slf4j-api/src/main/java/org/slf4j/helpers/BasicMarkerFactory.java

/**
 * Copyright (c) 2004-2011 QOS.ch
 * All rights reserved.
 *
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 *
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 *
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */
package org.slf4j.helpers;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.slf4j.IMarkerFactory;
import org.slf4j.Marker;

/**
 * An almost trivial implementation of the {@link IMarkerFactory}
 * interface which creates {@link BasicMarker} instances.
 * 
 * <p>Simple logging systems can conform to the SLF4J API by binding
 * {@link org.slf4j.MarkerFactory} with an instance of this class.
 *
 * @author Ceki G&uuml;lc&uuml;
 */
public class BasicMarkerFactory implements IMarkerFactory {

    private final ConcurrentMap<String, Marker> markerMap = new ConcurrentHashMap<>();

    /**
     * Regular users should <em>not</em> create
     * <code>BasicMarkerFactory</code> instances. <code>Marker</code>
     * instances can be obtained using the static {@link
     * org.slf4j.MarkerFactory#getMarker} method.
     */
    public BasicMarkerFactory() {
    }

    /**
     * Manufacture a {@link BasicMarker} instance by name. If the instance has been 
     * created earlier, return the previously created instance. 
     * 
     * @param name the name of the marker to be created
     * @return a Marker instance
     */
    public Marker getMarker(String name) {
        if (name == null) {
            throw new IllegalArgumentException("Marker name cannot be null");
        }

        Marker marker = markerMap.get(name);
        if (marker == null) {
            marker = new BasicMarker(name);
            Marker oldMarker = markerMap.putIfAbsent(name, marker);
            if (oldMarker != null) {
                marker = oldMarker;
            }
        }
        return marker;
    }

    /**
     * Does the name marked already exist?
     */
    public boolean exists(String name) {
        if (name == null) {
            return false;
        }
        return markerMap.containsKey(name);
    }

    public boolean detachMarker(String name) {
        if (name == null) {
            return false;
        }
        return (markerMap.remove(name) != null);
    }

    public Marker getDetachedMarker(String name) {
        return new BasicMarker(name);
    }

}