Remove MagicAccessor, add MethodHandle - upgrade to JDK 24+

[PRIESt512]

Background

After the removal of MagicAccessorImpl, a replacement is needed to make serialization work in newer versions of Java.
A MethodHandle-based replacement was chosen as an alternative.

For BigDecimal the following classes are generated:

public final class Delegate0_BigDecimal implements Delegate {
    private final Map fields;
    private static final MethodHandle WRITE_OBJECT__VOID_MH;
    private static final MethodHandle READ_OBJECT__VOID_MH;
    private static final MethodHandle INTVAL_GET_BIGINTEGER_MH;
    private static final MethodHandle INTVAL_SET_BIGINTEGER_MH;
    private static final MethodHandle SCALE_GET_INT_MH;
    private static final MethodHandle SCALE_SET_INT_MH;

    public Delegate0_BigDecimal(Map var1) {
        this.fields = var1;
    }

    static {
        try {
            MethodHandles.Lookup var0 = MethodHandles.privateLookupIn(BigDecimal.class, MethodHandles.lookup());
            WRITE_OBJECT__VOID_MH = var0.findVirtual(BigDecimal.class, "writeObject", MethodHandlesReflection.findMethodTypeForWriteObject());
            READ_OBJECT__VOID_MH = var0.findVirtual(BigDecimal.class, "readObject", MethodHandlesReflection.findMethodTypeForReadObject());
            Field var2 = BigDecimal.class.getDeclaredField("intVal");
            var2.setAccessible(true);
            INTVAL_SET_BIGINTEGER_MH = var0.unreflectSetter(var2);
            INTVAL_GET_BIGINTEGER_MH = var0.unreflectGetter(var2);
            var2 = BigDecimal.class.getDeclaredField("scale");
            var2.setAccessible(true);
            SCALE_SET_INT_MH = var0.unreflectSetter(var2);
            SCALE_GET_INT_MH = var0.unreflectGetter(var2);
        } catch (ReflectiveOperationException var3) {
            throw new ExceptionInInitializerError(var3);
        } catch (Throwable var4) {
            throw new RuntimeException(var4);
        }
    }

    public final void calcSize(Object var1, CalcSizeStream var2) throws IOException {
        try {
            BigDecimal var5 = (BigDecimal)var1;
            WRITE_OBJECT__VOID_MH.invokeExact(var5, NullObjectOutputStream.INSTANCE);
            var2.writeObject(INTVAL_GET_BIGINTEGER_MH.invokeExact(var5));
            var2.count += 4;
        } catch (Throwable var4) {
            throw new RuntimeException(var4);
        }
    }

    public final void write(Object var1, DataStream var2) throws IOException {
        try {
            BigDecimal var5 = (BigDecimal)var1;
            WRITE_OBJECT__VOID_MH.invokeExact(var5, NullObjectOutputStream.INSTANCE);
            var2.writeObject(INTVAL_GET_BIGINTEGER_MH.invokeExact(var5));
            var2.writeInt(SCALE_GET_INT_MH.invokeExact(var5));
        } catch (Throwable var4) {
            throw new RuntimeException(var4);
        }
    }

    public final Object read(DataStream var1) throws IOException, ClassNotFoundException {
        try {
            BigDecimal var2 = (BigDecimal)JavaInternals.unsafe.allocateInstance(BigDecimal.class);
            var1.register(var2);
            INTVAL_SET_BIGINTEGER_MH.invokeExact(var2, (BigInteger)var1.readObject());
            SCALE_SET_INT_MH.invokeExact(var2, var1.readInt());
            READ_OBJECT__VOID_MH.invokeExact(var2, new GetFieldInputStream(var2, this.fields));
            return var2;
        } catch (Exception var4) {
            throw new RuntimeException(var4);
        } catch (Throwable var5) {
            throw new RuntimeException(var5);
        }
    }

    public final void skip(DataStream var1) throws IOException, ClassNotFoundException {
        var1.readObject();
        var1.skipBytes(4);
    }

    public final void toJson(Object var1, StringBuilder var2) throws IOException {
        try {
            BigDecimal var5 = (BigDecimal)var1;
            var2.append("{\"intVal\":");
            Json.appendObject(var2, INTVAL_GET_BIGINTEGER_MH.invokeExact(var5));
            var2.append(",\"scale\":");
            var2.append(SCALE_GET_INT_MH.invokeExact(var5)).append('}');
        } catch (Throwable var4) {
            throw new RuntimeException(var4);
        }
    }

    public final Object fromJson(JsonReader var1) throws IOException, ClassNotFoundException {
        try {
            var1.expect(123, "Expected object");
            BigDecimal var2 = (BigDecimal)JavaInternals.unsafe.allocateInstance(BigDecimal.class);
            if (var1.skipWhitespace() != 125) {
                while(true) {
                    label35: {
                        var1.skipWhitespace();
                        var1.expect(58, "Expected key-value pair");
                        var1.skipWhitespace();
                        switch (var3) {
                            case "intVal":
                                INTVAL_SET_BIGINTEGER_MH.invokeExact(var2, var1.next == 110 ? (BigInteger)var1.readNull() : (BigInteger)var1.readObject(BigInteger.class));
                                break label35;
                            case "scale":
                                SCALE_SET_INT_MH.invokeExact(var2, var1.readInt());
                                break label35;
                        }

