org.filesys.util.db.DBConnectionPool Maven / Gradle / Ivy
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/*
* Copyright (C) 2006-2010 Alfresco Software Limited.
*
* This file is part of Alfresco
*
* Alfresco is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Alfresco is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Alfresco. If not, see m_freePool;
private Hashtable m_allocPool;
// Connection reaper thread
private DBConnectionReaper m_reaper;
private Thread m_reaperThread;
// Database connection status
private boolean m_online;
// Database connection pool event listener
private DBConnectionPoolListener m_dbListener;
// Database callbacks, used to override various default actions
private DBCallbacks m_callback;
/**
* Database Connection Reaper Thread Class
*
* Check for connections whose lease has expired and return them to the free connection
* pool.
*/
protected class DBConnectionReaper implements Runnable {
// Debug enable
private static final boolean DEBUG = false;
// Reaper wakeup interval
private long m_wakeup;
// Shutdown request flag
private boolean m_shutdown = false;
// Database online check interval, as number of thread wakeups
private int m_onlineCheckInterval = ConnectionCheck;
/**
* Class constructor
*
* @param intvl long
*/
public DBConnectionReaper(long intvl) {
m_wakeup = intvl;
}
/**
* Shutdown the connection reaper
*/
public final void shutdownRequest() {
m_shutdown = true;
m_reaperThread.interrupt();
}
/**
* Set the database online check interval
*
* @param interval int
*/
public final void setOnlineCheckInterval(int interval) {
m_onlineCheckInterval = interval;
}
/**
* Connection reaper thread
*/
public void run() {
// Load the initial free connection pool
synchronized (m_freePool) {
try {
// Allocate a pool of connections
while (m_freePool.size() < getMinimumPoolSize()) {
Connection conn = createConnection();
if (conn != null)
m_freePool.add(conn);
}
// Indicate that the connection pool is online
m_online = true;
notifyConnectionPoolState();
}
catch (SQLException ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
}
}
// Loop forever, or until shutdown
int loopCnt = 1;
while (m_shutdown == false) {
// Sleep for a while
try {
Thread.sleep(m_wakeup);
}
catch (InterruptedException ex) {
}
// Check if there is a shutdown pending
if (m_shutdown == true)
break;
// Update the loop counter
loopCnt++;
// Check for expired connection leases
synchronized (m_allocPool) {
// DEBUG
if ( DEBUG)
Debug.println("DBConnectionReaper allocPool=" + m_allocPool.size() + ", freePool=" + m_freePool.size());
// Get the current time
long timeNow = System.currentTimeMillis();
// Enumerate the allocated connection pool
Enumeration enm = m_allocPool.keys();
boolean removeConn = false;
while (enm.hasMoreElements()) {
// Get the connection
Connection conn = enm.nextElement();
Long expire = m_allocPool.get(conn);
// Check if the connection lease has expired
if (expire.longValue() != PermanentLease && expire.longValue() < timeNow)
removeConn = true;
else if (expire.longValue() == PermanentLease) {
try {
// Check if the connection has been closed or the server is down
if (conn.isClosed())
removeConn = true;
else {
// Toggle the auto-commit flag on the connection, this will check the connection on most
// databases
boolean autoCommit = conn.getAutoCommit();
conn.setAutoCommit(true);
conn.setAutoCommit(autoCommit);
}
}
catch (SQLException ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
removeConn = true;
}
// DEBUG
if (removeConn == true)
Debug.println("DBConnectionReaper Permanent lease connection error");
}
// Check if the connection should be closed
if (removeConn == true) {
// Connection lease has expired, remove from the allocated list and close the connection
m_allocPool.remove(conn);
try {
conn.close();
Debug.println("DBConnectionReaper closed expired connection, conn=" + conn);
}
catch (SQLException ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
}
}
}
}
// Check if the free pool has grown too far
synchronized (m_freePool) {
// Release connections from the free pool until below the maximum connection limit
while (m_freePool.size() > getMaximumPoolSize()) {
// DEBUG
if ( DEBUG)
Debug.println("DBConnectionReaper trimming free pool, " + m_freePool.size() + "/" + getMaximumPoolSize());
