content: /*
   * Copyright 1999-2018 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.core.distributed.id;
  
  import com.alibaba.nacos.common.spi.NacosServiceLoader;
  import com.alibaba.nacos.consistency.IdGenerator;
  import org.springframework.stereotype.Component;
  
  import java.util.Collection;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.NoSuchElementException;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.function.Function;
  
  /**
   * Id generator manager.
   *
   * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
   */
  @Component
  public class IdGeneratorManager {
      
      private final Map<String, IdGenerator> generatorMap = new ConcurrentHashMap<>();
      
      private final Function<String, IdGenerator> supplier;
      
      public IdGeneratorManager() {
          this.supplier = s -> {
              IdGenerator generator;
              Collection<IdGenerator> idGenerators = NacosServiceLoader.load(IdGenerator.class);
              Iterator<IdGenerator> iterator = idGenerators.iterator();
              if (iterator.hasNext()) {
                  generator = iterator.next();
              } else {
                  generator = new SnowFlowerIdGenerator();
              }
              generator.init();
              return generator;
          };
      }
      
      public void register(String resource) {
          generatorMap.computeIfAbsent(resource, s -> supplier.apply(resource));
      }
      
      /**
       * Register resources that need to use the ID generator.
       *
       * @param resources resource name list
       */
      public void register(String... resources) {
          for (String resource : resources) {
              generatorMap.computeIfAbsent(resource, s -> supplier.apply(resource));
          }
      }
      
      /**
       * request next id by resource name.
       *
       * @param resource resource name
       * @return id
       */
      public long nextId(String resource) {
          if (generatorMap.containsKey(resource)) {
              return generatorMap.get(resource).nextId();
          }
          throw new NoSuchElementException(
                  "The resource is not registered with the distributed " + "ID resource for the time being.");
      }
      
      public Map<String, IdGenerator> getGeneratorMap() {
          return generatorMap;
      }
  }
  