Changes related to canonical query format implementation.

query_classifier.cc: Now query can be parsed outside query_classifier_get_type by calling function parse_query. It creates parsing_info_t struct which is then added to the GWBUF which also includes the query. Parsing information follows the buffered query and it is freed at the same time with query buffer, in gwbuf_free.
buffer.c: additions of parsing information to gwbuf struct.
modutil.c: added function which returns query from GWBUF in plain text string.
readwritesplit.c:routeQuery now only calls query_classifier_get_type to get the query type instead of extracting plain text query from the GWBUF buffer.

server/include/buffer.h

@@ -43,6 +43,7 @@
  */
 #include <skygw_debug.h>
 
+EXTERN_C_BLOCK_BEGIN
 
 typedef enum 
 {
@@ -73,6 +74,20 @@ typedef struct  {
 	int		refcount;		/*< Reference count on the buffer */
 } SHARED_BUF;
 
+
+typedef struct parsing_info_st {
+#if defined(SS_DEBUG)
+        skygw_chk_t pi_chk_top;     
+#endif
+        void* pi_handle;                        /*< parsing info object pointer */
+        char* pi_query_plain_str;               /*< query as plain string */
+        void (*pi_done_fp)(void *);             /*< clean-up function for parsing info */
+#if defined(SS_DEBUG)
+        skygw_chk_t pi_chk_tail;
+#endif
+} parsing_info_t;
+
+
 /**
  * The buffer structure used by the descriptor control blocks.
  *
@@ -86,7 +101,7 @@ typedef struct gwbuf {
 	void		*start;	/*< Start of the valid data */
 	void		*end;	/*< First byte after the valid data */
 	SHARED_BUF	*sbuf;  /*< The shared buffer with the real data */
-	int		command;/*< The command type for the queue */
+	void            *gwbuf_parsing_info; /*< parsing info object pointer */
 	gwbuf_type_t    gwbuf_type; /*< buffer's data type information */
 } GWBUF;
 
@@ -121,4 +136,10 @@ extern unsigned int	gwbuf_length(GWBUF *head);
 extern GWBUF            *gwbuf_clone_portion(GWBUF *head, size_t offset, size_t len);
 extern GWBUF            *gwbuf_clone_transform(GWBUF *head, gwbuf_type_t type);
 extern void             gwbuf_set_type(GWBUF *head, gwbuf_type_t type);
+void*                   gwbuf_get_parsing_info(GWBUF* buf);
+
+
+EXTERN_C_BLOCK_END
+
+
 #endif