| /* |
| * 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 org.apache.commons.collections.ArrayStack; |
| 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.exception.LdapException; |
| import org.apache.directory.api.ldap.model.name.Rdn; |
| 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.ParentIdAndRdn; |
| import org.apache.directory.server.xdbm.Store; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| |
| /** |
| * A Cursor over entries satisfying one level scope constraints with alias |
| * dereferencing considerations when enabled during search. |
| * We use the Rdn index to fetch all the descendants of a given entry. |
| * |
| * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> |
| */ |
| public class DescendantCursor extends AbstractIndexCursor<String> |
| { |
| /** 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(); |
| |
| /** Error message for unsupported operations */ |
| private static final String UNSUPPORTED_MSG = I18n.err( I18n.ERR_719 ); |
| |
| /** The entry database/store */ |
| private final Store db; |
| |
| /** The prefetched element */ |
| private IndexEntry prefetched; |
| |
| /** The current Cursor over the entries in the scope of the search base */ |
| private Cursor<IndexEntry<ParentIdAndRdn, String>> currentCursor; |
| |
| /** The current Parent ID */ |
| private String currentParentId; |
| |
| /** The stack of cursors used to process the depth-first traversal */ |
| private ArrayStack cursorStack; |
| |
| /** The stack of parentIds used to process the depth-first traversal */ |
| private ArrayStack parentIdStack; |
| |
| /** The initial entry ID we are looking descendants for */ |
| private String baseId; |
| |
| /** A flag to tell that we are in the top level cursor or not */ |
| private boolean topLevel; |
| |
| protected static final boolean TOP_LEVEL = true; |
| protected static final boolean INNER = false; |
| |
| |
| /** |
| * Creates a Cursor over entries satisfying one level scope criteria. |
| * |
| * @param db the entry store |
| * @param evaluator an IndexEntry (candidate) evaluator |
| * @throws Exception on db access failures |
| */ |
| public DescendantCursor( Store db, String baseId, String parentId, |
| Cursor<IndexEntry<ParentIdAndRdn, String>> cursor ) |
| throws Exception |
| { |
| this( db, baseId, parentId, cursor, TOP_LEVEL ); |
| } |
| |
| |
| /** |
| * Creates a Cursor over entries satisfying one level scope criteria. |
| * |
| * @param db the entry store |
| * @param evaluator an IndexEntry (candidate) evaluator |
| * @throws Exception on db access failures |
| */ |
| public DescendantCursor( Store db, String baseId, String parentId, |
| Cursor<IndexEntry<ParentIdAndRdn, String>> cursor, |
| boolean topLevel ) |
| throws Exception |
| { |
| this.db = db; |
| currentParentId = parentId; |
| currentCursor = cursor; |
| cursorStack = new ArrayStack(); |
| parentIdStack = new ArrayStack(); |
| this.baseId = baseId; |
| this.topLevel = topLevel; |
| |
| if ( IS_DEBUG ) |
| { |
| LOG_CURSOR.debug( "Creating ChildrenCursor {}", this ); |
| } |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| protected String getUnsupportedMessage() |
| { |
| return UNSUPPORTED_MSG; |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void beforeFirst() throws LdapException, CursorException |
| { |
| checkNotClosed( "beforeFirst()" ); |
| setAvailable( false ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void afterLast() throws LdapException, CursorException |
| { |
| throw new UnsupportedOperationException( getUnsupportedMessage() ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean first() throws LdapException, CursorException |
| { |
| beforeFirst(); |
| |
| return next(); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean last() throws LdapException, CursorException |
| { |
| throw new UnsupportedOperationException( getUnsupportedMessage() ); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean previous() throws LdapException, CursorException |
| { |
| checkNotClosed( "next()" ); |
| |
| boolean hasPrevious = currentCursor.previous(); |
| |
| if ( hasPrevious ) |
| { |
| IndexEntry entry = currentCursor.get(); |
| |
| if ( ( ( ParentIdAndRdn ) entry.getTuple().getKey() ).getParentId().equals( currentParentId ) ) |
| { |
| prefetched = entry; |
| return true; |
| } |
| } |
| |
| return false; |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public boolean next() throws LdapException, CursorException |
| { |
| checkNotClosed( "next()" ); |
| boolean finished = false; |
| |
