1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/jdk/internal/dynalink/support/Guards.java Thu Feb 14 13:22:26 2013 +0100
1.3 @@ -0,0 +1,360 @@
1.4 +/*
1.5 + * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Oracle designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Oracle in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 + * or visit www.oracle.com if you need additional information or have any
1.26 + * questions.
1.27 + */
1.28 +
1.29 +/*
1.30 + * This file is available under and governed by the GNU General Public
1.31 + * License version 2 only, as published by the Free Software Foundation.
1.32 + * However, the following notice accompanied the original version of this
1.33 + * file, and Oracle licenses the original version of this file under the BSD
1.34 + * license:
1.35 + */
1.36 +/*
1.37 + Copyright 2009-2013 Attila Szegedi
1.38 +
1.39 + Licensed under both the Apache License, Version 2.0 (the "Apache License")
1.40 + and the BSD License (the "BSD License"), with licensee being free to
1.41 + choose either of the two at their discretion.
1.42 +
1.43 + You may not use this file except in compliance with either the Apache
1.44 + License or the BSD License.
1.45 +
1.46 + If you choose to use this file in compliance with the Apache License, the
1.47 + following notice applies to you:
1.48 +
1.49 + You may obtain a copy of the Apache License at
1.50 +
1.51 + http://www.apache.org/licenses/LICENSE-2.0
1.52 +
1.53 + Unless required by applicable law or agreed to in writing, software
1.54 + distributed under the License is distributed on an "AS IS" BASIS,
1.55 + WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
1.56 + implied. See the License for the specific language governing
1.57 + permissions and limitations under the License.
1.58 +
1.59 + If you choose to use this file in compliance with the BSD License, the
1.60 + following notice applies to you:
1.61 +
1.62 + Redistribution and use in source and binary forms, with or without
1.63 + modification, are permitted provided that the following conditions are
1.64 + met:
1.65 + * Redistributions of source code must retain the above copyright
1.66 + notice, this list of conditions and the following disclaimer.
1.67 + * Redistributions in binary form must reproduce the above copyright
1.68 + notice, this list of conditions and the following disclaimer in the
1.69 + documentation and/or other materials provided with the distribution.
1.70 + * Neither the name of the copyright holder nor the names of
1.71 + contributors may be used to endorse or promote products derived from
1.72 + this software without specific prior written permission.
1.73 +
1.74 + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
1.75 + IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
1.76 + TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
1.77 + PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
1.78 + BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.79 + CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.80 + SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
1.81 + BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
1.82 + WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
1.83 + OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
1.84 + ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.85 +*/
1.86 +
1.87 +package jdk.internal.dynalink.support;
1.88 +
1.89 +import java.lang.invoke.MethodHandle;
1.90 +import java.lang.invoke.MethodHandles;
1.91 +import java.lang.invoke.MethodType;
1.92 +import java.util.logging.Level;
1.93 +import java.util.logging.Logger;
1.94 +import jdk.internal.dynalink.linker.LinkerServices;
1.95 +
1.96 +
1.97 +/**
1.98 + * Utility methods for creating typical guards. TODO: introduce reasonable caching of created guards.
1.99 + *
1.100 + * @author Attila Szegedi
1.101 + */
1.102 +public class Guards {
1.103 + private static final Logger LOG = Logger
1.104 + .getLogger(Guards.class.getName(), "jdk.internal.dynalink.support.messages");
1.105 +
1.106 + private Guards() {
1.107 + }
1.108 +
1.109 + /**
1.110 + * Creates a guard method handle with arguments of a specified type, but with boolean return value. When invoked, it
1.111 + * returns true if the first argument is of the specified class (exactly of it, not a subclass). The rest of the
1.112 + * arguments will be ignored.
1.113 + *
1.114 + * @param clazz the class of the first argument to test for
1.115 + * @param type the method type
1.116 + * @return a method handle testing whether its first argument is of the specified class.
