1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/jdk/internal/dynalink/DynamicLinker.java Thu Feb 14 13:22:26 2013 +0100
1.3 @@ -0,0 +1,281 @@
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;
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.lang.invoke.MutableCallSite;
1.93 +import java.util.List;
1.94 +import jdk.internal.dynalink.linker.GuardedInvocation;
1.95 +import jdk.internal.dynalink.linker.GuardingDynamicLinker;
1.96 +import jdk.internal.dynalink.linker.LinkRequest;
1.97 +import jdk.internal.dynalink.linker.LinkerServices;
1.98 +import jdk.internal.dynalink.support.CallSiteDescriptorFactory;
1.99 +import jdk.internal.dynalink.support.LinkRequestImpl;
1.100 +import jdk.internal.dynalink.support.Lookup;
1.101 +import jdk.internal.dynalink.support.RuntimeContextLinkRequestImpl;
1.102 +
1.103 +
1.104 +/**
1.105 + * The linker for {@link RelinkableCallSite} objects. Users of it (scripting frameworks and language runtimes) have to
1.106 + * create a linker using the {@link DynamicLinkerFactory} and invoke its link method from the invokedynamic bootstrap
1.107 + * methods to set the target of all the call sites in the code they generate. Usual usage would be to create one class
1.108 + * per language runtime to contain one linker instance as:
1.109 + *
1.110 + * <pre>
1.111 + * class MyLanguageRuntime {
1.112 + * private static final GuardingDynamicLinker myLanguageLinker = new MyLanguageLinker();
1.113 + * private static final DynamicLinker dynamicLinker = createDynamicLinker();
1.114 + *
1.115 + * private static DynamicLinker createDynamicLinker() {
1.116 + * final DynamicLinkerFactory factory = new DynamicLinkerFactory();
1.117 + * factory.setPrioritizedLinker(myLanguageLinker);
1.118 + * return factory.createLinker();
1.119 + * }
1.120 + *
1.121 + * public static CallSite bootstrap(MethodHandles.Lookup caller, String name, MethodType type) {
1.122 + * return dynamicLinker.link(new MonomorphicCallSite(CallSiteDescriptorFactory.create(lookup, name, type)));
1.123 + * }
1.124 + * }
1.125 + * </pre>
1.126 + *
1.127 + * Note how there are three components you will need to provide here:
1.128 + * <ul>
1.129 + * <li>You're expected to provide a {@link GuardingDynamicLinker} for your own language. If your runtime doesn't
1.130 + * have its own language and/or object model (i.e. it's a generic scripting shell), you don't need to implement a
1.131 + * dynamic linker; you would simply not invoke the {@code setPrioritizedLinker} method on the factory, or even better,
1.132 + * simply use {@link DefaultBootstrapper}.</li>
1.133 + * <li>The performance of the programs can depend on your choice of the class to represent call sites. The above
1.134 + * example used {@link MonomorphicCallSite}, but you might want to use {@link ChainedCallSite} instead. You'll need to
1.135 + * experiment and decide what fits your language runtime the best. You can subclass either of these or roll your own if
1.136 + * you need to.</li>
1.137 + * <li>You also need to provide {@link CallSiteDescriptor}s to your call sites. They are immutable objects that contain
1.138 + * all the information about the call site: the class performing the lookups, the name of the method being invoked, and
1.139 + * the method signature. The library has a default {@link CallSiteDescriptorFactory} for descriptors that you can use,
1.140 + * or you can create your own descriptor classes, especially if you need to add further information (values passed in
1.141 + * additional parameters to the bootstrap method) to them.</li>
1.142 + * </ul>
1.143 + *
1.144 + * @author Attila Szegedi
1.145 + */
1.146 +public class DynamicLinker {
1.147 +
1.148 + private static final String CLASS_NAME = DynamicLinker.class.getName();
1.149 + private static final String RELINK_METHOD_NAME = "relink";
1.150 +
1.151 + private final LinkerServices linkerServices;
1.152 + private final int runtimeContextArgCount;
1.153 + private final boolean syncOnRelink;
1.154 + private final int unstableRelinkThreshold;
1.155 +
1.156 + /**
1.157 + * Creates a new dynamic linker.
