer - must be direct. It is assumed that the `position()` of this buffer marks the offset at which the compressed data are to be written, and that the `limit()` of this buffer is the maximum compressed data size to allow.

When this method returns successfully, its `position()` will be set to its current `position()` plus the compressed size of the data.

srcBuf - the source buffer - must be direct. It is assumed that the `position()` of this buffer marks the beginning of the uncompressed data to be compressed, and that the `limit()` of this buffer marks its end.

When this method returns successfully, its `position()` will be set to the initial `limit()`.

Returns:

the size of the compressed data

compress

public java.nio.ByteBuffer compress(java.nio.ByteBuffer srcBuf)
                             throws ZstdException

Compresses the data in buffer 'srcBuf'

Parameters:

srcBuf - the source buffer - must be direct. It is assumed that the `position()` of the buffer marks the beginning of the uncompressed data to be compressed, and that the `limit()` of this buffer marks its end.

When this method returns successfully, its `position()` will be set to its initial `limit()`.

Returns:

A newly allocated direct ByteBuffer containing the compressed data.

Throws:

ZstdException

compress

public int compress(byte[] dst,
                    byte[] src)

compress

public byte[] compress(byte[] src)

close

public void close()

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable