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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.LifecycleAware;
20  import com.lmax.disruptor.Sequence;
21  import com.lmax.disruptor.SequenceReportingEventHandler;
22  
23  /**
24   * This event handler gets passed messages from the RingBuffer as they become
25   * available. Processing of these messages is done in a separate thread,
26   * controlled by the {@code Executor} passed to the {@code Disruptor}
27   * constructor.
28   */
29  public class RingBufferLogEventHandler implements
30          SequenceReportingEventHandler<RingBufferLogEvent>, LifecycleAware {
31  
32      private static final int NOTIFY_PROGRESS_THRESHOLD = 50;
33      private Sequence sequenceCallback;
34      private int counter;
35      private long threadId = -1;
36  
37      @Override
38      public void setSequenceCallback(final Sequence sequenceCallback) {
39          this.sequenceCallback = sequenceCallback;
40      }
41  
42      @Override
43      public void onEvent(final RingBufferLogEvent event, final long sequence,
44              final boolean endOfBatch) throws Exception {
45          event.execute(endOfBatch);
46          event.clear();
47  
48          // notify the BatchEventProcessor that the sequence has progressed.
49          // Without this callback the sequence would not be progressed
50          // until the batch has completely finished.
51          if (++counter > NOTIFY_PROGRESS_THRESHOLD) {
52              sequenceCallback.set(sequence);
53              counter = 0;
54          }
55      }
56  
57      /**
58       * Returns the thread ID of the background consumer thread, or {@code -1} if the background thread has not started
59       * yet.
60       * @return the thread ID of the background consumer thread, or {@code -1}
61       */
62      public long getThreadId() {
63          return threadId;
64      }
65  
66      @Override
67      public void onStart() {
68          threadId = Thread.currentThread().getId();
69      }
70  
71      @Override
72      public void onShutdown() {
73      }
74  }