| /* |
| * 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.cursor; |
| |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.List; |
| |
| import org.apache.directory.api.ldap.model.constants.Loggers; |
| import org.apache.directory.api.ldap.model.cursor.Cursor; |
| import org.apache.directory.api.ldap.model.cursor.CursorException; |
| import org.apache.directory.api.ldap.model.cursor.InvalidCursorPositionException; |
| import org.apache.directory.api.ldap.model.exception.LdapException; |
| import org.apache.directory.api.ldap.model.filter.ExprNode; |
| import org.apache.directory.server.i18n.I18n; |
| import org.apache.directory.server.xdbm.AbstractIndexCursor; |
| import org.apache.directory.server.xdbm.IndexEntry; |
| import org.apache.directory.server.xdbm.search.Evaluator; |
| import org.apache.directory.server.xdbm.search.impl.ScanCountComparator; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| |
| /** |
| * A Cursor returning candidates satisfying a logical conjunction expression. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| */ |
| public class AndCursor<V> extends AbstractIndexCursor<V> |
| { |
| /** A dedicated log for cursors */ |
| private static final Logger LOG_CURSOR = LoggerFactory.getLogger( Loggers.CURSOR_LOG.getName() ); |
| |
| /** Speedup for logs */ |
| private static final boolean IS_DEBUG = LOG_CURSOR.isDebugEnabled(); |
| |
| /** The message for unsupported operations */ |
| private static final String UNSUPPORTED_MSG = I18n.err( I18n.ERR_707 ); |
| |
| /** */ |
| private final Cursor<IndexEntry<V, String>> wrapped; |
| |
| /** The evaluators used for the members of the And filter */ |
| private final List<Evaluator<? extends ExprNode>> evaluators; |
| |
| |
| /** |
| * Creates an instance of a AndCursor. It wraps an index cursor and the list |
| * of evaluators associated with all the elements connected by the And. |
| * |
| * @param wrapped The encapsulated IndexCursor |
| * @param evaluators The list of evaluators associated wth the elements |
| */ |
| public AndCursor( Cursor<IndexEntry<V, String>> wrapped, |
| List<Evaluator<? extends ExprNode>> evaluators ) |
| { |
| if ( IS_DEBUG ) |
| { |
| LOG_CURSOR.debug( "Creating AndCursor {}", this ); |
| } |
| |
| this.wrapped = wrapped; |
| this.evaluators = optimize( evaluators ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| protected String getUnsupportedMessage() |
| { |
| return UNSUPPORTED_MSG; |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void beforeFirst() throws LdapException, CursorException |
| { |
| checkNotClosed( "beforeFirst()" ); |
| wrapped.beforeFirst(); |
| setAvailable( false ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void afterLast() throws LdapException, CursorException |
| { |
| checkNotClosed( "afterLast()" ); |
| wrapped.afterLast(); |
| setAvailable( false ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean first() throws LdapException, CursorException |
| { |
| beforeFirst(); |
| |
| return next(); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean last() throws LdapException, CursorException |
| { |
| afterLast(); |
| |
| return previous(); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean previous() throws LdapException, CursorException |
| { |
| while ( wrapped.previous() ) |
| { |
| checkNotClosed( "previous()" ); |
| |
| IndexEntry<V, String> candidate = wrapped.get(); |
| |
| if ( matches( candidate ) ) |
| { |
| return setAvailable( true ); |
| } |
| } |
| |
| return setAvailable( false ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean next() throws LdapException, CursorException |
| { |
| while ( wrapped.next() ) |
| { |
| checkNotClosed( "next()" ); |
| IndexEntry<V, String> candidate = wrapped.get(); |
| |
| if ( matches( candidate ) ) |
| { |
| return setAvailable( true ); |
| } |
| } |
| |
| return setAvailable( false ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public IndexEntry<V, String> get() throws CursorException |
| { |
| checkNotClosed( "get()" ); |
| |
| if ( available() ) |
| { |
| return wrapped.get(); |
| } |
| |
| throw new InvalidCursorPositionException( I18n.err( I18n.ERR_708 ) ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void close() |
| { |
| if ( IS_DEBUG ) |
| { |
| LOG_CURSOR.debug( "Closing AndCursor {}", this ); |
| } |
| |
| super.close(); |
| wrapped.close(); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void close( Exception cause ) |
| { |
| if ( IS_DEBUG ) |
| { |
| LOG_CURSOR.debug( "Closing AndCursor {}", this ); |
| } |
| |
| super.close( cause ); |
| wrapped.close( cause ); |
| } |
| |
| |
| /** |
| * Takes a set of Evaluators and copies then sorts them in a new list with |
| * increasing scan counts on their expression nodes. This is done to have |
| * the Evaluators with the least scan count which have the highest |
| * probability of rejecting a candidate first. That will increase the |
| * chance of shorting the checks on evaluators early so extra lookups and |
| * comparisons are avoided. |
| * |
| * @param unoptimized the unoptimized list of Evaluators |
| * @return optimized Evaluator list with increasing scan count ordering |
| */ |
| private List<Evaluator<? extends ExprNode>> optimize( |
| List<Evaluator<? extends ExprNode>> unoptimized ) |
| { |
| List<Evaluator<? extends ExprNode>> optimized = new ArrayList<Evaluator<? extends ExprNode>>( |
| unoptimized.size() ); |
| optimized.addAll( unoptimized ); |
| |
| Collections.sort( optimized, new ScanCountComparator() ); |
| |
| return optimized; |
| } |
| |
| |
| /** |
| * Checks if the entry is a valid candidate by using the evaluators. |
| */ |
| private boolean matches( IndexEntry<V, String> indexEntry ) throws LdapException |
| { |
| for ( Evaluator<?> evaluator : evaluators ) |
| { |
| if ( !evaluator.evaluate( indexEntry ) ) |
| { |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| |
| /** |
| * Dumps the evaluators |
| */ |
| private String dumpEvaluators( String tabs ) |
| { |
| StringBuilder sb = new StringBuilder(); |
| |
| for ( Evaluator<? extends ExprNode> evaluator : evaluators ) |
| { |
| sb.append( evaluator.toString( tabs + " >>" ) ); |
| } |
| |
| return sb.toString(); |
| } |
| |
| |
| /** |
| * @see Object#toString() |
| */ |
| public String toString( String tabs ) |
| { |
| StringBuilder sb = new StringBuilder(); |
| |
| sb.append( tabs ).append( "AndCursor (" ); |
| |
| if ( available() ) |
| { |
| sb.append( "available) :\n" ); |
| } |
| else |
| { |
| sb.append( "absent) :\n" ); |
| } |
| |
| if ( ( evaluators != null ) && ( evaluators.size() > 0 ) ) |
| { |
| sb.append( dumpEvaluators( tabs ) ); |
| } |
| |
| sb.append( wrapped.toString( tabs + " " ) ); |
| |
| return sb.toString(); |
| } |
| |
| |
| /** |
| * @see Object#toString() |
| */ |
| public String toString() |
| { |
| return toString( "" ); |
| } |
| } |