ArrayNullFillBench.java

import org.openjdk.jmh.annotations.*;
import sun.misc.Unsafe;
import sun.nio.ch.DirectBuffer;

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.nio.ByteBuffer;
import java.nio.LongBuffer;
import java.util.Arrays;
import java.util.concurrent.TimeUnit;

@State(Scope.Benchmark)
public class ArrayNullFillBench {

    private final int size = 100;                                                                                                                                                                          ;

    public Object[] objectHolderForFill = new Object[size];
    public Object[] objectHolderForArrayCopy = new Object[size];
    public Object[] nullsArray = new Object[size];
    public byte[] nullBytes = new byte[size*8];
    public long[] nullLongs = new long[size];

    public ByteBuffer referenceHolderByteBuffer = ByteBuffer.allocateDirect(size*8);
    public LongBuffer referenceHolderLongBuffer = allocateDirectLongBuffer(size);
    long referenceHolderUnsafe = unsafe.allocateMemory(size*8);

    private static Unsafe unsafe = getUnsafe();

    private static Unsafe getUnsafe() {
        try {
            Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
            theUnsafe.setAccessible(true);
            return (Unsafe) theUnsafe.get(null);
        } catch (Exception e) {
            throw new AssertionError(e);
        }
    }

    public static LongBuffer allocateDirectLongBuffer(int capacity) {
        final ByteBuffer db = ByteBuffer.allocateDirect(capacity*8);
        try {
            Class<? extends LongBuffer> directLongBufferUClazz = (Class<? extends LongBuffer>) Class.forName("java.nio.DirectLongBufferU");
            Constructor<? extends LongBuffer>  constructor = (Constructor<? extends LongBuffer>) directLongBufferUClazz.getDeclaredConstructors()[0];
            constructor.setAccessible(true);
            return constructor.newInstance((DirectBuffer) db, -1, 0, capacity, capacity, 0);
        } catch (ClassNotFoundException | InstantiationException | InvocationTargetException | IllegalAccessException e) {
            throw new AssertionError(e);
        }
    }

    @Setup(Level.Invocation)
    public void fillArrays() {
        Arrays.fill(objectHolderForFill, new Object());
        Arrays.fill(objectHolderForArrayCopy, new Object());
        long addr = referenceHolderUnsafe;
        long pos = 0;
        referenceHolderLongBuffer.clear();
        referenceHolderByteBuffer.clear();
        for (int i = 0; i < size; i++) {
            referenceHolderByteBuffer.putLong(1L);
            referenceHolderLongBuffer.put(1L);
            unsafe.putLong(addr + (pos << 0), 1L);
            pos += 1 << 3;
        }
        referenceHolderByteBuffer.clear();
        referenceHolderLongBuffer.clear();
    }

    @Benchmark
    @BenchmarkMode(Mode.SampleTime)
    @OutputTimeUnit(TimeUnit.NANOSECONDS)
    public void arrayFill() {
        Arrays.fill(objectHolderForFill, null);
    }

    @Benchmark
    @BenchmarkMode(Mode.SampleTime)
    @OutputTimeUnit(TimeUnit.NANOSECONDS)
    public void arrayCopy() {
        System.arraycopy(nullsArray, 0, objectHolderForArrayCopy, 0, objectHolderForArrayCopy.length);
    }

    @Benchmark
    @BenchmarkMode(Mode.SampleTime)
    @OutputTimeUnit(TimeUnit.NANOSECONDS)
    public void directByteBufferManualLoop() {
        while (referenceHolderByteBuffer.hasRemaining()) {
            referenceHolderByteBuffer.putLong(0);
        }
    }

    @Benchmark
    @BenchmarkMode(Mode.SampleTime)
    @OutputTimeUnit(TimeUnit.NANOSECONDS)
    public void directByteBufferBatch() {
        referenceHolderByteBuffer.put(nullBytes, 0, nullBytes.length);
    }

    @Benchmark
    @BenchmarkMode(Mode.SampleTime)
    @OutputTimeUnit(TimeUnit.NANOSECONDS)
    public void directLongBufferManualLoop() {
        while (referenceHolderLongBuffer.hasRemaining()) {
            referenceHolderLongBuffer.put(0L);
        }
    }

    @Benchmark
    @BenchmarkMode(Mode.SampleTime)
    @OutputTimeUnit(TimeUnit.NANOSECONDS)
    public void directLongBufferBatch() {
        referenceHolderLongBuffer.put(nullLongs, 0, nullLongs.length);
    }


    @Benchmark
    @BenchmarkMode(Mode.SampleTime)
    @OutputTimeUnit(TimeUnit.NANOSECONDS)
    public void unsafeArrayManualLoop() {
        long addr = referenceHolderUnsafe;
        long pos = 0;
        for (int i = 0; i < size; i++) {
            unsafe.putLong(addr + pos, 0L);
            pos += 1 << 3;
        }
    }

    @Benchmark
    @BenchmarkMode(Mode.SampleTime)
    @OutputTimeUnit(TimeUnit.NANOSECONDS)
    public void unsafeArraySetMemory() {
        unsafe.setMemory(referenceHolderUnsafe, size*8, (byte) 0);
    }

}