Markers in Logback

Question

So I'm really new to Logback and have a question about how I should go about implementing something.

Say I have two appenders: and I want appender "a" to accept markers that are only 1 or 2, but I want appender "b" to accept markers that are only 1 or 3. What type of filter should I use? Is there anything for this?

Answer 1

One option is to use the Event Evaluator. You can also write your own Filter; in fact the built-in example does (almost) what you want.

The filter below should be close to what you are looking for.

import ch.qos.logback.classic.spi.LoggingEvent;
import ch.qos.logback.core.filter.Filter;
import ch.qos.logback.core.spi.FilterReply;
import org.slf4j.Marker;
import org.slf4j.MarkerFactory;

import java.util.ArrayList;
import java.util.List;

public class OneTwoMarkerFilter extends Filter
{
    private final List<Marker> markers = new ArrayList<Marker>();

    public MarkerFilter()
    {
        markers.add(MarkerFactory.getMarker("1"));
        markers.add(MarkerFactory.getMarker("2"));
    }

    @Override
    public FilterReply decide(Object event)
    {
        if (!isStarted())
        {
            return FilterReply.NEUTRAL;
        }

        LoggingEvent logEvent = (LoggingEvent) event;

        Marker eventMarker = logEvent.getMarker();

        if (eventMarker != null && markers.contains(eventMarker))
        {
            return FilterReply.NEUTRAL;
        }
        else
        {
            return FilterReply.DENY;
        }
    }
}

Please note I have not tested this.

Answer 2

Uriah's answer is great!

And I think to extend AbstractMatcherFilter may be a better beginning.

public class MarkerFilter extends AbstractMatcherFilter<ILoggingEvent> {
    private Marker markerToMatch = null;
    @Override
    public void start() {
        if (null != this.markerToMatch)
            super.start();
         else
            addError("!!! no marker yet !!!");
    }
    @Override
    public FilterReply decide(ILoggingEvent event) {
        Marker marker = event.getMarker();
        if (!isStarted())
            return FilterReply.NEUTRAL;
        if (null == marker)
            return onMismatch;
        if (markerToMatch.contains(marker))
            return onMatch;
        return onMismatch;
    }
    public void setMarker(String markerStr) {
        if(null != markerStr)
            markerToMatch = MarkerFactory.getMarker(markerStr);
    }
}

<filter class="your.pkg.MarkerFilter">
    <marker>YOUR_MARKER</marker>
    <onMatch>ACCEPT</onMatch>
    <onMismatch>DENY</onMismatch>
</filter>

You should override decide in AbstractMatcherFilter, just replace markerToMatch.contains(marker) with your logic, and decide which marker is matched(i.e., accepted).

usage:

log.info(MarkerFacotry.getMarker("YOUR_MARKER"), "---msg---");