| 1 | /* |
| 2 | Copyright (C) 2002-2004 MySQL AB |
| 3 | |
| 4 | This program is free software; you can redistribute it and/or modify |
| 5 | it under the terms of version 2 of the GNU General Public License as |
| 6 | published by the Free Software Foundation. |
| 7 | |
| 8 | There are special exceptions to the terms and conditions of the GPL |
| 9 | as it is applied to this software. View the full text of the |
| 10 | exception in file EXCEPTIONS-CONNECTOR-J in the directory of this |
| 11 | software distribution. |
| 12 | |
| 13 | This program is distributed in the hope that it will be useful, |
| 14 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | GNU General Public License for more details. |
| 17 | |
| 18 | You should have received a copy of the GNU General Public License |
| 19 | along with this program; if not, write to the Free Software |
| 20 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 21 | */ |
| 22 | |
| 23 | package com.mysql.jdbc; |
| 24 | |
| 25 | import java.sql.SQLException; |
| 26 | import java.util.ArrayList; |
| 27 | import java.util.List; |
| 28 | |
| 29 | /** |
| 30 | * Model for result set data backed by a cursor. Only works for forward-only |
| 31 | * result sets (but still works with updatable concurrency). |
| 32 | * |
| 33 | * @version $Id: CursorRowProvider.java,v 1.1.2.1 2005/05/19 18:31:49 mmatthews |
| 34 | * Exp $ |
| 35 | */ |
| 36 | public class CursorRowProvider implements RowData { |
| 37 | |
| 38 | private final static int BEFORE_START_OF_ROWS = -1; |
| 39 | |
| 40 | /** |
| 41 | * The cache of rows we have retrieved from the server. |
| 42 | */ |
| 43 | private List fetchedRows; |
| 44 | |
| 45 | /** |
| 46 | * Where we are positionaly in the entire result set, used mostly to |
| 47 | * facilitate easy 'isBeforeFirst()' and 'isFirst()' methods. |
| 48 | */ |
| 49 | private int currentPositionInEntireResult = BEFORE_START_OF_ROWS; |
| 50 | |
| 51 | /** |
| 52 | * Position in cache of rows, used to determine if we need to fetch more |
| 53 | * rows from the server to satisfy a request for the next row. |
| 54 | */ |
| 55 | private int currentPositionInFetchedRows = BEFORE_START_OF_ROWS; |
| 56 | |
| 57 | /** |
| 58 | * The result set that we 'belong' to. |
| 59 | */ |
| 60 | private ResultSet owner; |
| 61 | |
| 62 | /** |
| 63 | * Have we been told from the server that we have seen the last row? |
| 64 | */ |
| 65 | private boolean lastRowFetched = false; |
| 66 | |
| 67 | /** |
| 68 | * Field-level metadata from the server. We need this, because it is not |
| 69 | * sent for each batch of rows, but we need the metadata to unpack the |
| 70 | * results for each field. |
| 71 | */ |
| 72 | private Field[] fields; |
| 73 | |
| 74 | /** |
| 75 | * Communications channel to the server |
| 76 | */ |
| 77 | private MysqlIO mysql; |
| 78 | |
| 79 | /** |
| 80 | * Identifier for the statement that created this cursor. |
| 81 | */ |
| 82 | private long statementIdOnServer; |
| 83 | |
| 84 | /** |
| 85 | * The prepared statement that created this cursor. |
| 86 | */ |
| 87 | private ServerPreparedStatement prepStmt; |
| 88 | |
| 89 | /** |
| 90 | * The server status for 'last-row-sent'...This might belong in mysqldefs, |
| 91 | * but it it only ever referenced from here. |
| 92 | */ |
| 93 | private static final int SERVER_STATUS_LAST_ROW_SENT = 128; |
| 94 | |
| 95 | /** |
| 96 | * Have we attempted to fetch any rows yet? |
