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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.async;
    18
    19  import com.lmax.disruptor.Sequence;
    20  import com.lmax.disruptor.SequenceReportingEventHandler;
    21
    22  /**
    23   * This event handler gets passed messages from the RingBuffer as they become
    24   * available. Processing of these messages is done in a separate thread,
    25   * controlled by the {@code Executor} passed to the {@code Disruptor}
    26   * constructor.
    27   */
    28  public class RingBufferLogEventHandler implements
    29          SequenceReportingEventHandler<RingBufferLogEvent> {
    30
    31      private static final int NOTIFY_PROGRESS_THRESHOLD = 50;
    32      private Sequence sequenceCallback;
    33      private int counter;
    34
    35      @Override
    36      public void setSequenceCallback(final Sequence sequenceCallback) {
    37          this.sequenceCallback = sequenceCallback;
    38      }
    39
    40      @Override
    41      public void onEvent(final RingBufferLogEvent event, final long sequence,
    42              final boolean endOfBatch) throws Exception {
    43          event.execute(endOfBatch);
    44          event.clear();
    45
    46          // notify the BatchEventProcessor that the sequence has progressed.
    47          // Without this callback the sequence would not be progressed
    48          // until the batch has completely finished.
    49          if (++counter > NOTIFY_PROGRESS_THRESHOLD) {
    50              sequenceCallback.set(sequence);
    51              counter = 0;
    52          }
    53      }
    54
    55  }