1.158 + *
1.159 + * @param linkerServices the linkerServices used by the linker, created by the factory.
1.160 + * @param runtimeContextArgCount see {@link DynamicLinkerFactory#setRuntimeContextArgCount(int)}
1.161 + */
1.162 + DynamicLinker(LinkerServices linkerServices, int runtimeContextArgCount, boolean syncOnRelink,
1.163 + int unstableRelinkThreshold) {
1.164 + if(runtimeContextArgCount < 0) {
1.165 + throw new IllegalArgumentException("runtimeContextArgCount < 0");
1.166 + }
1.167 + if(unstableRelinkThreshold < 0) {
1.168 + throw new IllegalArgumentException("unstableRelinkThreshold < 0");
1.169 + }
1.170 + this.runtimeContextArgCount = runtimeContextArgCount;
1.171 + this.linkerServices = linkerServices;
1.172 + this.syncOnRelink = syncOnRelink;
1.173 + this.unstableRelinkThreshold = unstableRelinkThreshold;
1.174 + }
1.175 +
1.176 + /**
1.177 + * Links an invokedynamic call site. It will install a method handle into the call site that invokes the relinking
1.178 + * mechanism of this linker. Next time the call site is invoked, it will be linked for the actual arguments it was
1.179 + * invoked with.
1.180 + *
1.181 + * @param callSite the call site to link.
1.182 + * @return the callSite, for easy call chaining.
1.183 + */
1.184 + public <T extends RelinkableCallSite> T link(final T callSite) {
1.185 + callSite.initialize(createRelinkAndInvokeMethod(callSite, 0));
1.186 + return callSite;
1.187 + }
1.188 +
1.189 + /**
1.190 + * Returns the object representing the lower level linker services of this class that are normally exposed to
1.191 + * individual language-specific linkers. While as a user of this class you normally only care about the
1.192 + * {@link #link(RelinkableCallSite)} method, in certain circumstances you might want to use the lower level services
1.193 + * directly; either to lookup specific method handles, to access the type converters, and so on.
1.194 + * @return the object representing the linker services of this class.
1.195 + */
1.196 + public LinkerServices getLinkerServices() {
1.197 + return linkerServices;
1.198 + }
1.199 +
1.200 + private static final MethodHandle RELINK = Lookup.findOwnSpecial(MethodHandles.lookup(), RELINK_METHOD_NAME,
1.201 + MethodHandle.class, RelinkableCallSite.class, int.class, Object[].class);
1.202 +
1.203 + private MethodHandle createRelinkAndInvokeMethod(final RelinkableCallSite callSite, int relinkCount) {
1.204 + // Make a bound MH of invoke() for this linker and call site
1.205 + final MethodHandle boundRelinker = MethodHandles.insertArguments(RELINK, 0, this, callSite, Integer.valueOf(
1.206 + relinkCount));
1.207 + // Make a MH that gathers all arguments to the invocation into an Object[]
1.208 + final MethodType type = callSite.getDescriptor().getMethodType();
1.209 + final MethodHandle collectingRelinker = boundRelinker.asCollector(Object[].class, type.parameterCount());
1.210 + return MethodHandles.foldArguments(MethodHandles.exactInvoker(type), collectingRelinker.asType(
1.211 + type.changeReturnType(MethodHandle.class)));
1.212 + }
1.213 +
1.214 + /**
1.215 + * Relinks a call site conforming to the invocation arguments.
