1 /*

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

     4  *

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

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

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

    10  *

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

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

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

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

    15  * accompanied this code).

    16  *

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

    18  * 2 along with this work; if not, write to the Free Software Foundation,

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

    20  *

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

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    25 

    26 /*

    27  * This file is available under and governed by the GNU General Public

    28  * License version 2 only, as published by the Free Software Foundation.

    29  * However, the following notice accompanied the original version of this

    30  * file, and Oracle licenses the original version of this file under the BSD

    31  * license:

    32  */

    33 /*

    34    Copyright 2009-2013 Attila Szegedi

    35 

    36    Licensed under both the Apache License, Version 2.0 (the "Apache License")

    37    and the BSD License (the "BSD License"), with licensee being free to

    38    choose either of the two at their discretion.

    39 

    40    You may not use this file except in compliance with either the Apache

    41    License or the BSD License.

    42 

    43    If you choose to use this file in compliance with the Apache License, the

    44    following notice applies to you:

    45 

    46        You may obtain a copy of the Apache License at

    47 

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

    49 

    50        Unless required by applicable law or agreed to in writing, software

    51        distributed under the License is distributed on an "AS IS" BASIS,

    52        WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or

    53        implied. See the License for the specific language governing

    54        permissions and limitations under the License.

    55 

    56    If you choose to use this file in compliance with the BSD License, the

    57    following notice applies to you:

    58 

    59        Redistribution and use in source and binary forms, with or without

    60        modification, are permitted provided that the following conditions are

    61        met:

    62        * Redistributions of source code must retain the above copyright

    63          notice, this list of conditions and the following disclaimer.

    64        * Redistributions in binary form must reproduce the above copyright

    65          notice, this list of conditions and the following disclaimer in the

    66          documentation and/or other materials provided with the distribution.

    67        * Neither the name of the copyright holder nor the names of

    68          contributors may be used to endorse or promote products derived from

    69          this software without specific prior written permission.

    70 

    71        THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS

    72        IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED

    73        TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A

    74        PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER

    75        BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

    76        CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

    77        SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR

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

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

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

    81        ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    82 */

    83 

    84 package jdk.internal.dynalink;

    85 

    86 import java.lang.invoke.MutableCallSite;

    87 import java.util.ArrayList;

    88 import java.util.Arrays;

    89 import java.util.Collections;

    90 import java.util.HashSet;

    91 import java.util.LinkedList;

    92 import java.util.List;

    93 import java.util.Set;

    94 import jdk.internal.dynalink.beans.BeansLinker;

    95 import jdk.internal.dynalink.linker.GuardingDynamicLinker;

    96 import jdk.internal.dynalink.linker.GuardingTypeConverterFactory;

    97 import jdk.internal.dynalink.linker.LinkRequest;

    98 import jdk.internal.dynalink.support.AutoDiscovery;

    99 import jdk.internal.dynalink.support.BottomGuardingDynamicLinker;

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

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

   102 import jdk.internal.dynalink.support.LinkerServicesImpl;

   103 import jdk.internal.dynalink.support.TypeConverterFactory;

   104 

   105 

   106 /**

   107  * A factory class for creating {@link DynamicLinker}s. The most usual dynamic linker is a linker that is a composition

   108  * of all {@link GuardingDynamicLinker}s known and pre-created by the caller as well as any

   109  * {@link AutoDiscovery automatically discovered} guarding linkers and the standard fallback {@link BeansLinker}. See

   110  * {@link DynamicLinker} documentation for tips on how to use this class.

   111  *

   112  * @author Attila Szegedi

   113  */

   114 public class DynamicLinkerFactory {

   115 

   116     /**

   117      * Default value for {@link #setUnstableRelinkThreshold(int) unstable relink threshold}.

   118      */

   119     public static final int DEFAULT_UNSTABLE_RELINK_THRESHOLD = 8;

   120 

   121     private ClassLoader classLoader = Thread.currentThread().getContextClassLoader();

   122     private List<? extends GuardingDynamicLinker> prioritizedLinkers;

   123     private List<? extends GuardingDynamicLinker> fallbackLinkers;

   124     private int runtimeContextArgCount = 0;

   125     private boolean syncOnRelink = false;

   126     private int unstableRelinkThreshold = DEFAULT_UNSTABLE_RELINK_THRESHOLD;

   127 

   128     /**

   129      * Sets the class loader for automatic discovery of available linkers. If not set explicitly, then the thread

   130      * context class loader at the time of the constructor invocation will be used.

