content: /*
   * 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 org.apache.beam.runners.dataflow.worker;
  
  import java.util.concurrent.atomic.AtomicReference;
  import org.apache.beam.runners.core.metrics.DirtyState;
  import org.apache.beam.runners.core.metrics.DistributionCell;
  import org.apache.beam.runners.core.metrics.DistributionData;
  import org.apache.beam.runners.core.metrics.MetricCell;
  import org.apache.beam.sdk.metrics.Distribution;
  import org.apache.beam.sdk.metrics.MetricName;
  
  /**
   * A version of {@link DistributionCell} that supports extracting the delta and clearing it out.
   *
   * <p>TODO: Modify the Beam DistributionCell to support extracting the delta.
   */
  public class DeltaDistributionCell implements Distribution, MetricCell<DistributionData> {
    private final AtomicReference<DistributionData> value =
        new AtomicReference<>(DistributionData.EMPTY);
    private final MetricName name;
  
    public DeltaDistributionCell(MetricName name) {
      this.name = name;
    }
  
    /** Increment the distribution by the given amount. */
    @Override
    public void update(long n) {
      update(DistributionData.singleton(n));
    }
  
    void update(DistributionData data) {
      DistributionData original;
      do {
        original = value.get();
      } while (!value.compareAndSet(original, original.combine(data)));
    }
  
    @Override
    public void reset() {
      value.set(DistributionData.EMPTY);
    }
  
    @Override
    public void update(long sum, long count, long min, long max) {
      update(DistributionData.create(sum, count, min, max));
    }
  
    @Override
    public DirtyState getDirty() {
      throw new UnsupportedOperationException(
          String.format("%s doesn't support the getDirty", getClass().getSimpleName()));
    }
  
    @Override
    public DistributionData getCumulative() {
      throw new UnsupportedOperationException("getCumulative is not supported by Streaming Metrics");
    }
  
    public DistributionData getAndReset() {
      return value.getAndUpdate(unused -> DistributionData.EMPTY);
    }
  
    @Override
    public MetricName getName() {
      return name;
    }
  }
  