--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/src/jdk.dynalink/share/classes/jdk/dynalink/DynamicLinker.java Tue Nov 24 10:19:34 2015 +0100
@@ -0,0 +1,349 @@
+/*
+ * 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.dynalink;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.invoke.MutableCallSite;
+import java.util.Objects;
+import jdk.dynalink.linker.GuardedInvocation;
+import jdk.dynalink.linker.GuardedInvocationTransformer;
+import jdk.dynalink.linker.GuardingDynamicLinker;
+import jdk.dynalink.linker.LinkRequest;
+import jdk.dynalink.linker.LinkerServices;
+import jdk.dynalink.linker.support.Lookup;
+import jdk.dynalink.linker.support.SimpleLinkRequest;
+import jdk.dynalink.support.ChainedCallSite;
+import jdk.dynalink.support.SimpleRelinkableCallSite;
+
+/**
+ * The linker for {@link RelinkableCallSite} objects. A dynamic linker is a main
+ * objects when using Dynalink, it coordinates linking of call sites with
+ * linkers of available language runtimes that are represented by
+ * {@link GuardingDynamicLinker} objects (you only need to deal with these if
+ * you are yourself implementing a language runtime with its own object model
+ * and/or type conversions). To use Dynalink, you have to create one or more
+ * dynamic linkers using a {@link DynamicLinkerFactory}. Subsequently, you need
+ * to invoke its {@link #link(RelinkableCallSite)} method from
+ * {@code invokedynamic} bootstrap methods to let it manage all the call sites
+ * they create. Usual usage would be to create at least 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 lookup, String name, MethodType type) {
+ * return dynamicLinker.link(
+ * new SimpleRelinkableCallSite(
+ * new CallSiteDescriptor(lookup, parseOperation(name), type)));
+ * }
+ *
+ * private static Operation parseOperation(String name) {
+ * ...
+ * }
+ * }
+ * </pre>
+ * The above setup of one static linker instance is often too simple. You will
+ * often have your language runtime have a concept of some kind of
+ * "context class loader" and you will want to create one dynamic linker per
+ * such class loader, to ensure it incorporates linkers for all other language
+ * runtimes visible to that class loader (see
+ * {@link DynamicLinkerFactory#setClassLoader(ClassLoader)}).
+ * <p>
+ * There are three components you need to provide in the above example:
+ * <ul>
+ *
+ * <li>You are expected to provide a {@link GuardingDynamicLinker} for your own
+ * language. If your runtime doesn't have its own object model or type
+ * conversions, you don't need to implement a {@code GuardingDynamicLinker}; you
+ * would simply not invoke the {@code setPrioritizedLinker} method on the factory.</li>
+ *
+ * <li>The performance of the programs can depend on your choice of the class to
+ * represent call sites. The above example used
+ * {@link SimpleRelinkableCallSite}, but you might want to use
+ * {@link ChainedCallSite} instead. You'll need to experiment and decide what
+ * fits your runtime the best. You can further subclass either of these or
+ * implement your own.</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 operation being invoked, and the
+ * method signature. You will have to supply your own scheme to encode and
+ * decode operations in the call site name or static parameters, that is why
+ * in the above example the {@code parseOperation} method is left unimplemented.</li>
+ *
+ * </ul>
+ */
+public final class DynamicLinker {
+ private static final String CLASS_NAME = DynamicLinker.class.getName();
+ private static final String RELINK_METHOD_NAME = "relink";
+
+ private static final String INITIAL_LINK_CLASS_NAME = "java.lang.invoke.MethodHandleNatives";
+ private static final String INITIAL_LINK_METHOD_NAME = "linkCallSite";
+ private static final String INVOKE_PACKAGE_PREFIX = "java.lang.invoke.";
+
+ private final LinkerServices linkerServices;
+ private final GuardedInvocationTransformer prelinkTransformer;
+ 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 prelinkTransformer see {@link DynamicLinkerFactory#setPrelinkTransformer(GuardedInvocationTransformer)}
+ * @param syncOnRelink see {@link DynamicLinkerFactory#setSyncOnRelink(boolean)}
+ * @param unstableRelinkThreshold see {@link DynamicLinkerFactory#setUnstableRelinkThreshold(int)}
+ */
+ DynamicLinker(final LinkerServices linkerServices, final GuardedInvocationTransformer prelinkTransformer,
+ final boolean syncOnRelink, final int unstableRelinkThreshold) {
+ if(unstableRelinkThreshold < 0) {
+ throw new IllegalArgumentException("unstableRelinkThreshold < 0");
+ }
+ this.linkerServices = linkerServices;
+ this.prelinkTransformer = prelinkTransformer;
+ 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 <T> the particular subclass of {@link RelinkableCallSite} for
+ * which to create a link.
