| /* |
| * Copyright (c) 2014, 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. |
| */ |
| package jdk.nashorn.internal.runtime; |
| |
| import static jdk.nashorn.internal.lookup.Lookup.MH; |
| |
| import java.io.Serializable; |
| import java.lang.invoke.MethodHandle; |
| import java.lang.invoke.MethodHandles; |
| import java.lang.ref.WeakReference; |
| import jdk.nashorn.internal.codegen.Compiler; |
| import jdk.nashorn.internal.codegen.CompilerConstants; |
| import jdk.nashorn.internal.codegen.ObjectClassGenerator; |
| |
| /** |
| * Encapsulates the allocation strategy for a function when used as a constructor. |
| */ |
| final public class AllocationStrategy implements Serializable { |
| private static final long serialVersionUID = 1L; |
| |
| private static final MethodHandles.Lookup LOOKUP = MethodHandles.lookup(); |
| |
| /** Number of fields in the allocated object */ |
| private final int fieldCount; |
| |
| /** Whether to use dual field representation */ |
| private final boolean dualFields; |
| |
| /** Name of class where allocator function resides */ |
| private transient String allocatorClassName; |
| |
| /** lazily generated allocator */ |
| private transient MethodHandle allocator; |
| |
| /** Last used allocator map */ |
| private transient AllocatorMap lastMap; |
| |
| /** |
| * Construct an allocation strategy with the given map and class name. |
| * @param fieldCount number of fields in the allocated object |
| * @param dualFields whether to use dual field representation |
| */ |
| public AllocationStrategy(final int fieldCount, final boolean dualFields) { |
| this.fieldCount = fieldCount; |
| this.dualFields = dualFields; |
| } |
| |
| private String getAllocatorClassName() { |
| if (allocatorClassName == null) { |
| // These classes get loaded, so an interned variant of their name is most likely around anyway. |
| allocatorClassName = Compiler.binaryName(ObjectClassGenerator.getClassName(fieldCount, dualFields)).intern(); |
| } |
| return allocatorClassName; |
| } |
| |
| /** |
| * Get the property map for the allocated object. |
| * @param prototype the prototype object |
| * @return the property map |
| */ |
| synchronized PropertyMap getAllocatorMap(final ScriptObject prototype) { |
| assert prototype != null; |
| final PropertyMap protoMap = prototype.getMap(); |
| |
| if (lastMap != null) { |
| if (!lastMap.hasSharedProtoMap()) { |
| if (lastMap.hasSamePrototype(prototype)) { |
| return lastMap.allocatorMap; |
| } |
| if (lastMap.hasSameProtoMap(protoMap) && lastMap.hasUnchangedProtoMap()) { |
| // Convert to shared prototype map. Allocated objects will use the same property map |
| // that can be used as long as none of the prototypes modify the shared proto map. |
| final PropertyMap allocatorMap = PropertyMap.newMap(null, getAllocatorClassName(), 0, fieldCount, 0); |
| final SharedPropertyMap sharedProtoMap = new SharedPropertyMap(protoMap); |
| allocatorMap.setSharedProtoMap(sharedProtoMap); |
| prototype.setMap(sharedProtoMap); |
| lastMap = new AllocatorMap(prototype, protoMap, allocatorMap); |
| return allocatorMap; |
| } |
| } |
| |
| if (lastMap.hasValidSharedProtoMap() && lastMap.hasSameProtoMap(protoMap)) { |
| prototype.setMap(lastMap.getSharedProtoMap()); |
| return lastMap.allocatorMap; |
| } |
| } |
| |
| final PropertyMap allocatorMap = PropertyMap.newMap(null, getAllocatorClassName(), 0, fieldCount, 0); |
| lastMap = new AllocatorMap(prototype, protoMap, allocatorMap); |
| |
| return allocatorMap; |
| } |
| |
| /** |
| * Allocate an object with the given property map |
| * @param map the property map |
| * @return the allocated object |
| */ |
| ScriptObject allocate(final PropertyMap map) { |
| try { |
| if (allocator == null) { |
| allocator = MH.findStatic(LOOKUP, Context.forStructureClass(getAllocatorClassName()), |
| CompilerConstants.ALLOCATE.symbolName(), MH.type(ScriptObject.class, PropertyMap.class)); |
| } |
| return (ScriptObject)allocator.invokeExact(map); |
| } catch (final RuntimeException | Error e) { |
| throw e; |
| } catch (final Throwable t) { |
| throw new RuntimeException(t); |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return "AllocationStrategy[fieldCount=" + fieldCount + "]"; |
| } |
| |
| static class AllocatorMap { |
| final private WeakReference<ScriptObject> prototype; |
| final private WeakReference<PropertyMap> prototypeMap; |
| |
| private PropertyMap allocatorMap; |
| |
| AllocatorMap(final ScriptObject prototype, final PropertyMap protoMap, final PropertyMap allocMap) { |
| this.prototype = new WeakReference<>(prototype); |
| this.prototypeMap = new WeakReference<>(protoMap); |
| this.allocatorMap = allocMap; |
| } |
| |
| boolean hasSamePrototype(final ScriptObject proto) { |
| return prototype.get() == proto; |
| } |
| |
| boolean hasSameProtoMap(final PropertyMap protoMap) { |
| return prototypeMap.get() == protoMap || allocatorMap.getSharedProtoMap() == protoMap; |
| } |
| |
| boolean hasUnchangedProtoMap() { |
| final ScriptObject proto = prototype.get(); |
| return proto != null && proto.getMap() == prototypeMap.get(); |
| } |
| |
| boolean hasSharedProtoMap() { |
| return getSharedProtoMap() != null; |
| } |
| |
| boolean hasValidSharedProtoMap() { |
| return hasSharedProtoMap() && getSharedProtoMap().isValidSharedProtoMap(); |
| } |
| |
| PropertyMap getSharedProtoMap() { |
| return allocatorMap.getSharedProtoMap(); |
| } |
| |
| } |
| } |