content: package com.ctrip.framework.apollo.internals;
  
  import java.util.List;
  import java.util.Properties;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.ctrip.framework.apollo.tracer.Tracer;
  import com.ctrip.framework.apollo.util.ExceptionUtil;
  import com.google.common.collect.Lists;
  
  /**
   * @author Jason Song(song_s@ctrip.com)
   */
  public abstract class AbstractConfigRepository implements ConfigRepository {
    private static final Logger logger = LoggerFactory.getLogger(AbstractConfigRepository.class);
    private List<RepositoryChangeListener> m_listeners = Lists.newCopyOnWriteArrayList();
  
    protected boolean trySync() {
      try {
        sync();
        return true;
      } catch (Throwable ex) {
        Tracer.logEvent("ApolloConfigException", ExceptionUtil.getDetailMessage(ex));
        logger
            .warn("Sync config failed, will retry. Repository {}, reason: {}", this.getClass(), ExceptionUtil
                .getDetailMessage(ex));
      }
      return false;
    }
  
    protected abstract void sync();
  
    @Override
    public void addChangeListener(RepositoryChangeListener listener) {
      if (!m_listeners.contains(listener)) {
        m_listeners.add(listener);
      }
    }
  
    @Override
    public void removeChangeListener(RepositoryChangeListener listener) {
      m_listeners.remove(listener);
    }
  
    protected void fireRepositoryChange(String namespace, Properties newProperties) {
      for (RepositoryChangeListener listener : m_listeners) {
        try {
          listener.onRepositoryChange(namespace, newProperties);
        } catch (Throwable ex) {
          Tracer.logError(ex);
          logger.error("Failed to invoke repository change listener {}", listener.getClass(), ex);
        }
      }
    }
  }
  