/* * 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.hadoop.hbase.regionserver; import java.util.concurrent.ConcurrentSkipListMap; import org.apache.hadoop.hbase.Cell; import org.apache.hadoop.hbase.CellComparator; /** * Like a {@link KeyValueSkipListSet}, but also exposes useful, atomic methods (e.g. * {@link #putIfAbsent(KeyValue)}). */ public class IndexKeyValueSkipListSet extends KeyValueSkipListSet { // this is annoying that we need to keep this extra pointer around here, but its pretty minimal // and means we don't need to change the HBase code. private ConcurrentSkipListMap<Cell, Cell> delegate; /** * Create a new {@link IndexKeyValueSkipListSet} based on the passed comparator. * @param comparator to use when comparing keyvalues. It is used both to determine sort order as * well as object equality in the map. * @return a map that uses the passed comparator */ public static IndexKeyValueSkipListSet create(CellComparator comparator) { ConcurrentSkipListMap<Cell, Cell> delegate = new ConcurrentSkipListMap<Cell, Cell>(comparator); IndexKeyValueSkipListSet ret = new IndexKeyValueSkipListSet(delegate); return ret; } /** * @param delegate map to which to delegate all calls */ public IndexKeyValueSkipListSet(ConcurrentSkipListMap<Cell, Cell> delegate) { super(delegate); this.delegate = delegate; } /** * Add the passed {@link KeyValue} to the set, only if one is not already set. This is equivalent * to * <pre> * if (!set.containsKey(key)) * return set.put(key); * else * return map.set(key); * </pre> * except that the action is performed atomically. * @param kv {@link KeyValue} to add * @return the previous value associated with the specified key, or <tt>null</tt> if there was no * previously stored key * @throws ClassCastException if the specified key cannot be compared with the keys currently in * the map * @throws NullPointerException if the specified key is null */ public Cell putIfAbsent(Cell kv) { return this.delegate.putIfAbsent(kv, kv); } }