JavaSuperAdapterLinker.java revision 1470:04ed602df062
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 26package jdk.nashorn.internal.runtime.linker; 27 28import static jdk.nashorn.internal.lookup.Lookup.EMPTY_GETTER; 29import static jdk.nashorn.internal.runtime.linker.JavaAdapterBytecodeGenerator.SUPER_PREFIX; 30 31import java.lang.invoke.MethodHandle; 32import java.lang.invoke.MethodHandles; 33import java.lang.invoke.MethodType; 34import jdk.internal.dynalink.CallSiteDescriptor; 35import jdk.internal.dynalink.beans.BeansLinker; 36import jdk.internal.dynalink.linker.GuardedInvocation; 37import jdk.internal.dynalink.linker.LinkRequest; 38import jdk.internal.dynalink.linker.LinkerServices; 39import jdk.internal.dynalink.linker.TypeBasedGuardingDynamicLinker; 40import jdk.internal.dynalink.support.Lookup; 41import jdk.nashorn.internal.runtime.ScriptRuntime; 42 43/** 44 * A linker for instances of {@code JavaSuperAdapter}. Only links {@code getMethod} calls, by forwarding them to the 45 * bean linker for the adapter class and prepending {@code super$} to method names. 46 * 47 */ 48final class JavaSuperAdapterLinker implements TypeBasedGuardingDynamicLinker { 49 private static final String GET_METHOD = "getMethod"; 50 private static final String DYN_GET_METHOD = "dyn:" + GET_METHOD; 51 private static final String DYN_GET_METHOD_FIXED = DYN_GET_METHOD + ":" + SUPER_PREFIX; 52 53 private static final MethodHandle ADD_PREFIX_TO_METHOD_NAME; 54 private static final MethodHandle BIND_DYNAMIC_METHOD; 55 private static final MethodHandle GET_ADAPTER; 56 private static final MethodHandle IS_ADAPTER_OF_CLASS; 57 58 static { 59 final Lookup lookup = new Lookup(MethodHandles.lookup()); 60 ADD_PREFIX_TO_METHOD_NAME = lookup.findOwnStatic("addPrefixToMethodName", Object.class, Object.class); 61 BIND_DYNAMIC_METHOD = lookup.findOwnStatic("bindDynamicMethod", Object.class, Object.class, Object.class); 62 GET_ADAPTER = lookup.findVirtual(JavaSuperAdapter.class, "getAdapter", MethodType.methodType(Object.class)); 63 IS_ADAPTER_OF_CLASS = lookup.findOwnStatic("isAdapterOfClass", boolean.class, Class.class, Object.class); 64 } 65 66 @Override 67 public boolean canLinkType(final Class<?> type) { 68 return type == JavaSuperAdapter.class; 69 } 70 71 @Override 72 public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices) 73 throws Exception { 74 final Object objSuperAdapter = linkRequest.getReceiver(); 75 if(!(objSuperAdapter instanceof JavaSuperAdapter)) { 76 return null; 77 } 78 79 final CallSiteDescriptor descriptor = linkRequest.getCallSiteDescriptor(); 80 if(!descriptor.tokenizeOperators().contains(GET_METHOD)) { 81 // We only handle getMethod 82 return null; 83 } 84 85 final Object adapter = ((JavaSuperAdapter)objSuperAdapter).getAdapter(); 86 87 // Replace argument (javaSuperAdapter, ...) => (adapter, ...) when delegating to BeansLinker 88 final Object[] args = linkRequest.getArguments(); 89 args[0] = adapter; 90 91 // Use R(T0, ...) => R(adapter.class, ...) call site type when delegating to BeansLinker. 92 final MethodType type = descriptor.getMethodType(); 93 final Class<?> adapterClass = adapter.getClass(); 94 final boolean hasFixedName = descriptor.getNameTokenCount() > 2; 95 final String opName = hasFixedName ? (DYN_GET_METHOD_FIXED + descriptor.getNameToken( 96 CallSiteDescriptor.NAME_OPERAND)) : DYN_GET_METHOD; 97 98 final CallSiteDescriptor newDescriptor = NashornCallSiteDescriptor.get(descriptor.getLookup(), opName, 99 type.changeParameterType(0, adapterClass), 0); 100 101 // Delegate to BeansLinker 102 final GuardedInvocation guardedInv = NashornBeansLinker.getGuardedInvocation( 103 BeansLinker.getLinkerForClass(adapterClass), linkRequest.replaceArguments(newDescriptor, args), 104 linkerServices); 105 106 final MethodHandle guard = IS_ADAPTER_OF_CLASS.bindTo(adapterClass); 107 if(guardedInv == null) { 108 // Short circuit the lookup here for non-existent methods by linking an empty getter. If we just returned 109 // null instead, BeansLinker would find final methods on the JavaSuperAdapter instead: getClass() and 110 // wait(). 