package er.extensions.jdbc;
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.SQLWarning;
import java.sql.Statement;
import java.util.Date;
import java.util.Hashtable;
import org.apache.log4j.Logger;
import com.webobjects.eoaccess.EOAdaptor;
import com.webobjects.eoaccess.EODatabaseContext;
import com.webobjects.eoaccess.EOModel;
import com.webobjects.eoaccess.EOModelGroup;
import com.webobjects.eocontrol.EOCooperatingObjectStore;
import com.webobjects.eocontrol.EOEnterpriseObject;
import com.webobjects.eocontrol.EOObjectStore;
import com.webobjects.eocontrol.EOObjectStoreCoordinator;
import com.webobjects.foundation.NSDictionary;
import com.webobjects.foundation.NSForwardException;
import com.webobjects.jdbcadaptor.JDBCAdaptor;
import com.webobjects.jdbcadaptor.JDBCPlugIn;
import er.extensions.foundation.ERXProperties;
import er.extensions.foundation.ERXValueUtilities;
/**
* Creates and manages a pool of JDBC connections. Useful for SQL statements without
* using / blocking EOF. Maintains one broker per each distinct connection dictionary.
* Connections are created on demand but not freed. You can change the behaviour of the
* broker by setting some parameters either via the system properties as
* <code>dbSomePropertyGLOBAL</code>, <code>ModelName.DBSomeProperty</code> or as
* <code>someProperty</code> in the connection dictionary.
* <dl>
* <dt>minConnections</dt>
* <dd>Minimum number of connections, default 1</dd>
* <dt>maxConnections</dt>
* <dd>Maximum number of connections, default 1</dd>
* <dt>maxCheckout</dt>
* <dd>Maximum number of seconds a connection should stay checked out, default 600</dd>
* <dt>connectionRecycle</dt>
* <dd>Number of days a connection should stay active, default 1.0</dd>
* </dl>
* The {@link er.extensions.foundation.ERXConfigurationManager} adds these entries to each
* EOModels connectionDictionary.<br/>
* Usage: check out a connection: <br/><code>
* <pre>
* java.sql.Connection con = ERXJDBCConnectionBroker.connectionBrokerForModel(myModel).getConnection();
* try {
* java.sql.Statement s = con.createStatement();
* //now do something with the Statement
* } finally {
* ERXJDBCConnectionBroker.connectionBrokerForModel(myModel).freeConnection(con);
* }
* </pre></code>
* @author Marc A. Mnich, based on version 1.0.13 3/12/02
* @author david@cluster9.com original Wonder version
* @author ak Major refactoring
*/
// CHECKME ak: How should the maxCheckout stuff work? We can't really close a
// connection while it still active??
public class ERXJDBCConnectionBroker implements ERXJDBCAdaptor.ConnectionBroker {
public static final Logger log = Logger.getLogger(ERXJDBCConnectionBroker.class);
private static Hashtable brokers = new Hashtable();
private Thread reaper;
private Thread pinger;
private ConnectionWrapper[] wrappers;
private String dbDriver, dbServer, dbLogin, dbPassword;
private int activeConnections, lastRoundRobinIndex, minimumConnections, maximumConnections, maxCheckoutMillis;
long maxConnectionMillis;
private boolean active = true;
private boolean supportsTransactions = false;
private static final int DEFAULTMAXCHECKOUTSECONDS = 600;
public static ERXJDBCConnectionBroker connectionBrokerForModelWithName(String modelName) {
return connectionBrokerForModel(EOModelGroup.defaultGroup().modelNamed(modelName));
}
public static ERXJDBCConnectionBroker connectionBrokerForModel(EOModel model) {
return connectionBrokerForConnectionDictionary(model.connectionDictionary());
}
public static ERXJDBCConnectionBroker connectionBrokerForEoInEditingContext(EOEnterpriseObject eo) {
EOObjectStore os = eo.editingContext().rootObjectStore();
if (os instanceof EOObjectStoreCoordinator) {
