/** Constructor. */
public DatabaseEventQueue() {
if (Debug.isLevelEnabled(Debug.OBJECT_LIFECYCLE))
Debug.log(
Debug.OBJECT_LIFECYCLE,
"QUEUE OPERATION: Creating event queue of type ["
+ StringUtils.getClassName(this)
+ "] ...");
queue = Collections.synchronizedList(new LinkedList());
}
/**
* Initialize the event queue.
*
* @param props A container of configuration properties.
* @exception FrameworkException Thrown if configuration is invalid.
*/
public void initialize(Map props) throws FrameworkException {
String temp = (String) props.get(LOAD_EVENT_BATCH_SIZE_PROP);
if (StringUtils.hasValue(temp)) {
maxDatabaseEventLoadSize = StringUtils.getInteger(temp);
if (Debug.isLevelEnabled(Debug.SYSTEM_CONFIG))
Debug.log(
Debug.SYSTEM_CONFIG,
"QUEUE OPERATION: Initializing: Maximum-database-event-batch-load-size is ["
+ maxDatabaseEventLoadSize
+ "] rows.");
}
}
/**
* Get the next queued item. Must be called after hasNext().
*
* @return The next item in the queue to process.
* @exception FrameworkException Thrown on errors.
*/
public Event next() throws FrameworkException {
if (queue.size() == 0) {
throw new FrameworkException("ERROR: Attempt was made to retrieve event from empty queue.");
}
Event event = (Event) queue.get(0);
if (Debug.isLevelEnabled(Debug.MSG_STATUS))
Debug.log(
Debug.MSG_STATUS,
"QUEUE OPERATION: Retrieving the following event from the database queue:\n"
+ event.describe());
return event;
}
// Release the given database resources, if non-null.
private static void releaseDatabaseResources(Connection dbConn, PreparedStatement ps) {
if (ps != null) {
try {
ps.close();
} catch (Exception e) {
Debug.warning("Failed to close the prepared statement:\n" + e.toString());
}
}
if (dbConn != null) {
try {
DBConnectionPool.getInstance().releaseConnection(dbConn);
} catch (Exception e) {
Debug.warning("Failed to release database connection back to the pool:\n" + e.toString());
}
}
}
/**
* Returns 'true' if the queue has more items to process.
*
* @param criteria An event containing the event-selection criteria.
* @return 'true' if queue has more items to process, otherwise 'false'.
* @exception FrameworkException Thrown on errors.
*/
public boolean hasNext(Event criteria) throws FrameworkException {
boolean available = (queue.size() > 0);
// If no events are available in memory, attempt to get more from the database.
if (!available) {
loadFromDatabase(criteria);
available = (queue.size() > 0);
}
if (Debug.isLevelEnabled(Debug.MSG_STATUS))
Debug.log(
Debug.MSG_STATUS,
"QUEUE OPERATION: Events available in database queue? [" + available + "].");
return available;
}
/**
* Add the event to the end of queue.
*
* @param event The event to add to the queue.
* @exception FrameworkException Thrown on errors.
*/
public void add(Event event) throws FrameworkException {
Debug.log(Debug.MSG_STATUS, "QUEUE OPERATION: Adding event to database queue ...");
Connection dbConn = null;
PreparedStatement ps = null;
long startTime = -1;
if (Debug.isLevelEnabled(Debug.BENCHMARK)) startTime = System.currentTimeMillis();
try {
event.id = PersistentSequence.getNextSequenceValue(SEQUENCE_NAME);
dbConn = DBConnectionPool.getInstance().acquireConnection();
event.arrivalTime = new java.sql.Timestamp(System.currentTimeMillis());
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "\n" + LINE + "\nExecuting SQL:\n" + INSERT_EVENT_SQL);
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "Event being inserted into database:\n" + event.describe());
if (Debug.isLevelEnabled(Debug.MSG_DATA))
Debug.log(Debug.MSG_DATA, "Event contents:\n" + event.message);
ps = dbConn.prepareStatement(INSERT_EVENT_SQL);
ps.setString(1, event.channelName);
ps.setInt(2, event.id);
DBLOBUtils.setCLOB(ps, 3, event.message);
ps.setTimestamp(4, event.arrivalTime);
int numRows = ps.executeUpdate();
if (numRows != 1) {
String errMsg =
"Execution of SQL statement ["
+ INSERT_EVENT_SQL
+ "] affected ["
+ numRows
+ "] rows.";
Debug.error(errMsg);
throw new FrameworkException(errMsg);
}
DBConnectionPool.getInstance().commit(dbConn);
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "Successfully committed SQL operation.\n" + LINE);
// NOTE: We don't add the item just inserted into the database into the in-memory
// queue, as we want it loaded by the separate dequeueing thread.
