Wed, 20 Aug 2014 10:25:28 +0200
8044638: Tidy up Nashorn codebase for code standards
8055199: Tidy up Nashorn codebase for code standards (August 2014)
Reviewed-by: lagergren, sundar
attila@90 | 1 | /* |
attila@90 | 2 | * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved. |
attila@90 | 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
attila@90 | 4 | * |
attila@90 | 5 | * This code is free software; you can redistribute it and/or modify it |
attila@90 | 6 | * under the terms of the GNU General Public License version 2 only, as |
attila@90 | 7 | * published by the Free Software Foundation. Oracle designates this |
attila@90 | 8 | * particular file as subject to the "Classpath" exception as provided |
attila@90 | 9 | * by Oracle in the LICENSE file that accompanied this code. |
attila@90 | 10 | * |
attila@90 | 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
attila@90 | 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
attila@90 | 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
attila@90 | 14 | * version 2 for more details (a copy is included in the LICENSE file that |
attila@90 | 15 | * accompanied this code). |
attila@90 | 16 | * |
attila@90 | 17 | * You should have received a copy of the GNU General Public License version |
attila@90 | 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
attila@90 | 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
attila@90 | 20 | * |
attila@90 | 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
attila@90 | 22 | * or visit www.oracle.com if you need additional information or have any |
attila@90 | 23 | * questions. |
attila@90 | 24 | */ |
attila@90 | 25 | |
attila@90 | 26 | /* |
attila@90 | 27 | * This file is available under and governed by the GNU General Public |
attila@90 | 28 | * License version 2 only, as published by the Free Software Foundation. |
attila@90 | 29 | * However, the following notice accompanied the original version of this |
attila@90 | 30 | * file, and Oracle licenses the original version of this file under the BSD |
attila@90 | 31 | * license: |
attila@90 | 32 | */ |
attila@90 | 33 | /* |
attila@90 | 34 | Copyright 2009-2013 Attila Szegedi |
attila@90 | 35 | |
attila@90 | 36 | Licensed under both the Apache License, Version 2.0 (the "Apache License") |
attila@90 | 37 | and the BSD License (the "BSD License"), with licensee being free to |
attila@90 | 38 | choose either of the two at their discretion. |
attila@90 | 39 | |
attila@90 | 40 | You may not use this file except in compliance with either the Apache |
attila@90 | 41 | License or the BSD License. |
attila@90 | 42 | |
attila@90 | 43 | If you choose to use this file in compliance with the Apache License, the |
attila@90 | 44 | following notice applies to you: |
attila@90 | 45 | |
attila@90 | 46 | You may obtain a copy of the Apache License at |
attila@90 | 47 | |
attila@90 | 48 | http://www.apache.org/licenses/LICENSE-2.0 |
attila@90 | 49 | |
attila@90 | 50 | Unless required by applicable law or agreed to in writing, software |
attila@90 | 51 | distributed under the License is distributed on an "AS IS" BASIS, |
attila@90 | 52 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or |
attila@90 | 53 | implied. See the License for the specific language governing |
attila@90 | 54 | permissions and limitations under the License. |
attila@90 | 55 | |
attila@90 | 56 | If you choose to use this file in compliance with the BSD License, the |
attila@90 | 57 | following notice applies to you: |
attila@90 | 58 | |
attila@90 | 59 | Redistribution and use in source and binary forms, with or without |
attila@90 | 60 | modification, are permitted provided that the following conditions are |
attila@90 | 61 | met: |
attila@90 | 62 | * Redistributions of source code must retain the above copyright |
attila@90 | 63 | notice, this list of conditions and the following disclaimer. |
attila@90 | 64 | * Redistributions in binary form must reproduce the above copyright |
attila@90 | 65 | notice, this list of conditions and the following disclaimer in the |
attila@90 | 66 | documentation and/or other materials provided with the distribution. |
attila@90 | 67 | * Neither the name of the copyright holder nor the names of |