1.117 + */
1.118 + @SuppressWarnings("boxing")
1.119 + public static MethodHandle isOfClass(Class<?> clazz, MethodType type) {
1.120 + final Class<?> declaredType = type.parameterType(0);
1.121 + if(clazz == declaredType) {
1.122 + LOG.log(Level.WARNING, "isOfClassGuardAlwaysTrue", new Object[] { clazz.getName(), 0, type });
1.123 + return constantTrue(type);
1.124 + }
1.125 + if(!declaredType.isAssignableFrom(clazz)) {
1.126 + LOG.log(Level.WARNING, "isOfClassGuardAlwaysFalse", new Object[] { clazz.getName(), 0, type });
1.127 + return constantFalse(type);
1.128 + }
1.129 + return getClassBoundArgumentTest(IS_OF_CLASS, clazz, 0, type);
1.130 + }
1.131 +
1.132 + /**
1.133 + * Creates a method handle with arguments of a specified type, but with boolean return value. When invoked, it
1.134 + * returns true if the first argument is instance of the specified class or its subclass). The rest of the arguments
1.135 + * will be ignored.
1.136 + *
1.137 + * @param clazz the class of the first argument to test for
1.138 + * @param type the method type
1.139 + * @return a method handle testing whether its first argument is of the specified class or subclass.
1.140 + */
1.141 + public static MethodHandle isInstance(Class<?> clazz, MethodType type) {
1.142 + return isInstance(clazz, 0, type);
1.143 + }
1.144 +
1.145 + /**
1.146 + * Creates a method handle with arguments of a specified type, but with boolean return value. When invoked, it
1.147 + * returns true if the n'th argument is instance of the specified class or its subclass). The rest of the arguments
1.148 + * will be ignored.
1.149 + *
1.150 + * @param clazz the class of the first argument to test for
1.151 + * @param pos the position on the argument list to test
1.152 + * @param type the method type
1.153 + * @return a method handle testing whether its first argument is of the specified class or subclass.
1.154 + */
1.155 + @SuppressWarnings("boxing")
1.156 + public static MethodHandle isInstance(Class<?> clazz, int pos, MethodType type) {
1.157 + final Class<?> declaredType = type.parameterType(pos);
1.158 + if(clazz.isAssignableFrom(declaredType)) {
1.159 + LOG.log(Level.WARNING, "isInstanceGuardAlwaysTrue", new Object[] { clazz.getName(), pos, type });
1.160 + return constantTrue(type);
1.161 + }
1.162 + if(!declaredType.isAssignableFrom(clazz)) {
1.163 + LOG.log(Level.WARNING, "isInstanceGuardAlwaysFalse", new Object[] { clazz.getName(), pos, type });
1.164 + return constantFalse(type);
1.165 + }
1.166 + return getClassBoundArgumentTest(IS_INSTANCE, clazz, pos, type);
1.167 + }
1.168 +
1.169 + /**
1.170 + * Creates a method handle that returns true if the argument in the specified position is a Java array.
1.171 + *
1.172 + * @param pos the position in the argument lit
1.173 + * @param type the method type of the handle
1.174 + * @return a method handle that returns true if the argument in the specified position is a Java array; the rest of
1.175 + * the arguments are ignored.
1.176 + */
1.177 + @SuppressWarnings("boxing")
1.178 + public static MethodHandle isArray(int pos, MethodType type) {
1.179 + final Class<?> declaredType = type.parameterType(pos);
1.180 + if(declaredType.isArray()) {
1.181 + LOG.log(Level.WARNING, "isArrayGuardAlwaysTrue", new Object[] { pos, type });
1.182 + return constantTrue(type);
1.183 + }
1.184 + if(!declaredType.isAssignableFrom(Object[].class)) {
1.185 + LOG.log(Level.WARNING, "isArrayGuardAlwaysFalse", new Object[] { pos, type });
1.186 + return constantFalse(type);
1.187 + }
1.188 + return asType(IS_ARRAY, pos, type);
1.189 + }
1.190 +
1.191 + /**
1.192 + * Return true if it is safe to strongly reference a class from the referred class loader from a class associated
1.193 + * with the referring class loader without risking a class loader memory leak.
