Filtering out events that have no Marker

Question

Markers in Logback can be very useful to filter events by their context (provided by the marker). Usually I use a TurboFilter to get rid of logging events that have (or don't have) a certain Marker associated with them:

<turboFilter class="ch.qos.logback.classic.turbo.MarkerFilter">
    <Marker>Data</Marker>
    <OnMatch>DENY</OnMatch>
</turboFilter>

Now though, I have a special use case in which I want to filter out all logging events that have no Marker associated with them. It is probably possible by providing a chain of TurboFilters for each of the Markers used that allow on match and pass on if not, but that might end up a rather large and tedious bit of configuration that has to be updated each time a new Marker is introduced.

Long story short: Is there a simple way to filter out all Logback logging events that do not come with a Marker?

Answer 1

Since there is no way to achieve this out of the box, I ended up implementing my own Filter, which is simple enough for this use case:

public class NoMarkerFilter extends MatchingFilter {

@Override
public FilterReply decide(final Marker marker, final Logger logger, final Level level, final String format,
        final Object[] params, final Throwable t) {
    if (!isStarted()) {
        return FilterReply.NEUTRAL;
    }

    if (marker == null) {
        return onMatch;
    }
    return onMismatch;
}

It can then be used in the configuration like this:

<turboFilter class="com.example.NoMarkerFilter">
    <OnMatch>DENY</OnMatch>
</turboFilter>