// Remove a connection from the free pool and close the connection
Connection conn = m_freePool.remove(0);
if (conn != null) {
try {
conn.close();
}
catch (SQLException ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
}
}
}
}
// Check the connections in the free pool to see if they have been timed out by the server
if (loopCnt % m_onlineCheckInterval == 0 || isOnline() == false) {
synchronized (m_freePool) {
// DEBUG
if ( DEBUG)
Debug.println( "DBConnectionReaper Checking free pool connection status ...");
// Check if the connections in the free pool are still connected/valid
int idx = 0;
while (idx < m_freePool.size()) {
// Get the current connection
Connection conn = m_freePool.get(idx);
try {
// Check if the connection is closed
if (conn.isClosed()) {
// Remove the connection from the free pool
m_freePool.remove(idx);
// DEBUG
if ( DEBUG)
Debug.println( "DBConnectionReaper Removed closed connection from free pool");
}
else {
// Toggle the auto-commit flag on the connection, this will check the connection on most
// databases
boolean autoCommit = conn.getAutoCommit();
conn.setAutoCommit(true);
conn.setAutoCommit(autoCommit);
// Update the connection index
idx++;
}
}
catch (SQLException ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
// Remove the current connection from the free pool
try {
m_freePool.remove(idx);
conn.close();
}
catch (Exception ex2) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
}
// DEBUG
if ( DEBUG)
Debug.println( "DBConnectionReaper Removed closed connection from free pool (exception)");
}
}
if (isOnline()) {
// Check if the free and allocated pools are empty, this indicates that the database server
// is offline
if (m_freePool.size() == 0 && m_allocPool.size() == 0) {
// Database server appears to be offline
m_online = false;
notifyConnectionPoolState();
}
}
else {
// Try and get a connection from the pool, this will check if the database server is back online
Connection conn = getConnection();
if (conn != null)
releaseConnection(conn);
}
// DEBUG
if ( DEBUG)
Debug.println( "DBConnectionReaper Free pool check done.");
}
}
}
}
}
;
/**
* Class constructor
*
* @param driver String
* @param dsn String
* @param user String
* @param pwd String
* @exception Exception Failed to initialize the connection pool
*/
public DBConnectionPool(String driver, String dsn, String user, String pwd)
throws Exception {
// Set the JDBC connection details
m_dbDriver = driver;
m_dsn = dsn;
m_user = user;
m_password = pwd;
// Call the common constructor code
commonConstructor();
}
/**
* Class constructor
*
* @param driver String
* @param dsn String
* @param user String
* @param pwd String
* @param initConns int
* @param maxConns int
* @exception Exception Failed to initialize the connection pool
*/
public DBConnectionPool(String driver, String dsn, String user, String pwd, int initConns, int maxConns)
throws Exception {
// Set the JDBC connection details
m_dbDriver = driver;
m_dsn = dsn;
m_user = user;
m_password = pwd;
// Set the pool size
if (initConns > 0)
m_minPoolSize = initConns;
if (maxConns > 0)
m_maxPoolSize = maxConns;
// Call the common constructor code
commonConstructor();
}
/**
* Class constructor
*
* @param driver String
* @param dsn String
* @param user String
* @param pwd String
* @param initConns int
* @param maxConns int
* @param callback DBCallbacks
* @exception Exception Failed to initialize the connection pool
*/
public DBConnectionPool(String driver, String dsn, String user, String pwd, int initConns, int maxConns, DBCallbacks callback)
throws Exception {
// Set the JDBC connection details
m_dbDriver = driver;
m_dsn = dsn;
m_user = user;
m_password = pwd;
// Set the callbacks interface
m_callback = callback;
// Set the pool size
if (initConns > 0)
m_minPoolSize = initConns;
if (maxConns > 0)
m_maxPoolSize = maxConns;
// Call the common constructor code
commonConstructor();
}
/**
* Common constructor code
*
* @exception Exception Failed to initialize the connection pool
*/
private void commonConstructor()
throws Exception {
// Load the database driver class
Class.forName(m_dbDriver).newInstance();
// Allocate the free and in use connection pools
m_freePool = new ArrayList();
m_allocPool = new Hashtable();
// Start the connection reaper thread
