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 6 * under the terms of the GNU General Public License version 2 only, as 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 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 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 Redistribution and use in source and binary forms, with or without 37 modification, are permitted provided that the following conditions are 38 met: 39 * Redistributions of source code must retain the above copyright 40 notice, this list of conditions and the following disclaimer. 41 * Redistributions in binary form must reproduce the above copyright 42 notice, this list of conditions and the following disclaimer in the 43 documentation and/or other materials provided with the distribution. 44 * Neither the name of the copyright holder nor the names of 45 contributors may be used to endorse or promote products derived from 46 this software without specific prior written permission. 47 48 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS 49 IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 50 TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 51 PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER 52 BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 53 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 54 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 55 BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 56 WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 57 OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 58 ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 59 */ 60 61 package jdk.dynalink.linker; 62 63 import java.lang.invoke.MethodHandle; 64 import java.lang.invoke.MethodType; 65 import java.util.List; 66 import jdk.dynalink.DynamicLinkerFactory; 67 68 /** 69 * The base interface for language-specific dynamic linkers. Such linkers 70 * always have to produce method handles with guards, as the validity of the 71 * method handle for calls at a call site inevitably depends on some condition 72 * (at the very least, it depends on the receiver belonging to the language 73 * runtime of the linker). Language runtime implementors will normally implement 74 * the linking logic for their own language as one or more 75 * {@link GuardingDynamicLinker} classes. They will typically set them as 76 * {@link DynamicLinkerFactory#setPrioritizedLinkers(List) prioritized linkers} 77 * in the {@code DynamicLinkerFactory} they configure for themselves, and maybe also 78 * set some as {@link DynamicLinkerFactory#setFallbackLinkers(List) fallback 79 * linkers} to handle language-specific "property not found" etc. conditions. 80 * <p> 81 * Consider implementing {@link TypeBasedGuardingDynamicLinker} interface 82 * instead of this interface for those linkers that are based on the Java class 83 * of the objects. If you need to implement language-specific type conversions, 84 * have your {@code GuardingDynamicLinker} also implement the 85 * {@link GuardingTypeConverterFactory} interface. 86 * <p> 87 * Languages can export linkers to other language runtimes for 88 * {@link DynamicLinkerFactory#setClassLoader(ClassLoader) automatic discovery} 89 * using a {@link GuardingDynamicLinkerExporter}. 90 */ 91 public interface GuardingDynamicLinker { 92 /** 93 * Creates a guarded invocation appropriate for a particular invocation with 94 * the specified arguments at a call site. 95 * 96 * @param linkRequest the object describing the request for linking a 97 * particular invocation 98 * @param linkerServices linker services 99 * @return a guarded invocation with a method handle suitable for the 100 * arguments, as well as a guard condition that if fails should trigger 101 * relinking. Must return null if it can't resolve the invocation. If the 102 * returned invocation is unconditional (which is actually quite rare), the 103 * guard in the return value can be null. The invocation can also have any 104 * number of switch points for asynchronous invalidation of the linkage, as 105 * well as a {@link Throwable} subclass that describes an expected exception 106 * condition that also triggers relinking (often it is faster to rely on an 107 * infrequent but expected {@link ClassCastException} than on an always 108 * evaluated {@code instanceof} guard). While the linker must produce an 109 * invocation with parameter types matching those in the call site 110 * descriptor of the link request, it should not try to match the return 111 * type expected at the call site except when it can do it with only the 112 * conversions that lose neither precision nor magnitude, see 113 * {@link LinkerServices#asTypeLosslessReturn(MethodHandle, MethodType)} for 114 * further explanation. 115 * @throws Exception if the operation fails for whatever reason 116 */ getGuardedInvocation(LinkRequest linkRequest, LinkerServices linkerServices)117 public GuardedInvocation getGuardedInvocation(LinkRequest linkRequest, LinkerServices linkerServices) 118 throws Exception; 119 } 120