1.194 + *
1.195 + * @param referrerLoader the referrer class loader
1.196 + * @param referredLoader the referred class loader
1.197 + * @return true if it is safe to strongly reference the class
1.198 + */
1.199 + public static boolean canReferenceDirectly(ClassLoader referrerLoader, final ClassLoader referredLoader) {
1.200 + if(referredLoader == null) {
1.201 + // Can always refer directly to a system class
1.202 + return true;
1.203 + }
1.204 + if(referrerLoader == null) {
1.205 + // System classes can't refer directly to any non-system class
1.206 + return false;
1.207 + }
1.208 + // Otherwise, can only refer directly to classes residing in same or
1.209 + // parent class loader.
1.210 +
1.211 + ClassLoader referrer = referrerLoader;
1.212 + do {
1.213 + if(referrer == referredLoader) {
1.214 + return true;
1.215 + }
1.216 + referrer = referrer.getParent();
1.217 + } while(referrer != null);
1.218 + return false;
1.219 + }
1.220 +
1.221 + private static MethodHandle getClassBoundArgumentTest(MethodHandle test, Class<?> clazz, int pos, MethodType type) {
1.222 + // Bind the class to the first argument of the test
1.223 + return asType(test.bindTo(clazz), pos, type);
1.224 + }
1.225 +
1.226 + /**
1.227 + * Takes a guard-test method handle, and adapts it to the requested type, returning a boolean. Only applies
1.228 + * conversions as per {@link MethodHandle#asType(MethodType)}.
1.229 + * @param test the test method handle
1.230 + * @param type the type to adapt the method handle to
1.231 + * @return the adapted method handle
1.232 + */
1.233 + public static MethodHandle asType(MethodHandle test, MethodType type) {
1.234 + return test.asType(getTestType(test, type));
1.235 + }
1.236 +
1.237 + /**
1.238 + * Takes a guard-test method handle, and adapts it to the requested type, returning a boolean. Applies the passed
1.239 + * {@link LinkerServices} object's {@link LinkerServices#asType(MethodHandle, MethodType)}.
1.240 + * @param linkerServices the linker services to use for type conversions
1.241 + * @param test the test method handle
1.242 + * @param type the type to adapt the method handle to
1.243 + * @return the adapted method handle
1.244 + */
1.245 + public static MethodHandle asType(LinkerServices linkerServices, MethodHandle test, MethodType type) {
1.246 + return linkerServices.asType(test, getTestType(test, type));
1.247 + }
1.248 +
1.249 + private static MethodType getTestType(MethodHandle test, MethodType type) {
1.250 + return type.dropParameterTypes(test.type().parameterCount(),
1.251 + type.parameterCount()).changeReturnType(boolean.class);
1.252 + }
1.253 +
1.254 + private static MethodHandle asType(MethodHandle test, int pos, MethodType type) {
1.255 + assert test != null;
1.256 + assert type != null;
1.257 + assert type.parameterCount() > 0;
1.258 + assert pos >= 0 && pos < type.parameterCount();
1.259 + assert test.type().parameterCount() == 1;
1.260 + assert test.type().returnType() == Boolean.TYPE;
1.261 + return MethodHandles.permuteArguments(test.asType(test.type().changeParameterType(0, type.parameterType(pos))),
1.262 + type.changeReturnType(Boolean.TYPE), new int[] { pos });
1.263 + }
1.264 +
1.265 + private static final MethodHandle IS_OF_CLASS = new Lookup(MethodHandles.lookup()).findStatic(Guards.class,
1.266 + "isOfClass", MethodType.methodType(Boolean.TYPE, Class.class, Object.class));
1.267 +
1.268 + private static final MethodHandle IS_INSTANCE = Lookup.PUBLIC.findVirtual(Class.class, "isInstance",
1.269 + MethodType.methodType(Boolean.TYPE, Object.class));
1.270 +
1.271 + private static final MethodHandle IS_ARRAY = new Lookup(MethodHandles.lookup()).findStatic(Guards.class, "isArray",
1.272 + MethodType.methodType(Boolean.TYPE, Object.class));
1.273 +
1.274 + private static final MethodHandle IS_IDENTICAL = new Lookup(MethodHandles.lookup()).findStatic(Guards.class,
1.275 + "isIdentical", MethodType.methodType(Boolean.TYPE, Object.class, Object.class));
1.276 +
1.277 + private static final MethodHandle IS_NULL = new Lookup(MethodHandles.lookup()).findStatic(Guards.class,
1.278 + "isNull", MethodType.methodType(Boolean.TYPE, Object.class));
1.279 +
1.280 + private static final MethodHandle IS_NOT_NULL = new Lookup(MethodHandles.lookup()).findStatic(Guards.class,
1.281 + "isNotNull", MethodType.methodType(Boolean.TYPE, Object.class));
1.282 +
1.283 + /**
1.284 + * Creates a guard method that tests its only argument for being of an exact particular class.