EOObjectStoreCoordinator osc = (EOObjectStoreCoordinator)os;
EOCooperatingObjectStore cos = osc.objectStoreForObject(eo);
if (cos instanceof EODatabaseContext) {
EODatabaseContext dbctx = (EODatabaseContext)cos;
EOAdaptor adaptor = dbctx.database().adaptor();
return ERXJDBCConnectionBroker.connectionBrokerForAdaptor(adaptor);
}
}
throw new IllegalStateException("No connection broker found for EC");
}
public static ERXJDBCConnectionBroker connectionBrokerForEntityNamed(String ename) {
return connectionBrokerForModel(EOModelGroup.defaultGroup().entityNamed(ename).model());
}
public static ERXJDBCConnectionBroker connectionBrokerForAdaptor(EOAdaptor adaptor) {
return connectionBrokerForConnectionDictionary(adaptor.connectionDictionary());
}
private static synchronized ERXJDBCConnectionBroker connectionBrokerForConnectionDictionary(NSDictionary d) {
String key = "";
String keys [] = new String[] {"URL", "username", "password", "driver", "plugin"};
for (int i = 0; i < keys.length; i++) {
key += d.objectForKey(keys[i]) + "\0";
}
ERXJDBCConnectionBroker broker = (ERXJDBCConnectionBroker) brokers.get(key);
if (broker == null) {
broker = newConnectionBrokerWithConnectionDictionary(d);
brokers.put(key, broker);
}
return broker;
}
private static ERXJDBCConnectionBroker newConnectionBrokerWithConnectionDictionary(NSDictionary dict) {
ERXJDBCConnectionBroker broker = null;
try {
broker = new ERXJDBCConnectionBroker(dict);
} catch(Exception ex) {
log.error("Error while creating broker: " + broker, ex);
throw new NSForwardException(ex, "Error while creating broker: " + broker);
}
return broker;
}
private ERXJDBCConnectionBroker(NSDictionary dict) {
setup(dict, DEFAULTMAXCHECKOUTSECONDS);
}
@Override
public String toString() {
return "<" +getClass().getName() +
": dbDriver = " + dbDriver +
", dbServer = " + dbServer +
", dbLogin = " + dbLogin +
", activeConnections = " + activeConnections +
", maximumConnections = " + maximumConnections +
", maxCheckoutMillis = " + maxCheckoutMillis +
", maxConnectionMillis = " + maxConnectionMillis;
}
private void setup(NSDictionary dict, int maxCheckoutSecond) {
dbDriver = (String) dict.objectForKey("driver");
dbServer = (String) dict.objectForKey("URL");
dbLogin = (String) dict.objectForKey("username");
dbPassword = (String) dict.objectForKey("password");
if (dbDriver == null || dbDriver.length() == 0) {
JDBCAdaptor jdbcAdaptor = new JDBCAdaptor("JDBC");
jdbcAdaptor.setConnectionDictionary(dict);
JDBCPlugIn plugIn = jdbcAdaptor.plugIn();
dbDriver = plugIn.defaultDriverName();
}
minimumConnections = ERXValueUtilities.intValueWithDefault(dict.objectForKey("minConnections"), ERXProperties.intForKeyWithDefault("er.extensions.ERXJDBCConnectionBroker.minConnections", 1));
maximumConnections = ERXValueUtilities.intValueWithDefault(dict.objectForKey("maxConnections"), ERXProperties.intForKeyWithDefault("er.extensions.ERXJDBCConnectionBroker.maxConnections", 1));
maxCheckoutMillis = ERXValueUtilities.intValueWithDefault(dict.objectForKey("maxCheckout"), ERXProperties.intForKeyWithDefault("er.extensions.ERXJDBCConnectionBroker.maxCheckout", maxCheckoutSecond)) * 1000;
maxConnectionMillis = ERXValueUtilities.bigDecimalValueWithDefault(dict.objectForKey("connectionRecycle"), BigDecimal.valueOf(1)).longValue() * 86400000;
if (maxConnectionMillis < 30000) { // Recycle no less than 30 seconds.
maxConnectionMillis = 30000;
}
// Initialize the pool of connections with the mininum connections:
// Problems creating connections may be caused during reboot when
// the servlet is started before the database is ready. Handle this
// by waiting and trying again. The loop allows 5 minutes for
// db reboot.
