net.jpountz.lz4

Class LZ4Factory

java.lang.Object

net.jpountz.lz4.LZ4Factory

public final class LZ4Factory
extends java.lang.Object

Entry point for the LZ4 API.

This class has 3 instances

• a native instance which is a JNI binding to the original LZ4 C implementation.
• a safe Java instance which is a pure Java port of the original C library,
• an unsafe Java instance which is a Java port using the unofficial Unsafe API.

Only the safe instance is guaranteed to work on your JVM, as a consequence it is advised to use the fastestInstance() or fastestJavaInstance() to pull a LZ4Factory instance.

All methods from this class are very costly, so you should get an instance once, and then reuse it whenever possible. This is typically done by storing a LZ4Factory instance in a static field.

Method Summary

Modifier and Type	Method and Description
LZ4Decompressor	decompressor() Deprecated. use fastDecompressor()
LZ4Compressor	fastCompressor() Return a blazing fast LZ4Compressor.
LZ4FastDecompressor	fastDecompressor() Return a LZ4FastDecompressor instance.
static LZ4Factory	fastestInstance() Return the fastest available LZ4Factory instance.
static LZ4Factory	fastestJavaInstance() Return the fastest available LZ4Factory instance which does not rely on JNI bindings.
LZ4Compressor	highCompressor() Return a LZ4Compressor which requires more memory than fastCompressor() and is slower but compresses more efficiently.
LZ4Compressor	highCompressor(int compressionLevel) Return a LZ4Compressor which requires more memory than fastCompressor() and is slower but compresses more efficiently.
static void	main(java.lang.String[] args) Prints the fastest instance.
static LZ4Factory	nativeInstance() Return a LZ4Factory instance that returns compressors and decompressors that are native bindings to the original C library.
LZ4SafeDecompressor	safeDecompressor() Return a LZ4SafeDecompressor instance.
static LZ4Factory	safeInstance() Return a LZ4Factory instance that returns compressors and decompressors that are written with Java's official API.
java.lang.String	toString()
LZ4UnknownSizeDecompressor	unknownSizeDecompressor() Deprecated. use safeDecompressor()
static LZ4Factory	unsafeInstance() Return a LZ4Factory instance that returns compressors and decompressors that may use Unsafe to speed up compression and decompression.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Detail

nativeInstance

public static LZ4Factory nativeInstance()

Return a LZ4Factory instance that returns compressors and decompressors that are native bindings to the original C library.

Please note that this instance has some traps you should be aware of:

1. Upon loading this instance, files will be written to the temporary directory of the system. Although these files are supposed to be deleted when the JVM exits, they might remain on systems that don't support removal of files being used such as Windows.
2. The instance can only be loaded once per JVM. This can be a problem if your application uses multiple class loaders (such as most servlet containers): this instance will only be available to the children of the class loader which has loaded it. As a consequence, it is advised to either not use this instance in webapps or to put this library in the lib directory of your servlet container so that it is loaded by the system class loader.

safeInstance

public static LZ4Factory safeInstance()

Return a LZ4Factory instance that returns compressors and decompressors that are written with Java's official API.

unsafeInstance

public static LZ4Factory unsafeInstance()

Return a LZ4Factory instance that returns compressors and decompressors that may use Unsafe to speed up compression and decompression.

fastestJavaInstance

public static LZ4Factory fastestJavaInstance()

Return the fastest available LZ4Factory instance which does not rely on JNI bindings. It first tries to load the unsafe instance, and then the safe Java instance if the JVM doesn't have a working Unsafe.

fastestInstance

public static LZ4Factory fastestInstance()

Return the fastest available LZ4Factory instance. If the class loader is the system class loader and if the native instance loads successfully, then the native instance is returned, otherwise the fastest Java instance is returned.

Please read javadocs of nativeInstance() before using this method.

fastCompressor

public LZ4Compressor fastCompressor()

Return a blazing fast LZ4Compressor.

highCompressor

public LZ4Compressor highCompressor()

Return a LZ4Compressor which requires more memory than fastCompressor() and is slower but compresses more efficiently.

highCompressor

public LZ4Compressor highCompressor(int compressionLevel)

Return a LZ4Compressor which requires more memory than fastCompressor() and is slower but compresses more efficiently. The compression level can be customized.

For current implementations, the following is true about compression level:

1. It should be in range [1, 17]
2. A compression level higher than 17 would be treated as 17.
3. A compression level lower than 1 would be treated as 9.

fastDecompressor

public LZ4FastDecompressor fastDecompressor()

Return a LZ4FastDecompressor instance.

safeDecompressor

public LZ4SafeDecompressor safeDecompressor()

Return a LZ4SafeDecompressor instance.

unknownSizeDecompressor

public LZ4UnknownSizeDecompressor unknownSizeDecompressor()

Deprecated. use safeDecompressor()

Return a LZ4UnknownSizeDecompressor instance.

decompressor

public LZ4Decompressor decompressor()

Deprecated. use fastDecompressor()

Return a LZ4Decompressor instance.

main

public static void main(java.lang.String[] args)

Prints the fastest instance.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object