   131      *

   132      * @param classLoader the class loader used for the autodiscovery of available linkers.

   133      */

   134     public void setClassLoader(ClassLoader classLoader) {

   135         this.classLoader = classLoader;

   136     }

   137 

   138     /**

   139      * Sets the prioritized linkers. Language runtimes using this framework will usually precreate at least the linker

   140      * for their own language. These linkers will be consulted first in the resulting dynamic linker, before any

   141      * autodiscovered linkers. If the framework also autodiscovers a linker of the same class as one of the prioritized

   142      * linkers, it will be ignored and the explicit prioritized instance will be used.

   143      *

   144      * @param prioritizedLinkers the list of prioritized linkers. Null can be passed to indicate no prioritized linkers

   145      * (this is also the default value).

   146      */

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

   148         this.prioritizedLinkers =

   149                 prioritizedLinkers == null ? null : new ArrayList<>(prioritizedLinkers);

   150     }

   151 

   152     /**

   153      * Sets the prioritized linkers. Language runtimes using this framework will usually precreate at least the linker

   154      * for their own language. These linkers will be consulted first in the resulting dynamic linker, before any

   155      * autodiscovered linkers. If the framework also autodiscovers a linker of the same class as one of the prioritized

   156      * linkers, it will be ignored and the explicit prioritized instance will be used.

   157      *

   158      * @param prioritizedLinkers a list of prioritized linkers.

   159      */

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

   161         setPrioritizedLinkers(Arrays.asList(prioritizedLinkers));

   162     }

   163 

   164     /**

   165      * Sets a single prioritized linker. Identical to calling {@link #setPrioritizedLinkers(List)} with a single-element

   166      * list.

   167      *

   168      * @param prioritizedLinker the single prioritized linker. Must not be null.

   169      * @throws IllegalArgumentException if null is passed.

   170      */

   171     public void setPrioritizedLinker(GuardingDynamicLinker prioritizedLinker) {

   172         if(prioritizedLinker == null) {

   173             throw new IllegalArgumentException("prioritizedLinker == null");

   174         }

   175         this.prioritizedLinkers = Collections.singletonList(prioritizedLinker);

   176     }

   177 

   178     /**

   179      * Sets the fallback linkers. These linkers will be consulted last in the resulting composite linker, after any

   180      * autodiscovered linkers. If the framework also autodiscovers a linker of the same class as one of the fallback

   181      * linkers, it will be ignored and the explicit fallback instance will be used.

   182      *

   183      * @param fallbackLinkers the list of fallback linkers. Can be empty to indicate the caller wishes to set no

   184      * fallback linkers.

   185      */

   186     public void setFallbackLinkers(List<? extends GuardingDynamicLinker> fallbackLinkers) {

   187         this.fallbackLinkers = fallbackLinkers == null ? null : new ArrayList<>(fallbackLinkers);

   188     }

   189 

   190     /**

   191      * Sets the fallback linkers. These linkers will be consulted last in the resulting composite linker, after any

   192      * autodiscovered linkers. If the framework also autodiscovers a linker of the same class as one of the fallback

   193      * linkers, it will be ignored and the explicit fallback instance will be used.

   194      *

   195      * @param fallbackLinkers the list of fallback linkers. Can be empty to indicate the caller wishes to set no

   196      * fallback linkers. If it is left as null, the standard fallback {@link BeansLinker} will be used.

   197      */

   198     public void setFallbackLinkers(GuardingDynamicLinker... fallbackLinkers) {

   199         setFallbackLinkers(Arrays.asList(fallbackLinkers));

   200     }

   201 

   202     /**

   203      * Sets the number of arguments in the call sites that represent the stack context of the language runtime creating

   204      * the linker. If the language runtime uses no context information passed on stack, then it should be zero

   205      * (the default value). If it is set to nonzero value, then every dynamic call site emitted by this runtime must

   206      * have the argument list of the form: {@code (this, contextArg1[, contextArg2[, ...]], normalArgs)}. It is

   207      * advisable to only pass one context-specific argument, though, of an easily recognizable, runtime specific type

   208      * encapsulating the runtime thread local state.

