package com.ning.compress.lzf.util;
import com.ning.compress.lzf.ChunkDecoder;
import com.ning.compress.lzf.impl.VanillaChunkDecoder;
import com.ning.compress.lzf.impl.UnsafeChunkDecoder;
/**
* Simple helper class used for loading
* {@link ChunkDecoder} implementations, based on criteria
* such as "fastest available".
*<p>
* Yes, it looks butt-ugly, but does the job. Nonetheless, if anyone
* has lipstick for this pig, let me know.
*/
public class ChunkDecoderFactory
{
private final static ChunkDecoderFactory _instance;
static {
Class<?> impl = null;
try {
// first, try loading optimal one, which uses Sun JDK Unsafe...
impl = (Class<?>) Class.forName(UnsafeChunkDecoder.class.getName());
} catch (Throwable t) { }
if (impl == null) {
impl = VanillaChunkDecoder.class;
}
_instance = new ChunkDecoderFactory(impl);
}
private final Class<? extends ChunkDecoder> _implClass;
@SuppressWarnings("unchecked")
private ChunkDecoderFactory(Class<?> imp)
{
_implClass = (Class<? extends ChunkDecoder>) imp;
}
/*
///////////////////////////////////////////////////////////////////////
// Public API
///////////////////////////////////////////////////////////////////////
*/
/**
* Method to use for getting decoder instance that uses the most optimal
* available methods for underlying data access. It should be safe to call
* this method as implementations are dynamically loaded; however, on some
* non-standard platforms it may be necessary to either directly load
* instances, or use {@link #safeInstance()}.
*/
public static ChunkDecoder optimalInstance() {
try {
return _instance._implClass.newInstance();
} catch (Exception e) {
throw new IllegalStateException("Failed to load a ChunkDecoder instance ("+e.getClass().getName()+"): "
+e.getMessage(), e);
}
}
/**
* Method that can be used to ensure that a "safe" decoder instance is loaded.
* Safe here means that it should work on any and all Java platforms.
*/
public static ChunkDecoder safeInstance() {
// this will always succeed loading; no need to use dynamic class loading or instantiation
return new VanillaChunkDecoder();
}
}