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.core.cluster.health;
  
  import com.alibaba.nacos.common.utils.StringUtils;
  
  import java.util.LinkedList;
  import java.util.List;
  
  /**
   * Holder of namespace detail injector.
   *
   * @author xiweng.yy
   */
  public class ModuleHealthCheckerHolder {
      
      private static final ModuleHealthCheckerHolder INSTANCE = new ModuleHealthCheckerHolder();
      
      private final List<AbstractModuleHealthChecker> moduleHealthCheckers;
      
      private ModuleHealthCheckerHolder() {
          this.moduleHealthCheckers = new LinkedList<>();
      }
      
      public static ModuleHealthCheckerHolder getInstance() {
          return INSTANCE;
      }
      
      public void registerChecker(AbstractModuleHealthChecker checker) {
          this.moduleHealthCheckers.add(checker);
      }
      
      /**
       * Do check readiness for modules.
       *
       * @return readiness result
       */
      public ReadinessResult checkReadiness() {
          List<String> readinessFailedModule = new LinkedList<>();
          for (AbstractModuleHealthChecker each : this.moduleHealthCheckers) {
              boolean moduleReadiness = each.readiness();
              if (!moduleReadiness) {
                  readinessFailedModule.add(each.getModuleName());
              }
          }
          if (readinessFailedModule.isEmpty()) {
              return new ReadinessResult(true, "OK");
          } else {
              String modules = StringUtils.join(readinessFailedModule, " and ");
              return new ReadinessResult(false, String.format("%s not in readiness", modules));
          }
      }
  }
  