package azkaban.utils;
import org.apache.log4j.PatternLayout;
import org.apache.log4j.spi.LoggingEvent;
/**
* When we use the log4j Kafka appender, it seems that the appender simply does not log the stack trace anywhere
* Seeing as the stack trace is a very important piece of information, we create our own PatternLayout class that
* appends the stack trace to the log message that reported it, so that all the information regarding that error
* can be found one in place.
*/
public class PatternLayoutEscaped extends PatternLayout {
public PatternLayoutEscaped(String s) {
super(s);
}
public PatternLayoutEscaped() {
super();
}
@Override
public String format(final LoggingEvent event) {
if (event.getMessage() instanceof String) {
return super.format(appendStackTraceToEvent(event));
}
return super.format(event);
}
/**
* Create a copy of event, but append a stack trace to the message (if it exists).
* Then it escapes the backslashes, tabs, newlines and quotes in its message as we are sending it as JSON and we
* don't want any corruption of the JSON object.
*/
private LoggingEvent appendStackTraceToEvent(LoggingEvent event) {
String message = event.getMessage().toString();
// If there is a stack trace available, print it out
if (event.getThrowableInformation() != null) {
String[] s = event.getThrowableStrRep();
for (String line: s) {
message += "\n" + line;
}
}
message = message
.replace("\\", "\\\\")
.replace("\n", "\\n")
.replace("\"", "\\\"")
.replace("\t", "\\t");
Throwable throwable = event.getThrowableInformation() == null ? null
: event.getThrowableInformation().getThrowable();
return new LoggingEvent(event.getFQNOfLoggerClass(),
event.getLogger(),
event.getTimeStamp(),
event.getLevel(),
message,
throwable);
}
}