| 1 | /* ============================================================= |
| 2 | * SmallSQL : a free Java DBMS library for the Java(tm) platform |
| 3 | * ============================================================= |
| 4 | * |
| 5 | * (C) Copyright 2004-2006, by Volker Berlin. |
| 6 | * |
| 7 | * Project Info: http://www.smallsql.de/ |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or modify it |
| 10 | * under the terms of the GNU Lesser General Public License as published by |
| 11 | * the Free Software Foundation; either version 2.1 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, but |
| 15 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 16 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| 17 | * License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
| 22 | * USA. |
| 23 | * |
| 24 | * [Java is a trademark or registered trademark of Sun Microsystems, Inc. |
| 25 | * in the United States and other countries.] |
| 26 | * |
| 27 | * --------------- |
| 28 | * IndexNode.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | */ |
| 33 | package smallsql.database; |
| 34 | |
| 35 | import java.sql.*; |
| 36 | |
| 37 | /** |
| 38 | * @author Volker Berlin |
| 39 | */ |
| 40 | class IndexNode { |
| 41 | final private boolean unique; |
| 42 | final private char digit; // unsigned short |
| 43 | |
| 44 | static final private IndexNode[] EMPTY_NODES = new IndexNode[0]; |
| 45 | /** |
| 46 | * Can be a PageIndex to the next page or a byte[] with rest data of the key. |
| 47 | */ |
| 48 | private IndexNode[] nodes = EMPTY_NODES; |
| 49 | |
| 50 | /** |
| 51 | * On this point of the tree there is no other value. There is only one value. |
| 52 | * That's the tree is cut here and the single value is saved. This is very large |
| 53 | * benefit if you have large strings and you can difference it with the |
| 54 | * first characters. |
| 55 | */ |
| 56 | private char[] remainderKey; |
| 57 | |
| 58 | /** |
| 59 | * Can save a Long, LongList with a rowOffset value or a IndexNode of the next root index. |
| 60 | */ |
| 61 | private Object value; |
| 62 | |
| 63 | /** |
| 64 | * The status array save the status of the digits. The follow table descript all valid combinations.<p><code> |
| 65 | * nodes value status |
| 66 | * ------------------------------------ |
| 67 | * null null NO_ENTRY |
| 68 | * IndexNode null NODE |
| 69 | * byte[] Long/LongList REMAINDER_VALUE |
| 70 | * null Long/LongList FINAL_VALUE |
| 71 | * IndexNode Long/LongList FINAL_VALUE + NODE |
| 72 | * null IndexNode ROOT |
| 73 | * byte[] IndexNode REMAINDER_VALUE + ROOT |
| 74 | * IndexNode IndexNode NODE + ROOT |
| 75 | * |
| 76 | * </code> |
| 77 | */ |
| 78 | |
| 79 | /** |
| 80 | * Create a new Node in the Index. |
| 81 | * @param unique descript if it is a unique index (primary key) or a multi value index is. |
| 82 | */ |
| 83 | IndexNode(boolean unique, char digit){ |
| 84 | this.unique = unique; |
| 85 | this.digit = digit; |
| 86 | } |
| 87 | |
| 88 | |
| 89 | final char getDigit(){ |
| 90 | return digit; |
| 91 | } |
| 92 | |
| 93 | |
| 94 | final boolean getUnique(){ |
| 95 | return unique; |
| 96 | } |
| 97 | |
| 98 | |
| 99 | /** |
| 100 | * Returns the current status for the digit. |
| 101 | * @param digit The digit must be in the range 0 between 255. |
| 102 | */ |
| 103 | final boolean isEmpty(){ |
| 104 | return nodes == EMPTY_NODES && value == null; |
| 105 | } |
| 106 | |
| 107 | |
| 108 | final void clear(){ |
| 109 | nodes = EMPTY_NODES; |
| 110 | value = null; |
| 111 | remainderKey = null; |
| 112 | } |
| 113 | |
| 114 | |
| 115 | final void clearValue(){ |
| 116 | value = null; |
| 117 | } |
| 118 | |