boolean success = false;
int maxTries = 20;
wrappers = new ConnectionWrapper[maximumConnections];
for (int tries = 1; tries < 20 && !success; tries++) {
try {
for (int j = 0; j < minimumConnections; j++) {
createWrapper();
}
success = true;
} catch (SQLException e) {
log.error("Can't create connection " + tries + " of " + maxTries + ", will retry in 15 seconds: " + e, e);
try {
Thread.sleep(15000);
} catch (InterruptedException e1) {
}
}
}
if (!success) {
throw new IllegalStateException("All attempts at connecting to Database exhausted: " + this);
}
Connection con = getConnection();
try {
supportsTransactions = (con.getTransactionIsolation() != 0);
if(supportsTransactions) {
con.setAutoCommit(false);
}
} catch (SQLException ex) {
log.error(ex, ex);
} finally {
freeConnection(con);
}
reaper = new Thread() {
/**
* Housekeeping thread. Runs in the background with low CPU overhead.
* Connections are checked for warnings and closure and are periodically
* restarted. This thread is a catchall for corrupted connections and
* prevents the buildup of open cursors. (Open cursors result when the
* application fails to close a Statement). This method acts as fault
* tolerance for bad connection/statement programming.
*/
@Override
public void run() {
while (true) {
synchronized (wrappers) {
for (int i = 0; i < activeConnections; i++) {
ConnectionWrapper connection = wrappers[i];
connection.clearWarnings();
}
}
synchronized (wrappers) {
for (int i = 0; i < activeConnections; i++) {
ConnectionWrapper connection = wrappers[i];
try {
connection.reap(maxCheckoutMillis, maxConnectionMillis);
} catch (SQLException e) {
log.error("Error while reaping: " + connection);
}
}
}
try {
Thread.sleep(20000);
} catch (InterruptedException e) {
return;
}
}
}
/**
* Less safe shutdown. Uses default timeout value. This method simply
* calls the <code>destroy()</code> method with a <code>millis</code>
* value of 10000 (10 seconds) and ignores <code>SQLException</code>
* thrown by that method.
*
* @see #destroy(int)
*/
@Override
public void destroy() {
try {
ERXJDBCConnectionBroker.this.destroy(10000);
} catch (SQLException e) {
}
}
};
pinger = new Thread(new Runnable() {
boolean b = ERXProperties.booleanForKeyWithDefault("er.extensions.ERXJDBCConnectionBroker.connectionPingEnabled", false);
int wait = ERXProperties.intForKeyWithDefault("er.extensions.ERXJDBCConnectionBroker.connectionPingInterval", 60 * 5);
public void run() {
log.debug("Starting up ConnectionPing");
while (b) {
synchronized (wrappers) {
for (int i = 0; i < wrappers.length; i++) {
ConnectionWrapper connection = wrappers[i];
connection.ping();
}
}
try {
Thread.sleep(wait * 1000);
} catch (InterruptedException e) {
return;
}
}
}
});
reaper.setName("ERXJDBCReaper");
reaper.setDaemon(true);
reaper.start();
pinger.setName("ERXJDBCPinger");
pinger.setDaemon(true);
pinger.start();
log.info("Started Broker : " + this);
}
/**
* This method hands out the connections in round-robin order. This
* prevents a faulty connection from locking up an application entirely.
* A browser 'refresh' will get the next connection while the faulty
* connection is cleaned up by the housekeeping thread.
*
* If the min number of threads are ever exhausted, new threads are
* added up the the max thread count. Finally, if all threads are in
* use, this method waits 2 seconds and tries again, up to ten times.
* After that, it returns a null.
*/
public Connection getConnection() {
Connection result = null;
if (!active) {
throw new IllegalStateException("Unsuccessful getConnection() request during destroy()");
}
boolean gotOne = false;
for(int tries = 0; tries <= 10; tries++) {
int loop = 0;
int roundRobin = lastRoundRobinIndex + 1;
do {
if (roundRobin >= activeConnections) {
roundRobin = 0;
}
synchronized (wrappers) {
ConnectionWrapper connection = wrappers[roundRobin];
if (connection.isFree()) {
lastRoundRobinIndex = roundRobin+1;
connection.lock();
result = connection.getConnection();
return result;
}
loop++;
roundRobin++;
}
} while ((!gotOne) && (loop <= activeConnections));
if (!gotOne) {
synchronized (this) {
// Add a new connections to the pool
if (activeConnections < maximumConnections) {
try {
createWrapper();
} catch (SQLException e) {
throw new NSForwardException(e, "Error: Unable to create new connection");
}
}
}
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
}
log.warn("Connections Exhausted! Will wait and try again in loop " + tries);
}
}
throw new IllegalStateException("No new connections found");
}
/**
* Returns the local JDBC ID for a connection.