1.285 + * @param clazz the class to test for.
1.286 + * @return the desired guard method.
1.287 + */
1.288 + public static MethodHandle getClassGuard(Class<?> clazz) {
1.289 + return IS_OF_CLASS.bindTo(clazz);
1.290 + }
1.291 +
1.292 + /**
1.293 + * Creates a guard method that tests its only argument for being an instance of a particular class.
1.294 + * @param clazz the class to test for.
1.295 + * @return the desired guard method.
1.296 + */
1.297 + public static MethodHandle getInstanceOfGuard(Class<?> clazz) {
1.298 + return IS_INSTANCE.bindTo(clazz);
1.299 + }
1.300 +
1.301 + /**
1.302 + * Creates a guard method that tests its only argument for being referentially identical to another object
1.303 + * @param obj the object used as referential identity test
1.304 + * @return the desired guard method.
1.305 + */
1.306 + public static MethodHandle getIdentityGuard(Object obj) {
1.307 + return IS_IDENTICAL.bindTo(obj);
1.308 + }
1.309 +
1.310 + /**
1.311 + * Returns a guard that tests whether the first argument is null.
1.312 + * @return a guard that tests whether the first argument is null.
1.313 + */
1.314 + public static MethodHandle isNull() {
1.315 + return IS_NULL;
1.316 + }
1.317 +
1.318 + /**
1.319 + * Returns a guard that tests whether the first argument is not null.
1.320 + * @return a guard that tests whether the first argument is not null.
1.321 + */
1.322 + public static MethodHandle isNotNull() {
1.323 + return IS_NOT_NULL;
1.324 + }
1.325 +
1.326 + @SuppressWarnings("unused")
1.327 + private static boolean isNull(Object obj) {
1.328 + return obj == null;
1.329 + }
1.330 +
1.331 + @SuppressWarnings("unused")
1.332 + private static boolean isNotNull(Object obj) {
1.333 + return obj != null;
1.334 + }
1.335 +
1.336 + @SuppressWarnings("unused")
1.337 + private static boolean isArray(Object o) {
1.338 + return o != null && o.getClass().isArray();
1.339 + }
1.340 +
1.341 + @SuppressWarnings("unused")
1.342 + private static boolean isOfClass(Class<?> c, Object o) {
1.343 + return o != null && o.getClass() == c;
1.344 + }
1.345 +
1.346 + @SuppressWarnings("unused")
1.347 + private static boolean isIdentical(Object o1, Object o2) {
1.348 + return o1 == o2;
1.349 + }
1.350 +
1.351 + private static MethodHandle constantTrue(MethodType type) {
1.352 + return constantBoolean(Boolean.TRUE, type);
1.353 + }
1.354 +
1.355 + private static MethodHandle constantFalse(MethodType type) {
1.356 + return constantBoolean(Boolean.FALSE, type);
1.357 + }
1.358 +
1.359 + private static MethodHandle constantBoolean(Boolean value, MethodType type) {
1.360 + return MethodHandles.permuteArguments(MethodHandles.constant(Boolean.TYPE, value),
1.361 + type.changeReturnType(Boolean.TYPE));
1.362 + }
1.363 +}
1.364 \ No newline at end of file
