content: /*
   * Copyright 1999-$toady.year 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.config.server.service.query.handler;
  
  import com.alibaba.nacos.common.utils.NamespaceUtil;
  import com.alibaba.nacos.config.server.model.CacheItem;
  import com.alibaba.nacos.config.server.service.ConfigCacheService;
  import com.alibaba.nacos.config.server.service.query.model.ConfigQueryChainRequest;
  import com.alibaba.nacos.config.server.service.query.model.ConfigQueryChainResponse;
  import com.alibaba.nacos.config.server.utils.GroupKey2;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.IOException;
  
  /**
   * ConfigChainEntryHandler.
   * The entry point handler for the responsibility chain, responsible for initializing the chain and handling configuration query requests.
   *
   * @author Nacos
   */
  public class ConfigChainEntryHandler extends AbstractConfigQueryHandler {
      
      private static final Logger LOGGER = LoggerFactory.getLogger(ConfigChainEntryHandler.class);
      
      private static final String CHAIN_ENTRY_HANDLER = "chainEntryHandler";
      
      private static final ThreadLocal<CacheItem> CACHE_ITEM_THREAD_LOCAL = new ThreadLocal<>();
      
      @Override
      public String getName() {
          return CHAIN_ENTRY_HANDLER;
      }
      
      @Override
      public ConfigQueryChainResponse handle(ConfigQueryChainRequest request) throws IOException {
      
          request.setTenant(NamespaceUtil.processNamespaceParameter(request.getTenant()));
          String groupKey = GroupKey2.getKey(request.getDataId(), request.getGroup(), request.getTenant());
          int lockResult = ConfigCacheService.tryConfigReadLock(groupKey);
          CacheItem cacheItem = ConfigCacheService.getContentCache(groupKey);
          
          if (lockResult > 0 && cacheItem != null) {
              try {
                  CACHE_ITEM_THREAD_LOCAL.set(cacheItem);
                  if (nextHandler != null) {
                      return nextHandler.handle(request);
                  } else {
                      LOGGER.warn("chainEntryHandler's next handler is null");
                      return new ConfigQueryChainResponse();
                  }
              } finally {
                  CACHE_ITEM_THREAD_LOCAL.remove();
                  ConfigCacheService.releaseReadLock(groupKey);
              }
          } else if (lockResult == 0 || cacheItem == null) {
              ConfigQueryChainResponse response = new ConfigQueryChainResponse();
              response.setStatus(ConfigQueryChainResponse.ConfigQueryStatus.CONFIG_NOT_FOUND);
              return response;
          } else {
              ConfigQueryChainResponse response = new ConfigQueryChainResponse();
              response.setStatus(ConfigQueryChainResponse.ConfigQueryStatus.CONFIG_QUERY_CONFLICT);
              return response;
          }
      }
      
      public static CacheItem getThreadLocalCacheItem() {
          return CACHE_ITEM_THREAD_LOCAL.get();
      }
  }