content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.metrics.aggregator;
  
  import alluxio.metrics.Metric;
  import alluxio.metrics.MultiValueMetricsAggregator;
  
  import com.google.common.base.Preconditions;
  
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  
  /**
   * An aggregator that aggregates the metrics into multiple values based on a single tag of the
   * metric.
   */
  public class SingleTagValueAggregator implements MultiValueMetricsAggregator {
    private final String mAggregationName;
    private final String mMetricName;
    private final String mTagName;
    /** Cached aggregated metric values. */
    private Map<String, Long> mAggregates;
  
    /**
     * Constructs a new instance of {@link SingleTagValueAggregator}.
     *
     * @param aggregationName the aggregated metric name
     * @param metricName metric name
     * @param tagName tag name
     */
    public SingleTagValueAggregator(String aggregationName,
        String metricName, String tagName) {
      Preconditions.checkNotNull(aggregationName, "aggregationName");
      Preconditions.checkNotNull(metricName, "metricName");
      Preconditions.checkNotNull(tagName, "tagName");
      mAggregationName = aggregationName;
      mMetricName = metricName;
      mTagName = tagName;
      mAggregates = new HashMap<>();
    }
  
    @Override
    public String getFilterMetricName() {
      return mMetricName;
    }
  
    @Override
    public Map<String, Long> updateValues(Set<Metric> set) {
      Map<String, Long> updated = new HashMap<>();
      for (Metric metric : set) {
        Map<String, String> tags = metric.getTags();
        if (tags.containsKey(mTagName)) {
          String ufsName =
              Metric.getMetricNameWithTags(mAggregationName, mTagName, tags.get(mTagName));
          long value = updated.getOrDefault(ufsName, 0L);
          updated.put(ufsName, (long) (value + metric.getValue()));
        }
      }
      synchronized (this) {
        mAggregates = updated;
      }
      return Collections.unmodifiableMap(mAggregates);
    }
  
    @Override
    public long getValue(String name) {
      return mAggregates.getOrDefault(name, 0L);
    }
  }
  