| /* |
| * 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.xdbm.search.impl; |
| |
| |
| import java.util.ArrayList; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| |
| import org.apache.directory.server.core.entry.ServerEntry; |
| import org.apache.directory.server.xdbm.IndexEntry; |
| import org.apache.directory.server.xdbm.AbstractIndexCursor; |
| import org.apache.directory.server.xdbm.IndexCursor; |
| import org.apache.directory.server.xdbm.search.Evaluator; |
| import org.apache.directory.shared.ldap.cursor.Cursor; |
| import org.apache.directory.shared.ldap.cursor.InvalidCursorPositionException; |
| import org.apache.directory.shared.ldap.filter.ExprNode; |
| |
| |
| |
| /** |
| * A Cursor returning candidates satisfying a logical disjunction expression. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| * @version $Rev$ |
| */ |
| public class OrCursor<V> extends AbstractIndexCursor<V, ServerEntry> |
| { |
| private static final String UNSUPPORTED_MSG = |
| "OrCursors are not ordered and do not support positioning by element."; |
| private final List<IndexCursor<V,ServerEntry>> cursors; |
| private final List<Evaluator<? extends ExprNode,ServerEntry>> evaluators; |
| private final List<Set<Long>> blacklists; |
| private int cursorIndex = -1; |
| private boolean available = false; |
| |
| |
| // TODO - do same evaluator fail fast optimization that we do in AndCursor |
| public OrCursor( List<IndexCursor<V, ServerEntry>> cursors, List<Evaluator<? extends ExprNode,ServerEntry>> evaluators ) |
| { |
| if ( cursors.size() <= 1 ) |
| { |
| throw new IllegalArgumentException( |
| "Must have 2 or more sub-expression Cursors for a disjunction" ); |
| } |
| |
| this.cursors = cursors; |
| this.evaluators = evaluators; |
| this.blacklists = new ArrayList<Set<Long>>(); |
| |
| for ( int ii = 0; ii < cursors.size(); ii++ ) |
| { |
| this.blacklists.add( new HashSet<Long>() ); |
| } |
| this.cursorIndex = 0; |
| } |
| |
| |
| public boolean available() |
| { |
| return available; |
| } |
| |
| |
| public void before( IndexEntry<V, ServerEntry> element ) throws Exception |
| { |
| throw new UnsupportedOperationException( UNSUPPORTED_MSG ); |
| } |
| |
| |
| public void after( IndexEntry<V, ServerEntry> element ) throws Exception |
| { |
| throw new UnsupportedOperationException( UNSUPPORTED_MSG ); |
| } |
| |
| |
| public void beforeValue( Long id, V value ) throws Exception |
| { |
| throw new UnsupportedOperationException( UNSUPPORTED_MSG ); |
| } |
| |
| |
| public void afterValue( Long id, V value ) throws Exception |
| { |
| throw new UnsupportedOperationException( UNSUPPORTED_MSG ); |
| } |
| |
| |
| public void beforeFirst() throws Exception |
| { |
| checkNotClosed( "beforeFirst()" ); |
| cursorIndex = 0; |
| cursors.get( cursorIndex ).beforeFirst(); |
| available = false; |
| } |
| |
| |
| public void afterLast() throws Exception |
| { |
| checkNotClosed( "afterLast()" ); |
| cursorIndex = cursors.size() - 1; |
| cursors.get( cursorIndex ).afterLast(); |
| available = false; |
| } |
| |
| |
| public boolean first() throws Exception |
| { |
| beforeFirst(); |
| return available = next(); |
| } |
| |
| |
| public boolean last() throws Exception |
| { |
| afterLast(); |
| return available = previous(); |
| } |
| |
| |
| private boolean isBlackListed( Long id ) |
| { |
| return blacklists.get( cursorIndex ).contains( id ); |
| } |
| |
| |
| /** |
| * The first sub-expression Cursor to advance to an entry adds the entry |
| * to the blacklists of other Cursors that might return that entry. |
| * |
| * @param indexEntry the index entry to blacklist |
| * @throws Exception if there are problems accessing underlying db |
| */ |
| private void blackListIfDuplicate( IndexEntry<?, ServerEntry> indexEntry ) throws Exception |
| { |
| for ( int ii = 0; ii < evaluators.size(); ii++ ) |
| { |
| if ( ii == cursorIndex ) |
| { |
| continue; |
| } |
| |
| if ( evaluators.get( ii ).evaluate( indexEntry ) ) |
| { |
| blacklists.get( ii ).add( indexEntry.getId() ); |
| } |
| } |
| } |
| |
| |
| public boolean previous() throws Exception |
| { |
| while ( cursors.get( cursorIndex ).previous() ) |
| { |
| checkNotClosed( "previous()" ); |
| IndexEntry<?,ServerEntry> candidate = cursors.get( cursorIndex ).get(); |
| if ( ! isBlackListed( candidate.getId() ) ) |
| { |
| blackListIfDuplicate( candidate ); |
| return available = true; |
| } |
| } |
| |
| while ( cursorIndex > 0 ) |
| { |
| checkNotClosed( "previous()" ); |
| cursorIndex--; |
| cursors.get( cursorIndex ).afterLast(); |
| |
| while ( cursors.get( cursorIndex ).previous() ) |
| { |
| checkNotClosed( "previous()" ); |
| IndexEntry<?,ServerEntry> candidate = cursors.get( cursorIndex ).get(); |
| if ( ! isBlackListed( candidate.getId() ) ) |
| { |
| blackListIfDuplicate( candidate ); |
| return available = true; |
| } |
| } |
| } |
| |
| return available = false; |
| } |
| |
| |
| public boolean next() throws Exception |
| { |
| while ( cursors.get( cursorIndex ).next() ) |
| { |
| checkNotClosed( "next()" ); |
| IndexEntry<?,ServerEntry> candidate = cursors.get( cursorIndex ).get(); |
| if ( ! isBlackListed( candidate.getId() ) ) |
| { |
| blackListIfDuplicate( candidate ); |
| return available = true; |
| } |
| } |
| |
| while ( cursorIndex < cursors.size() - 1 ) |
| { |
| checkNotClosed( "previous()" ); |
| cursorIndex++; |
| cursors.get( cursorIndex ).beforeFirst(); |
| |
| while ( cursors.get( cursorIndex ).next() ) |
| { |
| checkNotClosed( "previous()" ); |
| IndexEntry<?,ServerEntry> candidate = cursors.get( cursorIndex ).get(); |
| if ( ! isBlackListed( candidate.getId() ) ) |
| { |
| blackListIfDuplicate( candidate ); |
| return available = true; |
| } |
| } |
| } |
| |
| return available = false; |
| } |
| |
| |
| public IndexEntry<V, ServerEntry> get() throws Exception |
| { |
| checkNotClosed( "get()" ); |
| if ( available ) |
| { |
| return cursors.get( cursorIndex ).get(); |
| } |
| |
| throw new InvalidCursorPositionException( "Cursor has not been positioned yet." ); |
| } |
| |
| |
| public boolean isElementReused() |
| { |
| return cursors.get( cursorIndex ).isElementReused(); |
| } |
| |
| |
| public void close() throws Exception |
| { |
| super.close(); |
| for ( Cursor<?> cursor : cursors ) |
| { |
| cursor.close(); |
| } |
| } |
| } |