attila@90 | 68 | contributors may be used to endorse or promote products derived from |
attila@90 | 69 | this software without specific prior written permission. |
attila@90 | 70 | |
attila@90 | 71 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS |
attila@90 | 72 | IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
attila@90 | 73 | TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A |
attila@90 | 74 | PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER |
attila@90 | 75 | BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
attila@90 | 76 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
attila@90 | 77 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
attila@90 | 78 | BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
attila@90 | 79 | WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
attila@90 | 80 | OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
attila@90 | 81 | ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
attila@90 | 82 | */ |
attila@90 | 83 | |
attila@90 | 84 | package jdk.internal.dynalink; |
attila@90 | 85 | |
attila@90 | 86 | import java.lang.invoke.MethodHandle; |
attila@90 | 87 | import java.lang.invoke.MethodHandles; |
attila@90 | 88 | import java.lang.invoke.MethodType; |
attila@90 | 89 | import java.lang.invoke.MutableCallSite; |
attila@90 | 90 | import java.util.List; |
attila@90 | 91 | import jdk.internal.dynalink.linker.GuardedInvocation; |
attila@90 | 92 | import jdk.internal.dynalink.linker.GuardingDynamicLinker; |
attila@90 | 93 | import jdk.internal.dynalink.linker.LinkRequest; |
attila@90 | 94 | import jdk.internal.dynalink.linker.LinkerServices; |
attila@90 | 95 | import jdk.internal.dynalink.support.CallSiteDescriptorFactory; |
attila@90 | 96 | import jdk.internal.dynalink.support.LinkRequestImpl; |
attila@90 | 97 | import jdk.internal.dynalink.support.Lookup; |
attila@90 | 98 | import jdk.internal.dynalink.support.RuntimeContextLinkRequestImpl; |
attila@90 | 99 | |
attila@90 | 100 | /** |
attila@90 | 101 | * The linker for {@link RelinkableCallSite} objects. Users of it (scripting frameworks and language runtimes) have to |
attila@90 | 102 | * create a linker using the {@link DynamicLinkerFactory} and invoke its link method from the invokedynamic bootstrap |
attila@90 | 103 | * methods to set the target of all the call sites in the code they generate. Usual usage would be to create one class |
attila@90 | 104 | * per language runtime to contain one linker instance as: |
attila@90 | 105 | * |
attila@90 | 106 | * <pre> |
attila@90 | 107 | * class MyLanguageRuntime { |
attila@90 | 108 | * private static final GuardingDynamicLinker myLanguageLinker = new MyLanguageLinker(); |
attila@90 | 109 | * private static final DynamicLinker dynamicLinker = createDynamicLinker(); |
attila@90 | 110 | * |
attila@90 | 111 | * private static DynamicLinker createDynamicLinker() { |
attila@90 | 112 | * final DynamicLinkerFactory factory = new DynamicLinkerFactory(); |
attila@90 | 113 | * factory.setPrioritizedLinker(myLanguageLinker); |
attila@90 | 114 | * return factory.createLinker(); |
attila@90 | 115 | * } |
attila@90 | 116 | * |
attila@90 | 117 | * public static CallSite bootstrap(MethodHandles.Lookup caller, String name, MethodType type) { |
attila@90 | 118 | * return dynamicLinker.link(new MonomorphicCallSite(CallSiteDescriptorFactory.create(lookup, name, type))); |
attila@90 | 119 | * } |
attila@90 | 120 | * } |
attila@90 | 121 | * </pre> |
attila@90 | 122 | * |
attila@90 | 123 | * Note how there are three components you will need to provide here: |
attila@90 | 124 | * <ul> |
attila@90 | 125 | * <li>You're expected to provide a {@link GuardingDynamicLinker} for your own language. If your runtime doesn't |
attila@90 | 126 | * have its own language and/or object model (i.e. it's a generic scripting shell), you don't need to implement a |
attila@90 | 127 | * dynamic linker; you would simply not invoke the {@code setPrioritizedLinker} method on the factory, or even better, |
attila@90 | 128 | * simply use {@link DefaultBootstrapper}.</li> |
attila@90 | 129 | * <li>The performance of the programs can depend on your choice of the class to represent call sites. The above |
