1   /**
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
   10    *
   11    * Unless required by applicable law or agreed to in writing, software
   12    * distributed under the License is distributed on an "AS IS" BASIS,
   13    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   14    * See the License for the specific language governing permissions and
   15    * limitations under the License.
   16    */
   17   package org.apache.kahadb.index;
   18   
   19   import java.io.IOException;
   20   import java.util.Iterator;
   21   import java.util.Map;
   22   
   23   import org.apache.kahadb.page.Transaction;
   24   import org.apache.kahadb.util.Marshaller;
   25   
   26   /**
   27    * Simpler than a Map
   28    * 
   29    * @version $Revision: 713421 $
   30    */
   31   public interface Index<Key,Value> {
   32       
   33       /**
   34        * Set the marshaller for key objects
   35        * 
   36        * @param marshaller
   37        */
   38       void setKeyMarshaller(Marshaller<Key> marshaller);
   39       
   40       /**
   41        * Set the marshaller for key objects
   42        * 
   43        * @param marshaller
   44        */
   45       void setValueMarshaller(Marshaller<Value> marshaller);
   46   
   47       /**
   48        * load indexes
   49        */
   50       void load(Transaction tx) throws IOException;
   51   
   52       /**
   53        * unload indexes
   54        * 
   55        * @throws IOException
   56        */
   57       void unload(Transaction tx) throws IOException;
   58   
   59       /**
   60        * clear the index
   61        * 
   62        * @throws IOException
   63        * 
   64        */
   65       void clear(Transaction tx) throws IOException;
   66   
   67       /**
   68        * @param key
   69        * @return true if it contains the key
   70        * @throws IOException
   71        */
   72       boolean containsKey(Transaction tx, Key key) throws IOException;
   73   
   74       /**
   75        * remove the index key
   76        * 
   77        * @param key
   78        * @return StoreEntry removed
   79        * @throws IOException
   80        */
   81       Value remove(Transaction tx, Key key) throws IOException;
   82   
   83       /**
   84        * store the key, item
   85        * 
   86        * @param key
   87        * @param entry
   88        * @throws IOException
   89        */
   90       Value put(Transaction tx, Key key, Value entry) throws IOException;
   91   
   92       /**
   93        * @param key
   94        * @return the entry
   95        * @throws IOException
   96        */
   97       Value get(Transaction tx, Key key) throws IOException;
   98   
   99       /**
  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   }