| 119 | |
| 120 | /** |
| 121 | * Returns the current value for the digit. |
| 122 | * @param digit The digit must be in the range 0 between 255. |
| 123 | */ |
| 124 | final Object getValue(){ |
| 125 | return value; |
| 126 | } |
| 127 | |
| 128 | |
| 129 | final IndexNode[] getChildNodes(){ |
| 130 | return nodes; |
| 131 | } |
| 132 | |
| 133 | |
| 134 | /** |
| 135 | * Returns the IndexNode for the node position digit. |
| 136 | * @param digit The digit must be in the range 0 between 255. |
| 137 | */ |
| 138 | final IndexNode getChildNode(char digit){ |
| 139 | int pos = findNodePos(digit); |
| 140 | if(pos >=0) return nodes[pos]; |
| 141 | return null; |
| 142 | } |
| 143 | |
| 144 | |
| 145 | final char[] getRemainderValue(){ |
| 146 | return remainderKey; |
| 147 | } |
| 148 | |
| 149 | |
| 150 | /** |
| 151 | * Add a node in the middle of a key value. |
| 152 | * @param digit The digit must be in the range 0 between 255. |
| 153 | */ |
| 154 | final IndexNode addNode(char digit) throws SQLException{ |
| 155 | if(remainderKey != null) moveRemainderValue(); |
| 156 | int pos = findNodePos( digit ); |
| 157 | if(pos == -1){ |
| 158 | IndexNode node = new IndexNode(unique, digit); |
| 159 | saveNode( node ); |
| 160 | return node; |
| 161 | }else{ |
| 162 | return nodes[pos]; |
| 163 | } |
| 164 | } |
| 165 | |
| 166 | |
| 167 | /** |
| 168 | * Remove a node. |
| 169 | * @param digit The digit must be in the range 0 between 255. |
| 170 | */ |
| 171 | final void removeNode(char digit){ |
| 172 | int pos = findNodePos( digit ); |
| 173 | if(pos != -1){ |
| 174 | int length = nodes.length-1; |
| 175 | IndexNode[] temp = new IndexNode[length]; |
| 176 | System.arraycopy(nodes, 0, temp, 0, pos); |
| 177 | System.arraycopy(nodes, pos+1, temp, pos, length-pos); |
| 178 | nodes = temp; |
| 179 | } |
| 180 | } |
| 181 | |
| 182 | |
| 183 | /** |
| 184 | * Add a node on the end of a key value. |
| 185 | * @param digit The digit must be in the range 0 between 255. |
| 186 | * @param rowOffset The value that is saved at the end of the tree. |
| 187 | */ |
| 188 | final void addNode(char digit, long rowOffset) throws SQLException{ |
| 189 | IndexNode node = addNode(digit); |
| 190 | if(node.remainderKey != null) node.moveRemainderValue(); |
| 191 | node.saveValue(rowOffset); |
| 192 | } |
| 193 | |
| 194 | |
| 195 | /** |
| 196 | * Save the rowOffset on the digit position. This can be used for FINAL_VALUE or REMAINDER_VALUE. |
| 197 | * The caller need to verify that there allready exist an equals value. |
| 198 | * This means that the digit and the remainder is equals. |
| 199 | * @param digit The digit must be in the range 0 between 255. |
| 200 | * @param rowOffset The value that is saved in the tree. |
| 201 | */ |
| 202 | final void saveValue(long rowOffset) throws SQLException{ |
| 203 | if(unique){ |
| 204 | if(value != null) throw Utils.createSQLException("Duplikate Key"); |
| 205 | value = new Long(rowOffset); |
| 206 | }else{ |
| 207 | LongTreeList list = (LongTreeList)value; |
| 208 | if(list == null){ |
| 209 | value = list = new LongTreeList(); |
| 210 | } |
| 211 | list.add(rowOffset); |
| 212 | } |
| 213 | } |
| 214 | |
| 215 | |
| 216 | /** |
| 217 | * Add a value on a tree node end without roll out the completly tree. |
| 218 | * This reduce the size of the tree if there are large enties with a high significance. |
| 219 | * for example: |
| 220 | * If you have large strings which are different on the on the first 3 charchters. |
| 221 | * Then you need only a tree size of 3. |
| 222 | * @param digit The digit must be in the range 0 between 255. |
| 223 | * @param rowOffset The result value. This is the value that is saved in the tree. |
