| /* |
| * 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.directory.server.core.partition.impl.btree.jdbm; |
| |
| |
| import java.io.IOException; |
| import java.util.Comparator; |
| import java.util.NoSuchElementException; |
| |
| import javax.naming.NamingEnumeration; |
| import javax.naming.NamingException; |
| |
| import org.apache.directory.server.core.partition.impl.btree.Tuple; |
| import org.apache.directory.shared.ldap.exception.LdapNamingException; |
| import org.apache.directory.shared.ldap.message.ResultCodeEnum; |
| |
| import jdbm.btree.BTree; |
| import jdbm.helper.TupleBrowser; |
| |
| |
| /** |
| * A NamingEnumeration that returns underlying keys in a BTree as values for a |
| * single key within a Tuple. This is used specifically for situations when tables |
| * support duplicate keys and a BTree is used for storing the values for that |
| * key. This enumeration thus advances a browser forwards or reverse returning |
| * keys from a BTree as Tuple values. The key provided in the constructor is always |
| * returned as the key of the Tuple. |
| * |
| * <p> |
| * WARNING: The tuple returned is reused every time for efficiency and populated |
| * a over and over again with the new value. The key never changes. |
| * </p> |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| * @version $Rev$ |
| */ |
| public class BTreeTupleEnumeration implements NamingEnumeration |
| { |
| private final Object key; |
| private final Tuple tuple = new Tuple(); |
| private final jdbm.helper.Tuple jdbmTuple = new jdbm.helper.Tuple(); |
| private final boolean stepForward; |
| private TupleBrowser browser; |
| private boolean success = false; |
| |
| |
| BTreeTupleEnumeration( BTree tree, Comparator<Object> comparator, Object key, Object val, boolean isGreaterThan ) |
| throws LdapNamingException |
| { |
| this.key = key; |
| stepForward = isGreaterThan; |
| |
| try |
| { |
| browser = tree.browse( val ); |
| |
| if ( ! isGreaterThan ) |
| { |
| boolean gotNextOk = browser.getNext( jdbmTuple ); |
| if ( gotNextOk ) |
| { |
| Object nextVal = jdbmTuple.getKey(); |
| int compared = comparator.compare( val, nextVal ); |
| if ( compared != 0 ) |
| { |
| browser.getPrevious( jdbmTuple ); |
| } |
| } |
| } |
| |
| prefetch(); |
| } |
| catch ( IOException e ) |
| { |
| LdapNamingException lne = new LdapNamingException( "Failure on btree: " + e.getMessage(), |
| ResultCodeEnum.OTHER ); |
| lne.setRootCause( e ); |
| throw lne; |
| } |
| } |
| |
| |
| BTreeTupleEnumeration( BTree tree, Object key ) throws NamingException |
| { |
| this.key = key; |
| stepForward = true; |
| |
| try |
| { |
| browser = tree.browse(); |
| prefetch(); |
| } |
| catch ( IOException e ) |
| { |
| LdapNamingException lne = new LdapNamingException( "Failure on btree: " + e.getMessage(), |
| ResultCodeEnum.OTHER ); |
| lne.setRootCause( e ); |
| throw lne; |
| } |
| } |
| |
| |
| private void prefetch() throws IOException |
| { |
| if ( stepForward ) |
| { |
| success = browser.getNext( jdbmTuple ); |
| } |
| else |
| { |
| success = browser.getPrevious( jdbmTuple ); |
| } |
| } |
| |
| |
| public void close() throws NamingException |
| { |
| success = false; |
| } |
| |
| |
| public boolean hasMore() throws NamingException |
| { |
| return success; |
| } |
| |
| |
| public Object next() throws NamingException |
| { |
| if ( ! success ) |
| { |
| throw new NoSuchElementException(); |
| } |
| |
| tuple.setKey( key ); |
| tuple.setValue( jdbmTuple.getKey() ); |
| try |
| { |
| prefetch(); |
| } |
| catch ( IOException e ) |
| { |
| LdapNamingException lne = new LdapNamingException( "Failure on btree: " + e.getMessage(), |
| ResultCodeEnum.OTHER ); |
| lne.setRootCause( e ); |
| throw lne; |
| } |
| return tuple; |
| } |
| |
| |
| public boolean hasMoreElements() |
| { |
| return success; |
| } |
| |
| |
| public Object nextElement() |
| { |
| try |
| { |
| return next(); |
| } |
| catch ( NamingException e ) |
| { |
| throw new NoSuchElementException( "Got IO Failure on btree: " + e.getCause().getMessage() ); |
| } |
| } |
| } |