Source Code Cross Referenced for ConnectionPool.java in  » GIS » GeoTools-2.4.1 » org » geotools » data » jdbc » Java Source Code / Java DocumentationJava Source Code and Java Documentation

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Java Source Code / Java Documentation » GIS » GeoTools 2.4.1 » org.geotools.data.jdbc 
Source Cross Referenced  Class Diagram Java Document (Java Doc) 


001:        /*
002:         *    GeoTools - OpenSource mapping toolkit
003:         *    http://geotools.org
004:         *    (C) 2003-2006, GeoTools Project Managment Committee (PMC)
005:         *    
006:         *    This library is free software; you can redistribute it and/or
007:         *    modify it under the terms of the GNU Lesser General Public
008:         *    License as published by the Free Software Foundation;
009:         *    version 2.1 of the License.
010:         *
011:         *    This library is distributed in the hope that it will be useful,
012:         *    but WITHOUT ANY WARRANTY; without even the implied warranty of
013:         *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014:         *    Lesser General Public License for more details.
015:         */
016:        package org.geotools.data.jdbc;
017:
018:        import java.sql.Connection;
019:        import java.sql.SQLException;
020:        import java.util.Iterator;
021:        import java.util.LinkedList;
022:        import java.util.logging.Level;
023:        import java.util.logging.Logger;
024:
025:        import javax.sql.ConnectionEvent;
026:        import javax.sql.ConnectionEventListener;
027:        import javax.sql.ConnectionPoolDataSource;
028:        import javax.sql.DataSource;
029:        import javax.sql.PooledConnection;
030:
031:        import org.geotools.data.jdbc.datasource.DataSourceFinder;
032:        import org.geotools.data.jdbc.datasource.DataSourceUtil;
033:
034:        /**
035:         * Provides a ConnectionPool that can be used by multiple data sources to get connections to a
036:         * single database.
037:         * 
038:         * <p>
039:         * This class should not be subclassed.
040:         * </p>
041:         *
042:         * @author Sean Geoghegan, Defence Science and Technology Organisation
043:         * @author Chris Holmes
044:         * @source $URL: http://svn.geotools.org/geotools/tags/2.4.1/modules/library/jdbc/src/main/java/org/geotools/data/jdbc/ConnectionPool.java $
045:         * @version $Id: ConnectionPool.java 27862 2007-11-12 19:51:19Z desruisseaux $
046:         * @deprecated Use {@link DataSource}, {@link DataSourceUtil} and {@link DataSourceFinder} instead
047:         */
048:        public final class ConnectionPool {
049:            /** A logger */
050:            private static final Logger LOGGER = org.geotools.util.logging.Logging
051:                    .getLogger("org.geotools.data.jdbc");
052:            /** The default wait time for cleaning the Pool - defaults to 30 secs */
053:            private static final long DEFAULT_POOL_CLEANER_WAIT = 30000;
054:            /** A mutex for synchronizing */
055:            private Object mutex = new Object();
056:            /** The data source we get the pooled connections from */
057:            private ConnectionPoolDataSource cpDataSource;
058:            /** List of available connections */
059:            private LinkedList availableConnections = new LinkedList();
060:            /** This of connections that are in use */
061:            private LinkedList usedConnections = new LinkedList();
062:            /** Handles ConnectionEvents and manages the lists */
063:            private ConnectionListManager listManager = new ConnectionListManager();
064:            /** Cleans the list of dead connections */
065:            private ConnectionPoolCleaner poolCleaner;
066:            /** Indicates that this Connection Pool is closed and it should not
067:             *  return connections on calls to getConnection()
068:             */
069:            private boolean closed = false;
070:
071:            /**
072:             * Creates a new Connection Pool using a ConnectionPoolDataSource.
073:             * 
074:             * <p>
075:             * This constructor will also spawn a thread for cleaning the connection pool every 30 seconds.
076:             * </p>
077:             *
078:             * @param cpDataSource The Connection Pool Data Source to get PooledConnections from.
079:             */
080:            public ConnectionPool(ConnectionPoolDataSource cpDataSource) {
081:                this .cpDataSource = cpDataSource;
082:                poolCleaner = new ConnectionPoolCleaner(
083:                        DEFAULT_POOL_CLEANER_WAIT);
084:
085:                Thread cleanerThread = new Thread(poolCleaner);
086:                cleanerThread.setDaemon(true);
087:                cleanerThread.start();
088:            }
089:
090:            /**
091:             * Gets a Connection from the Connection Pool.
092:             * 
093:             * <p>
094:             * If no available connections exist a new connection will be created and added to the pool.
095:             * When the returned connection is closed it will be added to the connection pool for other
096:             * requests to this method.