m_reaper = new DBConnectionReaper(getLeaseTime());
m_reaperThread = new Thread(m_reaper);
m_reaperThread.setDaemon(true);
m_reaperThread.setName("DBConnectionReaper");
m_reaperThread.start();
}
/**
* Get the JDBC driver details
*
* @return String
*/
public final String getDriver() {
return m_dbDriver;
}
/**
* Get the connection details
*
* @return String
*/
public final String getDSN() {
return m_dsn;
}
/**
* Get the user name
*
* @return String
*/
public final String getUserName() {
return m_user;
}
/**
* Get the password
*
* @return String
*/
public final String getPassword() {
return m_password;
}
/**
* Get the minimum pool size
*
* @return int
*/
public final int getMinimumPoolSize() {
return m_minPoolSize;
}
/**
* Get the maximum pool size
*
* @return int
*/
public final int getMaximumPoolSize() {
return m_maxPoolSize;
}
/**
* Get the connection lease time, in milliseconds
*
* @return long
*/
public final long getLeaseTime() {
return m_leaseTime;
}
/**
* Get the available connection count
*
* @return int
*/
public final synchronized int getAvailableConnections() {
return m_freePool.size();
}
/**
* Get the in use connection count
*
* @return int
*/
public final synchronized int getAllocatedConnections() {
return m_allocPool.size();
}
/**
* Get a connection from the pool
*
* @return Connection
*/
public final Connection getConnection() {
// Get a timestamp for the connection
long expireTime = System.currentTimeMillis() + getLeaseTime();
return getConnection(expireTime);
}
/**
* Check if the connection pool is online
*
* @return boolean
*/
public final boolean isOnline() {
return m_online;
}
/**
* Get a connection from the pool with the specified lease time. A lease time of -1 indicates that
* the connection lease is permanent.
*
* @param expireTime long
* @return Connection
*/
public final Connection getConnection(long expireTime) {
// Check for a connection in the free pool
Connection conn = null;
synchronized (m_freePool) {
// Check if the free pool has a connection
if (m_freePool.size() > 0) {
// Get the connection
conn = m_freePool.remove(0);
try {
if (conn.isClosed())
conn = null;
}
catch (SQLException ex) {
conn = null;
Debug.println("%%%%% SQL Connection Error: " + ex.toString());
}
}
else if (isOnline() == false) {
// Try and create a new connection, if we succeed then the database server is back online
try {
// Create a new database connection
conn = createConnection();
}
catch (SQLException ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
}
}
}
// Check if the database server is back online
if (isOnline() == false) {
if (conn != null) {
m_online = true;
notifyConnectionPoolState();
}
else
return null;
}
// Allocate a new connection if there are spare slots available
synchronized (m_allocPool) {
// If the connection is valid add it to the allocated pool
if (conn != null)
m_allocPool.put(conn, new Long(expireTime));
else {
// If a connection has not been allocated and there are spare slots available then
// create a new connection.
if (m_allocPool.size() < getMaximumPoolSize()) {
try {
// Create a new connection
conn = createConnection();
// Add the connection to the in use list
m_allocPool.put(conn, new Long(expireTime));
}
catch (SQLException ex) {
conn = null;
Debug.println("%%%%% SQL Connection Error: " + ex.toString());
}
}
}
}
// Return the connection
return conn;
}
/**
* Release a connection back to the free pool
*
* @param conn Connection
*/
public final void releaseConnection(Connection conn) {
// Remove the connection from the in use pool and put it back in the free list
synchronized (m_allocPool) {
Object curConn = m_allocPool.remove(conn);
if (curConn == null)
return;
}
// Add the connection to the free pool
synchronized (m_freePool) {
// Add the connection back to the free pool, if not closed
try {
if (conn.isClosed() == false) {
m_freePool.add(conn);
}
else
Debug.println("***** Connection closed *****");
}
catch (Exception ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
}
}
}
/**
* Renew a lease on a connection for the default lease time
*
* @param conn Connection
*/
public final void renewLease(Connection conn) {
renewLease(conn, System.currentTimeMillis() + getLeaseTime());
}
/**
* Renew a lease on a connection to hold onto the connection for longer
*
* @param conn Connection
