processing/src/main/java/org/apache/druid/query/topn/DefaultTopNQueryMetricsFactory.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 org.apache.druid.query.topn;

import com.google.common.annotations.VisibleForTesting;
import org.apache.druid.guice.LazySingleton;

@LazySingleton
public class DefaultTopNQueryMetricsFactory implements TopNQueryMetricsFactory
{
  private static final TopNQueryMetricsFactory INSTANCE = new DefaultTopNQueryMetricsFactory();

  /**
   * Should be used only in tests, directly or indirectly (via {@link TopNQueryQueryToolChest#TopNQueryQueryToolChest}).
   */
  @VisibleForTesting
  public static TopNQueryMetricsFactory instance()
  {
    return INSTANCE;
  }

  @Override
  public TopNQueryMetrics makeMetrics()
  {
    return new DefaultTopNQueryMetrics();
  }
}