} catch (SQLException sqle) {
throw new DatabaseException(
"ERROR: Could not execute SQL statement:\n" + DBInterface.getSQLErrorMessage(sqle));
} catch (Exception e) {
throw new DatabaseException("ERROR: Could not execute SQL statement:\n" + e.toString());
} finally {
releaseDatabaseResources(dbConn, ps);
if (Debug.isLevelEnabled(Debug.BENCHMARK) && (startTime > 0)) {
long stopTime = System.currentTimeMillis();
Debug.log(
Debug.BENCHMARK,
"ELAPSED TIME ["
+ (stopTime - startTime)
+ "] msec: "
+ "SQL: Time to insert event into PersistentEvent database table.");
}
}
}
/**
* Reset any events meeting the given criteria so that they can be retried.
*
* @param criteria An event containing the event-selection criteria.
* @return The number of events reset.
* @exception FrameworkException Thrown on errors.
*/
protected static int reset(Event criteria) throws FrameworkException {
Debug.log(
Debug.MSG_STATUS, "QUEUE OPERATION: Resetting events in database for database queue ...");
if (!StringUtils.hasValue(criteria.channelName)) {
throw new FrameworkException(
"ERROR: Event channel name is a required queue search criteria.");
}
Connection dbConn = null;
PreparedStatement ps = null;
long startTime = -1;
if (Debug.isLevelEnabled(Debug.BENCHMARK)) startTime = System.currentTimeMillis();
try {
dbConn = DBConnectionPool.getInstance().acquireConnection();
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(
Debug.DB_DATA, "Criteria used to reset events in database:\n" + criteria.describe());
// If no identifier was given that uniquely identifies a single event ...
if (criteria.id == 0) {
// Use last error time and error count, if available.
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "\n" + LINE + "\nExecuting SQL:\n" + UPDATE_EVENT_RETRY_SQL);
ps = dbConn.prepareStatement(UPDATE_EVENT_RETRY_SQL);
ps.setString(1, criteria.channelName);
if (criteria.lastErrorTime == null) ps.setNull(2, Types.DATE);
else ps.setTimestamp(2, criteria.lastErrorTime);
if (criteria.errorCount < 1) ps.setNull(3, Types.INTEGER);
else ps.setInt(3, criteria.errorCount);
} else {
// An Id was given which should uniquely identify a single event, so we should
// skip using any other qualifying criteria, if present.
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(
Debug.DB_DATA, "\n" + LINE + "\nExecuting SQL:\n" + UPDATE_EVENT_RETRY_BY_ID_SQL);
ps = dbConn.prepareStatement(UPDATE_EVENT_RETRY_BY_ID_SQL);
ps.setString(1, criteria.channelName);
ps.setInt(2, criteria.id);
}
int numRows = ps.executeUpdate();
DBConnectionPool.getInstance().commit(dbConn);
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(
Debug.DB_DATA, "Committed SQL execution affected [" + numRows + "] rows.\n" + LINE);
return numRows;
} catch (SQLException sqle) {
throw new DatabaseException(
"ERROR: Could not execute SQL statement:\n" + DBInterface.getSQLErrorMessage(sqle));
} catch (Exception e) {
throw new DatabaseException("ERROR: Could not execute SQL statement:\n" + e.toString());
} finally {
releaseDatabaseResources(dbConn, ps);
if (Debug.isLevelEnabled(Debug.BENCHMARK) && (startTime > 0)) {
long stopTime = System.currentTimeMillis();
Debug.log(
Debug.BENCHMARK,
"ELAPSED TIME ["
+ (stopTime - startTime)
+ "] msec: "
+ "SQL: Time to reset event(s) in PersistentEvent database table.");
}
}
}
/**
* Load any available events from the database up to the configured maximum.