| 224 | * @param value The key value. |
| 225 | * @param digitCount The count of digits from value that need to indexing in the tree. |
| 226 | * The range is from 1 to 3; |
| 227 | */ |
| 228 | final void addRemainderKey(long rowOffset, long remainderValue, int charCount) throws SQLException{ |
| 229 | saveRemainderValue(remainderValue, charCount); |
| 230 | value = (unique) ? (Object)new Long(rowOffset) : new LongTreeList(rowOffset); |
| 231 | } |
| 232 | |
| 233 | |
| 234 | final void addRemainderKey(long rowOffset, char[] remainderValue, int offset) throws SQLException{ |
| 235 | saveRemainderValue(remainderValue, offset); |
| 236 | value = (unique) ? (Object)new Long(rowOffset) : new LongTreeList(rowOffset); |
| 237 | } |
| 238 | |
| 239 | |
| 240 | /** |
| 241 | * Add a new root index on the position of digit at the end of the tree. |
| 242 | * This is needed for multi columns index at the end of the first (not last) |
| 243 | * column key value. |
| 244 | * @param digit The digit must be in the range 0 between 255. |
| 245 | */ |
| 246 | final IndexNode addRoot(char digit) throws SQLException{ |
| 247 | IndexNode node = addNode(digit); |
| 248 | if(node.remainderKey != null) node.moveRemainderValue(); |
| 249 | return node.addRoot(); |
| 250 | } |
| 251 | |
| 252 | |
| 253 | final IndexNode addRootValue(char[] remainderValue, int offset) throws SQLException{ |
| 254 | saveRemainderValue(remainderValue, offset); |
| 255 | return addRoot(); |
| 256 | } |
| 257 | |
| 258 | |
| 259 | final IndexNode addRootValue( long remainderValue, int digitCount) throws SQLException{ |
| 260 | saveRemainderValue(remainderValue, digitCount); |
| 261 | return addRoot(); |
| 262 | } |
| 263 | |
| 264 | |
| 265 | /** |
| 266 | * Move a REMAINDER_VALUE node to the next node level. |
| 267 | * @param digit |
| 268 | * @throws SQLException |
| 269 | */ |
| 270 | private final void moveRemainderValue() throws SQLException{ |
| 271 | Object rowOffset = value; |
| 272 | char[] puffer = remainderKey; |
| 273 | value = null; |
| 274 | remainderKey = null; |
| 275 | IndexNode newNode = addNode(puffer[0]); |
| 276 | if(puffer.length == 1){ |
| 277 | newNode.value = rowOffset; |
| 278 | }else{ |
| 279 | newNode.moveRemainderValueSub( rowOffset, puffer); |
| 280 | } |
| 281 | } |
| 282 | |
| 283 | |
| 284 | private final void moveRemainderValueSub( Object rowOffset, char[] remainderValue){ |
| 285 | int length = remainderValue.length-1; |
| 286 | this.remainderKey = new char[length]; |
| 287 | value = rowOffset; |
| 288 | System.arraycopy( remainderValue, 1, this.remainderKey, 0, length); |
| 289 | } |
| 290 | |
| 291 | |
| 292 | private final void saveRemainderValue(char[] remainderValue, int offset){ |
| 293 | int length = remainderValue.length-offset; |
| 294 | this.remainderKey = new char[length]; |
| 295 | System.arraycopy( remainderValue, offset, this.remainderKey, 0, length); |
| 296 | } |
| 297 | |
| 298 | |
| 299 | private final void saveRemainderValue( long remainderValue, int charCount){ |
| 300 | this.remainderKey = new char[charCount]; |
| 301 | for(int i=charCount-1, d=0; i>=0; i--){ |
| 302 | this.remainderKey[d++] = (char)(remainderValue >> (i<<4)); |
| 303 | } |
| 304 | } |
| 305 | |
| 306 | /** |
| 307 | * Return the root IndexNode for the digit. If does not exists then it create one. |
| 308 | * @param digit |
| 309 | */ |
| 310 | final IndexNode addRoot() throws SQLException{ |
| 311 | IndexNode root = (IndexNode)value; |
| 312 | if(root == null){ |
| 313 | value = root = new IndexNode(unique, (char)-1); |
| 314 | } |
| 315 | return root; |
| 316 | } |
| 317 | |
| 318 | |