attila@90 | 130 | * example used {@link MonomorphicCallSite}, but you might want to use {@link ChainedCallSite} instead. You'll need to |
attila@90 | 131 | * experiment and decide what fits your language runtime the best. You can subclass either of these or roll your own if |
attila@90 | 132 | * you need to.</li> |
attila@90 | 133 | * <li>You also need to provide {@link CallSiteDescriptor}s to your call sites. They are immutable objects that contain |
attila@90 | 134 | * all the information about the call site: the class performing the lookups, the name of the method being invoked, and |
attila@90 | 135 | * the method signature. The library has a default {@link CallSiteDescriptorFactory} for descriptors that you can use, |
attila@90 | 136 | * or you can create your own descriptor classes, especially if you need to add further information (values passed in |
attila@90 | 137 | * additional parameters to the bootstrap method) to them.</li> |
attila@90 | 138 | * </ul> |
attila@90 | 139 | * |
attila@90 | 140 | * @author Attila Szegedi |
attila@90 | 141 | */ |
attila@90 | 142 | public class DynamicLinker { |
attila@90 | 143 | |
attila@90 | 144 | private static final String CLASS_NAME = DynamicLinker.class.getName(); |
attila@90 | 145 | private static final String RELINK_METHOD_NAME = "relink"; |
attila@90 | 146 | |
attila@443 | 147 | private static final String INITIAL_LINK_CLASS_NAME = "java.lang.invoke.MethodHandleNatives"; |
attila@443 | 148 | private static final String INITIAL_LINK_METHOD_NAME = "linkCallSite"; |
attila@443 | 149 | |
attila@90 | 150 | private final LinkerServices linkerServices; |
attila@90 | 151 | private final int runtimeContextArgCount; |
attila@90 | 152 | private final boolean syncOnRelink; |
attila@90 | 153 | private final int unstableRelinkThreshold; |
attila@90 | 154 | |
attila@90 | 155 | /** |
attila@90 | 156 | * Creates a new dynamic linker. |
attila@90 | 157 | * |
attila@90 | 158 | * @param linkerServices the linkerServices used by the linker, created by the factory. |
attila@90 | 159 | * @param runtimeContextArgCount see {@link DynamicLinkerFactory#setRuntimeContextArgCount(int)} |
attila@90 | 160 | */ |
attila@962 | 161 | DynamicLinker(final LinkerServices linkerServices, final int runtimeContextArgCount, final boolean syncOnRelink, |
attila@962 | 162 | final int unstableRelinkThreshold) { |
attila@90 | 163 | if(runtimeContextArgCount < 0) { |
attila@90 | 164 | throw new IllegalArgumentException("runtimeContextArgCount < 0"); |
attila@90 | 165 | } |
attila@90 | 166 | if(unstableRelinkThreshold < 0) { |
attila@90 | 167 | throw new IllegalArgumentException("unstableRelinkThreshold < 0"); |
attila@90 | 168 | } |
attila@90 | 169 | this.runtimeContextArgCount = runtimeContextArgCount; |
attila@90 | 170 | this.linkerServices = linkerServices; |
attila@90 | 171 | this.syncOnRelink = syncOnRelink; |
attila@90 | 172 | this.unstableRelinkThreshold = unstableRelinkThreshold; |
attila@90 | 173 | } |
attila@90 | 174 | |
attila@90 | 175 | /** |
attila@90 | 176 | * Links an invokedynamic call site. It will install a method handle into the call site that invokes the relinking |
attila@90 | 177 | * mechanism of this linker. Next time the call site is invoked, it will be linked for the actual arguments it was |
attila@90 | 178 | * invoked with. |
attila@90 | 179 | * |
attila@90 | 180 | * @param callSite the call site to link. |
attila@90 | 181 | * @return the callSite, for easy call chaining. |
attila@90 | 182 | */ |
attila@90 | 183 | public <T extends RelinkableCallSite> T link(final T callSite) { |
attila@90 | 184 | callSite.initialize(createRelinkAndInvokeMethod(callSite, 0)); |
attila@90 | 185 | return callSite; |
attila@90 | 186 | } |
attila@90 | 187 | |
attila@90 | 188 | /** |
attila@90 | 189 | * Returns the object representing the lower level linker services of this class that are normally exposed to |
attila@90 | 190 | * individual language-specific linkers. While as a user of this class you normally only care about the |
attila@90 | 191 | * {@link #link(RelinkableCallSite)} method, in certain circumstances you might want to use the lower level services |
attila@90 | 192 | * directly; either to lookup specific method handles, to access the type converters, and so on. |
