| /* |
| * |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the 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. |
| * |
| */ |
| |
| package org.apache.royale.compiler.internal.definitions.references; |
| |
| import org.apache.royale.compiler.definitions.references.IReference; |
| import org.apache.royale.compiler.definitions.references.ReferenceFactory; |
| import com.google.common.collect.MapMaker; |
| |
| import java.lang.ref.WeakReference; |
| import java.util.Map; |
| import java.util.WeakHashMap; |
| import java.util.concurrent.ConcurrentMap; |
| |
| /** |
| * A cache to manage instances of {@link IReference}. |
| * <p> |
| * Clients should use {@link ReferenceFactory} to get {@link IReference}s; this |
| * class is just an implementation detail. |
| */ |
| public class ReferenceCache |
| { |
| public ReferenceCache() |
| { |
| threadLocalLexicalCache = new ThreadLocal<Map<String, WeakReference<LexicalReference>>>() |
| { |
| @Override |
| protected Map<String, WeakReference<LexicalReference>> initialValue() |
| { |
| // Use a WeakHashMap with WeakRefs as values - the Strings and LexicalRefs |
| // will be kept alive or not by the shared cache |
| return new WeakHashMap<String, WeakReference<LexicalReference>>(); |
| } |
| }; |
| } |
| |
| /** |
| * Map of name to LexicalReference. |
| */ |
| private final ConcurrentMap<String, LexicalReference> lexicalCache = |
| new MapMaker().weakValues().makeMap(); |
| |
| /** |
| * Thread local cache for lexical references - improves performance, as we |
| * can look here without worrying about locking or contention, and only look |
| * at the shared cache if we have a miss here. |
| */ |
| private final ThreadLocal<Map<String, WeakReference<LexicalReference>>> threadLocalLexicalCache; |
| |
| /** |
| * Gets a {@link LexicalReference} representing <code>name</code>. If one |
| * already exists, it is returned. If one does not exist a new one is |
| * created, cached, and returned. |
| * |
| * @param name the name you want a lexical ref for |
| * @return the LexicalReference representing name |
| */ |
| public LexicalReference getLexicalReference(String name) |
| { |
| Map<String, WeakReference<LexicalReference>> cache = threadLocalLexicalCache.get(); |
| WeakReference<LexicalReference> weakRef = cache.get(name); |
| LexicalReference ref = weakRef != null ? weakRef.get() : null; |
| if (ref != null) |
| return ref; |
| |
| LexicalReference newref = new LexicalReference(name); |
| ref = lexicalCache.putIfAbsent(name, newref); |
| if (ref == null) |
| ref = newref; |
| |
| cache.put(name, new WeakReference<LexicalReference>(ref)); |
| return ref; |
| } |
| } |