| /* |
| * 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.util.Iterator; |
| import java.util.LinkedList; |
| import java.util.concurrent.atomic.AtomicReference; |
| import jdk.internal.dynalink.linker.GuardedInvocation; |
| import jdk.internal.dynalink.support.AbstractRelinkableCallSite; |
| import jdk.internal.dynalink.support.Lookup; |
| |
| /** |
| * A relinkable call site that maintains a chain of linked method handles. In the default implementation, up to 8 method |
| * handles can be chained, cascading from one to the other through |
| * {@link MethodHandles#guardWithTest(MethodHandle, MethodHandle, MethodHandle)}. When this call site has to link a new |
| * method handle and the length of the chain is already at the maximum, it will throw away the oldest method handle. |
| * Switchpoint-invalidated handles in the chain are removed eagerly (on each linking request, and whenever a |
| * switchpoint-invalidated method handle is traversed during invocation). There is currently no profiling |
| * attached to the handles in the chain, so they are never reordered based on usage; the most recently linked method |
| * handle is always at the start of the chain. |
| */ |
| public class ChainedCallSite extends AbstractRelinkableCallSite { |
| private static final MethodHandle PRUNE_CATCHES = |
| MethodHandles.insertArguments( |
| Lookup.findOwnSpecial( |
| MethodHandles.lookup(), |
| "prune", |
| MethodHandle.class, |
| MethodHandle.class, |
| boolean.class), |
| 2, |
| true); |
| |
| private static final MethodHandle PRUNE_SWITCHPOINTS = |
| MethodHandles.insertArguments( |
| Lookup.findOwnSpecial( |
| MethodHandles.lookup(), |
| "prune", |
| MethodHandle.class, |
| MethodHandle.class, |
| boolean.class), |
| 2, |
| false); |
| |
| private final AtomicReference<LinkedList<GuardedInvocation>> invocations = new AtomicReference<>(); |
| |
| /** |
| * 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. If your override returns a value less than 1, the code will break. |
| * @return the maximum number of method handles in the chain. |
| */ |
| protected int getMaxChainLength() { |
| return 8; |
| } |
| |
| @Override |
| public void relink(final GuardedInvocation guardedInvocation, final MethodHandle fallback) { |
| relinkInternal(guardedInvocation, fallback, false, false); |
| } |
| |
| @Override |
| public void resetAndRelink(final GuardedInvocation guardedInvocation, final MethodHandle fallback) { |
| relinkInternal(guardedInvocation, fallback, true, false); |
| } |
| |
| private MethodHandle relinkInternal(final GuardedInvocation invocation, final MethodHandle relink, final boolean reset, final boolean removeCatches) { |
| final LinkedList<GuardedInvocation> currentInvocations = invocations.get(); |
| @SuppressWarnings({ "unchecked", "rawtypes" }) |
| final LinkedList<GuardedInvocation> newInvocations = |
| currentInvocations == null || reset ? new LinkedList<>() : (LinkedList)currentInvocations.clone(); |
| |
| // 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() == 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, getPruneSwitchpoints()); |
| final MethodHandle pruneAndInvokeCatches = makePruneAndInvokeMethod(relink, getPruneCatches()); |
| |
| // Fold the new chain |
| MethodHandle target = relink; |
| for(final GuardedInvocation inv: newInvocations) { |
| target = inv.compose(target, pruneAndInvokeSwitchPoints, pruneAndInvokeCatches); |
| } |
| |
| // If nobody else updated the call site while we were rebuilding the chain, set the target to our chain. In case |
| // we lost the race for multithreaded update, just do nothing. Either the other thread installed the same thing |
| // we wanted to install, or otherwise, we'll be asked to relink again. |
| if(invocations.compareAndSet(currentInvocations, newInvocations)) { |
| setTarget(target); |
| } |
| return target; |
| } |
| |
| /** |
| * Get the switchpoint pruning function for a chained call site |
| * @return function that removes invalidated switchpoints tied to callsite guard chain and relinks |
| */ |
| protected MethodHandle getPruneSwitchpoints() { |
| return PRUNE_SWITCHPOINTS; |
| } |
| |
| /** |
| * Get the catch pruning function for a chained call site |
| * @return function that removes all catches tied to callsite guard chain and relinks |
| */ |
| protected MethodHandle getPruneCatches() { |
| return PRUNE_CATCHES; |
| } |
| |
| /** |
| * Creates a method that rebuilds our call chain, pruning it of any invalidated switchpoints, and then invokes that |
| * chain. |
| * @param relink the ultimate fallback for the chain (the {@code DynamicLinker}'s relink). |
| * @return a method handle for prune-and-invoke |
| */ |
| private MethodHandle makePruneAndInvokeMethod(final MethodHandle relink, final MethodHandle prune) { |
| // Bind prune to (this, relink) |
| final MethodHandle boundPrune = MethodHandles.insertArguments(prune, 0, this, relink); |
| // 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); |
| } |
| } |
