Source Code Cross Referenced for DifferentialSynchronizationStrategy.java in  » Database-JDBC-Connection-Pool » HA-JDBC » net » sf » hajdbc » sync » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » Database JDBC Connection Pool » HA JDBC » net.sf.hajdbc.sync 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         * HA-JDBC: High-Availability JDBC
003:         * Copyright (c) 2004-2007 Paul Ferraro
004:         * 
005:         * This library is free software; you can redistribute it and/or modify it 
006:         * under the terms of the GNU Lesser General Public License as published by the 
007:         * Free Software Foundation; either version 2.1 of the License, or (at your 
008:         * option) any later version.
009:         * 
010:         * This library is distributed in the hope that it will be useful, but WITHOUT
011:         * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 
012:         * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License 
013:         * for more details.
014:         * 
015:         * You should have received a copy of the GNU Lesser General Public License
016:         * along with this library; if not, write to the Free Software Foundation, 
017:         * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
018:         * 
019:         * Contact: ferraro@users.sourceforge.net
020:         */
021:        package net.sf.hajdbc.sync;
022:
023:        import java.sql.Connection;
024:        import java.sql.PreparedStatement;
025:        import java.sql.ResultSet;
026:        import java.sql.SQLException;
027:        import java.sql.Statement;
028:        import java.util.ArrayList;
029:        import java.util.Arrays;
030:        import java.util.Collection;
031:        import java.util.Collections;
032:        import java.util.LinkedHashSet;
033:        import java.util.List;
034:        import java.util.Map;
035:        import java.util.Set;
036:        import java.util.TreeMap;
037:        import java.util.concurrent.Callable;
038:        import java.util.concurrent.ExecutionException;
039:        import java.util.concurrent.ExecutorService;
040:        import java.util.concurrent.Future;
041:
042:        import net.sf.hajdbc.Dialect;
043:        import net.sf.hajdbc.Messages;
044:        import net.sf.hajdbc.SynchronizationContext;
045:        import net.sf.hajdbc.SynchronizationStrategy;
046:        import net.sf.hajdbc.TableProperties;
047:        import net.sf.hajdbc.UniqueConstraint;
048:        import net.sf.hajdbc.util.SQLExceptionFactory;
049:        import net.sf.hajdbc.util.Strings;
050:
051:        import org.slf4j.Logger;
052:        import org.slf4j.LoggerFactory;
053:
054:        /**
055:         * Database-independent synchronization strategy that only updates differences between two databases.
056:         * This strategy is best used when there are <em>few</em> differences between the active database and the inactive database (i.e. barely out of sync).
057:         * The following algorithm is used:
058:         * <ol>
059:         *  <li>Drop the foreign keys on the inactive database (to avoid integrity constraint violations)</li>
060:         *  <li>For each database table:
061:         *   <ol>
062:         *    <li>Drop the unique constraints on the table (to avoid integrity constraint violations)</li>
063:         *    <li>Find the primary key(s) of the table</li>
064:         *    <li>Query all rows in the inactive database table, sorting by the primary key(s)</li>
065:         *    <li>Query all rows on the active database table</li>
066:         *    <li>For each row in table:
067:         *     <ol>
068:         *      <li>If primary key of the rows are the same, determine whether or not row needs to be updated</li>
069:         *      <li>Otherwise, determine whether row should be deleted, or a new row is to be inserted</li>
070:         *     </ol>
071:         *    </li>
072:         *    <li>Re-create the unique constraints on the table (to avoid integrity constraint violations)</li>
073:         *   </ol>
074:         *  </li>
075:         *  <li>Re-create the foreign keys on the inactive database</li>
076:         *  <li>Synchronize sequences</li>
077:         * </ol>
078:         * @author  Paul Ferraro
079:         * @version $Revision: 2012 $
080:         * @since   1.0
081:         */
082:        public class DifferentialSynchronizationStrategy implements 
083:                SynchronizationStrategy {
084:            private static Logger logger = LoggerFactory
085:                    .getLogger(DifferentialSynchronizationStrategy.class);
086:
087:            private int fetchSize = 0;
088:            private int maxBatchSize = 100;
089:
090:            /**
091:             * @see net.sf.hajdbc.SynchronizationStrategy#synchronize(net.sf.hajdbc.SynchronizationContext)
092:             */
093:            @Override
094:            public <D> void synchronize(SynchronizationContext<D> context)
095:                    throws SQLException {
096:                Map<Short, String> primaryKeyColumnMap = new TreeMap<Short, String>();
097:                Set<Integer> primaryKeyColumnIndexSet = new LinkedHashSet<Integer>();
098:
099:                Connection sourceConnection = context.getConnection(context
100:                        .getSourceDatabase());
101:                Connection targetConnection = context.getConnection(context
102:                        .getTargetDatabase());
103:
104:                Dialect dialect = context.getDialect();
105:
106:                ExecutorService executor = context.getExecutor();
107:
108:                targetConnection.setAutoCommit(true);
109:
110:                SynchronizationSupport.dropForeignKeys(context);
111:
112:                try {
113:                    for (TableProperties table : context
114:                            .getDatabaseProperties().getTables()) {
115:                        SynchronizationSupport.dropUniqueConstraints(context,
116:                                table);
117:
118:                        targetConnection.setAutoCommit(false);
119:
120:                        primaryKeyColumnMap.clear();
121:                        primaryKeyColumnIndexSet.clear();
122:
123:                        String tableName = table.getName();
124:
125:                        UniqueConstraint primaryKey = table.getPrimaryKey();
126:
127:                        if (primaryKey == null) {
128:                            throw new SQLException(Messages.getMessage(
129:                                    Messages.PRIMARY_KEY_REQUIRED, this 
130:                                            .getClass().getName(), tableName));
131:                        }
132:
133:                        List<String> primaryKeyColumnList = primaryKey
134:                                .getColumnList();
135:
136:                        Collection<String> columns = table.getColumns();
137:
138:                        // List of colums for select statement - starting with primary key
139:                        List<String> columnList = new ArrayList<String>(columns
140:                                .size());
141:
142:                        columnList.addAll(primaryKeyColumnList);
143:
144:                        for (String column : columns) {
145:                            if (!primaryKeyColumnList.contains(column)) {
146:                                columnList.add(column);
147:                            }
148:                        }
149:
150:                        List<String> nonPrimaryKeyColumnList = columnList
151:                                .subList(primaryKeyColumnList.size(),
152:                                        columnList.size());
153:
154:                        String commaDelimitedColumns = Strings.join(columnList,
155:                                Strings.PADDED_COMMA);
156:
157:                        // Retrieve table rows in primary key order
158:                        final String selectSQL = "SELECT " + commaDelimitedColumns + " FROM " + tableName + " ORDER BY " + Strings.join(primaryKeyColumnList, Strings.PADDED_COMMA); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
159:
160:                        final Statement targetStatement = targetConnection
161:                                .createStatement();
162:
163:                        targetStatement.setFetchSize(this .fetchSize);
164:
165:                        logger.debug(selectSQL);
166:
167:                        Callable<ResultSet> callable = new Callable<ResultSet>() {
168:                            public ResultSet call() throws SQLException {
169:                                return targetStatement.executeQuery(selectSQL);
170:                            }
171:                        };
172:
173:                        Future<ResultSet> future = executor.submit(callable);
174:
175:                        Statement sourceStatement = sourceConnection
176:                                .createStatement();
177:                        sourceStatement.setFetchSize(this .fetchSize);
178:
179:                        ResultSet sourceResultSet = sourceStatement
180:                                .executeQuery(selectSQL);
181:
182:                        ResultSet inactiveResultSet = future.get();
183:
184:                        String primaryKeyWhereClause = " WHERE " + Strings.join(primaryKeyColumnList, " = ? AND ") + " = ?"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
185:
186:                        // Construct DELETE SQL
187:                        String deleteSQL = "DELETE FROM " + tableName + primaryKeyWhereClause; //$NON-NLS-1$
188:
189:                        logger.debug(deleteSQL);
190:
191:                        PreparedStatement deleteStatement = targetConnection
192:                                .prepareStatement(deleteSQL);
193:
194:                        // Construct INSERT SQL
195:                        String insertSQL = "INSERT INTO " + tableName + " (" + commaDelimitedColumns + ") VALUES (" + Strings.join(Collections.nCopies(columnList.size(), Strings.QUESTION), Strings.PADDED_COMMA) + ")"; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
196:
197:                        logger.debug(insertSQL);
198:
199:                        PreparedStatement insertStatement = targetConnection
200:                                .prepareStatement(insertSQL);
201:
202:                        // Construct UPDATE SQL
203:                        String updateSQL = "UPDATE " + tableName + " SET " + Strings.join(nonPrimaryKeyColumnList, " = ?, ") + " = ?" + primaryKeyWhereClause; //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
204:
205:                        logger.debug(updateSQL);
206:
207:                        PreparedStatement updateStatement = targetConnection
208:                                .prepareStatement(updateSQL);
209:
210:                        boolean hasMoreActiveResults = sourceResultSet.next();
211:                        boolean hasMoreInactiveResults = inactiveResultSet
212:                                .next();
213:
214:                        int insertCount = 0;
215:                        int updateCount = 0;
216:                        int deleteCount = 0;
217:
218:                        while (hasMoreActiveResults || hasMoreInactiveResults) {
219:                            int compare = 0;
220:
221:                            if (!hasMoreActiveResults) {
222:                                compare = 1;
