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  package org.apache.cayenne.query;
  
  /**
   * Defines query result caching policy.
   * 
   * @since 3.0
   */
  public enum QueryCacheStrategy {
  
      /**
       * A default cache policy stating that the query results should not be cached.
       */
      NO_CACHE,
  
      /**
       * A cache policy stating that query results shall be cached by the ObjectContext that
       * originated the query, independent from any other ObjectContexts.
       */
      LOCAL_CACHE,
  
      /**
       * A cache policy stating that query results shall be cached by the ObjectContext that
       * originated the query, independent from any other ObjectContexts, however the query
       * that uses this policy should treat current cache state as expired, and force the
       * database fetch.
       */
      LOCAL_CACHE_REFRESH,
  
      /**
       * A cache policy ruling that query results shall be cached in a shared location
       * accessible by all ObjectContexts.
       */
      SHARED_CACHE,
  
      /**
       * A cache policy ruling that query results shall be cached in a shared location
       * accessible by all ObjectContexts, however the query that uses this policy should
       * treat current cache state as expired, and force the database fetch.
       */
      SHARED_CACHE_REFRESH;
  
      /**
       * Returns QueryCacheStrategy for the specified string name or default strategy for
       * invalid names.
       */
      public static QueryCacheStrategy safeValueOf(String string) {
          try {
              return QueryCacheStrategy.valueOf(string);
          }
          catch (IllegalArgumentException e) {
              return getDefaultStrategy();
          }
      }
  
      /**
       * Returns the default strategy - {@link #NO_CACHE}.
       */
      public static QueryCacheStrategy getDefaultStrategy() {
          return NO_CACHE;
      }
  }
  