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.storage.ttl;
  
  import lombok.extern.slf4j.Slf4j;
  import org.apache.skywalking.oap.server.core.CoreModule;
  import org.apache.skywalking.oap.server.core.CoreModuleConfig;
  import org.apache.skywalking.oap.server.core.analysis.metrics.Metrics;
  import org.apache.skywalking.oap.server.core.cluster.ClusterModule;
  import org.apache.skywalking.oap.server.core.cluster.ClusterNodesQuery;
  import org.apache.skywalking.oap.server.core.cluster.RemoteInstance;
  import org.apache.skywalking.oap.server.core.storage.IHistoryDeleteDAO;
  import org.apache.skywalking.oap.server.core.storage.StorageModule;
  import org.apache.skywalking.oap.server.core.storage.model.IModelManager;
  import org.apache.skywalking.oap.server.core.storage.model.Model;
  import org.apache.skywalking.oap.server.library.module.ModuleManager;
  import org.apache.skywalking.oap.server.library.util.CollectionUtils;
  import org.apache.skywalking.oap.server.library.util.RunnableWithExceptionProtection;
  
  import java.io.IOException;
  import java.util.Collections;
  import java.util.List;
  import java.util.concurrent.Executors;
  import java.util.concurrent.TimeUnit;
  
  /**
   * TTL = Time To Live
   *
   * DataTTLKeeperTimer is an internal timer, it drives the {@link IHistoryDeleteDAO} to remove the expired data. TTL
   * configurations are provided in {@link CoreModuleConfig}, some storage implementations, such as ES6/ES7, provides an
   * override TTL, which could be more suitable for the implementation. No matter which TTL configurations are set, they
   * are all driven by this timer.
   */
  @Slf4j
  public enum DataTTLKeeperTimer {
      INSTANCE;
  
      private ModuleManager moduleManager;
      private ClusterNodesQuery clusterNodesQuery;
      private CoreModuleConfig moduleConfig;
  
      public void start(ModuleManager moduleManager, CoreModuleConfig moduleConfig) {
          this.moduleManager = moduleManager;
          this.clusterNodesQuery = moduleManager.find(ClusterModule.NAME).provider().getService(ClusterNodesQuery.class);
          this.moduleConfig = moduleConfig;
  
          Executors.newSingleThreadScheduledExecutor()
                   .scheduleAtFixedRate(
                       new RunnableWithExceptionProtection(
                           this::delete,
                           t -> log.error("Remove data in background failure.", t)
                       ), moduleConfig
                           .getDataKeeperExecutePeriod(), moduleConfig.getDataKeeperExecutePeriod(), TimeUnit.MINUTES);
      }
  
      /**
       * DataTTLKeeperTimer starts in every OAP node, but the deletion only work when it is as the first node in the OAP
       * node list from {@link ClusterNodesQuery}.
       */
      private void delete() {
          IModelManager modelGetter = moduleManager.find(CoreModule.NAME).provider().getService(IModelManager.class);
          List<Model> models = modelGetter.allModels();
  
          List<RemoteInstance> remoteInstances = clusterNodesQuery.queryRemoteNodes();
          // Sort the instances as same as RemoteClientManager#refresh did.
          Collections.sort(remoteInstances);
          if (CollectionUtils.isNotEmpty(remoteInstances) && !remoteInstances.get(0).getAddress().isSelf()) {
              log.info(
                  "The selected first getAddress is {}. The remove stage is skipped.",
                  remoteInstances.get(0).toString()
              );
              return;
          }
  
          log.info("Beginning to remove expired metrics from the storage.");
          models.forEach(this::execute);
      }
  
      private void execute(Model model) {
          try {
              if (!model.isTimeSeries()) {
                  return;
              }
              if (log.isDebugEnabled()) {
                  log.debug(
                      "Model {}, is record? {}. RecordDataTTL {}, MetricsDataTTL {}",
                      model.getName(),
                      model.isRecord(),
                      moduleConfig.getRecordDataTTL(),
                      moduleConfig.getMetricsDataTTL());
              }
              moduleManager.find(StorageModule.NAME)
                           .provider()
                           .getService(IHistoryDeleteDAO.class)
                           .deleteHistory(model, Metrics.TIME_BUCKET,
                                          model.isRecord() ? moduleConfig.getRecordDataTTL() : moduleConfig.getMetricsDataTTL()
                           );
          } catch (IOException e) {
              log.warn("History of {} delete failure", model.getName());
              log.error(e.getMessage(), e);
          }
      }
  }
  