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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements. See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache license, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License. You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the license for the specific language governing permissions and
15   * limitations under the license.
16   */
17  package org.apache.logging.log4j.core.pattern;
18  
19  import java.lang.management.ManagementFactory;
20  
21  import org.apache.logging.log4j.core.LogEvent;
22  import org.apache.logging.log4j.core.config.plugins.Plugin;
23  
24  /**
25   * Returns the relative time in milliseconds since JVM Startup.
26   */
27  @Plugin(name = "RelativeTimePatternConverter", category = "Converter")
28  @ConverterKeys({ "r", "relative" })
29  public class RelativeTimePatternConverter extends LogEventPatternConverter {
30      /**
31       * Cached formatted timestamp.
32       */
33      private long lastTimestamp = Long.MIN_VALUE;
34      private final long startTime = ManagementFactory.getRuntimeMXBean().getStartTime();
35      private String relative;
36  
37      /**
38       * Private constructor.
39       */
40      public RelativeTimePatternConverter() {
41          super("Time", "time");
42      }
43  
44      /**
45       * Obtains an instance of RelativeTimePatternConverter.
46       *
47       * @param options options, currently ignored, may be null.
48       * @return instance of RelativeTimePatternConverter.
49       */
50      public static RelativeTimePatternConverter newInstance(
51          final String[] options) {
52          return new RelativeTimePatternConverter();
53      }
54  
55      /**
56       * {@inheritDoc}
57       */
58      @Override
59      public void format(final LogEvent event, final StringBuilder toAppendTo) {
60          final long timestamp = event.getTimeMillis();
61  
62          synchronized (this) {
63              if (timestamp != lastTimestamp) {
64                  lastTimestamp = timestamp;
65                  relative = Long.toString(timestamp - startTime);
66              }
67          }
68          toAppendTo.append(relative);
69      }
70  }