io.virtdata.libbasics.shared.from_long.to_int.SignedHash Maven / Gradle / Ivy

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With inspiration from other libraries

There is a newer version: 2.12.15

package io.virtdata.libbasics.shared.from_long.to_int;

import io.virtdata.annotations.ThreadSafeMapper;
import org.greenrobot.essentials.hash.Murmur3F;

import java.nio.ByteBuffer;
import java.util.function.LongToIntFunction;

@ThreadSafeMapper
public class SignedHash implements LongToIntFunction {

    ThreadLocal bb_TL = ThreadLocal.withInitial(() -> ByteBuffer.allocate(Long.BYTES));
    ThreadLocal murmur3f_TL = ThreadLocal.withInitial(Murmur3F::new);

    @Override
    public int applyAsInt(long value) {
        Murmur3F murmur3F = murmur3f_TL.get();
        ByteBuffer bb = bb_TL.get();
        murmur3F.reset();
        bb.putLong(0,value);
        murmur3F.update(bb.array(),0,Long.BYTES);
        long result= murmur3F.getValue();
        return (int) (result & Integer.MAX_VALUE);
    }
}