vyazelenko

import static org.junit.Assert.*;
import static org.hamcrest.CoreMatchers.*;

import java.io.File;
import java.io.IOException;

import org.junit.Test;
import org.junit.rules.TemporaryFolder;

public class TemporaryFolderTest {

vyazelenko

public static void copyFieldByField(Object src, Object dest) {
    copyFields(src, dest, src.getClass());
}

private static void copyFields(Object src, Object dest, Class<?> klass) {
    Field[] fields = klass.getDeclaredFields();
    for (Field f : fields) {
        f.setAccessible(true);
        copyFieldValue(src, dest, f);
    }

vyazelenko

@GenerateMicroBenchmark
public Object copyFieldByFieldGetFieldsEveryTime() {
    return FieldsCopy.INSTANCE.copy();
}

@GenerateMicroBenchmark
public Object copyFieldByFieldUseCacheFields() {
    return CachedFieldsCopy.INSTANCE.copy();
}

vyazelenko

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;

class Base {
    int x = 13;
}

class Derived extends Base {
    public long m;
}

vyazelenko

private static MethodHandle prepareGetter(MethodHandle mh) {
  return mh.asType(mh.type().changeParameterType(0, Object.class)
    .changeReturnType(Object.class));
}

private static MethodHandle prepareSetter(MethodHandle mh) {
  return mh.asType(mh.type().changeParameterType(0, Object.class)
    .changeParameterType(1, Object.class));
}

vyazelenko

package com.vyazelenko.blog.copyobject.primitives.clone;

import com.vyazelenko.blog.copyobject.primitives.BaseClass;

public class CloneCopy extends BaseClass implements Cloneable {
    public static final CloneCopy INSTANCE;

    static {
        INSTANCE = new CloneCopy();
        INSTANCE.init();

vyazelenko

package com.vyazelenko.blog.copyobject.primitives.constructor;

import com.vyazelenko.blog.copyobject.primitives.BaseClass;

public class ConstructorCopy extends BaseClass implements Cloneable {
    public static final ConstructorCopy INSTANCE;

    static {
        INSTANCE = new ConstructorCopy();
        INSTANCE.init();

vyazelenko

package com.vyazelenko.blog.copyobject.primitives;

import com.vyazelenko.blog.copyobject.Copyable;
import com.vyazelenko.blog.copyobject.HashUtils;

abstract class Root implements Copyable {
    private int field1;
    private char field2;
    public boolean field6;
    byte abc;

vyazelenko

/*
 * Defined in the hotspot/src/share/vm/classfile/vmSymbols.hpp
 */

#define VM_SYMBOLS_DO(template, do_alias)                                                         \
  /* commonly used class names */                                                                 \
  template(java_lang_System,                          "java/lang/System")                         \
  template(java_lang_Object,                          "java/lang/Object")                         \
...

vyazelenko

java -XX:+PrintCompilation com.vyazelenko.blog.copyobject.TestClone
     59    1             java.lang.String::hashCode (55 bytes)
     61    2             java.lang.String::indexOf (70 bytes)
     69    3             sun.nio.cs.UTF_8$Encoder::encode (361 bytes)
     77    4             java.util.ArrayList::add (29 bytes)
     77    5             java.util.ArrayList::ensureCapacityInternal (23 bytes)
     77    7     n       java.lang.Object::clone (native)   
     78    6             java.util.ArrayList::ensureExplicitCapacity (26 bytes)
     78    8             com.vyazelenko.blog.copyobject.TestClone::callCopy (7 bytes)
     78    9             com.vyazelenko.blog.copyobject.primitives.clone.CloneCopy::copy (5 bytes)