*
* @param criteria An event containing the event-selection criteria.
* @return The next available event on the queue.
* @exception FrameworkException Thrown on errors.
*/
private void loadFromDatabase(Event criteria) throws FrameworkException {
Debug.log(Debug.MSG_STATUS, "QUEUE OPERATION: Loading events from database into queue ...");
if (!StringUtils.hasValue(criteria.channelName)) {
throw new FrameworkException(
"ERROR: Event channel name is a required queue search criteria.");
}
Connection dbConn = null;
PreparedStatement ps = null;
long startTime = -1;
if (Debug.isLevelEnabled(Debug.BENCHMARK)) startTime = System.currentTimeMillis();
try {
dbConn = DBConnectionPool.getInstance().acquireConnection();
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "\n" + LINE + "\nExecuting SQL:\n" + QUERY_EVENT_SQL);
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(
Debug.DB_DATA, "Criteria used in query against database:\n" + criteria.describe());
ps = dbConn.prepareStatement(QUERY_EVENT_SQL);
ps.setString(1, criteria.channelName);
ResultSet rs = ps.executeQuery();
for (int counter = 0; (counter < maxDatabaseEventLoadSize) && rs.next(); counter++) {
Event event = new Event();
event.channelName = rs.getString(CHANNEL_NAME_COL);
event.id = rs.getInt(ID_COL);
event.message = DBLOBUtils.getCLOB(rs, MESSAGE_COL);
if (Debug.isLevelEnabled(Debug.MSG_LIFECYCLE))
Debug.log(Debug.MSG_LIFECYCLE, "Event contents:\n" + event.message);
event.arrivalTime = rs.getTimestamp(ARRIVAL_TIME_COL);
event.errorStatus = rs.getString(ERROR_STATUS_COL);
event.errorCount = rs.getInt(ERROR_COUNT_COL);
event.lastErrorMessage = rs.getString(LAST_ERROR_MESSAGE_COL);
event.lastErrorTime = rs.getTimestamp(LAST_ERROR_TIME_COL);
// Add item to in-memory buffer.
if (Debug.isLevelEnabled(Debug.MSG_STATUS))
Debug.log(
Debug.MSG_STATUS,
"Adding event [" + event.describe() + "] to in-memory queue buffer.");
queue.add(event);
if (Debug.isLevelEnabled(Debug.MSG_STATUS))
Debug.log(Debug.MSG_STATUS, "In-memory queue buffer size [" + queue.size() + "].");
}
if (Debug.isLevelEnabled(Debug.DB_DATA)) Debug.log(Debug.DB_DATA, "\n" + LINE);
} catch (SQLException sqle) {
throw new DatabaseException(
"ERROR: Could not execute SQL statement:\n" + DBInterface.getSQLErrorMessage(sqle));
} catch (Exception e) {
throw new DatabaseException("ERROR: Could not execute SQL statement:\n" + e.toString());
} finally {
releaseDatabaseResources(dbConn, ps);
if (Debug.isLevelEnabled(Debug.BENCHMARK) && (startTime > 0)) {
long stopTime = System.currentTimeMillis();
Debug.log(
Debug.BENCHMARK,
"ELAPSED TIME ["
+ (stopTime - startTime)
+ "] msec: "
+ "SQL: Time to load event(s) from PersistentEvent database table.");
}
}
}
/**
* Update the given event as indicated.
*
* @param event The event to update.
* @param eventStatus The event delivery status.
* @exception FrameworkException Thrown on errors.