097:             * </p>
098:             *
099:             * @return A Connection from the ConnectionPool.
100:             *
101:             * @throws SQLException If an error occurs getting the connection or if the 
102:             * connection pool has been closed by a previous call to close().
103:             */
104:            public Connection getConnection() throws SQLException {
105:                if (closed) {
106:                    throw new SQLException(
107:                            "The ConnectionPool has been closed.");
108:                }
109:
110:                Connection conn = null;
111:
112:                synchronized (mutex) {
113:                    if (availableConnections.size() > 0) {
114:                        LOGGER.fine("Getting available connection.");
115:
116:                        ManagedPooledConnection mConn = (ManagedPooledConnection) availableConnections
117:                                .removeFirst();
118:
119:                        conn = mConn.pooledConn.getConnection();
120:
121:                        mConn.lastUsed = System.currentTimeMillis();
122:                        mConn.inUse = true;
123:                        usedConnections.add(mConn);
124:                    } else {
125:                        LOGGER
126:                                .fine("No available connections, creating a new one.");
127:
128:                        PooledConnection pConn = cpDataSource
129:                                .getPooledConnection();
130:
131:                        conn = pConn.getConnection();
132:
133:                        pConn.addConnectionEventListener(listManager);
134:
135:                        ManagedPooledConnection mConn = new ManagedPooledConnection(
136:                                pConn);
137:
138:                        mConn.inUse = true;
139:                        mConn.lastUsed = System.currentTimeMillis();
140:                        usedConnections.add(mConn);
141:                    }
142:                }
143:
144:                return conn;
145:            }
146:
147:            /**
148:             * Helper method to get the ManagedPooledConnection for a given PooledConnection.
149:             *
150:             * @param conn The PooledConnection
151:             *
152:             * @return The ManagedPooledConnection that contains the PooledConnection.
153:             */
154:            private ManagedPooledConnection getInUseManagedPooledConnection(
155:                    PooledConnection conn) {
156:                ManagedPooledConnection returnConn = null;
157:
158:                for (Iterator iter = usedConnections.iterator(); iter.hasNext();) {
159:                    ManagedPooledConnection mConn = (ManagedPooledConnection) iter
160:                            .next();
161:
162:                    if (mConn.pooledConn == conn) {
163:                        returnConn = mConn;
164:                    }
165:                }
166:
167:                return returnConn;
168:            }
169:
170:            /** Closes all the PooledConnections in the the ConnectionPool.
171:             *  The current behaviour is to first close all the used connections,
172:             *  then close all the available connections.  This method will also set
173:             *  the state of the ConnectionPool to closed, caused any future calls
174:             *  to getConnection to throw an SQLException.
175:             */
176:            public void close() {
177:                if (closed) {
178:                    return;
179:                }
180:                synchronized (mutex) {
181:                    int size = usedConnections.size();
182:                    for (int i = 0; i < size; i++) {
183:                        ManagedPooledConnection mPool = (ManagedPooledConnection) usedConnections
184:                                .removeFirst();
185:                        mPool.pooledConn
186:                                .removeConnectionEventListener(listManager);
187:                        try {
188:                            mPool.pooledConn.close();
189:                        } catch (SQLException e) {
190:                            LOGGER.warning("Failed to close PooledConnection: "
191:                                    + e);
192:                        }
193:                    }
194:
195:                    size = availableConnections.size();
196:                    for (int i = 0; i < size; i++) {
197:                        ManagedPooledConnection mPool = (ManagedPooledConnection) availableConnections
198:                                .removeFirst();
199:                        mPool.pooledConn
200:                                .removeConnectionEventListener(listManager);
201:                        try {
202:                            mPool.pooledConn.close();
203:                        } catch (SQLException e) {
204:                            LOGGER.warning("Failed to close PooledConnection: "
205:                                    + e);
206:                        }
207:                    }
208:                    closed = true;
209:                }
210:            }
211:
212:            /** Checks whether the ConnectionPool has been closed.
213:             * 
214:             * @return True if the connection pool is closed. If the Pool is closed
215:             * future calls to getConnection will throw an SQLException.
216:             */
217:            public boolean isClosed() {
218:                return closed;
219:            }
220:
221:            /**
222:             * A ConnectionEventListener for managing the list of connections in the pool.
223:             *
224:             * @author Sean Geoghegan, Defence Science and Technology Organisation
225:             * @author Chris Holmes
226:             * @version $Id: ConnectionPool.java 27862 2007-11-12 19:51:19Z desruisseaux $
227:             */
228:            private class ConnectionListManager implements 
229:                    ConnectionEventListener {
230:                /**
231:                 * This is called when a logical connection is closed.  The pooled connection is returned
232:                 * to the list of available connections.