223:                            } else if (!hasMoreInactiveResults) {
224:                                compare = -1;
225:                            } else {
226:                                for (int i = 1; i <= primaryKeyColumnList
227:                                        .size(); ++i) {
228:                                    Object activeObject = sourceResultSet
229:                                            .getObject(i);
230:                                    Object inactiveObject = inactiveResultSet
231:                                            .getObject(i);
232:
233:                                    // We assume that the primary keys column types are Comparable
234:                                    compare = this .compare(activeObject,
235:                                            inactiveObject);
236:
237:                                    if (compare != 0) {
238:                                        break;
239:                                    }
240:                                }
241:                            }
242:
243:                            if (compare > 0) {
244:                                deleteStatement.clearParameters();
245:
246:                                for (int i = 1; i <= primaryKeyColumnList
247:                                        .size(); ++i) {
248:                                    int type = dialect.getColumnType(table
249:                                            .getColumnProperties(columnList
250:                                                    .get(i - 1)));
251:
252:                                    deleteStatement.setObject(i,
253:                                            inactiveResultSet.getObject(i),
254:                                            type);
255:                                }
256:
257:                                deleteStatement.addBatch();
258:
259:                                deleteCount += 1;
260:
261:                                if ((deleteCount % this .maxBatchSize) == 0) {
262:                                    deleteStatement.executeBatch();
263:                                    deleteStatement.clearBatch();
264:                                }
265:                            } else if (compare < 0) {
266:                                insertStatement.clearParameters();
267:
268:                                for (int i = 1; i <= columnList.size(); ++i) {
269:                                    int type = dialect.getColumnType(table
270:                                            .getColumnProperties(columnList
271:                                                    .get(i - 1)));
272:
273:                                    Object object = SynchronizationSupport
274:                                            .getObject(sourceResultSet, i, type);
275:
276:                                    if (sourceResultSet.wasNull()) {
277:                                        insertStatement.setNull(i, type);
278:                                    } else {
279:                                        insertStatement.setObject(i, object,
280:                                                type);
281:                                    }
282:                                }
283:
284:                                insertStatement.addBatch();
285:
286:                                insertCount += 1;
287:
288:                                if ((insertCount % this .maxBatchSize) == 0) {
289:                                    insertStatement.executeBatch();
290:                                    insertStatement.clearBatch();
291:                                }
292:                            } else // if (compare == 0)
293:                            {
294:                                updateStatement.clearParameters();
295:
296:                                boolean updated = false;
297:
298:                                for (int i = primaryKeyColumnList.size() + 1; i <= columnList
299:                                        .size(); ++i) {
300:                                    int type = dialect.getColumnType(table
301:                                            .getColumnProperties(columnList
302:                                                    .get(i - 1)));
303:
304:                                    Object activeObject = SynchronizationSupport
305:                                            .getObject(sourceResultSet, i, type);
306:                                    Object inactiveObject = SynchronizationSupport
307:                                            .getObject(inactiveResultSet, i,
308:                                                    type);
309:
310:                                    int index = i - primaryKeyColumnList.size();
311:
312:                                    if (sourceResultSet.wasNull()) {
313:                                        updateStatement.setNull(index, type);
314:
315:                                        updated |= !inactiveResultSet.wasNull();
316:                                    } else {
317:                                        updateStatement.setObject(index,
318:                                                activeObject, type);
319:
320:                                        updated |= inactiveResultSet.wasNull();
321:                                        updated |= !equals(activeObject,
322:                                                inactiveObject);
323:                                    }
324:                                }
325:
326:                                if (updated) {
327:                                    for (int i = 1; i <= primaryKeyColumnList
328:                                            .size(); ++i) {
