Package com.github.luben.zstd

Class ZstdCompressCtx

java.lang.Object

com.github.luben.zstd.ZstdCompressCtx

All Implemented Interfaces:

java.io.Closeable

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.
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.
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	setLevel(int level)	Set compression level
ZstdCompressCtx	setLong(int windowLog)	Enable or disable LongDistanceMatching and set the window size

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: 3

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

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 then 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

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.io.Closeable