/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. The ASF licenses this file to You
* under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License. For additional information regarding
* copyright in this work, please see the NOTICE file in the top level
* directory of this distribution.
*/
package org.apache.roller.business.pings;
import java.util.Iterator;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.roller.RollerException;
import org.apache.roller.business.RollerFactory;
import org.apache.roller.config.PingConfig;
import org.apache.roller.config.RollerRuntimeConfig;
import org.apache.roller.pojos.PingQueueEntryData;
import org.apache.roller.pojos.PingTargetData;
import org.apache.roller.pojos.WebsiteData;
/**
* Ping Queue Processor. Singleton encapsulating logic for processing the weblog update ping queue.
*
* @author <a href="mailto:anil@busybuddha.org">Anil Gangolli</a>
*/
public class PingQueueProcessor {
private static final Log logger = LogFactory.getLog(PingQueueProcessor.class);
private static PingQueueProcessor theInstance;
private PingQueueManager pingQueueMgr;
public static PingQueueProcessor getInstance() {
return theInstance;
}
private PingQueueProcessor() throws RollerException {
pingQueueMgr = RollerFactory.getRoller().getPingQueueManager();
}
/**
* Initialize the singleton. This is called during <code>RollerContext</code> initialization.
*
* @throws RollerException
*/
public static synchronized void init() throws RollerException {
if (theInstance != null) {
logger.warn("Ignoring duplicate initialization of PingQueueProcessor!");
return;
}
theInstance = new PingQueueProcessor();
if (logger.isDebugEnabled()) logger.debug("Ping queue processor initialized.");
}
/**
* Process the ping queue. Performs one pass through the ping queue, processing every entry once. On ping failure
* an entry is requeued for processing on subsequent passes until the configured maximum number of attempts is
* reached.
*/
public synchronized void processQueue() {
if (PingConfig.getSuspendPingProcessing()) {
logger.info("Ping processing has been suspended. Skipping current round of ping queue processing.");
return;
}
String absoluteContextUrl = RollerRuntimeConfig.getAbsoluteContextURL();
if (absoluteContextUrl == null) {
logger.warn("WARNING: Skipping current ping queue processing round because we cannot yet determine the site's absolute context url.");
return;
}
// TODO: Group by ping target and ping all sites for that target?
// We're currently not taking advantage of grouping by ping target site and then sending
// all of the pings for that target at once. If it becomes an efficiency issue, we should do
// that.
try {
if (logger.isDebugEnabled()) logger.debug("Started processing ping queue.");
// Get all of the entries
List entries = pingQueueMgr.getAllQueueEntries();
// Process each entry
for (Iterator i = entries.iterator(); i.hasNext();) {
PingQueueEntryData pingQueueEntry = (PingQueueEntryData) i.next();
processQueueEntry(pingQueueEntry);
}
if (logger.isDebugEnabled()) logger.debug("Finished processing ping queue.");
} catch (Exception ex) {
logger.error("Unexpected exception processing ping queue! Aborting this pass of ping queue processing.", ex);
}
}
/**
* Process an individual ping queue entry.
*
* @param pingQueueEntry the ping queue entry
* @throws RollerException only if there are problems processing the queue. Exceptions from sending pings are
* handled, not thrown.
*/
private void processQueueEntry(PingQueueEntryData pingQueueEntry) throws RollerException {
if (logger.isDebugEnabled()) logger.debug("Processing ping queue entry: " + pingQueueEntry);
PingTargetData pingTarget = pingQueueEntry.getPingTarget();
WebsiteData website = pingQueueEntry.getWebsite();
boolean pingSucceeded = false;
if (PingConfig.getLogPingsOnly()) {
// Just log the ping and pretend it succeeded.
logger.info("Logging simulated ping for ping queue entry " + pingQueueEntry);
pingSucceeded = true;
} else {
// Actually process the ping
try {
// Send the ping
WeblogUpdatePinger.sendPing(pingTarget, website);
// Consider successful ping transmission if we didn't get an exception. We don't care here
// about the result of the ping if it was transmitted.
pingSucceeded = true;
} catch (Exception ex) {
// Handle the ping error, either removing or requeuing the ping queue entry.
handlePingError(pingQueueEntry, ex);
}
}
// We do this outside of the previous try-catch because we don't want an exception here to be considered a ping error.
if (pingSucceeded) {
if (logger.isDebugEnabled()) logger.debug("Processed ping: " + pingQueueEntry);
pingQueueMgr.removeQueueEntry(pingQueueEntry);
}
}
/**
* Handle any ping error.
*
* @param pingQueueEntry the ping queue entry
* @param ex the exception that occurred on the ping attempt
* @throws RollerException
*/
private void handlePingError(PingQueueEntryData pingQueueEntry, Exception ex)
throws RollerException {
if ((pingQueueEntry.incrementAttempts() < PingConfig.getMaxPingAttempts()) && WeblogUpdatePinger.shouldRetry(ex)) {
// We have attempts remaining, and it looks like we should retry,
// so requeue the entry for processing on subsequent rounds
logger.debug("Error on ping attempt (" + pingQueueEntry.getAttempts() + ") for " + pingQueueEntry + ": [" + ex.getMessage() + "]. Will re-queue for later attempts.");
logger.debug("Error on last ping attempt was: ", ex);
pingQueueMgr.saveQueueEntry(pingQueueEntry);
} else {
// Remove the entry
logger.warn("Error on ping attempt (" + pingQueueEntry.getAttempts() + ") for " + pingQueueEntry + ": [" + ex.getMessage() + "]. Entry will be REMOVED from ping queue.");
logger.debug("Error on last ping attempt was: ", ex);
pingQueueMgr.removeQueueEntry(pingQueueEntry);
// TODO: mark ping target invalid?
}
}
}