content: /*
   * Copyright 1999-2023 Alibaba Group Holding Ltd.
   *
   * Licensed 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 com.alibaba.nacos.naming.pojo.instance;
  
  import com.alibaba.nacos.api.naming.pojo.Instance;
  import com.alibaba.nacos.api.naming.spi.generator.InstanceIdGenerator;
  import com.alibaba.nacos.core.distributed.id.SnowFlowerIdGenerator;
  
  import static com.alibaba.nacos.api.common.Constants.NAMING_INSTANCE_ID_SPLITTER;
  import static com.alibaba.nacos.api.common.Constants.SNOWFLAKE_INSTANCE_ID_GENERATOR;
  
  /**
   * SnowFlake InstanceId Generator..
   *
   * @author : huangtianhui
   */
  public class SnowFlakeInstanceIdGenerator implements InstanceIdGenerator {
      
      private static final SnowFlowerIdGenerator SNOW_FLOWER_ID_GENERATOR = new SnowFlowerIdGenerator();
  
      private static volatile boolean initialize = false;
  
      private static final Object LOCK = new Object();
  
      /**
       * initialize the workerId and ensure that it is only initialized once.
       */
      private void ensureWorkerIdInitialization() {
          if (!initialize) {
              synchronized (LOCK) {
                  if (!initialize) {
                      SNOW_FLOWER_ID_GENERATOR.init();
                      initialize = true;
                  }
              }
          }
      }
  
      @Override
      public String generateInstanceId(Instance instance) {
          ensureWorkerIdInitialization();
          return SNOW_FLOWER_ID_GENERATOR.nextId() + NAMING_INSTANCE_ID_SPLITTER
                  + instance.getClusterName() + NAMING_INSTANCE_ID_SPLITTER
                  + instance.getServiceName();
      }
      
      @Override
      public String type() {
          return SNOWFLAKE_INSTANCE_ID_GENERATOR;
      }
  }
  