attila@90 | 193 | * @return the object representing the linker services of this class. |
attila@90 | 194 | */ |
attila@90 | 195 | public LinkerServices getLinkerServices() { |
attila@90 | 196 | return linkerServices; |
attila@90 | 197 | } |
attila@90 | 198 | |
attila@90 | 199 | private static final MethodHandle RELINK = Lookup.findOwnSpecial(MethodHandles.lookup(), RELINK_METHOD_NAME, |
attila@90 | 200 | MethodHandle.class, RelinkableCallSite.class, int.class, Object[].class); |
attila@90 | 201 | |
attila@962 | 202 | private MethodHandle createRelinkAndInvokeMethod(final RelinkableCallSite callSite, final int relinkCount) { |
attila@90 | 203 | // Make a bound MH of invoke() for this linker and call site |
attila@90 | 204 | final MethodHandle boundRelinker = MethodHandles.insertArguments(RELINK, 0, this, callSite, Integer.valueOf( |
attila@90 | 205 | relinkCount)); |
attila@90 | 206 | // Make a MH that gathers all arguments to the invocation into an Object[] |
attila@90 | 207 | final MethodType type = callSite.getDescriptor().getMethodType(); |
attila@90 | 208 | final MethodHandle collectingRelinker = boundRelinker.asCollector(Object[].class, type.parameterCount()); |
attila@90 | 209 | return MethodHandles.foldArguments(MethodHandles.exactInvoker(type), collectingRelinker.asType( |
attila@90 | 210 | type.changeReturnType(MethodHandle.class))); |
attila@90 | 211 | } |
attila@90 | 212 | |
attila@90 | 213 | /** |
attila@90 | 214 | * Relinks a call site conforming to the invocation arguments. |
attila@90 | 215 | * |
attila@90 | 216 | * @param callSite the call site itself |
attila@90 | 217 | * @param arguments arguments to the invocation |
attila@90 | 218 | * @return return the method handle for the invocation |
attila@90 | 219 | * @throws Exception rethrows any exception thrown by the linkers |
attila@90 | 220 | */ |
attila@90 | 221 | @SuppressWarnings("unused") |
attila@962 | 222 | private MethodHandle relink(final RelinkableCallSite callSite, final int relinkCount, final Object... arguments) throws Exception { |
attila@90 | 223 | final CallSiteDescriptor callSiteDescriptor = callSite.getDescriptor(); |
attila@90 | 224 | final boolean unstableDetectionEnabled = unstableRelinkThreshold > 0; |
attila@90 | 225 | final boolean callSiteUnstable = unstableDetectionEnabled && relinkCount >= unstableRelinkThreshold; |
attila@90 | 226 | final LinkRequest linkRequest = |
attila@90 | 227 | runtimeContextArgCount == 0 ? new LinkRequestImpl(callSiteDescriptor, callSiteUnstable, arguments) |
attila@90 | 228 | : new RuntimeContextLinkRequestImpl(callSiteDescriptor, callSiteUnstable, arguments, |
attila@90 | 229 | runtimeContextArgCount); |
attila@90 | 230 | |
attila@90 | 231 | // Find a suitable method handle with a guard |
attila@90 | 232 | GuardedInvocation guardedInvocation = linkerServices.getGuardedInvocation(linkRequest); |
attila@90 | 233 | |
attila@90 | 234 | // None found - throw an exception |
attila@90 | 235 | if(guardedInvocation == null) { |
attila@90 | 236 | throw new NoSuchDynamicMethodException(callSiteDescriptor.toString()); |
attila@90 | 237 | } |
attila@90 | 238 | |
attila@90 | 239 | // If our call sites have a runtime context, and the linker produced a context-stripped invocation, adapt the |
attila@90 | 240 | // produced invocation into contextual invocation (by dropping the context...) |
attila@90 | 241 | if(runtimeContextArgCount > 0) { |
attila@90 | 242 | final MethodType origType = callSiteDescriptor.getMethodType(); |
attila@90 | 243 | final MethodHandle invocation = guardedInvocation.getInvocation(); |
attila@90 | 244 | if(invocation.type().parameterCount() == origType.parameterCount() - runtimeContextArgCount) { |
attila@90 | 245 | final List<Class<?>> prefix = origType.parameterList().subList(1, runtimeContextArgCount + 1); |
attila@90 | 246 | final MethodHandle guard = guardedInvocation.getGuard(); |
attila@90 | 247 | guardedInvocation = guardedInvocation.dropArguments(1, prefix); |
attila@90 | 248 | } |
attila@90 | 249 | } |
attila@90 | 250 | |
attila@101 | 251 | int newRelinkCount = relinkCount; |
attila@101 | 252 | // Note that the short-circuited "&&" evaluation below ensures we'll increment the relinkCount until |
