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.group;
  
  import java.io.FileNotFoundException;
  import java.io.StringReader;
  import lombok.extern.slf4j.Slf4j;
  import org.apache.skywalking.oap.server.configuration.api.ConfigChangeWatcher;
  import org.apache.skywalking.oap.server.core.CoreModule;
  import org.apache.skywalking.oap.server.core.config.group.uri.quickmatch.QuickUriGroupingRule;
  import org.apache.skywalking.oap.server.library.module.ModuleProvider;
  import org.apache.skywalking.oap.server.library.util.ResourceUtils;
  
  /**
   * The config change watcher for endpoint name grouping rule.
   */
  @Slf4j
  public class EndpointNameGroupingRuleWatcher extends ConfigChangeWatcher {
      private final EndpointNameGrouping grouping;
      private volatile String ruleSetting;
  
      public EndpointNameGroupingRuleWatcher(ModuleProvider provider,
                                             EndpointNameGrouping grouping) throws FileNotFoundException {
          super(CoreModule.NAME, provider, "endpoint-name-grouping");
          this.grouping = grouping;
          // This is just a place holder text representing the original text.
          ruleSetting = "SkyWalking endpoint rule";
          grouping.setEndpointGroupingRule(new EndpointGroupingRuleReader(
              ResourceUtils.read("endpoint-name-grouping.yml")).read());
      }
  
      @Override
      public void notify(final ConfigChangeEvent value) {
          if (value.getEventType().equals(EventType.DELETE)) {
              ruleSetting = null;
              grouping.setEndpointGroupingRule(new QuickUriGroupingRule());
          } else {
              ruleSetting = value.getNewValue();
              grouping.setEndpointGroupingRule(new EndpointGroupingRuleReader(new StringReader(ruleSetting)).read());
          }
      }
  
      @Override
      public String value() {
          return ruleSetting;
      }
  }
  