001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019package org.apache.directory.server.xdbm; 020 021 022import java.io.IOException; 023 024import org.apache.directory.api.ldap.model.constants.Loggers; 025import org.apache.directory.api.ldap.model.cursor.CursorException; 026import org.apache.directory.api.ldap.model.cursor.InvalidCursorPositionException; 027import org.apache.directory.api.ldap.model.exception.LdapException; 028import org.apache.directory.server.core.api.partition.PartitionTxn; 029import org.apache.directory.server.i18n.I18n; 030import org.slf4j.Logger; 031import org.slf4j.LoggerFactory; 032 033 034/** 035 * A Cursor over a single element. 036 * 037 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 038 */ 039public class SingletonIndexCursor<V> extends AbstractIndexCursor<V> 040{ 041 /** A dedicated log for cursors */ 042 private static final Logger LOG_CURSOR = LoggerFactory.getLogger( Loggers.CURSOR_LOG.getName() ); 043 044 /** Speedup for logs */ 045 private static final boolean IS_DEBUG = LOG_CURSOR.isDebugEnabled(); 046 047 private boolean beforeFirst = true; 048 private boolean afterLast; 049 private boolean onSingleton; 050 private final IndexEntry<V, String> singleton; 051 052 053 public SingletonIndexCursor( PartitionTxn partitionTxn, IndexEntry<V, String> singleton ) 054 { 055 if ( IS_DEBUG ) 056 { 057 LOG_CURSOR.debug( "Creating SingletonIndexCursor {}", this ); 058 } 059 060 this.singleton = singleton; 061 this.partitionTxn = partitionTxn; 062 } 063 064 065 /** 066 * {@inheritDoc} 067 */ 068 protected String getUnsupportedMessage() 069 { 070 return UNSUPPORTED_MSG; 071 } 072 073 074 /** 075 * {@inheritDoc} 076 */ 077 @Override 078 public boolean available() 079 { 080 return onSingleton; 081 } 082 083 084 /** 085 * {@inheritDoc} 086 */ 087 @Override 088 public void beforeFirst() throws LdapException, CursorException 089 { 090 checkNotClosed(); 091 beforeFirst = true; 092 afterLast = false; 093 onSingleton = false; 094 } 095 096 097 /** 098 * {@inheritDoc} 099 */ 100 @Override 101 public void afterLast() throws LdapException, CursorException 102 { 103 checkNotClosed(); 104 beforeFirst = false; 105 afterLast = true; 106 onSingleton = false; 107 } 108 109 110 /** 111 * {@inheritDoc} 112 */ 113 @Override 114 public boolean first() throws LdapException, CursorException 115 { 116 checkNotClosed(); 117 beforeFirst = false; 118 onSingleton = true; 119 afterLast = false; 120 return true; 121 } 122 123 124 /** 125 * {@inheritDoc} 126 */ 127 @Override 128 public boolean last() throws LdapException, CursorException 129 { 130 checkNotClosed(); 131 beforeFirst = false; 132 onSingleton = true; 133 afterLast = false; 134 return true; 135 } 136 137 138 /** 139 * {@inheritDoc} 140 */ 141 @Override 142 public boolean isFirst() 143 { 144 return onSingleton; 145 } 146 147 148 /** 149 * {@inheritDoc} 150 */ 151 @Override 152 public boolean isLast() 153 { 154 return onSingleton; 155 } 156 157 158 /** 159 * {@inheritDoc} 160 */ 161 @Override 162 public boolean isAfterLast() 163 { 164 return afterLast; 165 } 166 167 168 /** 169 * {@inheritDoc} 170 */ 171 @Override 172 public boolean isBeforeFirst() 173 { 174 return beforeFirst; 175 } 176 177 178 /** 179 * {@inheritDoc} 180 */ 181 @Override 182 public boolean previous() throws LdapException, CursorException 183 { 184 checkNotClosed(); 185 if ( beforeFirst ) 186 { 187 return false; 188 } 189 190 if ( afterLast ) 191 { 192 beforeFirst = false; 193 onSingleton = true; 194 afterLast = false; 195 return true; 196 } 197 198 // must be on the singleton 199 beforeFirst = true; 200 onSingleton = false; 201 afterLast = false; 202 return false; 203 } 204 205 206 /** 207 * {@inheritDoc} 208 */ 209 @Override 210 public boolean next() throws LdapException, CursorException 211 { 212 checkNotClosed(); 213 214 if ( beforeFirst ) 215 { 216 beforeFirst = false; 217 onSingleton = true; 218 afterLast = false; 219 return true; 220 } 221 222 if ( afterLast ) 223 { 224 return false; 225 } 226 227 // must be on the singleton 228 beforeFirst = false; 229 onSingleton = false; 230 afterLast = true; 231 return false; 232 } 233 234 235 /** 236 * {@inheritDoc} 237 */ 238 public IndexEntry<V, String> get() throws CursorException 239 { 240 checkNotClosed(); 241 242 if ( onSingleton ) 243 { 244 return singleton; 245 } 246 247 if ( beforeFirst ) 248 { 249 throw new InvalidCursorPositionException( I18n.err( I18n.ERR_705 ) ); 250 } 251 else 252 { 253 throw new InvalidCursorPositionException( I18n.err( I18n.ERR_706 ) ); 254 } 255 } 256 257 258 /** 259 * {@inheritDoc} 260 */ 261 @Override 262 public void close() throws IOException 263 { 264 if ( IS_DEBUG ) 265 { 266 LOG_CURSOR.debug( "Closing SingletonIndexCursor {}", this ); 267 } 268 269 super.close(); 270 } 271 272 273 /** 274 * {@inheritDoc} 275 */ 276 @Override 277 public void close( Exception cause ) throws IOException 278 { 279 if ( IS_DEBUG ) 280 { 281 LOG_CURSOR.debug( "Closing SingletonIndexCursor {}", this ); 282 } 283 284 super.close( cause ); 285 } 286}