--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/src/jdk/internal/dynalink/DynamicLinker.java Thu Feb 14 13:22:26 2013 +0100
@@ -0,0 +1,281 @@
+/*
+ * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file, and Oracle licenses the original version of this file under the BSD
+ * license:
+ */
+/*
+ Copyright 2009-2013 Attila Szegedi
+
+ Licensed under both the Apache License, Version 2.0 (the "Apache License")
+ and the BSD License (the "BSD License"), with licensee being free to
+ choose either of the two at their discretion.
+
+ You may not use this file except in compliance with either the Apache
+ License or the BSD License.
+
+ If you choose to use this file in compliance with the Apache License, the
+ following notice applies to you:
+
+ You may obtain a copy of the Apache License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ implied. See the License for the specific language governing
+ permissions and limitations under the License.
+
+ If you choose to use this file in compliance with the BSD License, the
+ following notice applies to you:
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are
+ met:
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+ * Neither the name of the copyright holder nor the names of
+ contributors may be used to endorse or promote products derived from
+ this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDER
+ BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+package jdk.internal.dynalink;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.invoke.MutableCallSite;
+import java.util.List;
+import jdk.internal.dynalink.linker.GuardedInvocation;
+import jdk.internal.dynalink.linker.GuardingDynamicLinker;
+import jdk.internal.dynalink.linker.LinkRequest;
+import jdk.internal.dynalink.linker.LinkerServices;
+import jdk.internal.dynalink.support.CallSiteDescriptorFactory;
+import jdk.internal.dynalink.support.LinkRequestImpl;
+import jdk.internal.dynalink.support.Lookup;
+import jdk.internal.dynalink.support.RuntimeContextLinkRequestImpl;
+
+
+/**
+ * The linker for {@link RelinkableCallSite} objects. Users of it (scripting frameworks and language runtimes) have to
+ * create a linker using the {@link DynamicLinkerFactory} and invoke its link method from the invokedynamic bootstrap
+ * methods to set the target of all the call sites in the code they generate. Usual usage would be to create one class
+ * per language runtime to contain one linker instance as:
+ *
+ * <pre>
+ * class MyLanguageRuntime {
+ * private static final GuardingDynamicLinker myLanguageLinker = new MyLanguageLinker();
+ * private static final DynamicLinker dynamicLinker = createDynamicLinker();
+ *
+ * private static DynamicLinker createDynamicLinker() {
+ * final DynamicLinkerFactory factory = new DynamicLinkerFactory();
+ * factory.setPrioritizedLinker(myLanguageLinker);
+ * return factory.createLinker();
+ * }
+ *
+ * public static CallSite bootstrap(MethodHandles.Lookup caller, String name, MethodType type) {
+ * return dynamicLinker.link(new MonomorphicCallSite(CallSiteDescriptorFactory.create(lookup, name, type)));
+ * }
+ * }
+ * </pre>
+ *
+ * Note how there are three components you will need to provide here:
+ * <ul>
+ * <li>You're expected to provide a {@link GuardingDynamicLinker} for your own language. If your runtime doesn't
+ * have its own language and/or object model (i.e. it's a generic scripting shell), you don't need to implement a
+ * dynamic linker; you would simply not invoke the {@code setPrioritizedLinker} method on the factory, or even better,
+ * simply use {@link DefaultBootstrapper}.</li>
+ * <li>The performance of the programs can depend on your choice of the class to represent call sites. The above
+ * example used {@link MonomorphicCallSite}, but you might want to use {@link ChainedCallSite} instead. You'll need to
+ * experiment and decide what fits your language runtime the best. You can subclass either of these or roll your own if
+ * you need to.</li>
+ * <li>You also need to provide {@link CallSiteDescriptor}s to your call sites. They are immutable objects that contain
+ * all the information about the call site: the class performing the lookups, the name of the method being invoked, and
+ * the method signature. The library has a default {@link CallSiteDescriptorFactory} for descriptors that you can use,
+ * or you can create your own descriptor classes, especially if you need to add further information (values passed in
+ * additional parameters to the bootstrap method) to them.</li>
+ * </ul>
+ *
+ * @author Attila Szegedi
+ */
+public class DynamicLinker {
+
+ private static final String CLASS_NAME = DynamicLinker.class.getName();
+ private static final String RELINK_METHOD_NAME = "relink";
+
+ private final LinkerServices linkerServices;
+ private final int runtimeContextArgCount;
+ private final boolean syncOnRelink;
+ private final int unstableRelinkThreshold;
+
+ /**
+ * Creates a new dynamic linker.
+ *
+ * @param linkerServices the linkerServices used by the linker, created by the factory.
+ * @param runtimeContextArgCount see {@link DynamicLinkerFactory#setRuntimeContextArgCount(int)}
+ */
+ DynamicLinker(LinkerServices linkerServices, int runtimeContextArgCount, boolean syncOnRelink,
+ int unstableRelinkThreshold) {
+ if(runtimeContextArgCount < 0) {
+ throw new IllegalArgumentException("runtimeContextArgCount < 0");
+ }
+ if(unstableRelinkThreshold < 0) {
+ throw new IllegalArgumentException("unstableRelinkThreshold < 0");
+ }
+ this.runtimeContextArgCount = runtimeContextArgCount;
+ this.linkerServices = linkerServices;
+ this.syncOnRelink = syncOnRelink;
+ this.unstableRelinkThreshold = unstableRelinkThreshold;
+ }
+
+ /**
+ * Links an invokedynamic call site. It will install a method handle into the call site that invokes the relinking
+ * mechanism of this linker. Next time the call site is invoked, it will be linked for the actual arguments it was
+ * invoked with.
