io.virtdata.int_int.Hash Maven / Gradle / Ivy
package io.virtdata.int_int;
import de.greenrobot.common.hash.Murmur3F;
import java.nio.ByteBuffer;
import java.util.function.IntUnaryOperator;
/**
* This uses the Murmur3F (64-bit optimized) version of Murmur3,
* not as a checksum, but as a simple hash. It doesn't bother
* pushing the high-64 bits of input, since it only uses the lower
* 64 bits of output. It does, however, return the absolute value.
* This is to make it play nice with users and other libraries.
*/
public class Hash implements IntUnaryOperator {
private ThreadLocal tlbb = new ThreadLocal() {
@Override
protected ByteBuffer initialValue() {
return ByteBuffer.allocate(Long.BYTES);
}
};
private Murmur3F murmur3F= new Murmur3F();
@Override
public int applyAsInt(int operand) {
ByteBuffer bb = tlbb.get();
murmur3F.reset();
bb.putInt(0,operand);
bb.putInt(4,operand);
bb.position(0);
murmur3F.update(bb.array());
long result= Math.abs(murmur3F.getValue());
return (int) result & Integer.MAX_VALUE;
}
}