| 319 | private final void saveNode(IndexNode node){ |
| 320 | int length = nodes.length; |
| 321 | IndexNode[] temp = new IndexNode[length+1]; |
| 322 | if(length == 0){ |
| 323 | temp[0] = node; |
| 324 | }else{ |
| 325 | int pos = findNodeInsertPos( node.digit, 0, length); |
| 326 | System.arraycopy(nodes, 0, temp, 0, pos); |
| 327 | System.arraycopy(nodes, pos, temp, pos+1, length-pos); |
| 328 | temp[pos] = node; |
| 329 | } |
| 330 | nodes = temp; |
| 331 | } |
| 332 | |
| 333 | |
| 334 | private final int findNodeInsertPos(char digit, int start, int end){ |
| 335 | if(start == end) return start; |
| 336 | int mid = start + (end - start)/2; |
| 337 | char nodeDigit = nodes[mid].digit; |
| 338 | if(nodeDigit == digit) return mid; |
| 339 | if(nodeDigit < digit){ |
| 340 | return findNodeInsertPos( digit, mid+1, end ); |
| 341 | }else{ |
| 342 | if(start == mid) return start; |
| 343 | return findNodeInsertPos( digit, start, mid ); |
| 344 | } |
| 345 | } |
| 346 | |
| 347 | |
| 348 | private final int findNodePos(char digit){ |
| 349 | return findNodePos(digit, 0, nodes.length); |
| 350 | } |
| 351 | |
| 352 | |
| 353 | private final int findNodePos(char digit, int start, int end){ |
| 354 | if(start == nodes.length) return -1; |
| 355 | int mid = start + (end - start)/2; |
| 356 | char nodeDigit = nodes[mid].digit; |
| 357 | if(nodeDigit == digit) return mid; |
| 358 | if(nodeDigit < digit){ |
| 359 | return findNodePos( digit, mid+1, end ); |
| 360 | }else{ |
| 361 | if(start == mid) return -1; |
| 362 | return findNodePos( digit, start, mid-1 ); |
| 363 | } |
| 364 | } |
| 365 | |
| 366 | void save(MemoryStream output){ |
| 367 | output.writeShort(digit); |
| 368 | output.writeShort(nodes.length); |
| 369 | for(int i=0; i<nodes.length; i++){ |
| 370 | output.writeShort( nodes[i].digit ); |
| 371 | } |
| 372 | |
| 373 | int length = remainderKey == null ? 0 : remainderKey.length; |
| 374 | output.writeInt(length); |
| 375 | if(length>0) output.writeChars(remainderKey); |
| 376 | |
| 377 | if(value == null){ |
| 378 | output.writeByte(0); |
| 379 | }else |
| 380 | if(value instanceof Long){ |
| 381 | output.writeByte(1); |
| 382 | output.writeLong( ((Long)value).longValue() ); |
| 383 | }else |
| 384 | if(value instanceof LongTreeList){ |
| 385 | output.writeByte(2); |
| 386 | ((LongTreeList)value).save(output); |
| 387 | }else |
| 388 | if(value instanceof IndexNode){ |
| 389 | output.writeByte(3); |
| 390 | ((IndexNode)value).saveRef(output); |
| 391 | } |
| 392 | } |
| 393 | |
| 394 | |
| 395 | |
| 396 | void saveRef(MemoryStream output){ |
| 397 | |
| 398 | } |
| 399 | |
| 400 | static IndexNode loadRef(MemoryStream input){ |
| 401 | throw new Error(); |
| 402 | } |
| 403 | |
| 404 | void load(MemoryStream input) throws SQLException{ |
| 405 | /*digit = (char)*/input.readShort(); |
| 406 | nodes = new IndexNode[input.readShort()]; |
| 407 | for(int i=0; i<nodes.length; i++){ |
| 408 | //output.writeShort( nodes[i].digit ); |
| 409 | } |
| 410 | |
| 411 | int length = input.readInt(); |
| 412 | remainderKey = (length>0) ? input.readChars(length) : null; |
| 413 | |
| 414 | int valueType = input.readByte(); |
| 415 | switch(valueType){ |
| 416 | case 0: |
| 417 | value = null; |
| 418 | break; |
| 419 | case 1: |
| 420 | value = new Long(input.readLong()); |
| 421 | break; |
| 422 | case 2: |
| 423 | value = new LongTreeList(input); |
| 424 | break; |
| 425 | case 3: |
| 426 | value = IndexNode.loadRef(input); |
| 427 | break; |
| 428 | default: throw Utils.createSQLException("Error in loading Index. Index fils is corrupt. ("+valueType+")"); |
| 429 | } |
| 430 | } |
| 431 | |
| 432 | |
| 433 | } |