attila@101 | 253 | // threshold + 1 but not beyond that. Threshold + 1 is treated as a special value to signal that resetAndRelink |
attila@101 | 254 | // has already executed once for the unstable call site; we only want the call site to throw away its current |
attila@101 | 255 | // linkage once, when it transitions to unstable. |
attila@101 | 256 | if(unstableDetectionEnabled && newRelinkCount <= unstableRelinkThreshold && newRelinkCount++ == unstableRelinkThreshold) { |
attila@101 | 257 | callSite.resetAndRelink(guardedInvocation, createRelinkAndInvokeMethod(callSite, newRelinkCount)); |
attila@90 | 258 | } else { |
attila@101 | 259 | callSite.relink(guardedInvocation, createRelinkAndInvokeMethod(callSite, newRelinkCount)); |
attila@90 | 260 | } |
attila@90 | 261 | if(syncOnRelink) { |
attila@90 | 262 | MutableCallSite.syncAll(new MutableCallSite[] { (MutableCallSite)callSite }); |
attila@90 | 263 | } |
attila@90 | 264 | return guardedInvocation.getInvocation(); |
attila@90 | 265 | } |
attila@90 | 266 | |
attila@90 | 267 | /** |
attila@443 | 268 | * Returns a stack trace element describing the location of the call site currently being linked on the current |
attila@90 | 269 | * thread. The operation internally creates a Throwable object and inspects its stack trace, so it's potentially |
attila@90 | 270 | * expensive. The recommended usage for it is in writing diagnostics code. |
attila@443 | 271 | * @return a stack trace element describing the location of the call site currently being linked, or null if it is |
attila@443 | 272 | * not invoked while a call site is being linked. |
attila@90 | 273 | */ |
attila@443 | 274 | public static StackTraceElement getLinkedCallSiteLocation() { |
attila@90 | 275 | final StackTraceElement[] trace = new Throwable().getStackTrace(); |
attila@90 | 276 | for(int i = 0; i < trace.length - 1; ++i) { |
attila@90 | 277 | final StackTraceElement frame = trace[i]; |
attila@443 | 278 | if(isRelinkFrame(frame) || isInitialLinkFrame(frame)) { |
attila@90 | 279 | return trace[i + 1]; |
attila@90 | 280 | } |
attila@90 | 281 | } |
attila@90 | 282 | return null; |
attila@90 | 283 | } |
attila@443 | 284 | |
attila@443 | 285 | /** |
attila@443 | 286 | * Deprecated because of not precise name. |
attila@443 | 287 | * @deprecated Use {@link #getLinkedCallSiteLocation()} instead. |
attila@443 | 288 | * @return see non-deprecated method |
attila@443 | 289 | */ |
attila@443 | 290 | @Deprecated |
attila@443 | 291 | public static StackTraceElement getRelinkedCallSiteLocation() { |
attila@443 | 292 | return getLinkedCallSiteLocation(); |
attila@443 | 293 | } |
attila@443 | 294 | |
attila@443 | 295 | /** |
attila@443 | 296 | * Returns true if the frame represents {@code MethodHandleNatives.linkCallSite()}, the frame immediately on top of |
attila@443 | 297 | * the call site frame when the call site is being linked for the first time. |
attila@443 | 298 | * @param frame the frame |
attila@443 | 299 | * @return true if this frame represents {@code MethodHandleNatives.linkCallSite()} |
attila@443 | 300 | */ |
attila@443 | 301 | private static boolean isInitialLinkFrame(final StackTraceElement frame) { |
attila@443 | 302 | return testFrame(frame, INITIAL_LINK_METHOD_NAME, INITIAL_LINK_CLASS_NAME); |
attila@443 | 303 | } |
attila@443 | 304 | |
attila@443 | 305 | /** |
attila@443 | 306 | * Returns true if the frame represents {@code DynamicLinker.relink()}, the frame immediately on top of the call |
attila@443 | 307 | * site frame when the call site is being relinked (linked for second and subsequent times). |
attila@443 | 308 | * @param frame the frame |
attila@443 | 309 | * @return true if this frame represents {@code DynamicLinker.relink()} |
attila@443 | 310 | */ |
attila@443 | 311 | private static boolean isRelinkFrame(final StackTraceElement frame) { |
attila@443 | 312 | return testFrame(frame, RELINK_METHOD_NAME, CLASS_NAME); |
attila@443 | 313 | } |
attila@443 | 314 | |
attila@443 | 315 | private static boolean testFrame(final StackTraceElement frame, final String methodName, final String className) { |
attila@443 | 316 | return methodName.equals(frame.getMethodName()) && className.equals(frame.getClassName()); |
attila@443 | 317 | } |
attila@90 | 318 | } |