OffsetTracker.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.common;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.HashMap;

/**
 * Offset tracker stores offset related metadata.
 *
 * @author Pawel Garbacki (pawel@pinterest.com)
 */
public class OffsetTracker {
    private static final Logger LOG = LoggerFactory.getLogger(OffsetTracker.class);

    private HashMap<TopicPartition, Long> mLastSeenOffset;
    private HashMap<TopicPartition, Long> mFirstSeendOffset;
    private HashMap<TopicPartition, Long> mCommittedOffsetCount;

    public OffsetTracker() {
        mLastSeenOffset = new HashMap<TopicPartition, Long>();
        mCommittedOffsetCount = new HashMap<TopicPartition, Long>();
        mFirstSeendOffset = new HashMap<TopicPartition, Long>();
    }

    public long getLastSeenOffset(TopicPartition topicPartition) {
        Long offset = mLastSeenOffset.get(topicPartition);
        if (offset == null) {
            return -2;
        }
        return offset.longValue();
    }

    public long setLastSeenOffset(TopicPartition topicPartition, long offset) {
        long lastSeenOffset = getLastSeenOffset(topicPartition);
        mLastSeenOffset.put(topicPartition, offset);
        if (lastSeenOffset + 1 != offset) {
            if (lastSeenOffset >= 0) {
                LOG.warn("offset for topic {} partition {} changed from {} to {}",
                        topicPartition.getTopic(),topicPartition.getPartition(),lastSeenOffset, offset);
            } else {
                LOG.info("starting to consume topic {} partition {} from offset {}",
                        topicPartition.getTopic(),topicPartition.getPartition(),offset);
            }
        }
        if (mFirstSeendOffset.get(topicPartition) == null) {
            mFirstSeendOffset.put(topicPartition, offset);
        }
        return lastSeenOffset;
    }

    public long getTrueCommittedOffsetCount(TopicPartition topicPartition) {
        Long committedOffsetCount = mCommittedOffsetCount.get(topicPartition);
        if (committedOffsetCount == null) {
            return -1L;
        }
        return committedOffsetCount;
    }

    public long getAdjustedCommittedOffsetCount(TopicPartition topicPartition) {
        long trueCommittedOffsetCount = getTrueCommittedOffsetCount(topicPartition);
        if (trueCommittedOffsetCount == -1L) {
            Long firstSeenOffset = mFirstSeendOffset.get(topicPartition);
            if (firstSeenOffset != null) {
                return firstSeenOffset;
            }
        }
        return trueCommittedOffsetCount;
    }

    public long setCommittedOffsetCount(TopicPartition topicPartition, long count) {
        long trueCommittedOffsetCount = getTrueCommittedOffsetCount(topicPartition);
        // Committed offsets should never go back.
        assert trueCommittedOffsetCount <= count: Long.toString(trueCommittedOffsetCount) +
                " <= " + count;
        mCommittedOffsetCount.put(topicPartition, count);
        return trueCommittedOffsetCount;
    }
}