content: /*
   * Copyright 1999-2020 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.core.v2.metadata;
  
  import com.alibaba.nacos.common.utils.TypeUtils;
  import com.alibaba.nacos.consistency.DataOperation;
  import com.alibaba.nacos.consistency.SerializeFactory;
  import com.alibaba.nacos.consistency.Serializer;
  import com.alibaba.nacos.consistency.cp.RequestProcessor4CP;
  import com.alibaba.nacos.consistency.entity.ReadRequest;
  import com.alibaba.nacos.consistency.entity.Response;
  import com.alibaba.nacos.consistency.entity.WriteRequest;
  import com.alibaba.nacos.consistency.snapshot.SnapshotOperation;
  import com.alibaba.nacos.core.distributed.ProtocolManager;
  import com.alibaba.nacos.naming.constants.Constants;
  import com.alibaba.nacos.naming.core.v2.ServiceManager;
  import com.alibaba.nacos.naming.core.v2.index.ServiceStorage;
  import com.alibaba.nacos.naming.core.v2.pojo.Service;
  import com.alibaba.nacos.naming.misc.Loggers;
  import org.springframework.stereotype.Component;
  
  import java.lang.reflect.Type;
  import java.util.Collections;
  import java.util.List;
  import java.util.Optional;
  import java.util.concurrent.locks.ReentrantReadWriteLock;
  
  /**
   * Service metadata processor.
   *
   * @author xiweng.yy
   */
  @Component
  public class ServiceMetadataProcessor extends RequestProcessor4CP {
      
      private final NamingMetadataManager namingMetadataManager;
      
      private final ServiceStorage serviceStorage;
      
      private final Serializer serializer;
      
      private final Type processType;
      
      private final ReentrantReadWriteLock lock;
      
      private final ReentrantReadWriteLock.ReadLock readLock;
      
      @SuppressWarnings("unchecked")
      public ServiceMetadataProcessor(NamingMetadataManager namingMetadataManager, ProtocolManager protocolManager,
              ServiceStorage serviceStorage) {
          this.namingMetadataManager = namingMetadataManager;
          this.serviceStorage = serviceStorage;
          this.serializer = SerializeFactory.getDefault();
          this.processType = TypeUtils.parameterize(MetadataOperation.class, ServiceMetadata.class);
          this.lock = new ReentrantReadWriteLock();
          this.readLock = lock.readLock();
          protocolManager.getCpProtocol().addRequestProcessors(Collections.singletonList(this));
      }
      
      @Override
      public List<SnapshotOperation> loadSnapshotOperate() {
          return Collections.singletonList(new ServiceMetadataSnapshotOperation(namingMetadataManager, lock));
      }
      
      @Override
      public Response onRequest(ReadRequest request) {
          return null;
      }
      
      @Override
      public Response onApply(WriteRequest request) {
          readLock.lock();
          try {
              MetadataOperation<ServiceMetadata> op = serializer.deserialize(request.getData().toByteArray(), processType);
              switch (DataOperation.valueOf(request.getOperation())) {
                  case ADD:
                      addClusterMetadataToService(op);
                      break;
                  case CHANGE:
                      updateServiceMetadata(op);
                      break;
                  case DELETE:
                      deleteServiceMetadata(op);
                      break;
                  default:
                      return Response.newBuilder().setSuccess(false)
                              .setErrMsg("Unsupported operation " + request.getOperation()).build();
              }
              return Response.newBuilder().setSuccess(true).build();
          } catch (Exception e) {
              Loggers.RAFT.error("onApply {} service metadata operation failed. ", request.getOperation(), e);
              String errorMessage = null == e.getMessage() ? e.getClass().getName() : e.getMessage();
              return Response.newBuilder().setSuccess(false).setErrMsg(errorMessage).build();
          } finally {
              readLock.unlock();
          }
      }
      
      private void addClusterMetadataToService(MetadataOperation<ServiceMetadata> op) {
          Service service = Service
                  .newService(op.getNamespace(), op.getGroup(), op.getServiceName(), op.getMetadata().isEphemeral());
          Optional<ServiceMetadata> currentMetadata = namingMetadataManager.getServiceMetadata(service);
          if (currentMetadata.isPresent()) {
              currentMetadata.get().getClusters().putAll(op.getMetadata().getClusters());
          } else {
              Service singleton = ServiceManager.getInstance().getSingleton(service);
              namingMetadataManager.updateServiceMetadata(singleton, op.getMetadata());
          }
      }
      
      private void updateServiceMetadata(MetadataOperation<ServiceMetadata> op) {
          Service service = Service
                  .newService(op.getNamespace(), op.getGroup(), op.getServiceName(), op.getMetadata().isEphemeral());
          Optional<ServiceMetadata> currentMetadata = namingMetadataManager.getServiceMetadata(service);
          if (currentMetadata.isPresent()) {
              ServiceMetadata newMetadata = mergeMetadata(currentMetadata.get(), op.getMetadata());
              Service singleton = ServiceManager.getInstance().getSingleton(service);
              namingMetadataManager.updateServiceMetadata(singleton, newMetadata);
          } else {
              Service singleton = ServiceManager.getInstance().getSingleton(service);
              namingMetadataManager.updateServiceMetadata(singleton, op.getMetadata());
          }
      }
      
      /**
       * Do not modified old metadata directly to avoid read half status.
       *
       * <p>Ephemeral variable should only use the value the metadata create.
       *
       * @param oldMetadata old metadata
       * @param newMetadata new metadata
       * @return merged metadata
       */
      private ServiceMetadata mergeMetadata(ServiceMetadata oldMetadata, ServiceMetadata newMetadata) {
          ServiceMetadata result = new ServiceMetadata();
          result.setEphemeral(oldMetadata.isEphemeral());
          result.setClusters(oldMetadata.getClusters());
          result.setProtectThreshold(newMetadata.getProtectThreshold());
          result.setSelector(newMetadata.getSelector());
          result.setExtendData(newMetadata.getExtendData());
          return result;
      }
      
      private void deleteServiceMetadata(MetadataOperation<ServiceMetadata> op) {
          Service service = Service.newService(op.getNamespace(), op.getGroup(), op.getServiceName());
          namingMetadataManager.removeServiceMetadata(service);
          Service removed = ServiceManager.getInstance().removeSingleton(service);
          if (removed != null) {
              service = removed;
          }
          serviceStorage.removeData(service);
      }
      
      @Override
      public String group() {
          return Constants.SERVICE_METADATA;
      }
  }
  