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.analysis.worker;
  
  import java.lang.reflect.InvocationTargetException;
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import lombok.Getter;
  import lombok.Setter;
  import org.apache.skywalking.oap.server.core.CoreModule;
  import org.apache.skywalking.oap.server.core.UnexpectedException;
  import org.apache.skywalking.oap.server.core.analysis.DownSampling;
  import org.apache.skywalking.oap.server.core.analysis.Stream;
  import org.apache.skywalking.oap.server.core.analysis.StreamProcessor;
  import org.apache.skywalking.oap.server.core.analysis.record.Record;
  import org.apache.skywalking.oap.server.core.analysis.topn.TopN;
  import org.apache.skywalking.oap.server.core.storage.IRecordDAO;
  import org.apache.skywalking.oap.server.core.storage.StorageBuilderFactory;
  import org.apache.skywalking.oap.server.core.storage.StorageDAO;
  import org.apache.skywalking.oap.server.core.storage.StorageException;
  import org.apache.skywalking.oap.server.core.storage.StorageModule;
  import org.apache.skywalking.oap.server.core.storage.annotation.Storage;
  import org.apache.skywalking.oap.server.core.storage.model.Model;
  import org.apache.skywalking.oap.server.core.storage.model.ModelCreator;
  import org.apache.skywalking.oap.server.core.storage.type.StorageBuilder;
  import org.apache.skywalking.oap.server.library.module.ModuleDefineHolder;
  
  /**
   * TopN is a special process, which hold a certain size of windows, and cache all top N records, save to the persistence
   * in low frequency.
   */
  public class TopNStreamProcessor implements StreamProcessor<TopN> {
  
      private static final TopNStreamProcessor PROCESSOR = new TopNStreamProcessor();
  
      @Getter
      private List<TopNWorker> persistentWorkers = new ArrayList<>();
      private Map<Class<? extends Record>, TopNWorker> workers = new HashMap<>();
      @Getter
      private int topNWorkerReportCycle = 10;
      @Setter
      @Getter
      private int topSize = 50;
  
      public static TopNStreamProcessor getInstance() {
          return PROCESSOR;
      }
  
      public void setTopNWorkerReportCycle(final int topNWorkerReportCycle) {
          if (topNWorkerReportCycle < 1) {
              return;
          }
          this.topNWorkerReportCycle = topNWorkerReportCycle;
      }
  
      public void create(ModuleDefineHolder moduleDefineHolder,
                         Stream stream,
                         Class<? extends TopN> topNClass) throws StorageException {
          final StorageBuilderFactory storageBuilderFactory = moduleDefineHolder.find(StorageModule.NAME)
                                                                                .provider()
                                                                                .getService(StorageBuilderFactory.class);
          final Class<? extends StorageBuilder> builder = storageBuilderFactory.builderOf(topNClass, stream.builder());
  
          StorageDAO storageDAO = moduleDefineHolder.find(StorageModule.NAME).provider().getService(StorageDAO.class);
          IRecordDAO recordDAO;
          try {
              recordDAO = storageDAO.newRecordDao(builder.getDeclaredConstructor().newInstance());
          } catch (InstantiationException | IllegalAccessException | NoSuchMethodException |
                   InvocationTargetException e) {
              throw new UnexpectedException(
                  "Create " + stream.builder().getSimpleName() + " top n record DAO failure.", e);
          }
  
          ModelCreator modelSetter = moduleDefineHolder.find(CoreModule.NAME).provider().getService(ModelCreator.class);
          // Top N metrics doesn't read data from database during the persistent process. Keep the timeRelativeID == false always.
          Model model = modelSetter.add(
              topNClass, stream.scopeId(), new Storage(stream.name(), false, DownSampling.Second));
  
          TopNWorker persistentWorker = new TopNWorker(
              moduleDefineHolder, model, topSize, topNWorkerReportCycle * 60 * 1000L, recordDAO);
          persistentWorkers.add(persistentWorker);
          workers.put(topNClass, persistentWorker);
      }
  
      @Override
      public void in(TopN topN) {
          TopNWorker worker = workers.get(topN.getClass());
          if (worker != null) {
              worker.in(topN);
          }
      }
  }
  