/*

 * Copyright (c) 2001, 2021, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package jdk.internal.reflect;

import sun.reflect.misc.ReflectUtil;

import java.lang.reflect.*;

import jdk.internal.misc.Unsafe;

/** Used only for the first few invocations of a Method; afterward,

    switches to bytecode-based implementation */

class NativeMethodAccessorImpl extends MethodAccessorImpl {

     private static final Unsafe U = Unsafe.getUnsafe();

     private static final long GENERATED_OFFSET

        = U.objectFieldOffset(NativeMethodAccessorImpl.class, "generated");

    private final Method method;

    private DelegatingMethodAccessorImpl parent;

    private int numInvocations;

    private volatile int generated;

    NativeMethodAccessorImpl(Method method) {

        this.method = method;

    }

    public Object invoke(Object obj, Object[] args)

        throws IllegalArgumentException, InvocationTargetException

    {

        // We can't inflate methods belonging to vm-anonymous classes because

        // that kind of class can't be referred to by name, hence can't be

        // found from the generated bytecode.

        if (++numInvocations > ReflectionFactory.inflationThreshold()

                && !method.getDeclaringClass().isHidden()

                && generated == 0

                && U.compareAndSetInt(this, GENERATED_OFFSET, 0, 1)) {

            try {

                MethodAccessorImpl acc = (MethodAccessorImpl)

                    new MethodAccessorGenerator().

                        generateMethod(method.getDeclaringClass(),

                                       method.getName(),

                                       method.getParameterTypes(),

                                       method.getReturnType(),

                                       method.getExceptionTypes(),

                                       method.getModifiers());

                parent.setDelegate(acc);

            } catch (Throwable t) {

                // Throwable happens in generateMethod, restore generated to 0

                generated = 0;

                throw t;

            }

        }

        return invoke0(method, obj, args);

    }

    void setParent(DelegatingMethodAccessorImpl parent) {

        this.parent = parent;

    }

    private static native Object invoke0(Method m, Object obj, Object[] args);

}