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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.util.concurrent.atomic.AtomicLong;
    20
    21  import org.apache.logging.log4j.core.LogEvent;
    22  import org.apache.logging.log4j.core.config.plugins.Plugin;
    23
    24
    25  /**
    26   * Formats the event sequence number.
    27   */
    28  @Plugin(name = "SequenceNumberPatternConverter", category = "Converter")
    29  @ConverterKeys({ "sn", "sequenceNumber" })
    30  public final class SequenceNumberPatternConverter extends LogEventPatternConverter {
    31
    32      private static final AtomicLong SEQUENCE = new AtomicLong();
    33
    34      /**
    35       * Singleton.
    36       */
    37      private static final SequenceNumberPatternConverter INSTANCE =
    38          new SequenceNumberPatternConverter();
    39
    40      /**
    41       * Private constructor.
    42       */
    43      private SequenceNumberPatternConverter() {
    44          super("Sequence Number", "sn");
    45      }
    46
    47      /**
    48       * Obtains an instance of SequencePatternConverter.
    49       *
    50       * @param options options, currently ignored, may be null.
    51       * @return instance of SequencePatternConverter.
    52       */
    53      public static SequenceNumberPatternConverter newInstance(
    54          final String[] options) {
    55          return INSTANCE;
    56      }
    57
    58      /**
    59       * {@inheritDoc}
    60       */
    61      @Override
    62      public void format(final LogEvent event, final StringBuilder toAppendTo) {
    63          toAppendTo.append(Long.toString(SEQUENCE.incrementAndGet()));
    64      }
    65  }