--- a/src/core/model/hash-implementation.h	Tue Nov 13 16:34:34 2012 -0800
+++ b/src/core/model/hash-implementation.h	Tue Nov 13 16:35:21 2012 -0800
@@ -60,6 +60,10 @@
    * \return 64-bit hash of the buffer
    */
   virtual Hash64_t  GetHash64  (const char * buffer, const size_t size);
+  /**
+   * Restore initial state
+   */
+  virtual void clear (void) = 0;
   /*
    * Destructor
    */