| /* |
| * 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.jackrabbit.oak.plugins.document.persistentCache; |
| |
| import java.util.Collection; |
| import java.util.Map; |
| import java.util.Set; |
| import java.util.concurrent.ConcurrentSkipListMap; |
| |
| public class MultiGenerationMap<K, V> implements Map<K, V> { |
| |
| private volatile CacheMap<K, V> write; |
| private ConcurrentSkipListMap<Integer, CacheMap<K, V>> read = |
| new ConcurrentSkipListMap<Integer, CacheMap<K, V>>(); |
| |
| MultiGenerationMap() { |
| } |
| |
| public void setWriteMap(CacheMap<K, V> m) { |
| write = m; |
| } |
| |
| public void addReadMap(int generation, CacheMap<K, V> m) { |
| read.put(generation, m); |
| } |
| |
| public void removeReadMap(int generation) { |
| read.remove(generation); |
| } |
| |
| @Override |
| public V put(K key, V value) { |
| CacheMap<K, V> m = write; |
| if (m == null) { |
| // closed concurrently |
| return null; |
| } |
| return m.put(key, value); |
| } |
| |
| @SuppressWarnings("unchecked") |
| @Override |
| public V get(Object key) { |
| ValueWithGenerationInfo<V> value = readValue(key); |
| if (value == null) { |
| return null; |
| } else if (!value.isCurrentGeneration()) { |
| put((K) key, value.value); |
| } |
| return value.getValue(); |
| } |
| |
| ValueWithGenerationInfo<V> readValue(Object key) { |
| for (int generation : read.descendingKeySet()) { |
| CacheMap<K, V> m = read.get(generation); |
| if (m != null) { |
| V value = m.get(key); |
| if (value != null) { |
| return new ValueWithGenerationInfo<V>(value, m == write); |
| } |
| } |
| } |
| return null; |
| } |
| |
| @Override |
| public boolean containsKey(Object key) { |
| for (int generation : read.descendingKeySet()) { |
| CacheMap<K, V> m = read.get(generation); |
| if (m != null) { |
| if (m.containsKey(key)) { |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| |
| @Override |
| public V remove(Object key) { |
| return write.remove(key); |
| } |
| |
| @Override |
| public void clear() { |
| write.clear(); |
| } |
| |
| @Override |
| public int size() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public boolean isEmpty() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public boolean containsValue(Object value) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public void putAll(Map<? extends K, ? extends V> m) { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public Set<K> keySet() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public Collection<V> values() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| @Override |
| public Set<java.util.Map.Entry<K, V>> entrySet() { |
| throw new UnsupportedOperationException(); |
| } |
| |
| static class ValueWithGenerationInfo<V> { |
| |
| private final V value; |
| |
| private final boolean isCurrentGeneration; |
| |
| private ValueWithGenerationInfo(V value, boolean isCurrentGeneration) { |
| this.value = value; |
| this.isCurrentGeneration = isCurrentGeneration; |
| } |
| |
| V getValue() { |
| return value; |
| } |
| |
| boolean isCurrentGeneration() { |
| return isCurrentGeneration; |
| } |
| } |
| } |