Logback NON-turbo filter checks whether the marker in the event matches the marker

MarkerFilter.java

/* MarkerFilter.java
 * Logback NON-turbo filter checks whether the marker in the event matches the marker.
 *
 * Copyright (C) 2011 TAKUMAKei
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.blogspot.takumakei.gist;

import org.slf4j.Marker;
import org.slf4j.MarkerFactory;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.filter.AbstractMatcherFilter;
import ch.qos.logback.core.spi.FilterReply;

/**
 * Non-turbo filter checks whether the marker in the event matches the marker specified by user.
 */
public class MarkerFilter extends AbstractMatcherFilter<ILoggingEvent> {
	protected Marker markerToMatch;

	/**
	 * Make a decision based on a logging event passed as an argument. 
	 */
	@Override
	public FilterReply decide(ILoggingEvent event) {
		if (!isStarted()) { // this means no marker property specified
			return FilterReply.NEUTRAL;
		}

		final Marker eventMarker = event.getMarker();
		if (eventMarker == null) { // the event has no marker
			return onMismatch;
		}

		if (markerToMatch.equals(eventMarker) || markerToMatch.contains(eventMarker)) {
			// MATCH!
			// this filter's marker exactly equals event's marker
			// or
			// this filter's marker contains event's marker.
			return onMatch;
		}

		// otherwise, mismatch
		return onMismatch;
	}

	@Override
	public void start() {
		if (null == markerToMatch) {
			addError("The marker property must be set for ["+getName()+"].");
			return;
		}
		super.start();
		addInfo("Filter["+getName()+"] matches the marker ["+markerToMatch.getName()
				+"], returns ["+onMatch+"] on match, ["+onMismatch+"] on mismatch");
	}

	/**
	 * The marker to match in the event.
	 * @param markerName
	 */
	public void setMarker(String markerName) {
		markerToMatch = MarkerFactory.getMarker(markerName);
	}
}