JNI array access benchmark

natives.c

#include <jni.h>

static int sum(jbyte* array, int length) {
    int result = 0;
    int i;
    for (i = 0; i < length; i++) {
        result += array[i];
    }
    return result;
}

JNIEXPORT jint JNICALL
Java_bench_Natives_arrayRegionImpl(JNIEnv* env, jclass cls, jbyteArray array) {
    static jbyte buf[1048576];
    jint length = (*env)->GetArrayLength(env, array);
    (*env)->GetByteArrayRegion(env, array, 0, length, buf);
    return sum(buf, length);
}

JNIEXPORT jint JNICALL
Java_bench_Natives_arrayElementsImpl(JNIEnv* env, jclass cls, jbyteArray array) {
    jboolean isCopy;
    jint length = (*env)->GetArrayLength(env, array);
    jbyte* buf = (*env)->GetByteArrayElements(env, array, &isCopy);
    jint result = sum(buf, length);
    (*env)->ReleaseByteArrayElements(env, array, buf, JNI_ABORT);
    return result;
}

JNIEXPORT jint JNICALL
Java_bench_Natives_arrayElementsCriticalImpl(JNIEnv* env, jclass cls, jbyteArray array) {
    jboolean isCopy;
    jint length = (*env)->GetArrayLength(env, array);
    jbyte* buf = (jbyte*) (*env)->GetPrimitiveArrayCritical(env, array, &isCopy);
    jint result = sum(buf, length);
    (*env)->ReleasePrimitiveArrayCritical(env, array, buf, JNI_ABORT);
    return result;
}

JNIEXPORT jint JNICALL
Java_bench_Natives_javaCriticalImpl(JNIEnv* env, jclass cls, jbyteArray array) {
    return Java_bench_Natives_arrayElementsCriticalImpl(env, cls, array);
}

JNIEXPORT jint JNICALL
JavaCritical_bench_Natives_javaCriticalImpl(jint length, jbyte* buf) {
    return sum(buf, length);
}

Natives.java

package bench;

import org.openjdk.jmh.annotations.*;

@State(Scope.Benchmark)
public class Natives {
    byte[] array;

    @Param({"16", "256", "4096", "65536", "1048576"})
    int length;

    @Setup
    public void setup() {
        array = new byte[length];
    }

    @Benchmark
    public int arrayRegion() {
        return arrayRegionImpl(array);
    }

    @Benchmark
    public int arrayElements() {
        return arrayElementsImpl(array);
    }

    @Benchmark
    public int arrayElementsCritical() {
        return arrayElementsCriticalImpl(array);
    }

    @Benchmark
    public int javaCritical() {
        return javaCriticalImpl(array);
    }

    static native int arrayRegionImpl(byte[] array);
    static native int arrayElementsImpl(byte[] array);
    static native int arrayElementsCriticalImpl(byte[] array);
    static native int javaCriticalImpl(byte[] array);

    static {
        System.loadLibrary("natives");
    }
}