                        var1.readObject();
                    }

                    if (var1.skipWhitespace() == 125) {
                        break;
                    }

                    var1.expect(44, "Unexpected end of object");
                    var1.skipWhitespace();
                }
            }

            var1.read();
            READ_OBJECT__VOID_MH.invokeExact(var2, new GetFieldInputStream(var2, this.fields));
            return var2;
        } catch (Exception var4) {
            throw new RuntimeException(var4);
        } catch (Throwable var5) {
            throw new RuntimeException(var5);
        }
    }
}

public final class Delegate1_BigInteger implements Delegate {
    private final Map fields;
    private static final MethodHandle SIGNUM_GET_INT_MH;
    private static final MethodHandle SIGNUM_SET_INT_MH;
    private static final MethodHandle MAG_GET_INT_ARRAY_MH;
    private static final MethodHandle MAG_SET_INT_ARRAY_MH;
    private static final MethodHandle BITCOUNTPLUSONE_GET_INT_MH;
    private static final MethodHandle BITCOUNTPLUSONE_SET_INT_MH;
    private static final MethodHandle BITLENGTHPLUSONE_GET_INT_MH;
    private static final MethodHandle BITLENGTHPLUSONE_SET_INT_MH;
    private static final MethodHandle LOWESTSETBITPLUSTWO_GET_INT_MH;
    private static final MethodHandle LOWESTSETBITPLUSTWO_SET_INT_MH;
    private static final MethodHandle FIRSTNONZEROINTNUMPLUSTWO_GET_INT_MH;
    private static final MethodHandle FIRSTNONZEROINTNUMPLUSTWO_SET_INT_MH;

    public Delegate1_BigInteger(Map var1) {
        this.fields = var1;
    }

    static {
        try {
            MethodHandles.Lookup var0 = MethodHandles.privateLookupIn(BigInteger.class, MethodHandles.lookup());
            Field var2 = BigInteger.class.getDeclaredField("signum");
            var2.setAccessible(true);
            SIGNUM_SET_INT_MH = var0.unreflectSetter(var2);
            SIGNUM_GET_INT_MH = var0.unreflectGetter(var2);
            var2 = BigInteger.class.getDeclaredField("mag");
            var2.setAccessible(true);
            MAG_SET_INT_ARRAY_MH = var0.unreflectSetter(var2);
            MAG_GET_INT_ARRAY_MH = var0.unreflectGetter(var2);
            var2 = BigInteger.class.getDeclaredField("bitCountPlusOne");
            var2.setAccessible(true);
            BITCOUNTPLUSONE_SET_INT_MH = var0.unreflectSetter(var2);
            BITCOUNTPLUSONE_GET_INT_MH = var0.unreflectGetter(var2);
            var2 = BigInteger.class.getDeclaredField("bitLengthPlusOne");
            var2.setAccessible(true);
            BITLENGTHPLUSONE_SET_INT_MH = var0.unreflectSetter(var2);
            BITLENGTHPLUSONE_GET_INT_MH = var0.unreflectGetter(var2);
            var2 = BigInteger.class.getDeclaredField("lowestSetBitPlusTwo");
            var2.setAccessible(true);
            LOWESTSETBITPLUSTWO_SET_INT_MH = var0.unreflectSetter(var2);
            LOWESTSETBITPLUSTWO_GET_INT_MH = var0.unreflectGetter(var2);
            var2 = BigInteger.class.getDeclaredField("firstNonzeroIntNumPlusTwo");
            var2.setAccessible(true);
            FIRSTNONZEROINTNUMPLUSTWO_SET_INT_MH = var0.unreflectSetter(var2);
            FIRSTNONZEROINTNUMPLUSTWO_GET_INT_MH = var0.unreflectGetter(var2);
        } catch (ReflectiveOperationException var3) {
            throw new ExceptionInInitializerError(var3);
        } catch (Throwable var4) {
            throw new RuntimeException(var4);
        }
    }

    public final void calcSize(Object var1, CalcSizeStream var2) throws IOException {
        try {
            BigInteger var5 = (BigInteger)var1;
            var2.writeObject(MAG_GET_INT_ARRAY_MH.invokeExact(var5));
            var2.count += 20;
        } catch (Throwable var4) {
            throw new RuntimeException(var4);
        }
    }

    public final void write(Object var1, DataStream var2) throws IOException {
        try {
            BigInteger var5 = (BigInteger)var1;
            var2.writeInt(SIGNUM_GET_INT_MH.invokeExact(var5));
            var2.writeObject(MAG_GET_INT_ARRAY_MH.invokeExact(var5));
            var2.writeInt(BITCOUNTPLUSONE_GET_INT_MH.invokeExact(var5));
            var2.writeInt(BITLENGTHPLUSONE_GET_INT_MH.invokeExact(var5));
            var2.writeInt(LOWESTSETBITPLUSTWO_GET_INT_MH.invokeExact(var5));
            var2.writeInt(FIRSTNONZEROINTNUMPLUSTWO_GET_INT_MH.invokeExact(var5));
        } catch (Throwable var4) {
            throw new RuntimeException(var4);
        }
    }

