--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.dynalink/share/classes/jdk/dynalink/support/ChainedCallSite.java Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,244 @@
+/*
+ * Copyright (c) 2010, 2016, 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.support;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.LinkedList;
+import jdk.dynalink.CallSiteDescriptor;
+import jdk.dynalink.linker.GuardedInvocation;
+import jdk.dynalink.linker.support.Lookup;
+
+/**
+ * A relinkable call site that implements a polymorphic inline caching strategy.
+ * It remembers up to 8 {@link GuardedInvocation}s it was linked with, and on
+ * each relink request builds a cascading chain of method handles of one
+ * invocation falling back to the next one. The number of remembered invocations
+ * can be customized by overriding {@link #getMaxChainLength()} in a subclass.
+ * When this call site is relinked with a new invocation and the length of the
+ * chain is already at the maximum, it will throw away the oldest invocation.
+ * Invocations with invalidated switch points and ones for which their
+ * invalidating exception triggered are removed eagerly from the chain. The
+ * invocations are never reordered; the most recently linked method handle is
+ * always at the start of the chain and the least recently linked at its end.
+ * The call site can be safely relinked on more than one thread concurrently.
+ * Race conditions in linking are resolved by throwing away the
+ * {@link GuardedInvocation} produced on the losing thread without incorporating
+ * it into the chain, so it can lead to repeated linking for the same arguments.
+ */
+public class ChainedCallSite extends AbstractRelinkableCallSite {
+ private static final MethodHandle PRUNE_CATCHES;
+ private static final MethodHandle PRUNE_SWITCHPOINTS;
+ static {
+ final MethodHandle PRUNE = Lookup.findOwnSpecial(MethodHandles.lookup(), "prune", MethodHandle.class,
+ MethodHandle.class, boolean.class);
+ PRUNE_CATCHES = MethodHandles.insertArguments(PRUNE, 2, true);
+ PRUNE_SWITCHPOINTS = MethodHandles.insertArguments(PRUNE, 2, false);
+ }
+
+ /**
+ * Contains the invocations currently linked into this call site's target. They are used when we are
+ * relinking to rebuild the guardWithTest chain. Valid values for this field are: {@code null} if there's
+ * no linked invocations, or an instance of {@link GuardedInvocation} if there is exactly one previous
+ * invocation, or an instance of {@code GuardedInvocation[]} if there is more than one previous
+ * invocation.
+ */
+ private Object invocations;
+
+ /**
+ * Creates a new chained call site.
+ * @param descriptor the descriptor for the call site.
+ */
+ public ChainedCallSite(final CallSiteDescriptor descriptor) {
+ super(descriptor);
+ }
+
+ /**
+ * The maximum number of method handles in the chain. Defaults to 8. You can
+ * override it in a subclass if you need to change the value.
+ * @return the maximum number of method handles in the chain. The return
+ * value is checked, and if your override returns a value less than 1, a
+ * {@link RuntimeException} will be thrown.
+ */
+ protected int getMaxChainLength() {
+ return 8;
+ }
+
+ @Override
+ public void relink(final GuardedInvocation guardedInvocation, final MethodHandle relinkAndInvoke) {
+ relinkInternal(guardedInvocation, relinkAndInvoke, false, false);
+ }
+
+ @Override
+ public void resetAndRelink(final GuardedInvocation guardedInvocation, final MethodHandle relinkAndInvoke) {
+ relinkInternal(guardedInvocation, relinkAndInvoke, true, false);
+ }
+
+ private MethodHandle relinkInternal(final GuardedInvocation invocation, final MethodHandle relink, final boolean reset, final boolean removeCatches) {
+ final Object currentInvocations = invocations;
+ final LinkedList<GuardedInvocation> newInvocations;
+ if (currentInvocations == null || reset) {
+ newInvocations = new LinkedList<>();
+ } else if (currentInvocations instanceof GuardedInvocation) {
+ newInvocations = new LinkedList<>();
+ newInvocations.add((GuardedInvocation)currentInvocations);
+ } else if (currentInvocations instanceof GuardedInvocation[]) {
+ newInvocations = new LinkedList<>(Arrays.asList(((GuardedInvocation[])currentInvocations)));
+ } else {
+ throw new AssertionError();
+ }
+
+ // First, prune the chain of invalidated switchpoints, we always do this
+ // We also remove any catches if the remove catches flag is set
+ for(final Iterator<GuardedInvocation> it = newInvocations.iterator(); it.hasNext();) {
+ final GuardedInvocation inv = it.next();
+ if(inv.hasBeenInvalidated() || (removeCatches && inv.getException() != null)) {
+ it.remove();
+ }
+ }
+
+ // prune() is allowed to invoke this method with invocation == null meaning we're just pruning the chain and not
+ // adding any new invocations to it.
+ if(invocation != null) {
+ // Remove oldest entry if we're at max length
+ if(newInvocations.size() == checkMaxChainLength(getMaxChainLength())) {
+ newInvocations.removeFirst();
+ }
+ newInvocations.addLast(invocation);
+ }
+
+ // prune-and-invoke is used as the fallback for invalidated switchpoints. If a switchpoint gets invalidated, we
+ // rebuild the chain and get rid of all invalidated switchpoints instead of letting them linger.
+ final MethodHandle pruneAndInvokeSwitchPoints = makePruneAndInvokeMethod(relink, PRUNE_SWITCHPOINTS);
+ final MethodHandle pruneAndInvokeCatches = makePruneAndInvokeMethod(relink, PRUNE_CATCHES);
+
+ // Fold the new chain
+ MethodHandle target = relink;
+ for(final GuardedInvocation inv: newInvocations) {
+ target = inv.compose(target, pruneAndInvokeSwitchPoints, pruneAndInvokeCatches);
+ }
+
+ switch (newInvocations.size()) {
+ case 0:
+ invocations = null;
+ break;
+ case 1:
+ invocations = newInvocations.getFirst();
+ break;
+ default:
+ invocations = newInvocations.toArray(new GuardedInvocation[0]);
+ }
+ setTarget(target);
+ return target;
+ }
+
+ private static int checkMaxChainLength(final int maxChainLength) {
+ if (maxChainLength > 0) {
+ return maxChainLength;
+ }
+ throw new RuntimeException("getMaxChainLength() returned a non-positive value");
+
+ }
+ /**
+ * Creates a method that rebuilds our call chain, pruning it of any invalidated switchpoints, and then invokes that
+ * chain.
+ * @param relinkAndInvoke the ultimate fallback for the chain passed from the dynamic linker.
+ * @return a method handle for prune-and-invoke
+ */
+ private MethodHandle makePruneAndInvokeMethod(final MethodHandle relinkAndInvoke, final MethodHandle prune) {
+ // Bind prune to (this, relink)
+ final MethodHandle boundPrune = MethodHandles.insertArguments(prune, 0, this, relinkAndInvoke);
+ // Make it ignore all incoming arguments
+ final MethodHandle ignoreArgsPrune = MethodHandles.dropArguments(boundPrune, 0, type().parameterList());
+ // Invoke prune, then invoke the call site target with original arguments
+ return MethodHandles.foldArguments(MethodHandles.exactInvoker(type()), ignoreArgsPrune);
+ }
+
+ @SuppressWarnings("unused")
+ private MethodHandle prune(final MethodHandle relink, final boolean catches) {
+ return relinkInternal(null, relink, false, catches);
+ }
+}