code: /*
   * 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.skywalking.oap.server.core.query;
  
  import java.io.IOException;
  import java.util.List;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.skywalking.oap.server.core.query.input.Duration;
  import org.apache.skywalking.oap.server.core.query.input.MetricsCondition;
  import org.apache.skywalking.oap.server.core.query.type.HeatMap;
  import org.apache.skywalking.oap.server.core.query.type.MetricsValues;
  import org.apache.skywalking.oap.server.core.query.type.NullableValue;
  import org.apache.skywalking.oap.server.core.storage.StorageModule;
  import org.apache.skywalking.oap.server.core.storage.annotation.ValueColumnMetadata;
  import org.apache.skywalking.oap.server.core.storage.query.IMetricsQueryDAO;
  import org.apache.skywalking.oap.server.library.module.ModuleManager;
  import org.apache.skywalking.oap.server.library.module.Service;
  
  @Slf4j
  public class MetricsQueryService implements Service {
      private final ModuleManager moduleManager;
      private IMetricsQueryDAO metricQueryDAO;
  
      public MetricsQueryService(ModuleManager moduleManager) {
          this.moduleManager = moduleManager;
      }
  
      private IMetricsQueryDAO getMetricQueryDAO() {
          if (metricQueryDAO == null) {
              metricQueryDAO = moduleManager.find(StorageModule.NAME).provider().getService(IMetricsQueryDAO.class);
          }
          return metricQueryDAO;
      }
  
      /**
       * Read metrics single value in the duration of required metrics
       */
      public NullableValue readMetricsValue(MetricsCondition condition, Duration duration) throws IOException {
          return getMetricQueryDAO().readMetricsValue(
              condition, ValueColumnMetadata.INSTANCE.getValueCName(condition.getName()), duration);
      }
  
      /**
       * Read time-series values in the duration of required metrics
       */
      public MetricsValues readMetricsValues(MetricsCondition condition, Duration duration) throws IOException {
          return getMetricQueryDAO().readMetricsValues(
              condition, ValueColumnMetadata.INSTANCE.getValueCName(condition.getName()), duration);
      }
  
      /**
       * Read value in the given time duration, usually as a linear.
       *
       * @param labels the labels you need to query.
       */
      public List<MetricsValues> readLabeledMetricsValues(MetricsCondition condition,
                                                          List<String> labels,
                                                          Duration duration) throws IOException {
          return getMetricQueryDAO().readLabeledMetricsValues(
              condition, ValueColumnMetadata.INSTANCE.getValueCName(condition.getName()), labels, duration);
      }
  
      /**
       * Heatmap is bucket based value statistic result.
       */
      public HeatMap readHeatMap(MetricsCondition condition, Duration duration) throws IOException {
          return getMetricQueryDAO().readHeatMap(
              condition, ValueColumnMetadata.INSTANCE.getValueCName(condition.getName()), duration);
      }
  }
  