111 return new GuardedInvocation(MethodHandles.dropArguments(EMPTY_GETTER, 1,type.parameterList().subList(1, 112 type.parameterCount())), guard).asType(descriptor); 113 } 114 115 final MethodHandle invocation = guardedInv.getInvocation(); 116 final MethodType invType = invocation.type(); 117 // For invocation typed R(T0, ...) create a dynamic method binder of type Object(R, T0) 118 final MethodHandle typedBinder = BIND_DYNAMIC_METHOD.asType(MethodType.methodType(Object.class, 119 invType.returnType(), invType.parameterType(0))); 120 // For invocation typed R(T0, T1, ...) create a dynamic method binder of type Object(R, T0, T1, ...) 121 final MethodHandle droppingBinder = MethodHandles.dropArguments(typedBinder, 2, 122 invType.parameterList().subList(1, invType.parameterCount())); 123 // Finally, fold the invocation into the binder to produce a method handle that will bind every returned 124 // DynamicMethod object from dyn:getMethod calls to the actual receiver 125 // Object(R(T0, T1, ...), T0, T1, ...) 126 final MethodHandle bindingInvocation = MethodHandles.foldArguments(droppingBinder, invocation); 127 128 final MethodHandle typedGetAdapter = asFilterType(GET_ADAPTER, 0, invType, type); 129 final MethodHandle adaptedInvocation; 130 if(hasFixedName) { 131 adaptedInvocation = MethodHandles.filterArguments(bindingInvocation, 0, typedGetAdapter); 132 } else { 133 // Add a filter that'll prepend "super$" to each name passed to the variable-name "dyn:getMethod". 134 final MethodHandle typedAddPrefix = asFilterType(ADD_PREFIX_TO_METHOD_NAME, 1, invType, type); 135 adaptedInvocation = MethodHandles.filterArguments(bindingInvocation, 0, typedGetAdapter, typedAddPrefix); 136 } 137 138 return guardedInv.replaceMethods(adaptedInvocation, guard).asType(descriptor); 139 } 140 141 /** 142 * Adapts the type of a method handle used as a filter in a position from a source method type to a target method type. 143 * @param filter the filter method handle 144 * @param pos the position in the argument list that it's filtering 145 * @param targetType the target method type for filtering 146 * @param sourceType the source method type for filtering 147 * @return a type adapted filter 148 */ 149 private static MethodHandle asFilterType(final MethodHandle filter, final int pos, final MethodType targetType, final MethodType sourceType) { 150 return filter.asType(MethodType.methodType(targetType.parameterType(pos), sourceType.parameterType(pos))); 151 } 152 153 @SuppressWarnings("unused") 154 private static Object addPrefixToMethodName(final Object name) { 155 return SUPER_PREFIX.concat(String.valueOf(name)); 156 } 157 158 /** 159 * Used to transform the return value of getMethod; transform a {@code DynamicMethod} into a 160 * {@code BoundDynamicMethod} while also accounting for the possibility of a non-existent method. 161 * @param dynamicMethod the dynamic method to bind 162 * @param boundThis the adapter underlying a super adapter, to which the dynamic method is bound. 163 * @return a dynamic method bound to the adapter instance. 164 */ 165 @SuppressWarnings("unused") 166 private static Object bindDynamicMethod(final Object dynamicMethod, final Object boundThis) { 167 return dynamicMethod == null ? ScriptRuntime.UNDEFINED : Bootstrap.bindCallable(dynamicMethod, boundThis, null); 168 } 169 170 /** 171 * Used as the guard of linkages, as the receiver is not guaranteed to be a JavaSuperAdapter. 172 * @param clazz the class the receiver's adapter is tested against. 173 * @param obj receiver 174 * @return true if the receiver is a super adapter, and its underlying adapter is of the specified class 175 */ 176 @SuppressWarnings("unused") 177 private static boolean isAdapterOfClass(final Class<?> clazz, final Object obj) { 178 return obj instanceof JavaSuperAdapter && clazz == (((JavaSuperAdapter)obj).getAdapter()).getClass(); 179 } 180} 181