69 lines
3.0 KiB
Java
69 lines
3.0 KiB
Java
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/*
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* Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package vm.mlvm.share;
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import java.lang.invoke.MethodHandle;
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import java.lang.invoke.MethodHandles;
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import java.lang.invoke.MethodType;
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import java.lang.reflect.InvocationTargetException;
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/**
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* WhiteBoxHelper class obtains a MethodHandle to a method defined in sun.hotspot.WhiteBox class.
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* If WhiteBox is not available or cannot be initialized, or the method is not available,
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* it throws an appropriate exception.
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*
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* This class was introduced to avoid "hard link" to WhiteBox.
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*
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*/
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public class WhiteBoxHelper {
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/**
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* Obtains {@link java.lang.invoke.MethodHandle} to a method in sun.hotspot.WhiteBox class.
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* If there is an error obtaining method handle, an exception is thrown.
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*
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* @param name Method name
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* @type Method type
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* @return {@link java.lang.invoke.MethodHandle} to the method. You can call it directly, WhiteBox instance is already bound to the handle.
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* @throws IllegalAccessException if method cannot be accessed (see {@link java.lang.invoke.MethodHandles.Lookup#findStatic()} for details)
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* @throws NoSuchMethodException if method cannot be found (see {@link java.lang.invoke.MethodHandles.Lookup#findStatic()} for details)
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* @throws ClassNotFoundException if WhiteBox class cannot be loaded
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* @throws InvocationTargetException if WhiteBox.getWhiteBox() method throws exception for some reason
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*/
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public static MethodHandle getMethod(String name, MethodType type)
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throws IllegalAccessException, NoSuchMethodException, ClassNotFoundException, InvocationTargetException {
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Class<?> wbClass = Class.forName("sun.hotspot.WhiteBox");
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MethodHandles.Lookup lu = MethodHandles.lookup();
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MethodHandle getWB = lu.findStatic(wbClass, "getWhiteBox", MethodType.methodType(wbClass));
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Object wb;
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try {
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wb = getWB.invoke();
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} catch (Throwable e) {
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throw new InvocationTargetException(e, "Can't obtain WhiteBox instance");
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}
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return lu.findVirtual(wbClass, name, type).bindTo(wb);
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}
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}
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