001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.kahadb.index;
018
019import java.io.IOException;
020import java.util.Iterator;
021import java.util.Map;
022
023import org.apache.kahadb.page.Transaction;
024import org.apache.kahadb.util.Marshaller;
025
026/**
027 * Simpler than a Map
028 * 
029 * 
030 */
031public interface Index<Key,Value> {
032    
033    /**
034     * Set the marshaller for key objects
035     * 
036     * @param marshaller
037     */
038    void setKeyMarshaller(Marshaller<Key> marshaller);
039    
040    /**
041     * Set the marshaller for key objects
042     * 
043     * @param marshaller
044     */
045    void setValueMarshaller(Marshaller<Value> marshaller);
046
047    /**
048     * load indexes
049     */
050    void load(Transaction tx) throws IOException;
051
052    /**
053     * unload indexes
054     * 
055     * @throws IOException
056     */
057    void unload(Transaction tx) throws IOException;
058
059    /**
060     * clear the index
061     * 
062     * @throws IOException
063     * 
064     */
065    void clear(Transaction tx) throws IOException;
066
067    /**
068     * @param key
069     * @return true if it contains the key
070     * @throws IOException
071     */
072    boolean containsKey(Transaction tx, Key key) throws IOException;
073
074    /**
075     * remove the index key
076     * 
077     * @param key
078     * @return StoreEntry removed
079     * @throws IOException
080     */
081    Value remove(Transaction tx, Key key) throws IOException;
082
083    /**
084     * store the key, item
085     * 
086     * @param key
087     * @param entry
088     * @throws IOException
089     */
090    Value put(Transaction tx, Key key, Value entry) throws IOException;
091
092    /**
093     * @param key
094     * @return the entry
095     * @throws IOException
096     */
097    Value get(Transaction tx, Key key) throws IOException;
098
099    /**
100     * @return true if the index is transient
101     */
102    boolean isTransient();
103    
104    /**
105     * @param tx
106     * @return
107     * @throws IOException
108     * @trhows UnsupportedOperationException 
109     *         if the index does not support fast iteration of the elements.
110     */
111    Iterator<Map.Entry<Key,Value>> iterator(final Transaction tx) throws IOException, UnsupportedOperationException;
112    
113}