| 97 | */ |
| 98 | private boolean firstFetchCompleted = false; |
| 99 | |
| 100 | /** |
| 101 | * Creates a new cursor-backed row provider. |
| 102 | * |
| 103 | * @param ioChannel |
| 104 | * connection to the server. |
| 105 | * @param creatingStatement |
| 106 | * statement that opened the cursor. |
| 107 | * @param metadata |
| 108 | * field-level metadata for the results that this cursor covers. |
| 109 | */ |
| 110 | public CursorRowProvider(MysqlIO ioChannel, |
| 111 | ServerPreparedStatement creatingStatement, Field[] metadata) { |
| 112 | this.currentPositionInEntireResult = BEFORE_START_OF_ROWS; |
| 113 | this.fields = metadata; |
| 114 | this.mysql = ioChannel; |
| 115 | this.statementIdOnServer = creatingStatement.getServerStatementId(); |
| 116 | this.prepStmt = creatingStatement; |
| 117 | } |
| 118 | |
| 119 | /** |
| 120 | * Returns true if we got the last element. |
| 121 | * |
| 122 | * @return DOCUMENT ME! |
| 123 | */ |
| 124 | public boolean isAfterLast() { |
| 125 | return lastRowFetched |
| 126 | && this.currentPositionInFetchedRows > this.fetchedRows.size(); |
| 127 | } |
| 128 | |
| 129 | /** |
| 130 | * Only works on non dynamic result sets. |
| 131 | * |
| 132 | * @param index |
| 133 | * row number to get at |
| 134 | * @return row data at index |
| 135 | * @throws SQLException |
| 136 | * if a database error occurs |
| 137 | */ |
| 138 | public Object[] getAt(int ind) throws SQLException { |
| 139 | notSupported(); |
| 140 | |
| 141 | return null; |
| 142 | } |
| 143 | |
| 144 | /** |
| 145 | * Returns if iteration has not occured yet. |
| 146 | * |
| 147 | * @return true if before first row |
| 148 | * @throws SQLException |
| 149 | * if a database error occurs |
| 150 | */ |
| 151 | public boolean isBeforeFirst() throws SQLException { |
| 152 | return this.currentPositionInEntireResult < 0; |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * Moves the current position in the result set to the given row number. |
| 157 | * |
| 158 | * @param rowNumber |
| 159 | * row to move to |
| 160 | * @throws SQLException |
| 161 | * if a database error occurs |
| 162 | */ |
| 163 | public void setCurrentRow(int rowNumber) throws SQLException { |
| 164 | notSupported(); |
| 165 | } |
| 166 | |
| 167 | /** |
| 168 | * Returns the current position in the result set as a row number. |
| 169 | * |
| 170 | * @return the current row number |
| 171 | * @throws SQLException |
| 172 | * if a database error occurs |
| 173 | */ |
| 174 | public int getCurrentRowNumber() throws SQLException { |
| 175 | return this.currentPositionInEntireResult + 1; |
| 176 | } |
| 177 | |
| 178 | /** |
| 179 | * Returns true if the result set is dynamic. |
| 180 | * |
| 181 | * This means that move back and move forward won't work because we do not |
| 182 | * hold on to the records. |
| 183 | * |
| 184 | * @return true if this result set is streaming from the server |
| 185 | */ |
| 186 | public boolean isDynamic() { |
| 187 | return true; |
| 188 | } |
| 189 | |
| 190 | /** |
| 191 | * Has no records. |
| 192 | * |
| 193 | * @return true if no records |
| 194 | * @throws SQLException |
| 195 | * if a database error occurs |
| 196 | */ |
| 197 | public boolean isEmpty() throws SQLException { |
| 198 | return this.isBeforeFirst() && this.isAfterLast(); |
| 199 | } |
| 200 | |
| 201 | /** |
| 202 | * Are we on the first row of the result set? |
| 203 | * |
