log4j set class and method summary length in pattern

Question

Currently I have sth like:

%d{HH:mm:ss.SSS} | %-5.5p | %-15.15t | %-30.70C.%-5.20M:%-3.5L | %msg%n

but this makes full.class.Name.method:line of different lengths - is it possible to make calss.method:line of fixed length ?

I would like sth like

%-60.60CML (but this of course doesn't work)

I would like to make calss.method.line have the same length on all log lines. (so as the actual message started in the same place)

Is it possible ?

Other wors said, is it possible to format multiple conversion characters with one conversion specifier ? Looking at

https://logging.apache.org/log4j/1.2/apidocs/org/apache/log4j/PatternLayout.html

Each conversion specifier starts with a percent sign (%) and is followed by optional format modifiers and a conversion character. The conversion character specifies the type of data

The pattern parser knows when it has reached the end of a conversion specifier when it reads a conversion character.

It's now written about multiple conversion characters, so maybe it's simply not possible ?

---

As @Remko Popma explained, what I want is not possible now:

No, each modifier applies to one conversion. But Log4j could add a new converter that means what you want. You can propose such a new converter on the mailing list or issue tracker.

I created issue: https://issues.apache.org/jira/browse/LOG4J2-2339

Answer 1

Based on help from @Remko-Popma

https://issues.apache.org/jira/browse/LOG4J2-2339

below is what worked for me:

<property name="pattern">%d{yyyy-MM-dd HH:mm:ss.SSS} | %-5.5p | %-15.15t | %-70.70CML | %-10.70X | %msg%n</property>

import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.pattern.ConverterKeys;
import org.apache.logging.log4j.core.pattern.NamePatternConverter;
import org.apache.logging.log4j.core.pattern.PatternConverter;

@Plugin(name = "ClassMethodLinePatternConverter", category = PatternConverter.CATEGORY)
@ConverterKeys({"CML", "classmethodline"})
public class ClassMethodLinePatternConverter extends NamePatternConverter {

    private static final String NA = "?";

    private ClassMethodLinePatternConverter(
        final String[] options) {
        super("Class Name", "class name", options);
    }

    public static ClassMethodLinePatternConverter newInstance(final String[] options) {
        return new ClassMethodLinePatternConverter(options);
    }

    /**
     * Format a logging event.
     *
     * @param event      event to format.
     * @param toAppendTo string buffer to which class name, method name and line will be appended.
     */
    @Override
    public void format(final LogEvent event, final StringBuilder toAppendTo) {
        final StackTraceElement element = event.getSource();
        if (element == null) {
            toAppendTo.append(NA);
        } else {
          toAppendTo.append(element.getClassName()).append(".").append(element.getMethodName()).append(":").append(element.getLineNumber());
        }
    }

}