    public final Object read(DataStream var1) throws IOException, ClassNotFoundException {
        try {
            BigInteger var2 = (BigInteger)JavaInternals.unsafe.allocateInstance(BigInteger.class);
            var1.register(var2);
            SIGNUM_SET_INT_MH.invokeExact(var2, var1.readInt());
            MAG_SET_INT_ARRAY_MH.invokeExact(var2, (int[])var1.readObject());
            BITCOUNTPLUSONE_SET_INT_MH.invokeExact(var2, var1.readInt());
            BITLENGTHPLUSONE_SET_INT_MH.invokeExact(var2, var1.readInt());
            LOWESTSETBITPLUSTWO_SET_INT_MH.invokeExact(var2, var1.readInt());
            FIRSTNONZEROINTNUMPLUSTWO_SET_INT_MH.invokeExact(var2, var1.readInt());
            return var2;
        } catch (Exception var4) {
            throw new RuntimeException(var4);
        } catch (Throwable var5) {
            throw new RuntimeException(var5);
        }
    }

    public final void skip(DataStream var1) throws IOException, ClassNotFoundException {
        var1.skipBytes(4);
        var1.readObject();
        var1.skipBytes(16);
    }

    public final void toJson(Object var1, StringBuilder var2) throws IOException {
        try {
            BigInteger var5 = (BigInteger)var1;
            var2.append("{\"signum\":");
            var2.append(SIGNUM_GET_INT_MH.invokeExact(var5)).append(",\"mag\":");
            Json.appendObject(var2, MAG_GET_INT_ARRAY_MH.invokeExact(var5));
            var2.append(",\"bitCountPlusOne\":");
            var2.append(BITCOUNTPLUSONE_GET_INT_MH.invokeExact(var5)).append(",\"bitLengthPlusOne\":");
            var2.append(BITLENGTHPLUSONE_GET_INT_MH.invokeExact(var5)).append(",\"lowestSetBitPlusTwo\":");
            var2.append(LOWESTSETBITPLUSTWO_GET_INT_MH.invokeExact(var5)).append(",\"firstNonzeroIntNumPlusTwo\":");
            var2.append(FIRSTNONZEROINTNUMPLUSTWO_GET_INT_MH.invokeExact(var5)).append('}');
        } catch (Throwable var4) {
            throw new RuntimeException(var4);
        }
    }

    public final Object fromJson(JsonReader var1) throws IOException, ClassNotFoundException {
        try {
            var1.expect(123, "Expected object");
            BigInteger var2 = (BigInteger)JavaInternals.unsafe.allocateInstance(BigInteger.class);
            if (var1.skipWhitespace() != 125) {
                while(true) {
                    label47: {
                        var1.skipWhitespace();
                        var1.expect(58, "Expected key-value pair");
                        var1.skipWhitespace();
                        switch (var3) {
                            case "signum":
                                SIGNUM_SET_INT_MH.invokeExact(var2, var1.readInt());
                                break label47;
                            case "mag":
                                MAG_SET_INT_ARRAY_MH.invokeExact(var2, var1.next == 110 ? (int[])var1.readNull() : (int[])var1.readObject(int[].class));
                                break label47;
                            case "lowestSetBitPlusTwo":
                                LOWESTSETBITPLUSTWO_SET_INT_MH.invokeExact(var2, var1.readInt());
                                break label47;
                            case "firstNonzeroIntNumPlusTwo":
                                FIRSTNONZEROINTNUMPLUSTWO_SET_INT_MH.invokeExact(var2, var1.readInt());
                                break label47;
                            case "bitLengthPlusOne":
                                BITLENGTHPLUSONE_SET_INT_MH.invokeExact(var2, var1.readInt());
                                break label47;
                            case "bitCountPlusOne":
                                BITCOUNTPLUSONE_SET_INT_MH.invokeExact(var2, var1.readInt());
                                break label47;
                        }

                        var1.readObject();
                    }

                    if (var1.skipWhitespace() == 125) {
                        break;
                    }

                    var1.expect(44, "Unexpected end of object");
                    var1.skipWhitespace();
                }
            }

            var1.read();
            return var2;
        } catch (Exception var4) {
            throw new RuntimeException(var4);
        } catch (Throwable var5) {
            throw new RuntimeException(var5);
        }
    }
}

For all other classes, similar generation logic occurs.

This branch passes all tests except one.nio.serial.SerializationTest#testStringBuilder, one.nio.serial.SerializationTest#testInetAddress

[PRIESt512]

@lehvolk does this development branch make sense? I was expecting feedback on it)

[lehvolk]

@PRIESt512 to be honest I've treated this branch as draft and haven't review it. Sorry for inconvenience

@max-kammerer implemented a fix #104 which has been tested on internal projects and seems almost ready for publishing