001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache license, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the license for the specific language governing permissions and
015     * limitations under the license.
016     */
017    package org.apache.logging.log4j.core.pattern;
018    
019    import java.lang.management.ManagementFactory;
020    
021    import org.apache.logging.log4j.core.LogEvent;
022    import org.apache.logging.log4j.core.config.plugins.Plugin;
023    
024    /**
025     * Returns the relative time in milliseconds since JVM Startup.
026     */
027    @Plugin(name = "RelativeTimePatternConverter", category = PatternConverter.CATEGORY)
028    @ConverterKeys({ "r", "relative" })
029    public class RelativeTimePatternConverter extends LogEventPatternConverter {
030        /**
031         * Cached formatted timestamp.
032         */
033        private long lastTimestamp = Long.MIN_VALUE;
034        private final long startTime = ManagementFactory.getRuntimeMXBean().getStartTime();
035        private String relative;
036    
037        /**
038         * Private constructor.
039         */
040        public RelativeTimePatternConverter() {
041            super("Time", "time");
042        }
043    
044        /**
045         * Obtains an instance of RelativeTimePatternConverter.
046         *
047         * @param options options, currently ignored, may be null.
048         * @return instance of RelativeTimePatternConverter.
049         */
050        public static RelativeTimePatternConverter newInstance(
051            final String[] options) {
052            return new RelativeTimePatternConverter();
053        }
054    
055        /**
056         * {@inheritDoc}
057         */
058        @Override
059        public void format(final LogEvent event, final StringBuilder toAppendTo) {
060            final long timestamp = event.getTimeMillis();
061    
062            synchronized (this) {
063                if (timestamp != lastTimestamp) {
064                    lastTimestamp = timestamp;
065                    relative = Long.toString(timestamp - startTime);
066                }
067            }
068            toAppendTo.append(relative);
069        }
070    }