LinkerServicesImpl.java

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/*
 * This file is available under and governed by the GNU General Public
 * License version 2 only, as published by the Free Software Foundation.
 * However, the following notice accompanied the original version of this
 * file, and Oracle licenses the original version of this file under the BSD
 * license:
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/*
   Copyright 2009-2013 Attila Szegedi

   Licensed under both the Apache License, Version 2.0 (the "Apache License")
   and the BSD License (the "BSD License"), with licensee being free to
   choose either of the two at their discretion.

   You may not use this file except in compliance with either the Apache
   License or the BSD License.

   If you choose to use this file in compliance with the Apache License, the
   following notice applies to you:

       You may obtain a copy of the Apache License at

           http://www.apache.org/licenses/LICENSE-2.0

       Unless required by applicable law or agreed to in writing, software
       distributed under the License is distributed on an "AS IS" BASIS,
       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
       implied. See the License for the specific language governing
       permissions and limitations under the License.

   If you choose to use this file in compliance with the BSD License, the
   following notice applies to you:

       Redistribution and use in source and binary forms, with or without
       modification, are permitted provided that the following conditions are
       met:
       * Redistributions of source code must retain the above copyright
         notice, this list of conditions and the following disclaimer.
       * Redistributions in binary form must reproduce the above copyright
         notice, this list of conditions and the following disclaimer in the
         documentation and/or other materials provided with the distribution.
       * Neither the name of the copyright holder nor the names of
         contributors may be used to endorse or promote products derived from
         this software without specific prior written permission.

       THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
       IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
       TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
       PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
       BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
       CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
       SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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*/

package jdk.internal.dynalink.support;

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodType;
import jdk.internal.dynalink.linker.ConversionComparator.Comparison;
import jdk.internal.dynalink.linker.GuardedInvocation;
import jdk.internal.dynalink.linker.GuardingDynamicLinker;
import jdk.internal.dynalink.linker.LinkRequest;
import jdk.internal.dynalink.linker.LinkerServices;
import jdk.internal.dynalink.linker.MethodHandleTransformer;

/**
 * Default implementation of the {@link LinkerServices} interface.
 *
 * @author Attila Szegedi
 */
public class LinkerServicesImpl implements LinkerServices {

    private static final RuntimePermission GET_CURRENT_LINK_REQUEST = new RuntimePermission("dynalink.getCurrentLinkRequest");
    private static final ThreadLocal<LinkRequest> threadLinkRequest = new ThreadLocal<>();

    private final TypeConverterFactory typeConverterFactory;
    private final GuardingDynamicLinker topLevelLinker;
    private final MethodHandleTransformer internalObjectsFilter;

    /**
     * Creates a new linker services object.
     *
     * @param typeConverterFactory the type converter factory exposed by the services.
     * @param topLevelLinker the top level linker used by the services.
     * @param internalObjectsFilter a method handle transformer that is supposed to act as the implementation of this
     * services' {@link #filterInternalObjects(java.lang.invoke.MethodHandle)} method.
     */
    public LinkerServicesImpl(final TypeConverterFactory typeConverterFactory,
            final GuardingDynamicLinker topLevelLinker, final MethodHandleTransformer internalObjectsFilter) {
        this.typeConverterFactory = typeConverterFactory;
        this.topLevelLinker = topLevelLinker;
        this.internalObjectsFilter = internalObjectsFilter;
    }

    @Override
    public boolean canConvert(final Class<?> from, final Class<?> to) {
        return typeConverterFactory.canConvert(from, to);
    }

    @Override
    public MethodHandle asType(final MethodHandle handle, final MethodType fromType) {
        return typeConverterFactory.asType(handle, fromType);
    }

    @Override
    public MethodHandle asTypeLosslessReturn(final MethodHandle handle, final MethodType fromType) {
        return Implementation.asTypeLosslessReturn(this, handle, fromType);
    }

    @Override
    public MethodHandle getTypeConverter(final Class<?> sourceType, final Class<?> targetType) {
        return typeConverterFactory.getTypeConverter(sourceType, targetType);
    }

    @Override
    public Comparison compareConversion(final Class<?> sourceType, final Class<?> targetType1, final Class<?> targetType2) {
        return typeConverterFactory.compareConversion(sourceType, targetType1, targetType2);
    }

    @Override
    public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest) throws Exception {
        final LinkRequest prevLinkRequest = threadLinkRequest.get();
        threadLinkRequest.set(linkRequest);
        try {
            return topLevelLinker.getGuardedInvocation(linkRequest, this);
        } finally {
            threadLinkRequest.set(prevLinkRequest);
        }
    }

    @Override
    public MethodHandle filterInternalObjects(final MethodHandle target) {
        return internalObjectsFilter != null ? internalObjectsFilter.transform(target) : target;
    }

    /**
     * Returns the currently processed link request, or null if the method is invoked outside of the linking process.
     * @return the currently processed link request, or null.
     * @throws SecurityException if the calling code doesn't have the {@code "dynalink.getCurrentLinkRequest"} runtime
     * permission.
     */
    public static LinkRequest getCurrentLinkRequest() {
        final SecurityManager sm = System.getSecurityManager();
        if(sm != null) {
            sm.checkPermission(GET_CURRENT_LINK_REQUEST);
        }
        return threadLinkRequest.get();
    }
}