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     */
017    package org.apache.activemq.store.kahadb.disk.index;
018    
019    import java.io.IOException;
020    import java.util.Iterator;
021    import java.util.Map;
022    
023    import org.apache.activemq.store.kahadb.disk.page.Transaction;
024    import org.apache.activemq.store.kahadb.disk.util.Marshaller;
025    
026    /**
027     * Simpler than a Map
028     * 
029     * 
030     */
031    public 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    }