content: package com.ctrip.framework.apollo.configservice.service.config;
  
  import com.ctrip.framework.apollo.biz.entity.Release;
  import com.ctrip.framework.apollo.biz.grayReleaseRule.GrayReleaseRulesHolder;
  import com.ctrip.framework.apollo.core.ConfigConsts;
  import com.ctrip.framework.apollo.core.dto.ApolloNotificationMessages;
  
  import com.google.common.base.Strings;
  
  import java.util.Map;
  import java.util.Objects;
  import org.springframework.beans.factory.annotation.Autowired;
  
  /**
   * @author Jason Song(song_s@ctrip.com)
   */
  public abstract class AbstractConfigService implements ConfigService {
    @Autowired
    private GrayReleaseRulesHolder grayReleaseRulesHolder;
  
    @Override
    public Release loadConfig(String clientAppId, String clientIp, String configAppId, String configClusterName,
        String configNamespace, String dataCenter, ApolloNotificationMessages clientMessages) {
      // load from specified cluster fist
      if (!Objects.equals(ConfigConsts.CLUSTER_NAME_DEFAULT, configClusterName)) {
        Release clusterRelease = findRelease(clientAppId, clientIp, configAppId, configClusterName, configNamespace,
            clientMessages);
  
        if (!Objects.isNull(clusterRelease)) {
          return clusterRelease;
        }
      }
  
      // try to load via data center
      if (!Strings.isNullOrEmpty(dataCenter) && !Objects.equals(dataCenter, configClusterName)) {
        Release dataCenterRelease = findRelease(clientAppId, clientIp, configAppId, dataCenter, configNamespace,
            clientMessages);
        if (!Objects.isNull(dataCenterRelease)) {
          return dataCenterRelease;
        }
      }
  
      // fallback to default release
      return findRelease(clientAppId, clientIp, configAppId, ConfigConsts.CLUSTER_NAME_DEFAULT, configNamespace,
          clientMessages);
    }
  
    /**
     * Find release
     * 
     * @param clientAppId the client's app id
     * @param clientIp the client ip
     * @param configAppId the requested config's app id
     * @param configClusterName the requested config's cluster name
     * @param configNamespace the requested config's namespace name
     * @param clientMessages the messages received in client side
     * @return the release
     */
    private Release findRelease(String clientAppId, String clientIp, String configAppId, String configClusterName,
        String configNamespace, ApolloNotificationMessages clientMessages) {
      Long grayReleaseId = grayReleaseRulesHolder.findReleaseIdFromGrayReleaseRule(clientAppId, clientIp, configAppId,
          configClusterName, configNamespace);
  
      Release release = null;
  
      if (grayReleaseId != null) {
        release = findActiveOne(grayReleaseId, clientMessages);
      }
  
      if (release == null) {
        release = findLatestActiveRelease(configAppId, configClusterName, configNamespace, clientMessages);
      }
  
      return release;
    }
  
    /**
     * Find active release by id
     */
    protected abstract Release findActiveOne(long id, ApolloNotificationMessages clientMessages);
  
    /**
     * Find active release by app id, cluster name and namespace name
     */
    protected abstract Release findLatestActiveRelease(String configAppId, String configClusterName,
        String configNamespaceName, ApolloNotificationMessages clientMessages);
  }
  