| while ( !finished ) |
| { |
| boolean hasNext = currentCursor.next(); |
| |
| // We will use a depth first approach. The alternative (Breadth-first) would be |
| // too memory consuming. |
| // The idea is to use a ChildrenCursor each time we have an entry with chidren, |
| // and process recursively. |
| if ( hasNext ) |
| { |
| IndexEntry cursorEntry = currentCursor.get(); |
| ParentIdAndRdn parentIdAndRdn = ( ( ParentIdAndRdn ) ( cursorEntry.getKey() ) ); |
| |
| // Check that we aren't out of the cursor's limit |
| if ( !parentIdAndRdn.getParentId().equals( currentParentId ) ) |
| { |
| // Ok, we went too far. Unstack the cursor and return |
| finished = cursorStack.size() == 0; |
| |
| if ( !finished ) |
| { |
| currentCursor.close(); |
| currentCursor = ( Cursor<IndexEntry<ParentIdAndRdn, String>> ) cursorStack.pop(); |
| currentParentId = ( String ) parentIdStack.pop(); |
| } |
| |
| // And continue... |
| } |
| else |
| { |
| // We have a candidate, it will be returned. |
| if ( topLevel ) |
| { |
| prefetched = new IndexEntry(); |
| prefetched.setId( cursorEntry.getId() ); |
| prefetched.setKey( baseId ); |
| } |
| else |
| { |
| prefetched = cursorEntry; |
| } |
| |
| // Check if the current entry has children or not. |
| if ( parentIdAndRdn.getNbDescendants() > 0 ) |
| { |
| String newParentId = ( String ) cursorEntry.getId(); |
| |
| // Yes, then create a new cursor and go down one level |
| Cursor<IndexEntry<ParentIdAndRdn, String>> cursor = db.getRdnIndex().forwardCursor(); |
| |
| IndexEntry<ParentIdAndRdn, String> startingPos = new IndexEntry<ParentIdAndRdn, String>(); |
| startingPos.setKey( new ParentIdAndRdn( newParentId, ( Rdn[] ) null ) ); |
| cursor.before( startingPos ); |
| |
| cursorStack.push( currentCursor ); |
| parentIdStack.push( currentParentId ); |
| |
| currentCursor = cursor; |
| currentParentId = newParentId; |
| } |
| |
| return true; |
| } |
| } |
| else |
| { |
| // The current cursor has been exhausted. Get back to the parent's cursor. |
| finished = cursorStack.size() == 0; |
| |
| if ( !finished ) |
| { |
| currentCursor.close(); |
| currentCursor = ( Cursor<IndexEntry<ParentIdAndRdn, String>> ) cursorStack.pop(); |
| currentParentId = ( String ) parentIdStack.pop(); |
| } |
| // and continue... |
| } |
| } |
| |
| return false; |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public IndexEntry<String, String> get() throws CursorException |
| { |
| checkNotClosed( "get()" ); |
| |
| return prefetched; |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public void close() |
| { |
| if ( IS_DEBUG ) |
| { |
| LOG_CURSOR.debug( "Closing ChildrenCursor {}", this ); |
| } |
| |
| // Close the cursors stored in the stack, if we have some |
| for ( Object cursor : cursorStack ) |
| { |
| ( ( Cursor<IndexEntry<?, ?>> ) cursor ).close(); |
| } |
| |
| // And finally, close the current cursor |
| currentCursor.close(); |
| |
| super.close(); |
| } |
| |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public void close( Exception cause ) |
| { |
| if ( IS_DEBUG ) |
| { |
| LOG_CURSOR.debug( "Closing ChildrenCursor {}", this ); |
| } |
| |
| // Close the cursors stored in the stack, if we have some |
| for ( Object cursor : cursorStack ) |
| { |
| ( ( Cursor<IndexEntry<?, ?>> ) cursor ).close( cause ); |
| } |
| |
| // And finally, close the current cursor |
| currentCursor.close( cause ); |
| |
| super.close( cause ); |
| } |
| |
| |
| /** |
| * Dumps the cursors |
| */ |
| private String dumpCursors( String tabs ) |
| { |
| StringBuilder sb = new StringBuilder(); |
| |
| for ( Object cursor : cursorStack ) |
| { |
| sb.append( ( ( Cursor<IndexEntry<ParentIdAndRdn, String>> ) cursor ).toString( tabs + " " ) ); |
| sb.append( "\n" ); |
| } |
| |
| return sb.toString(); |
| } |
| |
| |
| /** |
| * @see Object#toString() |
| */ |
| public String toString( String tabs ) |
| { |
| StringBuilder sb = new StringBuilder(); |
| |
| sb.append( tabs ).append( "DescendantCursor (" ); |
| |
| if ( available() ) |
| { |
| sb.append( "available)" ); |
| } |
| else |
| { |
| sb.append( "absent)" ); |
| } |
| |
| sb.append( "#baseId<" ).append( baseId ); |
| sb.append( ", " ).append( db ).append( "> :\n" ); |
| |
| sb.append( dumpCursors( tabs + " " ) ); |
| |
| if ( currentCursor != null ) |
| { |
| sb.append( tabs + " <current>\n" ); |
| sb.append( currentCursor.toString( tabs + " " ) ); |
| } |
| |
| return sb.toString(); |
| } |
| |
| |
| /** |
| * @see Object#toString() |
| */ |
| public String toString() |
| { |
| return toString( "" ); |
| } |
| } |