| 204 | * @return true if on first row |
| 205 | * @throws SQLException |
| 206 | * if a database error occurs |
| 207 | */ |
| 208 | public boolean isFirst() throws SQLException { |
| 209 | return this.currentPositionInEntireResult == 0; |
| 210 | } |
| 211 | |
| 212 | /** |
| 213 | * Are we on the last row of the result set? |
| 214 | * |
| 215 | * @return true if on last row |
| 216 | * @throws SQLException |
| 217 | * if a database error occurs |
| 218 | */ |
| 219 | public boolean isLast() throws SQLException { |
| 220 | return this.lastRowFetched |
| 221 | && this.currentPositionInFetchedRows == (this.fetchedRows |
| 222 | .size() - 1); |
| 223 | } |
| 224 | |
| 225 | /** |
| 226 | * Adds a row to this row data. |
| 227 | * |
| 228 | * @param row |
| 229 | * the row to add |
| 230 | * @throws SQLException |
| 231 | * if a database error occurs |
| 232 | */ |
| 233 | public void addRow(byte[][] row) throws SQLException { |
| 234 | notSupported(); |
| 235 | } |
| 236 | |
| 237 | /** |
| 238 | * Moves to after last. |
| 239 | * |
| 240 | * @throws SQLException |
| 241 | * if a database error occurs |
| 242 | */ |
| 243 | public void afterLast() throws SQLException { |
| 244 | notSupported(); |
| 245 | } |
| 246 | |
| 247 | /** |
| 248 | * Moves to before first. |
| 249 | * |
| 250 | * @throws SQLException |
| 251 | * if a database error occurs |
| 252 | */ |
| 253 | public void beforeFirst() throws SQLException { |
| 254 | notSupported(); |
| 255 | } |
| 256 | |
| 257 | /** |
| 258 | * Moves to before last so next el is the last el. |
| 259 | * |
| 260 | * @throws SQLException |
| 261 | * if a database error occurs |
| 262 | */ |
| 263 | public void beforeLast() throws SQLException { |
| 264 | notSupported(); |
| 265 | } |
| 266 | |
| 267 | /** |
| 268 | * We're done. |
| 269 | * |
| 270 | * @throws SQLException |
| 271 | * if a database error occurs |
| 272 | */ |
| 273 | public void close() throws SQLException { |
| 274 | |
| 275 | this.fields = null; |
| 276 | this.owner = null; |
| 277 | } |
| 278 | |
| 279 | /** |
| 280 | * Returns true if another row exists. |
| 281 | * |
| 282 | * @return true if more rows |
| 283 | * @throws SQLException |
| 284 | * if a database error occurs |
| 285 | */ |
| 286 | public boolean hasNext() throws SQLException { |
| 287 | |
| 288 | if (this.fetchedRows != null && this.fetchedRows.size() == 0) { |
| 289 | return false; |
| 290 | } |
| 291 | |
| 292 | if (this.currentPositionInEntireResult != BEFORE_START_OF_ROWS) { |
| 293 | // Case, we've fetched some rows, but are not at end of fetched |
| 294 | // block |
| 295 | if (this.currentPositionInFetchedRows < (this.fetchedRows.size() - 1)) { |
| 296 | return true; |
| 297 | } else if (this.currentPositionInFetchedRows == this.fetchedRows |
| 298 | .size() |
| 299 | && this.lastRowFetched) { |
| 300 | return false; |
| 301 | } else { |
| 302 | // need to fetch to determine |
| 303 | fetchMoreRows(); |
| 304 | |
| 305 | return (this.fetchedRows.size() > 0); |
| 306 | } |
| 307 | } |
| 308 | |
| 309 | // Okay, no rows _yet_, so fetch 'em |
| 310 | |
| 311 | fetchMoreRows(); |
| 312 | |
| 313 | return this.fetchedRows.size() > 0; |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * Moves the current position relative 'rows' from the current position. |
| 318 | * |
| 319 | * @param rows |
| 320 | * the relative number of rows to move |
| 321 | * @throws SQLException |
