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.sdk.metrics;
  
  import com.google.auto.value.AutoValue;
  import com.google.auto.value.extension.memoized.Memoized;
  import java.io.Serializable;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /** Metrics are keyed by the step name they are associated with and the name of the metric. */
  @AutoValue
  public abstract class MetricKey implements Serializable {
  
    /** The step name that is associated with this metric or Null if none is associated. */
    public abstract @Nullable String stepName();
  
    /** The name of the metric. */
    public abstract MetricName metricName();
  
    @Override
    @Memoized
    public String toString() {
      return stepName() + ":" + metricName();
    }
  
    public static MetricKey create(@Nullable String stepName, MetricName metricName) {
      return new AutoValue_MetricKey(stepName, metricName);
    }
  }
  