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.config;
  
  import org.apache.skywalking.oap.server.configuration.api.ConfigChangeWatcher;
  import org.apache.skywalking.oap.server.core.CoreModule;
  import org.apache.skywalking.oap.server.library.module.ModuleProvider;
  import java.util.HashSet;
  import java.util.Set;
  import java.util.concurrent.atomic.AtomicReference;
  
  public class SearchableTracesTagsWatcher extends ConfigChangeWatcher {
  
      private AtomicReference<Set<String>> searchableTags;
  
      private final String initialSettingsString;
  
      private volatile String dynamicSettingsString;
  
      public SearchableTracesTagsWatcher(String config, ModuleProvider provider) {
          super(CoreModule.NAME, provider, "searchableTracesTags");
          searchableTags = new AtomicReference<>(new HashSet<>());
          initialSettingsString = config;
  
          activeSetting(config);
      }
  
      private void activeSetting(String config) {
          Set<String> tags = new HashSet<>();
          String[] settings = config.split(",");
          for (String setting : settings) {
              tags.add(setting);
          }
  
          searchableTags.set(tags);
      }
  
      public Set<String> getSearchableTags() {
          return searchableTags.get();
      }
  
      @Override
      public void notify(ConfigChangeEvent value) {
          if (EventType.DELETE.equals(value.getEventType())) {
              dynamicSettingsString = null;
              activeSetting(initialSettingsString);
          } else {
              dynamicSettingsString = value.getNewValue();
              activeSetting(value.getNewValue());
          }
      }
  
      @Override
      public String value() {
          return dynamicSettingsString;
      }
  }