| 322 | * if a database error occurs |
| 323 | */ |
| 324 | public void moveRowRelative(int rows) throws SQLException { |
| 325 | notSupported(); |
| 326 | } |
| 327 | |
| 328 | /** |
| 329 | * Returns the next row. |
| 330 | * |
| 331 | * @return the next row value |
| 332 | * @throws SQLException |
| 333 | * if a database error occurs |
| 334 | */ |
| 335 | public Object[] next() throws SQLException { |
| 336 | |
| 337 | this.currentPositionInEntireResult++; |
| 338 | this.currentPositionInFetchedRows++; |
| 339 | |
| 340 | // Catch the forced scroll-passed-end |
| 341 | if (this.fetchedRows != null && this.fetchedRows.size() == 0) { |
| 342 | return null; |
| 343 | } |
| 344 | |
| 345 | if (this.currentPositionInFetchedRows > (this.fetchedRows.size() - 1)) { |
| 346 | fetchMoreRows(); |
| 347 | this.currentPositionInFetchedRows = 0; |
| 348 | } |
| 349 | |
| 350 | Object[] row = (Object[]) this.fetchedRows |
| 351 | .get(this.currentPositionInFetchedRows); |
| 352 | |
| 353 | return row; |
| 354 | } |
| 355 | |
| 356 | /** |
| 357 | * |
| 358 | */ |
| 359 | private void fetchMoreRows() throws SQLException { |
| 360 | if (this.lastRowFetched) { |
| 361 | this.fetchedRows = new ArrayList(0); |
| 362 | return; |
| 363 | } |
| 364 | |
| 365 | synchronized (this.owner.connection.getMutex()) { |
| 366 | if (!this.firstFetchCompleted) { |
| 367 | this.firstFetchCompleted = true; |
| 368 | } |
| 369 | |
| 370 | int numRowsToFetch = this.owner.getFetchSize(); |
| 371 | |
| 372 | if (numRowsToFetch == 0) { |
| 373 | numRowsToFetch = this.prepStmt.getFetchSize(); |
| 374 | } |
| 375 | |
| 376 | if (numRowsToFetch == Integer.MIN_VALUE) { |
| 377 | // Handle the case where the user used 'old' |
| 378 | // streaming result sets |
| 379 | |
| 380 | numRowsToFetch = 1; |
| 381 | } |
| 382 | |
| 383 | this.fetchedRows = this.mysql.fetchRowsViaCursor(this.fetchedRows, |
| 384 | this.statementIdOnServer, this.fields, numRowsToFetch); |
| 385 | this.currentPositionInFetchedRows = BEFORE_START_OF_ROWS; |
| 386 | |
| 387 | if ((this.mysql.getServerStatus() & SERVER_STATUS_LAST_ROW_SENT) != 0) { |
| 388 | this.lastRowFetched = true; |
| 389 | } |
| 390 | } |
| 391 | } |
| 392 | |
| 393 | /** |
| 394 | * Removes the row at the given index. |
| 395 | * |
| 396 | * @param index |
| 397 | * the row to move to |
| 398 | * @throws SQLException |
| 399 | * if a database error occurs |
| 400 | */ |
| 401 | public void removeRow(int ind) throws SQLException { |
| 402 | notSupported(); |
| 403 | } |
| 404 | |
| 405 | /** |
| 406 | * Only works on non dynamic result sets. |
| 407 | * |
| 408 | * @return the size of this row data |
| 409 | */ |
| 410 | public int size() { |
| 411 | return RESULT_SET_SIZE_UNKNOWN; |
| 412 | } |
| 413 | |
| 414 | private void nextRecord() throws SQLException { |
| 415 | |
| 416 | } |
| 417 | |
| 418 | private void notSupported() throws SQLException { |
| 419 | throw new OperationNotSupportedException(); |
| 420 | } |
| 421 | |
| 422 | /* |
| 423 | * (non-Javadoc) |
| 424 | * |
| 425 | * @see com.mysql.jdbc.RowProvider#setOwner(com.mysql.jdbc.ResultSet) |
| 426 | */ |
| 427 | public void setOwner(ResultSet rs) { |
| 428 | this.owner = rs; |
| 429 | } |
| 430 | |
| 431 | /* |
| 432 | * (non-Javadoc) |
| 433 | * |
| 434 | * @see com.mysql.jdbc.RowProvider#getOwner() |
| 435 | */ |
| 436 | public ResultSet getOwner() { |
| 437 | return this.owner; |
| 438 | } |
| 439 | |
| 440 | } |