MessageWriter.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.pinterest.secor.writer;

import com.pinterest.secor.common.FileRegistry;
import com.pinterest.secor.common.LogFilePath;
import com.pinterest.secor.common.OffsetTracker;
import com.pinterest.secor.common.SecorConfig;
import com.pinterest.secor.common.TopicPartition;
import com.pinterest.secor.io.FileWriter;
import com.pinterest.secor.io.KeyValue;
import com.pinterest.secor.message.Message;
import com.pinterest.secor.message.ParsedMessage;
import com.pinterest.secor.util.CompressionUtil;
import com.pinterest.secor.util.IdUtil;
import com.pinterest.secor.util.StatsUtil;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;

/**
 * Message writer appends Kafka messages to local log files.
 *
 * @author Pawel Garbacki (pawel@pinterest.com)
 */
public class MessageWriter {
    private static final Logger LOG = LoggerFactory.getLogger(MessageWriter.class);

    protected SecorConfig mConfig;
    protected OffsetTracker mOffsetTracker;
    protected FileRegistry mFileRegistry;
    protected String mFileExtension;
    protected CompressionCodec mCodec;
    protected String mLocalPrefix;
    protected final int mGeneration;

    public MessageWriter(SecorConfig config, OffsetTracker offsetTracker,
                         FileRegistry fileRegistry) throws Exception {
        mConfig = config;
        mOffsetTracker = offsetTracker;
        mFileRegistry = fileRegistry;
        if (mConfig.getCompressionCodec() != null && !mConfig.getCompressionCodec().isEmpty()) {
            mCodec = CompressionUtil.createCompressionCodec(mConfig.getCompressionCodec());
            mFileExtension = mCodec.getDefaultExtension();
        }
        if (mConfig.getFileExtension() != null && !mConfig.getFileExtension().isEmpty()) {
            mFileExtension = mConfig.getFileExtension();
        } else if (mFileExtension == null){
            mFileExtension = "";
        }
        
        mLocalPrefix = mConfig.getLocalPath() + '/' + IdUtil.getLocalMessageDir();
        mGeneration = mConfig.getGeneration();
    }

    public void adjustOffset(Message message) throws IOException {
        TopicPartition topicPartition = new TopicPartition(message.getTopic(),
                                                           message.getKafkaPartition());
        long lastSeenOffset = mOffsetTracker.getLastSeenOffset(topicPartition);
        if (message.getOffset() != lastSeenOffset + 1) {
            StatsUtil.incr("secor.consumer_rebalance_count." + topicPartition.getTopic());
            // There was a rebalancing event since we read the last message.
            LOG.debug("offset of message {} does not follow sequentially the last seen offset {}. " +
                            "Deleting files in topic {} partition {}",
                    message, lastSeenOffset, topicPartition.getTopic(), topicPartition.getPartition());

            mFileRegistry.deleteTopicPartition(topicPartition);
        }
        mOffsetTracker.setLastSeenOffset(topicPartition, message.getOffset());
    }

    public void write(ParsedMessage message) throws Exception {
        TopicPartition topicPartition = new TopicPartition(message.getTopic(),
                                                           message.getKafkaPartition());
        long offset = mOffsetTracker.getAdjustedCommittedOffsetCount(topicPartition);
        LogFilePath path = new LogFilePath(mLocalPrefix, mGeneration, offset, message,
        		mFileExtension);
        FileWriter writer = mFileRegistry.getOrCreateWriter(path, mCodec);
        writer.write(new KeyValue(message.getOffset(), message.getKafkaKey(), message.getPayload()));
        LOG.debug("appended message {} to file {}.  File length {}",
                  message, path, writer.getLength());
    }
}