/*
* Copyright (C) The Apache Software Foundation. All rights reserved.
*
* This software is published under the terms of the Apache Software License
* version 1.1, a copy of which has been included with this distribution in
* the LICENSE.txt file.
*/
package org.apache.log4j.varia;
import org.apache.log4j.spi.ErrorHandler;
import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.Appender;
import org.apache.log4j.Logger;
import org.apache.log4j.helpers.LogLog;
import java.util.Vector;
/**
*
* The <code>FallbackErrorHandler</code> implements the ErrorHandler
* interface such that a secondary appender may be specified. This
* secondary appender takes over if the primary appender fails for
* whatever reason.
*
* <p>The error message is printed on <code>System.err</code>, and
* logged in the new secondary appender.
*
* @author Ceki Gücü
* */
public class FallbackErrorHandler implements ErrorHandler {
Appender backup;
Appender primary;
Vector loggers;
public FallbackErrorHandler() {
}
/**
<em>Adds</em> the logger passed as parameter to the list of
loggers that we need to search for in case of appender failure.
*/
public
void setLogger(Logger logger) {
LogLog.debug("FB: Adding logger [" + logger.getName() + "].");
if(loggers == null) {
loggers = new Vector();
}
loggers.addElement(logger);
}
/**
No options to activate.
*/
public
void activateOptions() {
}
/**
Prints the message and the stack trace of the exception on
<code>System.err</code>. */
public
void error(String message, Exception e, int errorCode) {
error(message, e, errorCode, null);
}
/**
Prints the message and the stack trace of the exception on
<code>System.err</code>.
*/
public
void error(String message, Exception e, int errorCode, LoggingEvent event) {
LogLog.debug("FB: The following error reported: " + message, e);
LogLog.debug("FB: INITIATING FALLBACK PROCEDURE.");
for(int i = 0; i < loggers.size(); i++) {
Logger l = (Logger) loggers.elementAt(i);
LogLog.debug("FB: Searching for ["+primary.getName()+"] in logger ["
+l.getName() + "].");
//if(l.isAttached(primary)) {
LogLog.debug("FB: Replacing ["+primary.getName()+"] by ["
+ backup.getName() + "] in logger ["+ l.getName() +"].");
l.removeAppender(primary);
LogLog.debug("FB: Adding appender ["+backup.getName()+"] to logger "
+ l.getName());
l.addAppender(backup);
}
}
/**
Print a the error message passed as parameter on
<code>System.err</code>.
*/
public
void error(String message) {
//if(firstTime) {
//LogLog.error(message);
//firstTime = false;
//}
}
/**
The appender to which this error handler is attached.
*/
public
void setAppender(Appender primary) {
LogLog.debug("FB: Setting primary appender to [" + primary.getName() + "].");
this.primary = primary;
}
/**
Set the backup appender.
*/
public
void setBackupAppender(Appender backup) {
LogLog.debug("FB: Setting backup appender to [" + backup.getName() + "].");
this.backup = backup;
}
}
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