329:                                        int type = dialect.getColumnType(table
330:                                                .getColumnProperties(columnList
331:                                                        .get(i - 1)));
332:
333:                                        updateStatement.setObject(i
334:                                                + nonPrimaryKeyColumnList
335:                                                        .size(),
336:                                                inactiveResultSet.getObject(i),
337:                                                type);
338:                                    }
339:
340:                                    updateStatement.addBatch();
341:
342:                                    updateCount += 1;
343:
344:                                    if ((updateCount % this .maxBatchSize) == 0) {
345:                                        updateStatement.executeBatch();
346:                                        updateStatement.clearBatch();
347:                                    }
348:                                }
349:                            }
350:
351:                            if (hasMoreActiveResults && (compare <= 0)) {
352:                                hasMoreActiveResults = sourceResultSet.next();
353:                            }
354:
355:                            if (hasMoreInactiveResults && (compare >= 0)) {
356:                                hasMoreInactiveResults = inactiveResultSet
357:                                        .next();
358:                            }
359:                        }
360:
361:                        if ((deleteCount % this .maxBatchSize) > 0) {
362:                            deleteStatement.executeBatch();
363:                        }
364:
365:                        deleteStatement.close();
366:
367:                        if ((insertCount % this .maxBatchSize) > 0) {
368:                            insertStatement.executeBatch();
369:                        }
370:
371:                        insertStatement.close();
372:
373:                        if ((updateCount % this .maxBatchSize) > 0) {
374:                            updateStatement.executeBatch();
375:                        }
376:
377:                        updateStatement.close();
378:
379:                        targetStatement.close();
380:                        sourceStatement.close();
381:
382:                        targetConnection.commit();
383:
384:                        targetConnection.setAutoCommit(true);
385:
386:                        SynchronizationSupport.restoreUniqueConstraints(
387:                                context, table);
388:
389:                        logger.info(Messages.getMessage(Messages.INSERT_COUNT,
390:                                insertCount, tableName));
391:                        logger.info(Messages.getMessage(Messages.UPDATE_COUNT,
392:                                updateCount, tableName));
393:                        logger.info(Messages.getMessage(Messages.DELETE_COUNT,
394:                                deleteCount, tableName));
395:                    }
396:                } catch (ExecutionException e) {
397:                    SynchronizationSupport.rollback(targetConnection);
398:
399:                    throw SQLExceptionFactory.createSQLException(e.getCause());
400:                } catch (InterruptedException e) {
401:                    SynchronizationSupport.rollback(targetConnection);
402:
403:                    throw SQLExceptionFactory.createSQLException(e.getCause());
404:                } catch (SQLException e) {
405:                    SynchronizationSupport.rollback(targetConnection);
406:
407:                    throw e;
408:                }
409:
410:                SynchronizationSupport.restoreForeignKeys(context);
411:
412:                SynchronizationSupport.synchronizeIdentityColumns(context);
413:                SynchronizationSupport.synchronizeSequences(context);
414:            }
415:
416:            private boolean equals(Object object1, Object object2) {
417:                if ((object1 instanceof  byte[]) && (object2 instanceof  byte[])) {
418:                    byte[] bytes1 = (byte[]) object1;
419:                    byte[] bytes2 = (byte[]) object2;
420:
421:                    if (bytes1.length != bytes2.length) {
422:                        return false;
423:                    }
424:
425:                    return Arrays.equals(bytes1, bytes2);
426:                }
427:
428:                return object1.equals(object2);
429:            }
430:
431:            @SuppressWarnings("unchecked")
432:            private int compare(Object object1, Object object2) {
433:                return ((Comparable) object1).compareTo(object2);
434:            }
435:
436:            /**
437:             * @return the fetchSize.
438:             */
439:            public int getFetchSize() {
440:                return this .fetchSize;
441:            }
442:
443:            /**
444:             * @param fetchSize the fetchSize to set.
445:             */
446:            public void setFetchSize(int fetchSize) {
447:                this .fetchSize = fetchSize;
448:            }
449:
450:            /**
451:             * @return Returns the maxBatchSize.
452:             */
453:            public int getMaxBatchSize() {
454:                return this .maxBatchSize;
455:            }
456:
457:            /**
458:             * @param maxBatchSize The maxBatchSize to set.
459:             */
460:            public void setMaxBatchSize(int maxBatchSize) {
461:                this.maxBatchSize = maxBatchSize;
462:            }
463:        }
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