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

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

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

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 *

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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:

 */

/*

   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

       BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,

       WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR

       OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF

       ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

package jdk.internal.dynalink;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodType;

import java.lang.invoke.MutableCallSite;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashSet;

import java.util.LinkedList;

import java.util.List;

import java.util.ServiceLoader;

import java.util.Set;

import jdk.internal.dynalink.beans.BeansLinker;

import jdk.internal.dynalink.linker.GuardedInvocation;

import jdk.internal.dynalink.linker.GuardedInvocationTransformer;

import jdk.internal.dynalink.linker.GuardingDynamicLinker;

import jdk.internal.dynalink.linker.GuardingTypeConverterFactory;

import jdk.internal.dynalink.linker.LinkRequest;

import jdk.internal.dynalink.linker.LinkerServices;

import jdk.internal.dynalink.linker.MethodHandleTransformer;

import jdk.internal.dynalink.linker.MethodTypeConversionStrategy;

import jdk.internal.dynalink.linker.support.CompositeGuardingDynamicLinker;

import jdk.internal.dynalink.linker.support.CompositeTypeBasedGuardingDynamicLinker;

import jdk.internal.dynalink.linker.support.TypeUtilities;

/**

 */

public final class DynamicLinkerFactory {

    /**

     * Default value for {@link #setUnstableRelinkThreshold(int) unstable relink

     * threshold}.

     */

    public static final int DEFAULT_UNSTABLE_RELINK_THRESHOLD = 8;

    private boolean classLoaderExplicitlySet = false;

    private ClassLoader classLoader;

    private List<? extends GuardingDynamicLinker> prioritizedLinkers;

    private List<? extends GuardingDynamicLinker> fallbackLinkers;

    private boolean syncOnRelink = false;

    private int unstableRelinkThreshold = DEFAULT_UNSTABLE_RELINK_THRESHOLD;

    private GuardedInvocationTransformer prelinkTransformer;

    private MethodTypeConversionStrategy autoConversionStrategy;

    private MethodHandleTransformer internalObjectsFilter;

    /**

     * Creates a new dynamic linker factory with default configuration. Upon

     * creation, the factory can be configured using various {@code setXxx()}

     * methods and used to create one or more dynamic linkers according to its

     * current configuration using {@link #createLinker()}.

     */

    public DynamicLinkerFactory() {

    }

    /**

     *

     * @param classLoader the class loader used for the automatic discovery of

     * available linkers.

     */

    public void setClassLoader(final ClassLoader classLoader) {

        this.classLoader = classLoader;

        classLoaderExplicitlySet = true;

    }

    /**

     *

     */

    public void setPrioritizedLinkers(final List<? extends GuardingDynamicLinker> prioritizedLinkers) {

    }

    /**

     *

     */

    public void setPrioritizedLinkers(final GuardingDynamicLinker... prioritizedLinkers) {

    }

    /**

     *

     */

    }

    /**

     *

     */

    }

    /**

     * @param syncOnRelink true for invoking sync on relink, false otherwise.

     */

    public void setSyncOnRelink(final boolean syncOnRelink) {

        this.syncOnRelink = syncOnRelink;

    }

    /**

     * @see LinkRequest#isCallSiteUnstable()

     */

    public void setUnstableRelinkThreshold(final int unstableRelinkThreshold) {

        if(unstableRelinkThreshold < 0) {

            throw new IllegalArgumentException("unstableRelinkThreshold < 0");

        }

        this.unstableRelinkThreshold = unstableRelinkThreshold;

    }

    /**

     */

    public void setPrelinkTransformer(final GuardedInvocationTransformer prelinkTransformer) {

        this.prelinkTransformer = prelinkTransformer;

    }

    /**

     * {@link MethodTypeConversionStrategy#asType(MethodHandle, MethodType)}

     */

    public void setAutoConversionStrategy(final MethodTypeConversionStrategy autoConversionStrategy) {

        this.autoConversionStrategy = autoConversionStrategy;

    }

    /**

     */

    public void setInternalObjectsFilter(final MethodHandleTransformer internalObjectsFilter) {

        this.internalObjectsFilter = internalObjectsFilter;

    }

    /**

     * @return the new dynamic Linker

     */

    public DynamicLinker createLinker() {

        // Treat nulls appropriately

        if(prioritizedLinkers == null) {

            prioritizedLinkers = Collections.emptyList();

        }

        if(fallbackLinkers == null) {

            fallbackLinkers = Collections.singletonList(new BeansLinker());

        }

        // Gather classes of all precreated (prioritized and fallback) linkers.

        // We'll filter out any discovered linkers of the same class.

        final Set<Class<? extends GuardingDynamicLinker>> knownLinkerClasses =

                new HashSet<>();

        addClasses(knownLinkerClasses, prioritizedLinkers);

        addClasses(knownLinkerClasses, fallbackLinkers);

        final ClassLoader effectiveClassLoader = classLoaderExplicitlySet ? classLoader : getThreadContextClassLoader();

        final List<GuardingDynamicLinker> discovered = new LinkedList<>();

        final ServiceLoader<GuardingDynamicLinker> linkerLoader = ServiceLoader.load(GuardingDynamicLinker.class, effectiveClassLoader);

        for(final GuardingDynamicLinker linker: linkerLoader) {

            discovered.add(linker);

        }

        // Now, concatenate ...

        final List<GuardingDynamicLinker> linkers =

                new ArrayList<>(prioritizedLinkers.size() + discovered.size()

                        + fallbackLinkers.size());

        // ... prioritized linkers, ...

        linkers.addAll(prioritizedLinkers);

        // ... filtered discovered linkers, ...

        for(final GuardingDynamicLinker linker: discovered) {

            if(!knownLinkerClasses.contains(linker.getClass())) {

                linkers.add(linker);

            }

        }

        // ... and finally fallback linkers.

        linkers.addAll(fallbackLinkers);

        final List<GuardingDynamicLinker> optimized = CompositeTypeBasedGuardingDynamicLinker.optimize(linkers);

        final GuardingDynamicLinker composite;

        switch(linkers.size()) {

            case 0: {

                composite = (r, s) -> null; // linker that can't link anything

                break;

            }

            case 1: {

                composite = optimized.get(0);

                break;

            }

            default: {

                composite = new CompositeGuardingDynamicLinker(optimized);

                break;

            }

        }

        final List<GuardingTypeConverterFactory> typeConverters = new LinkedList<>();

        for(final GuardingDynamicLinker linker: linkers) {

            if(linker instanceof GuardingTypeConverterFactory) {

                typeConverters.add((GuardingTypeConverterFactory)linker);

            }

        }

        if(prelinkTransformer == null) {

            prelinkTransformer = (inv, request, linkerServices) -> inv.asType(linkerServices, request.getCallSiteDescriptor().getMethodType());

        }

        return new DynamicLinker(new LinkerServicesImpl(new TypeConverterFactory(typeConverters,

                autoConversionStrategy), composite, internalObjectsFilter), prelinkTransformer,

                syncOnRelink, unstableRelinkThreshold);

    }

    private static ClassLoader getThreadContextClassLoader() {

        return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {

            @Override

            public ClassLoader run() {

                return Thread.currentThread().getContextClassLoader();

            }

        }, ClassLoaderGetterContextProvider.GET_CLASS_LOADER_CONTEXT);

    }

    private static void addClasses(final Set<Class<? extends GuardingDynamicLinker>> knownLinkerClasses,

            final List<? extends GuardingDynamicLinker> linkers) {

        for(final GuardingDynamicLinker linker: linkers) {

            knownLinkerClasses.add(linker.getClass());

        }

    }

}