* @param expireTime long
*/
public final void renewLease(Connection conn, long expireTime) {
synchronized (m_allocPool) {
// Check that the connection is in the allocated pool
if (m_allocPool.remove(conn) == null)
return;
// Update the expire time for the lease and add back to the allocated pool
m_allocPool.put(conn, new Long(expireTime));
}
}
/**
* Close the connection pool
*/
public final void closePool() {
// Shutdown the connection reaper thread
m_reaper.shutdownRequest();
// Close all allocated database connections
if (m_allocPool.size() > 0) {
// Close all allocated connections
Enumeration enm = m_allocPool.keys();
while (enm.hasMoreElements()) {
// Close the connection
Connection conn = enm.nextElement();
try {
conn.close();
}
catch (SQLException ex) {
}
}
// Clear the allocated pool
m_allocPool.clear();
}
// Close all free database connections
if (m_freePool.size() > 0) {
// Close the free pool connections
for (int i = 0; i < m_freePool.size(); i++) {
// Get the current connection
Connection conn = m_freePool.get(i);
try {
conn.close();
}
catch (SQLException ex) {
}
}
// Clear the free pool
m_freePool.clear();
}
}
/**
* Set the connection pool initial and maximum sizes
*
* @param initSize int
* @param maxSize int
*/
public final void setPoolSize(int initSize, int maxSize) {
m_minPoolSize = initSize;
m_maxPoolSize = maxSize;
}
/**
* Set the default connection lease time
*
* @param leaseTime long
*/
public final void setDefaultLeaseTime(long leaseTime) {
m_leaseTime = leaseTime;
}
/**
* Set the online check interval, in seconds
*
* @param interval int
*/
public final void setOnlineCheckInterval(int interval) {
// Set the reaper thread online check interval, convert seconds to thread wakeups
int wakeups = interval / (int) DefaultLease;
if (wakeups < 1)
wakeups = 1;
m_reaper.setOnlineCheckInterval(wakeups);
}
/**
* Check if there is a connection pool listener
*
* @return boolean
*/
public final boolean hasConnectionPoolListener() {
return m_dbListener != null ? true : false;
}
/**
* Add a database connection pool listener
*
* @param l DBConnectionPoolListener
*/
public final void addConnectionPoolListener(DBConnectionPoolListener l) {
m_dbListener = l;
}
/**
* Remove a database connection pool listener
*
* @return DBConnectionPoolListener
*/
public final DBConnectionPoolListener removeConnectionPoolListener() {
DBConnectionPoolListener l = m_dbListener;
m_dbListener = null;
return l;
}
/**
* Create a new database connection
*
* @return Connection
* @throws SQLException Error creating the connection
*/
protected final Connection createConnection()
throws SQLException {
// Create a new database connection, use the callback interface if available
if ( m_callback != null) {
// Use the callback interface to delegate the connection creation
return m_callback.createConnectionForPool(getDSN(), getUserName(), getPassword());
}
// Use the default connection creation
return DriverManager.getConnection(getDSN(), getUserName(), getPassword());
}
/**
* Notify the connection pool listener of an online/offline state change
*/
protected final void notifyConnectionPoolState() {
// DEBUG
Debug.println("DBConnectionPool: Database server is " + (isOnline() ? "OnLine" : "OffLine"));
// Inform the connection pool listener
if (hasConnectionPoolListener())
m_dbListener.databaseOnlineStatus(isOnline() ? DBStatus.Online : DBStatus.Offline);
else
Debug.println("DBConnectionPool: No listener");
}
/**
* Wait for a valid database connection, up to the specified number of seconds
*
* @param waitSecs int
* @return boolean
*/
public final boolean waitForConnection(int waitSecs) {
Connection dbConn = null;
long timeEnd = System.currentTimeMillis() + (waitSecs * 1000L);
while ( dbConn == null && System.currentTimeMillis() < timeEnd) {
try {
// Get a database connection
dbConn = createConnection();
}
catch ( SQLException ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
}
catch ( Exception ex) {
if ( Debug.hasDumpStackTraces())
Debug.println( ex);
}
// Check if we got a valid database connection
if ( dbConn == null) {
// Wait a while before trying to get the database connection
try {
Thread.sleep(1000);
}
catch ( InterruptedException ex) {
return false;
}
}
}
// Return the database connection status
return dbConn != null ? true : false;
}
}