*/
private ConnectionWrapper wrapperForConnection(Connection conn) {
synchronized (wrappers) {
for (int i = 0; i < activeConnections; i++) {
ConnectionWrapper connection = wrappers[i];
if (connection.getConnection() == conn) {
return connection;
}
}
return null;
}
}
/**
* Frees a connection. Replaces connection back into the main pool for
* reuse.
*/
public void freeConnection(Connection conn) {
ConnectionWrapper wrapper = wrapperForConnection(conn);
if (wrapper != null) {
wrapper.unlock();
} else {
log.error("Could not free connection: " + conn);
}
}
private Connection createConnection() throws SQLException {
try {
Class.forName(dbDriver);
Connection conn = DriverManager.getConnection(dbServer, dbLogin, dbPassword);
return conn;
} catch (ClassNotFoundException e2) {
throw NSForwardException._runtimeExceptionForThrowable(e2);
}
}
private synchronized void createWrapper() throws SQLException {
if(wrappers[activeConnections] == null) {
if(activeConnections < maximumConnections) {
wrappers[activeConnections] = new ConnectionWrapper(this);
activeConnections++;
} else {
throw new IllegalStateException("Trying to get more wrappers than available: " + activeConnections + " vs " + maximumConnections);
}
}
}
private void destroy(int millis) throws SQLException {
active = false;
pinger.interrupt();
// Wait until the housekeeping thread has died.
try {
pinger.join(millis);
} catch (InterruptedException e) {
}
// Shut down the background housekeeping thread
reaper.interrupt();
// Wait until the housekeeping thread has died.
try {
reaper.join(millis);
} catch (InterruptedException e) {
}
// The housekeeping thread could still be running
// (e.g. if millis is too small). This case is ignored.
// At worst, this method will throw an exception with the
// clear indication that the timeout was too short.
long startTime = System.currentTimeMillis();
// Wait for freeConnection() to return any connections
// that are still used at this time.
int openChannelCount;
long elapsed = System.currentTimeMillis() - startTime;
while ((openChannelCount = getOpenChannelCount()) > 0
&& elapsed <= millis) {
try {
Thread.sleep(500);
} catch (InterruptedException e) {
}
elapsed = System.currentTimeMillis() - startTime;
}
// Close all connections, whether safe or not
for (int i = 0; i < activeConnections; i++) {
wrappers[i].close();
}
if (openChannelCount > 0) {
//bt-test successful
String msg = "Unsafe shutdown: Had to close " + openChannelCount + " active DB connections after " + millis + "ms";
// Throwing following Exception is essential because servlet
// authors are likely to have their own error logging requirements.
throw new SQLException(msg);
}
}
private int getOpenChannelCount() {
int useCount = 0;
synchronized (wrappers) {
for (int i = 0; i < activeConnections; i++) {
if (!wrappers[i].isFree()) {
useCount++;
}
}
}
return useCount;
}
public boolean supportsTransaction() {
return supportsTransactions;
}
private static class ConnectionWrapper {
private String pingStatement = ERXProperties.stringForKeyWithDefault("er.extensions.ERXJDBCConnectionBroker.connectionPingSQL", "SELECT 1+1;");
private static final int FREE = 0;
private static final int BUSY = 1;
private static final int OFFLINE = 2;
private Connection connection;
private ERXJDBCConnectionBroker broker;
private int status;
private long lockTime;
private long creationDate;
public ConnectionWrapper(ERXJDBCConnectionBroker broker) throws SQLException {
this.broker = broker;
connection = broker.createConnection();
status = FREE;
lockTime = 0;
}
@Override
public String toString() {
return getClass().getName() +
": connection = " + connection +
": status = " + status +
": lockTime = " + lockTime +
": creationDate = " + creationDate;
}
public Connection getConnection() {
return connection;
}
public void setConnection(Connection connection) {
creationDate = (new Date()).getTime();
this.connection = connection;
}
public long getCreationDate() {
return creationDate;