1.216 + *
1.217 + * @param callSite the call site itself
1.218 + * @param arguments arguments to the invocation
1.219 + * @return return the method handle for the invocation
1.220 + * @throws Exception rethrows any exception thrown by the linkers
1.221 + */
1.222 + @SuppressWarnings("unused")
1.223 + private MethodHandle relink(RelinkableCallSite callSite, int relinkCount, Object... arguments) throws Exception {
1.224 + final CallSiteDescriptor callSiteDescriptor = callSite.getDescriptor();
1.225 + final boolean unstableDetectionEnabled = unstableRelinkThreshold > 0;
1.226 + final boolean callSiteUnstable = unstableDetectionEnabled && relinkCount >= unstableRelinkThreshold;
1.227 + final LinkRequest linkRequest =
1.228 + runtimeContextArgCount == 0 ? new LinkRequestImpl(callSiteDescriptor, callSiteUnstable, arguments)
1.229 + : new RuntimeContextLinkRequestImpl(callSiteDescriptor, callSiteUnstable, arguments,
1.230 + runtimeContextArgCount);
1.231 +
1.232 + // Find a suitable method handle with a guard
1.233 + GuardedInvocation guardedInvocation = linkerServices.getGuardedInvocation(linkRequest);
1.234 +
1.235 + // None found - throw an exception
1.236 + if(guardedInvocation == null) {
1.237 + throw new NoSuchDynamicMethodException(callSiteDescriptor.toString());
1.238 + }
1.239 +
1.240 + // If our call sites have a runtime context, and the linker produced a context-stripped invocation, adapt the
1.241 + // produced invocation into contextual invocation (by dropping the context...)
1.242 + if(runtimeContextArgCount > 0) {
1.243 + final MethodType origType = callSiteDescriptor.getMethodType();
1.244 + final MethodHandle invocation = guardedInvocation.getInvocation();
1.245 + if(invocation.type().parameterCount() == origType.parameterCount() - runtimeContextArgCount) {
1.246 + final List<Class<?>> prefix = origType.parameterList().subList(1, runtimeContextArgCount + 1);
1.247 + final MethodHandle guard = guardedInvocation.getGuard();
1.248 + guardedInvocation = guardedInvocation.dropArguments(1, prefix);
1.249 + }
1.250 + }
1.251 +
1.252 + if(unstableDetectionEnabled && relinkCount <= unstableRelinkThreshold && relinkCount++ == unstableRelinkThreshold) {
1.253 + // Note that we'll increase the relinkCount until threshold+1 and not increase it beyond that. Threshold+1
1.254 + // is treated as a special value to signal that resetAndRelink has already executed once for the unstable
1.255 + // call site; we only want the call site to throw away its current linkage once, when it transitions to
1.256 + // unstable.
1.257 + callSite.resetAndRelink(guardedInvocation, createRelinkAndInvokeMethod(callSite, relinkCount));
1.258 + } else {
1.259 + callSite.relink(guardedInvocation, createRelinkAndInvokeMethod(callSite, relinkCount));
1.260 + }
1.261 + if(syncOnRelink) {
1.262 + MutableCallSite.syncAll(new MutableCallSite[] { (MutableCallSite)callSite });
1.263 + }
1.264 + return guardedInvocation.getInvocation();
1.265 + }
1.266 +
1.267 + /**
1.268 + * Returns a stack trace element describing the location of the call site currently being relinked on the current
1.269 + * thread. The operation internally creates a Throwable object and inspects its stack trace, so it's potentially
1.270 + * expensive. The recommended usage for it is in writing diagnostics code.
1.271 + * @return a stack trace element describing the location of the call site currently being relinked, or null if it is
1.272 + * not invoked while a call site is being relinked.
1.273 + */
1.274 + public static StackTraceElement getRelinkedCallSiteLocation() {
1.275 + final StackTraceElement[] trace = new Throwable().getStackTrace();
1.276 + for(int i = 0; i < trace.length - 1; ++i) {
1.277 + final StackTraceElement frame = trace[i];
1.278 + if(RELINK_METHOD_NAME.equals(frame.getMethodName()) && CLASS_NAME.equals(frame.getClassName())) {
1.279 + return trace[i + 1];
1.280 + }
1.281 + }
1.282 + return null;
1.283 + }
1.284 +}