+ *
+ * @param callSite the call site to link.
+ * @return the callSite, for easy call chaining.
+ */
+ public <T extends RelinkableCallSite> T link(final T callSite) {
+ callSite.initialize(createRelinkAndInvokeMethod(callSite, 0));
+ return callSite;
+ }
+
+ /**
+ * Returns the object representing the lower level linker services of this class that are normally exposed to
+ * individual language-specific linkers. While as a user of this class you normally only care about the
+ * {@link #link(RelinkableCallSite)} method, in certain circumstances you might want to use the lower level services
+ * directly; either to lookup specific method handles, to access the type converters, and so on.
+ * @return the object representing the linker services of this class.
+ */
+ public LinkerServices getLinkerServices() {
+ return linkerServices;
+ }
+
+ private static final MethodHandle RELINK = Lookup.findOwnSpecial(MethodHandles.lookup(), RELINK_METHOD_NAME,
+ MethodHandle.class, RelinkableCallSite.class, int.class, Object[].class);
+
+ private MethodHandle createRelinkAndInvokeMethod(final RelinkableCallSite callSite, int relinkCount) {
+ // Make a bound MH of invoke() for this linker and call site
+ final MethodHandle boundRelinker = MethodHandles.insertArguments(RELINK, 0, this, callSite, Integer.valueOf(
+ relinkCount));
+ // Make a MH that gathers all arguments to the invocation into an Object[]
+ final MethodType type = callSite.getDescriptor().getMethodType();
+ final MethodHandle collectingRelinker = boundRelinker.asCollector(Object[].class, type.parameterCount());
+ return MethodHandles.foldArguments(MethodHandles.exactInvoker(type), collectingRelinker.asType(
+ type.changeReturnType(MethodHandle.class)));
+ }
+
+ /**
+ * Relinks a call site conforming to the invocation arguments.
+ *
+ * @param callSite the call site itself
+ * @param arguments arguments to the invocation
+ * @return return the method handle for the invocation
+ * @throws Exception rethrows any exception thrown by the linkers
+ */
+ @SuppressWarnings("unused")
+ private MethodHandle relink(RelinkableCallSite callSite, int relinkCount, Object... arguments) throws Exception {
+ final CallSiteDescriptor callSiteDescriptor = callSite.getDescriptor();
+ final boolean unstableDetectionEnabled = unstableRelinkThreshold > 0;
+ final boolean callSiteUnstable = unstableDetectionEnabled && relinkCount >= unstableRelinkThreshold;
+ final LinkRequest linkRequest =
+ runtimeContextArgCount == 0 ? new LinkRequestImpl(callSiteDescriptor, callSiteUnstable, arguments)
+ : new RuntimeContextLinkRequestImpl(callSiteDescriptor, callSiteUnstable, arguments,
+ runtimeContextArgCount);
+
+ // Find a suitable method handle with a guard
+ GuardedInvocation guardedInvocation = linkerServices.getGuardedInvocation(linkRequest);
+
+ // None found - throw an exception
+ if(guardedInvocation == null) {
+ throw new NoSuchDynamicMethodException(callSiteDescriptor.toString());
+ }
+
+ // If our call sites have a runtime context, and the linker produced a context-stripped invocation, adapt the
+ // produced invocation into contextual invocation (by dropping the context...)
+ if(runtimeContextArgCount > 0) {
+ final MethodType origType = callSiteDescriptor.getMethodType();
+ final MethodHandle invocation = guardedInvocation.getInvocation();
+ if(invocation.type().parameterCount() == origType.parameterCount() - runtimeContextArgCount) {
+ final List<Class<?>> prefix = origType.parameterList().subList(1, runtimeContextArgCount + 1);
+ final MethodHandle guard = guardedInvocation.getGuard();
+ guardedInvocation = guardedInvocation.dropArguments(1, prefix);
+ }
+ }
+
+ if(unstableDetectionEnabled && relinkCount <= unstableRelinkThreshold && relinkCount++ == unstableRelinkThreshold) {
+ // Note that we'll increase the relinkCount until threshold+1 and not increase it beyond that. Threshold+1
+ // is treated as a special value to signal that resetAndRelink has already executed once for the unstable
+ // call site; we only want the call site to throw away its current linkage once, when it transitions to
+ // unstable.
+ callSite.resetAndRelink(guardedInvocation, createRelinkAndInvokeMethod(callSite, relinkCount));
+ } else {
+ callSite.relink(guardedInvocation, createRelinkAndInvokeMethod(callSite, relinkCount));
+ }
+ if(syncOnRelink) {
+ MutableCallSite.syncAll(new MutableCallSite[] { (MutableCallSite)callSite });
+ }
+ return guardedInvocation.getInvocation();
+ }
+
+ /**
+ * Returns a stack trace element describing the location of the call site currently being relinked on the current
+ * thread. The operation internally creates a Throwable object and inspects its stack trace, so it's potentially
+ * expensive. The recommended usage for it is in writing diagnostics code.
+ * @return a stack trace element describing the location of the call site currently being relinked, or null if it is
+ * not invoked while a call site is being relinked.
+ */
+ public static StackTraceElement getRelinkedCallSiteLocation() {
+ final StackTraceElement[] trace = new Throwable().getStackTrace();
+ for(int i = 0; i < trace.length - 1; ++i) {
+ final StackTraceElement frame = trace[i];
+ if(RELINK_METHOD_NAME.equals(frame.getMethodName()) && CLASS_NAME.equals(frame.getClassName())) {
+ return trace[i + 1];
+ }
+ }
+ return null;
+ }
+}