}
public void setCreationDate(long creationDate) {
this.creationDate = creationDate;
}
public long getLockTime() {
return lockTime;
}
public void setLockTime(long lockTime) {
this.lockTime = lockTime;
}
public int getStatus() {
return status;
}
public void setStatus(int status) {
this.status = status;
}
public boolean isFree() {
if(getStatus() == FREE) {
return true;
}
return false;
}
private void close() {
try {
if(getConnection() != null) {
getConnection().close();
setConnection(null);
setStatus(OFFLINE);
}
} catch (SQLException ex) {
log.warn("Cannot close connection: " + this, ex);
}
}
public void unlock() {
if(getStatus() != BUSY) {
throw new IllegalStateException("Attempt to unlock non-busy channel: " + this);
}
setStatus(FREE);
setLockTime(0L);
try {
if (getConnection().isReadOnly()) {
getConnection().setReadOnly(true);
}
// AK: PG MUST and other probably should have set the autocommit to true on putting back in pool
if(!getConnection().getAutoCommit()) {
getConnection().setAutoCommit(true);
}
}
catch (SQLException e) {
log.error(e, e);
}
}
public void lock() {
if(!isFree()) {
throw new IllegalStateException("Attempt to lock busy channel: " + this);
}
setStatus(OFFLINE);
setLockTime(System.currentTimeMillis());
try {
if (getConnection().isReadOnly()) {
getConnection().setReadOnly(false);
}
if(getConnection().getAutoCommit()) {
getConnection().setAutoCommit(false);
}
} catch (SQLException e) {
throw new NSForwardException(e, "Could not set read only to false for connection: "+ this);
} finally {
setStatus(BUSY);
}
}
private void clearWarnings() {
try {
SQLWarning warning = getConnection().getWarnings();
if (warning != null) {
log.warn("Warnings on connection " + this + ": " + warning);
getConnection().clearWarnings();
}
} catch (SQLException e) {
log.warn("Cannot access Warnings: " + e);
}
}
private void ping() {
if (isFree()) {
setStatus(OFFLINE);
Connection c = getConnection();
log.debug("Pinging connection " + connection);
try {
c.isClosed();
c.setReadOnly(false);
c.createStatement().executeQuery(pingStatement);
} catch (SQLException e) {
log.error("Could not ping connection " + c + ", reason: " + e.getMessage(), e);
} finally {
try {
c.rollback();
} catch (SQLException e1) {
throw new NSForwardException(e1, "could not rollback connection!");
}
}
setStatus(FREE);
}
}
private void reap(long maxCheckoutMillis, long maxConnectionAgeMillis) throws SQLException {
boolean restart = false;
Connection reapingConnection = getConnection();
try {
if(!isFree()) {
// Check the time it's been checked out and recycle
long checkoutMillis = System.currentTimeMillis() - getLockTime();
log.debug("Connection is in use for " + checkoutMillis + " ms: " + this);
if (maxCheckoutMillis != 0) {
if (checkoutMillis > maxCheckoutMillis) {
restart = true;
log.info("Connection " + this + " failed to be returned in time, recycling");
}
}
if(!restart) {
// In normal use and not too old, catch it next time!
return;
}
}
// Take offline (2 indicates housekeeping lock)
setStatus(OFFLINE);
if(!restart) {
long connectionAgeMillis = System.currentTimeMillis() - getCreationDate();
if (connectionAgeMillis > maxConnectionAgeMillis) {
// Force a reset at the max conn time
restart = true;
}
}
if(!restart) {
Statement stmt = null;
try {
stmt = reapingConnection.createStatement();
} catch (SQLException e) {
restart = true;
} finally {
try {
if (stmt != null) {
stmt.close();
}
} catch (SQLException e1) {
restart = true;
}
}
}
if(!restart) {
// Some DBs return an object even if DB is shut down
if (reapingConnection.isClosed()) {
restart = true;
}
}
// Connection has a problem, restart it
} catch (SQLException e) {
restart = true;
}
if(restart) {
log.debug("Recycling connection: " + this);
try {
getConnection().close();
} catch (SQLException e0) {
log.error("Can't close connection, might have been closed already. Trying to recycle anyway");
}
setConnection(broker.createConnection());
}
setStatus(FREE);
}
}
}