001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements. See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache license, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License. You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the license for the specific language governing permissions and
015     * limitations under the license.
016     */
017    package org.apache.logging.log4j.core.async;
018    
019    import com.lmax.disruptor.Sequence;
020    import com.lmax.disruptor.SequenceReportingEventHandler;
021    
022    /**
023     * This event handler gets passed messages from the RingBuffer as they become
024     * available. Processing of these messages is done in a separate thread,
025     * controlled by the {@code Executor} passed to the {@code Disruptor}
026     * constructor.
027     */
028    public class RingBufferLogEventHandler implements
029            SequenceReportingEventHandler<RingBufferLogEvent> {
030    
031        private static final int NOTIFY_PROGRESS_THRESHOLD = 50;
032        private Sequence sequenceCallback;
033        private int counter;
034    
035        @Override
036        public void setSequenceCallback(final Sequence sequenceCallback) {
037            this.sequenceCallback = sequenceCallback;
038        }
039    
040        @Override
041        public void onEvent(final RingBufferLogEvent event, final long sequence,
042                final boolean endOfBatch) throws Exception {
043            event.execute(endOfBatch);
044            event.clear();
045    
046            // notify the BatchEventProcessor that the sequence has progressed.
047            // Without this callback the sequence would not be progressed
048            // until the batch has completely finished.
049            if (++counter > NOTIFY_PROGRESS_THRESHOLD) {
050                sequenceCallback.set(sequence);
051                counter = 0;
052            }
053        }
054    
055    }