*/
public void update(Event event, EventStatus eventStatus) throws FrameworkException {
if (Debug.isLevelEnabled(Debug.MSG_STATUS))
Debug.log(
Debug.MSG_STATUS,
"QUEUE OPERATION: Updating database queue using event status ["
+ eventStatus.name
+ "] ...");
// If no consumers were available, the event delivery wasn't attempted so leave
// the queue in its current state.
if (eventStatus == EventStatus.NO_CONSUMERS_AVAILABLE) {
Debug.log(
Debug.MSG_STATUS, "Skipping queue update, as no consumers were available to process it.");
return;
}
Connection dbConn = null;
PreparedStatement ps = null;
long startTime = -1;
if (Debug.isLevelEnabled(Debug.BENCHMARK)) startTime = System.currentTimeMillis();
try {
dbConn = DBConnectionPool.getInstance().acquireConnection();
if (eventStatus == EventStatus.DELIVERY_SUCCESSFUL) {
// If the event was successfully delivered, update status in database to delivered.
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "\n" + LINE + "\nExecuting SQL:\n" + UPDATE_EVENT_SUCCESS_SQL);
ps = dbConn.prepareStatement(UPDATE_EVENT_SUCCESS_SQL);
java.sql.Timestamp ts = new java.sql.Timestamp(System.currentTimeMillis());
ps.setTimestamp(1, ts);
ps.setString(2, event.channelName);
ps.setInt(3, event.id);
} else if (eventStatus == EventStatus.DELIVERY_FAILED) {
// If the event delivery failed, we mark it as failed in the database.
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "\n" + LINE + "\nExecuting SQL:\n" + UPDATE_EVENT_ERROR_SQL);
// Truncate error message if it's larger than database column.
if ((event.lastErrorMessage != null)
&& (event.lastErrorMessage.length() > MAX_ERROR_MESSAGE_LENGTH))
event.lastErrorMessage = event.lastErrorMessage.substring(0, MAX_ERROR_MESSAGE_LENGTH);
event.lastErrorTime = new java.sql.Timestamp(System.currentTimeMillis());
ps = dbConn.prepareStatement(UPDATE_EVENT_ERROR_SQL);
ps.setTimestamp(1, event.lastErrorTime);
ps.setString(2, event.lastErrorMessage);
ps.setString(3, event.channelName);
ps.setInt(4, event.id);
} else {
throw new FrameworkException(
"ERROR: Invalid event update type [" + eventStatus.name + "].");
}
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "Event being operated on in database:\n" + event.describe());
int numRows = ps.executeUpdate();
if (numRows > 1) {
String errMsg = "Execution of update SQL statement affected [" + numRows + "] rows.";
Debug.error(errMsg);
throw new FrameworkException(errMsg);
}
DBConnectionPool.getInstance().commit(dbConn);
if (Debug.isLevelEnabled(Debug.DB_DATA))
Debug.log(Debug.DB_DATA, "Successfully committed SQL operation.\n" + LINE);
// At this point, the event should be removed from the in-memory buffer of events as well,
// irrespective of processing outcome.
if (Debug.isLevelEnabled(Debug.MSG_STATUS))
Debug.log(
Debug.MSG_STATUS,
"Removing event [" + event.describe() + "] from in-memory queue buffer.");
boolean removed = queue.remove(event);
if (Debug.isLevelEnabled(Debug.MSG_STATUS))
Debug.log(
Debug.MSG_STATUS,
"Event removed? ["
+ removed
+ "]. In-memory queue buffer size ["
+ queue.size()
+ "].");
} catch (SQLException sqle) {
throw new DatabaseException(
"ERROR: Could not execute SQL statement:\n" + DBInterface.getSQLErrorMessage(sqle));
} catch (Exception e) {
throw new DatabaseException("ERROR: Could not execute SQL statement:\n" + e.toString());
} finally {
releaseDatabaseResources(dbConn, ps);
if (Debug.isLevelEnabled(Debug.BENCHMARK) && (startTime > 0)) {
long stopTime = System.currentTimeMillis();
Debug.log(
Debug.BENCHMARK,
"ELAPSED TIME ["
+ (stopTime - startTime)
+ "] msec: "
+ "SQL: Time to update event in PersistentEvent database table.");
}
}
}