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JDBC connection pooling utility, supporting time-based expiry, statement caching, connection validation, and easy configuration using a pool manager.
/*
---------------------------------------------------------------------------
DBPool : Java Database Connection Pooling class type of pooled objects
*/
public class PoolTracer implements ObjectPoolListener
{
/** Logging utility. */
private final LogUtil logger = new LogUtil();
/** Default DateFormat instance. */
private static final DateFormat DEFAULT_DATEFORMAT = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss,SSS");
/** Default format string for log messages. */
private static final String DEFAULT_FORMAT_STRING =
"name={0}, " +
"minpool={1,number,#}, " +
"maxpool={2,number,#}, " +
"maxsize={3,number,#}, " +
"idleTimeout={4,number,#}, " +
"out={5,number,#}, " +
"free={6,number,#}, " +
"hitRate={8,number,0.0##%}, " +
"event={9}";
/** {@code MessageFormat} instance for preparing log messages. */
private MessageFormat msgFormat;
/**
* Creates a new {@code PoolTracer} which logs to the specified
* {@code PrintWriter}.
* @param pool {@code ObjectPool} for which to trace activity
* @param logWriter {@code PrintWriter} to use for writing trace activity
* @param closeOnExit whether to close the {@code PrintWriter} on release
*/
public PoolTracer(ObjectPool pool, PrintWriter logWriter, boolean closeOnExit)
{
logger.setLog(logWriter, closeOnExit);
logger.setDateFormat(DEFAULT_DATEFORMAT);
setMessageFormat(null);
pool.addObjectPoolListener(this);
}
/**
* Creates a new {@code PoolTracer} which logs to the specified file.
* Note: if the file already exists it is truncated to zero-length, then used
* for writing the log.
* @param pool {@code ObjectPool} for which to trace activity
* @param file {@code File} to which to log trace activity
* @throws FileNotFoundException if unable to find specified file
*/
public PoolTracer(ObjectPool pool, File file) throws FileNotFoundException
{
this(pool, new PrintWriter(file), true);
}
/**
* Creates a new ObjectPoolAudit which logs to the specified File.
* @param pool {@code ObjectPool} for which to trace activity
* @param filename name of file to which to log trace activity
* @throws FileNotFoundException if unable to find specified file
*/
public PoolTracer(ObjectPool pool, String filename) throws FileNotFoundException
{
this(pool, new PrintWriter(filename), true);
}
/**
* Creates a new {@code PoolTracer} which logs to the specified file.
* Note: if the file already exists it is truncated to zero-length, then used
* for writing the log.
* @param props {@code Properties} defining trace activity
* @throws FileNotFoundException if unable to find file specified in properties
*/
public PoolTracer(Properties props) throws FileNotFoundException
{
Properties p = convertToLC(props);
// Find file property, and spew if not found.
String filename = p.getProperty("file");
if (filename == null || filename.equals(""))
throw new IllegalArgumentException("Property not specified: file");
logger.setLog(new PrintWriter(new File(filename)), true);
String dateFormat = p.getProperty("dateformat");
if (dateFormat != null && !dateFormat.trim().equals(""))
logger.setDateFormat(new SimpleDateFormat(dateFormat));
else
logger.setDateFormat(DEFAULT_DATEFORMAT);
String format = p.getProperty("format");
if (format != null && !format.trim().equals(""))
setMessageFormat(new MessageFormat(format));
else
setMessageFormat(null);
}
// Converts property keys to lower-case for easier redudant checking.
private static Properties convertToLC(Properties p)
{
Properties props = new Properties();
for (Enumeration e = p.propertyNames(); e.hasMoreElements();)
{
String key = (String)e.nextElement();
props.put(key.toLowerCase(), p.getProperty(key));
}
return props;
}
/**
* Sets the date formatter for the logging.
* The default is the same as used by the {@link LogUtil} class.
* @param df {@code DateFormat} instance to use for formatting log messages
*/
public synchronized void setDateFormat(DateFormat df)
{
logger.setDateFormat(df);
}
/**
* Sets the {@code MessageFormat} instance used for formatting log messages.
* To use the default instance, just call this method with a null argument.
* Format strings are specified using the following variables:
*
* - {0} - pool name (string)
* - {1} - minpool (integer)
* - {2} - maxpool (integer)
* - {3} - maxsize (integer)
* - {4} - idle timeout (long)
* - {5} - items checked out (integer)
* - {6} - free item count (integer)
* - {7} - current pool size (i.e. {5}+{6}, integer)
* - {8} - hit rate (float)
* - {9} - event type (string)
*
* The default format is as follows:
*
* {0}: minpool={1,number,#}, maxpool={2,number,#}, maxsize={3,number,#}, idleTimeout={4,number,#}, out={5,number,#}, free={6,number,#}, hitRate={8,number,0.0##%}
*
* @param mf {@code MessageFormat} instance to use for formatting log messages
*/
public final void setMessageFormat(MessageFormat mf)
{
msgFormat = (mf == null) ? new MessageFormat(DEFAULT_FORMAT_STRING) : mf;
}
/**
* Returns the current {@code MessageFormat} instance used for formatting log messages.
* @return The current {@code MessageFormat} instance used for formatting log messages
*/
public MessageFormat getMessageFormatInstance()
{
return msgFormat;
}
/**
* Writes an entry containing the pool statistics to the log file.
* @param evt event instance to log
*/
protected void logPoolStats(ObjectPoolEvent evt)
{
Object[] o = new Object[10];
o[0] = evt.getPool().getName();
o[1] = evt.getMinPool();
o[2] = evt.getMaxPool();
o[3] = evt.getMaxSize();
o[4] = evt.getIdleTimeout();
o[5] = evt.getCheckedOut();
o[6] = evt.getFreeCount();
o[7] = evt.getSize();
o[8] = evt.getPoolHitRate();
o[9] = evt.getTypeString();
String msg = msgFormat.format(o);
logger.log(msg);
}
@Override
public void poolInitCompleted(ObjectPoolEvent evt)
{
}
@Override
public void validationError(ObjectPoolEvent evt)
{
}
@Override
public void maxPoolLimitReached(ObjectPoolEvent evt)
{
}
@Override
public void maxPoolLimitExceeded(ObjectPoolEvent evt)
{
}
@Override
public void maxSizeLimitReached(ObjectPoolEvent evt)
{
}
@Override
public void maxSizeLimitError(ObjectPoolEvent evt)
{
}
@Override
public void poolCheckIn(ObjectPoolEvent evt)
{
logPoolStats(evt);
}
@Override
public void poolCheckOut(ObjectPoolEvent evt)
{
logPoolStats(evt);
}
@Override
public void poolParametersChanged(ObjectPoolEvent evt)
{
logPoolStats(evt);
}
@Override
public void poolFlushed(ObjectPoolEvent evt)
{
logPoolStats(evt);
}
@Override
public void poolReleased(ObjectPoolEvent evt)
{
logPoolStats(evt);
evt.getPool().removeObjectPoolListener(this);
logger.close();
}
}
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