   209      *

   210      * @param runtimeContextArgCount the number of language runtime context arguments in call sites.

   211      */

   212     public void setRuntimeContextArgCount(int runtimeContextArgCount) {

   213         if(runtimeContextArgCount < 0) {

   214             throw new IllegalArgumentException("runtimeContextArgCount < 0");

   215         }

   216         this.runtimeContextArgCount = runtimeContextArgCount;

   217     }

   218 

   219     /**

   220      * Sets whether the linker created by this factory will invoke {@link MutableCallSite#syncAll(MutableCallSite[])}

   221      * after a call site is relinked. Defaults to false. You probably want to set it to true if your runtime supports

   222      * multithreaded execution of dynamically linked code.

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

   224      */

   225     public void setSyncOnRelink(boolean syncOnRelink) {

   226         this.syncOnRelink = syncOnRelink;

   227     }

   228 

   229     /**

   230      * Sets the unstable relink threshold; the number of times a call site is relinked after which it will be

   231      * considered unstable, and subsequent link requests for it will indicate this.

   232      * @param unstableRelinkThreshold the new threshold. Must not be less than zero. The value of zero means that

   233      * call sites will never be considered unstable.

   234      * @see LinkRequest#isCallSiteUnstable()

   235      */

   236     public void setUnstableRelinkThreshold(int unstableRelinkThreshold) {

   237         if(unstableRelinkThreshold < 0) {

   238             throw new IllegalArgumentException("unstableRelinkThreshold < 0");

   239         }

   240         this.unstableRelinkThreshold = unstableRelinkThreshold;

   241     }

   242 

   243     /**

   244      * Creates a new dynamic linker consisting of all the prioritized, autodiscovered, and fallback linkers.

   245      *

   246      * @return the new dynamic Linker

   247      */

   248     public DynamicLinker createLinker() {

   249         // Treat nulls appropriately

   250         if(prioritizedLinkers == null) {

   251             prioritizedLinkers = Collections.emptyList();

   252         }

   253         if(fallbackLinkers == null) {

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

   255         }

   256 

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

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

   259         final Set<Class<? extends GuardingDynamicLinker>> knownLinkerClasses = new HashSet<>();

   260         addClasses(knownLinkerClasses, prioritizedLinkers);

   261         addClasses(knownLinkerClasses, fallbackLinkers);

   262 

   263         final List<GuardingDynamicLinker> discovered = AutoDiscovery.loadLinkers(classLoader);

   264         // Now, concatenate ...

   265         final List<GuardingDynamicLinker> linkers = new ArrayList<>(prioritizedLinkers.size() + discovered.size()

   266                 + fallbackLinkers.size());

   267         // ... prioritized linkers, ...

   268         linkers.addAll(prioritizedLinkers);

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

   270         for(GuardingDynamicLinker linker: discovered) {

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

   272                 linkers.add(linker);

   273             }

   274         }

   275         // ... and finally fallback linkers.

   276         linkers.addAll(fallbackLinkers);

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

   278         final GuardingDynamicLinker composite;

   279         switch(linkers.size()) {

   280             case 0: {

   281                 composite = BottomGuardingDynamicLinker.INSTANCE;

   282                 break;

   283             }

   284             case 1: {

   285                 composite = optimized.get(0);

   286                 break;

   287             }

   288             default: {

   289                 composite = new CompositeGuardingDynamicLinker(optimized);

   290                 break;

   291             }

   292         }

   293 

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

   295         for(GuardingDynamicLinker linker: linkers) {

   296             if(linker instanceof GuardingTypeConverterFactory) {

   297                 typeConverters.add((GuardingTypeConverterFactory)linker);

   298             }

   299         }

   300 

   301         return new DynamicLinker(new LinkerServicesImpl(new TypeConverterFactory(typeConverters), composite),

   302                 runtimeContextArgCount, syncOnRelink, unstableRelinkThreshold);

   303     }

   304 

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

   306             List<? extends GuardingDynamicLinker> linkers) {

   307         for(GuardingDynamicLinker linker: linkers) {

   308             knownLinkerClasses.add(linker.getClass());

   309         }

   310     }

   311 }