233:                 *
234:                 * @param event The Connection event.
235:                 *
236:                 * @see javax.sql.ConnectionEventListener#connectionClosed(javax.sql.ConnectionEvent)
237:                 */
238:                public void connectionClosed(ConnectionEvent event) {
239:                    LOGGER
240:                            .fine("Connection closed - adding to available connections.");
241:
242:                    PooledConnection conn = (PooledConnection) event
243:                            .getSource();
244:                    synchronized (mutex) {
245:                        ManagedPooledConnection mConn = getInUseManagedPooledConnection(conn);
246:
247:                        mConn.inUse = false;
248:
249:                        usedConnections.remove(mConn);
250:                        availableConnections.addLast(mConn);
251:                    }
252:                }
253:
254:                /**
255:                 * Called when an error occurs on the Connection. This removes the connection from the
256:                 * pool.
257:                 *
258:                 * @param event The ConnectionEvent indicating an error.
259:                 *
260:                 * @see javax.sql.ConnectionEventListener#connectionErrorOccurred(javax.sql.ConnectionEvent)
261:                 */
262:                public void connectionErrorOccurred(ConnectionEvent event) {
263:                    PooledConnection conn = (PooledConnection) event
264:                            .getSource();
265:                    synchronized (mutex) {
266:                        ManagedPooledConnection mConn = getInUseManagedPooledConnection(conn);
267:
268:                        conn.removeConnectionEventListener(this );
269:
270:                        try {
271:                            conn.close();
272:                        } catch (SQLException e) {
273:                            // don't need to do anything here, just log it
274:                            LOGGER.log(Level.WARNING,
275:                                    "Error closing a connection", e);
276:                        }
277:
278:                        usedConnections.remove(mConn);
279:                    }
280:                }
281:            }
282:
283:            /**
284:             * Runnable class that handles cleaning of invalid connections from the connection pool.  A
285:             * connection is removed from the pool when its isValid method return false.  The Constructor
286:             * for the ConnectionPoolCleaner has a parameter that defines how often the pool cleaner will
287:             * run.
288:             * 
289:             * <p>
290:             * The Pool Cleaner has come to clean ze pool.
291:             * </p>
292:             *
293:             * @author Sean Geoghegan, Defence Science and Technology Organisation
294:             * @author Chris Holmes
295:             * @version $Id: ConnectionPool.java 27862 2007-11-12 19:51:19Z desruisseaux $
296:             */
297:            private class ConnectionPoolCleaner implements  Runnable {
298:                /** Time to wait between cleaning */
299:                private long waitTime;
300:                /** Run loop flag */
301:                private boolean active = true;
302:
303:                /** Creates a new ConnectionPoolCleaner
304:                 * 
305:                 * @param waitTime The frequency of the cleaning.
306:                 */
307:                ConnectionPoolCleaner(long waitTime) {
308:                    this .waitTime = waitTime;
309:                }
310:
311:                /** Stops the Pool cleaner.
312:                 * 
313:                 */
314:                void disable() {
315:                    active = false;
316:                }
317:
318:                /**
319:                 * Executes the Connection Pool Cleaning.
320:                 */
321:                public void run() {
322:                    while (active) {
323:                        synchronized (mutex) {
324:                            for (Iterator iter = availableConnections
325:                                    .iterator(); iter.hasNext();) {
326:                                ManagedPooledConnection conn = (ManagedPooledConnection) iter
327:                                        .next();
328:
329:                                conn.pooledConn
330:                                        .removeConnectionEventListener(listManager);
331:
332:                                if (!conn.isValid()) {
333:                                    LOGGER
334:                                            .fine("Connection invalid, removing from pool");
335:
336:                                    try {
337:                                        conn.pooledConn.close();
338:                                    } catch (SQLException e) {
339:                                        LOGGER
340:                                                .log(
341:                                                        Level.WARNING,
342:                                                        "Error closing dead connection",
343:                                                        e);
344:                                    }
345:
346:                                    iter.remove();
347:                                } else {
348:                                    // Connection is fine, add the list manager again.
349:                                    conn.pooledConn
350:                                            .addConnectionEventListener(listManager);
351:                                }
352:                            }
353:                        }
354:
355:                        try {
356:                            Thread.sleep(waitTime);
357:                        } catch (InterruptedException e) {
358:                            LOGGER
359:                                    .log(
360:                                            Level.WARNING,
361:                                            "Interrupted exception when wait in Pool Cleaner",
362:                                            e);
363:                        }
364:                    }
365:                }
366:            }
367:        }
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