1 /*

     2  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

     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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     7  * published by the Free Software Foundation.  Oracle designates this

     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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    24  */

    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.dynalink;

    85 

    86 import java.lang.invoke.CallSite;

    87 import java.lang.invoke.MethodHandle;

    88 import jdk.dynalink.linker.GuardedInvocation;

    89 import jdk.dynalink.support.ChainedCallSite;

    90 import jdk.dynalink.support.SimpleRelinkableCallSite;

    91 

    92 /**

    93  * Interface for call sites managed by a {@link DynamicLinker}. Users of

    94  * Dynalink must use subclasses of {@link CallSite} that also implement this

    95  * interface as their call site implementations. There is a readily usable

    96  * {@link SimpleRelinkableCallSite} subclass that implements monomorphic inline

    97  * caching strategy as well as {@link ChainedCallSite} that implements a

    98  * polymorphic inline caching strategy and retains a chain of previously linked

    99  * method handles. A relinkable call site will be managed by a

   100  * {@link DynamicLinker} object after being associated with it using its

   101  * {@link DynamicLinker#link(RelinkableCallSite)} method.

   102  */

   103 public interface RelinkableCallSite {

   104     /**

   105      * Invoked by dynamic linker to initialize the relinkable call site by

   106      * setting a relink-and-invoke method handle. The call site implementation

   107      * is supposed to set this method handle as its target using

   108      * {@link CallSite#setTarget(MethodHandle)}. Relink-and-invoke is the

   109      * initial method handle set by

   110      * {@link DynamicLinker#link(RelinkableCallSite)} that will cause the call

   111      * site to be relinked to an appropriate target on its first invocation

   112      * based on its arguments, and that linked target will then be invoked

   113      * (hence the name). This linking protocol effectively delays linking until

   114      * the call site is invoked with actual arguments and thus ensures that

   115      * linkers can make nuanced linking decisions based on those arguments and

   116      * not just on the static method type of the call site.

   117      * @param relinkAndInvoke a relink-and-invoke method handle supplied by

   118      * Dynalink.

   119      */

   120     public void initialize(MethodHandle relinkAndInvoke);

   121 

   122     /**

   123      * Returns the descriptor for this call site.

   124      *

   125      * @return the descriptor for this call site.

   126      */

   127     public CallSiteDescriptor getDescriptor();

   128 

   129     /**

   130      * This method will be called by the dynamic linker every time the call site

   131      * is relinked (but see

   132      * {@link #resetAndRelink(GuardedInvocation, MethodHandle)} for an

   133      * exception). It will be passed a {@code GuardedInvocation} that the call

   134      * site should incorporate into its target method handle. When this method

   135      * is called, the call site is allowed to keep other non-invalidated

   136      * invocations around for implementation of polymorphic inline caches and

   137      * compose them with this invocation to form its final target.

   138      *

   139      * @param guardedInvocation the guarded invocation that the call site should

   140      * incorporate into its target method handle.

   141      * @param relinkAndInvoke a relink-and-invoke method handle. This is a

   142      * method handle matching the method type of the call site that is supplied

   143      * by the {@link DynamicLinker} as a callback. It should be used by this

   144      * call site as the ultimate fallback when it can't invoke its target with

   145      * the passed arguments. The fallback method is such that when it's invoked,

   146      * it'll try to obtain an adequate target {@link GuardedInvocation} for the

   147      * invocation, and subsequently invoke

   148      * {@link #relink(GuardedInvocation, MethodHandle)} or

   149      * {@link #resetAndRelink(GuardedInvocation, MethodHandle)}, and finally

   150      * invoke the target.

   151      */

   152     public void relink(GuardedInvocation guardedInvocation, MethodHandle relinkAndInvoke);

   153 

   154     /**

   155      * This method will be called by the dynamic linker every time the call site

   156      * is relinked <b>and</b> the linker wishes the call site to throw away any

   157      * prior linkage state (that is how it differs from

   158      * {@link #relink(GuardedInvocation, MethodHandle)}). It will be passed a

   159      * {@code GuardedInvocation} that the call site should use to build its new

   160      * target method handle. When this method is called, the call site is

   161      * discouraged from keeping any previous state, and is supposed to only

   162      * link the current invocation.

   163      *

   164      * @param guardedInvocation the guarded invocation that the call site should

   165      * use to build its target method handle.

   166      * @param relinkAndInvoke a relink-and-invoke method handle. This is a

   167      * method handle matching the method type of the call site that is supplied

   168      * by the {@link DynamicLinker} as a callback. It should be used by this

   169      * call site as the ultimate fallback when it can't invoke its target with

   170      * the passed arguments. The fallback method is such that when it's invoked,

   171      * it'll try to obtain an adequate target {@link GuardedInvocation} for the

   172      * invocation, and subsequently invoke

   173      * {@link #relink(GuardedInvocation, MethodHandle)} or

   174      * {@link #resetAndRelink(GuardedInvocation, MethodHandle)}, and finally

   175      * invoke the target.

   176      */

   177     public void resetAndRelink(GuardedInvocation guardedInvocation, MethodHandle relinkAndInvoke);

   178 }