Package net.jpountz.lz4

Class LZ4Compressor

java.lang.Object

net.jpountz.lz4.LZ4Compressor

public abstract class LZ4Compressor
extends Object

LZ4 compressor.

Instances of this class are thread-safe.

Constructor Summary

Constructors

Constructor	Description
LZ4Compressor()

Method Summary

Modifier and Type	Method	Description
final byte[]	compress(byte[] src)	Convenience method, equivalent to calling compress(src, 0, src.length).
final int	compress(byte[] src, byte[] dest)	Convenience method, equivalent to calling compress(src, 0, src.length, dest, 0).
final byte[]	compress(byte[] src, int srcOff, int srcLen)	Convenience method which returns src[srcOff:srcOff+srcLen] compressed.
final int	compress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff)	Convenience method, equivalent to calling compress(src, srcOff, srcLen, dest, destOff, dest.length - destOff).
abstract int	compress(byte[] src, int srcOff, int srcLen, byte[] dest, int destOff, int maxDestLen)	Compresses src[srcOff:srcOff+srcLen] into dest[destOff:destOff+maxDestLen] and returns the compressed length.
abstract int	compress(ByteBuffer src, int srcOff, int srcLen, ByteBuffer dest, int destOff, int maxDestLen)	Compresses src[srcOff:srcOff+srcLen] into dest[destOff:destOff+maxDestLen] and returns the compressed length.
final void	compress(ByteBuffer src, ByteBuffer dest)	Compresses src into dest.
final int	maxCompressedLength(int length)	Returns the maximum compressed length for an input of size length.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Details

LZ4Compressor

public LZ4Compressor()

Method Details

maxCompressedLength

public final int maxCompressedLength(int length)

Returns the maximum compressed length for an input of size length.

Parameters:

length - the input size in bytes

Returns:

the maximum compressed length in bytes

compress

public abstract int compress(byte[] src,
 int srcOff,
 int srcLen,
 byte[] dest,
 int destOff,
 int maxDestLen)

Compresses src[srcOff:srcOff+srcLen] into dest[destOff:destOff+maxDestLen] and returns the compressed length. This method will throw a LZ4Exception if this compressor is unable to compress the input into less than maxDestLen bytes. To prevent this exception to be thrown, you should make sure that maxDestLen >= maxCompressedLength(srcLen).

Parameters:

src - the source data

srcOff - the start offset in src

srcLen - the number of bytes to compress

dest - the destination buffer

destOff - the start offset in dest

maxDestLen - the maximum number of bytes to write in dest

Returns:

the compressed size

Throws:

LZ4Exception - if maxDestLen is too small

compress

public abstract int compress(ByteBuffer src,
 int srcOff,
 int srcLen,
 ByteBuffer dest,
 int destOff,
 int maxDestLen)

Compresses src[srcOff:srcOff+srcLen] into dest[destOff:destOff+maxDestLen] and returns the compressed length. This method will throw a LZ4Exception if this compressor is unable to compress the input into less than maxDestLen bytes. To prevent this exception to be thrown, you should make sure that maxDestLen >= maxCompressedLength(srcLen). ByteBuffer positions remain unchanged.

Parameters:

src - the source data

srcOff - the start offset in src

srcLen - the number of bytes to compress

dest - the destination buffer

destOff - the start offset in dest

maxDestLen - the maximum number of bytes to write in dest

Returns:

the compressed size

Throws:

LZ4Exception - if maxDestLen is too small

compress

public final int compress(byte[] src,
 int srcOff,
 int srcLen,
 byte[] dest,
 int destOff)

Convenience method, equivalent to calling compress(src, srcOff, srcLen, dest, destOff, dest.length - destOff).

Parameters:

src - the source data

srcOff - the start offset in src

srcLen - the number of bytes to compress

dest - the destination buffer

destOff - the start offset in dest

Returns:

the compressed size

Throws:

LZ4Exception - if dest is too small

compress

public final int compress(byte[] src,
 byte[] dest)

Convenience method, equivalent to calling compress(src, 0, src.length, dest, 0).

Parameters:

src - the source data

dest - the destination buffer

Returns:

the compressed size

Throws:

LZ4Exception - if dest is too small

compress

public final byte[] compress(byte[] src,
 int srcOff,
 int srcLen)

Convenience method which returns src[srcOff:srcOff+srcLen] compressed.

Warning: this method has an important overhead due to the fact that it needs to allocate a buffer to compress into, and then needs to resize this buffer to the actual compressed length.

Here is how this method is implemented:

 final int maxCompressedLength = maxCompressedLength(srcLen);
 final byte[] compressed = new byte[maxCompressedLength];
 final int compressedLength = compress(src, srcOff, srcLen, compressed, 0);
 return Arrays.copyOf(compressed, compressedLength);
 

Parameters:

src - the source data

srcOff - the start offset in src

srcLen - the number of bytes to compress

Returns:

the compressed data

compress

public final byte[] compress(byte[] src)

Convenience method, equivalent to calling compress(src, 0, src.length).

Parameters:

src - the source data

Returns:

the compressed data

compress

public final void compress(ByteBuffer src,
 ByteBuffer dest)

Compresses src into dest. Calling this method will update the positions of both ByteBuffers.

Parameters:

src - the source data

dest - the destination buffer

Throws:

LZ4Exception - if dest is too small

toString

public String toString()

Overrides:

toString in class Object