+ * @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 linker services of this class that
+ * are normally exposed to individual {@link GuardingDynamicLinker
+ * 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, final 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(final RelinkableCallSite callSite, final int relinkCount, final Object... arguments) throws Exception {
+ final CallSiteDescriptor callSiteDescriptor = callSite.getDescriptor();
+ final boolean unstableDetectionEnabled = unstableRelinkThreshold > 0;
+ final boolean callSiteUnstable = unstableDetectionEnabled && relinkCount >= unstableRelinkThreshold;
+ final LinkRequest linkRequest = new SimpleLinkRequest(callSiteDescriptor, callSiteUnstable, arguments);
+
+ GuardedInvocation guardedInvocation = linkerServices.getGuardedInvocation(linkRequest);
+
+ // None found - throw an exception
+ if(guardedInvocation == null) {
+ throw new NoSuchDynamicMethodException(callSiteDescriptor.toString());
+ }
+
+ // Make sure we transform the invocation before linking it into the call site. This is typically used to match the
+ // return type of the invocation to the call site.
+ guardedInvocation = prelinkTransformer.filter(guardedInvocation, linkRequest, linkerServices);
+ Objects.requireNonNull(guardedInvocation);
+
+ int newRelinkCount = relinkCount;
+ // Note that the short-circuited "&&" evaluation below ensures we'll increment the relinkCount until
+ // threshold + 1 but not 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.
+ if(unstableDetectionEnabled && newRelinkCount <= unstableRelinkThreshold && newRelinkCount++ == unstableRelinkThreshold) {
+ callSite.resetAndRelink(guardedInvocation, createRelinkAndInvokeMethod(callSite, newRelinkCount));
+ } else {
+ callSite.relink(guardedInvocation, createRelinkAndInvokeMethod(callSite, newRelinkCount));
+ }
+ if(syncOnRelink) {
+ MutableCallSite.syncAll(new MutableCallSite[] { (MutableCallSite)callSite });
+ }
+ return guardedInvocation.getInvocation();
+ }
+
+ /**
+ * Returns a stack trace element describing the location of the
+ * {@code invokedynamic} call site currently being linked on the current
+ * thread. The operation is potentially expensive as it needs to generate a
+ * stack trace to inspect it and is intended for use in diagnostics code.
+ * For "free-floating" call sites (not associated with an
+ * {@code invokedynamic} instruction), the result is not well-defined.
+ *
+ * @return a stack trace element describing the location of the call site
+ * currently being linked, or null if it is not invoked while a call
+ * site is being linked.
+ */
+ public static StackTraceElement getLinkedCallSiteLocation() {
+ final StackTraceElement[] trace = new Throwable().getStackTrace();
+ for(int i = 0; i < trace.length - 1; ++i) {
+ final StackTraceElement frame = trace[i];
+ // If we found any of our linking entry points on the stack...
+ if(isRelinkFrame(frame) || isInitialLinkFrame(frame)) {
+ // ... then look for the first thing calling it that isn't j.l.invoke
+ for (int j = i + 1; j < trace.length; ++j) {
+ final StackTraceElement frame2 = trace[j];
+ if (!frame2.getClassName().startsWith(INVOKE_PACKAGE_PREFIX)) {
+ return frame2;
+ }
+ }
+ }
+ }
+ return null;
+ }
+
+ /**
+ * Returns {@code true} if the frame represents {@code MethodHandleNatives.linkCallSite()},
+ * the frame immediately on top of the call site frame when the call site is
+ * being linked for the first time.
+ *
+ * @param frame the frame
+ *
+ * @return {@code true} if this frame represents {@code MethodHandleNatives.linkCallSite()}.
+ */
+ private static boolean isInitialLinkFrame(final StackTraceElement frame) {
+ return testFrame(frame, INITIAL_LINK_METHOD_NAME, INITIAL_LINK_CLASS_NAME);
+ }
+
+ /**
+ * Returns {@code true} if the frame represents {@code DynamicLinker.relink()},
+ * the frame immediately on top of the call site frame when the call site is
+ * being relinked (linked for second and subsequent times).
+ *
+ * @param frame the frame
+ *
+ * @return {@code true} if this frame represents {@code DynamicLinker.relink()}.
+ */
+ private static boolean isRelinkFrame(final StackTraceElement frame) {
+ return testFrame(frame, RELINK_METHOD_NAME, CLASS_NAME);
+ }
+
+ private static boolean testFrame(final StackTraceElement frame, final String methodName, final String className) {
+ return methodName.equals(frame.getMethodName()) && className.equals(frame.getClassName());
+ }
+}