contrib/kafka/src/java/com/twitter/heron/spouts/kafka/KafkaMetric.java

/*
 * Copyright 2016 Twitter, Inc.
 *
 * Licensed 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.twitter.heron.spouts.kafka;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

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

import backtype.storm.metric.api.ICombiner;
import backtype.storm.metric.api.IMetric;

import kafka.api.OffsetRequest;

public final class KafkaMetric {
  // Utility class. Not to be instantiated.
  private KafkaMetric() {
  }

  // MaxMetric is used for max latency type metrics.
  public static class MaxMetric implements ICombiner<Long> {
    @Override
    public Long identity() {
      return new Long(0);
    }

    @Override
    public Long combine(Long l1, Long l2) {
      if (l1 == null) {
        return l2;
      }
      if (l2 == null) {
        return l1;
      }
      return Math.max(l1, l2);
    }
  }

  // PartitionManager metrics map will be connected to this
  public static class PartitionMetric implements IMetric {
    public static final Logger LOG = LoggerFactory.getLogger(KafkaMetric.PartitionMetric.class);
    private PartitionCoordinator coordinator;
    public PartitionMetric(PartitionCoordinator coordinator) {
      this.coordinator = coordinator;
    }

    @Override
    public Object getValueAndReset() {
      Map ret = new HashMap();
      try {
        List<PartitionManager> pms = coordinator.getMyManagedPartitions();
        for (PartitionManager pm : pms) {
          ret.putAll(pm.getMetricsDataMap());
        }
      } catch (Exception e) {
        LOG.warn("Metrics Tick: Exception when computing partition metric.", e);
        ret.put(String.format("metricException/%s", e.getClass().getSimpleName()), 1);
      }
      return ret;
    }
  }

  // OffsetMetric is used for storing kafka partition offset related data.
  public static class OffsetMetric implements IMetric {
    public static final Logger LOG = LoggerFactory.getLogger(KafkaMetric.OffsetMetric.class);
    private long lastCalculatedTotalSpoutLag = 0;
    private PartitionCoordinator coordinator;

    /** Ctor */
    public void setCoordinator(PartitionCoordinator zkCoordinator) {
      coordinator = zkCoordinator;
    }

    public long getLastCalculatedTotalSpoutLag() {
      return lastCalculatedTotalSpoutLag;
    }

    @Override
    public Object getValueAndReset() {
      long totalSpoutLag = 0;
      long totalLatestTimeOffset = 0;
      long totalLatestEmittedOffset = 0;
      long totalLatestCommittedOffset = 0;
      HashMap ret = new HashMap();
      try {
        List<PartitionManager> managedPartitions = coordinator.getMyManagedPartitions();
        for (PartitionManager partitionManager: managedPartitions) {
          long latestTimeOffset =
              partitionManager.getOffsetForTimestamp(OffsetRequest.LatestTime());
          long latestEmittedOffset = partitionManager.lastCompletedOffset();
          long latestCommittedOffset = partitionManager.getCommitedTo();
          long spoutLag = latestTimeOffset - latestEmittedOffset;
          totalSpoutLag += spoutLag;
          totalLatestTimeOffset += latestTimeOffset;
          totalLatestEmittedOffset += latestEmittedOffset;
          totalLatestCommittedOffset += latestCommittedOffset;
          String strPartitionId = partitionManager.getPartitionId().toString();
          ret.put(String.format("%s/spoutLag", strPartitionId), spoutLag);
          ret.put(String.format("%s/latestTime", strPartitionId), latestTimeOffset);
          ret.put(String.format("%s/latestEmittedOffset", strPartitionId), latestEmittedOffset);
          ret.put(String.format("%s/latestCommittedOffset", strPartitionId), latestCommittedOffset);
        }
        ret.put("totalSpoutLag", totalSpoutLag);
        ret.put("totalLatestTime", totalLatestTimeOffset);
        ret.put("totalLatestEmittedOffset", totalLatestEmittedOffset);
        ret.put("totalLatestCommittedOffset", totalLatestCommittedOffset);
        lastCalculatedTotalSpoutLag = totalSpoutLag;
      } catch (Exception e) {
        LOG.warn("Metrics Tick: Exception when computing kafkaOffset metric.", e);
        ret.put(String.format("metricException/%s", e.getClass().getSimpleName()), 1);
      }
      return ret;
    }
  }
}