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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 = PatternConverter.CATEGORY)
    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  }