MXS-852: Map client PS handle to internal ID

Mapping the handles returned to the client to a session command ID allows
the mapping of client handle to the backend specific handle. Currently,
the mapping is used for diagnostic output only.

include/maxscale/protocol/mysql.h

@@ -536,4 +536,13 @@ uint8_t mxs_mysql_get_command(GWBUF* buffer);
  */
 bool mxs_mysql_extract_ps_response(GWBUF* buffer, MXS_PS_RESPONSE* out);
 
+/**
+ * @brief Extract the ID of a COM_STMT_EXECUTE
+ *
+ * @param buffer Buffer containing a COM_STMT_EXECUTE packet
+ *
+ * @return The ID of the prepared statement being executed or 0 on failure
+ */
+uint32_t mxs_mysql_extract_execute(GWBUF* buffer);
+
 MXS_END_DECLS

server/modules/protocol/MySQL/mysql_common.c

@@ -1636,3 +1636,16 @@ bool mxs_mysql_extract_ps_response(GWBUF* buffer, MXS_PS_RESPONSE* out)
 
     return rval;
 }
+
+uint32_t mxs_mysql_extract_execute(GWBUF* buffer)
+{
+    uint32_t rval = 0;
+    uint8_t id[MYSQL_PS_ID_SIZE];
+
+    if (gwbuf_copy_data(buffer, MYSQL_PS_ID_OFFSET, sizeof(id), id) == sizeof(id))
+    {
+        rval = gw_mysql_get_byte4(id);
+    }
+
+    return rval;
+}

server/modules/routing/readwritesplit/readwritesplit.hh

@@ -154,7 +154,8 @@ struct rwsplit_config_t
                                              * been idle for too long */
 };
 
-typedef std::map<uint64_t, uint32_t> HandleMap;
+typedef std::map<uint64_t, uint32_t> BackendHandleMap;
+typedef std::map<uint32_t, uint64_t> ClientHandleMap;
 
 class RWBackend: public mxs::Backend
 {
@@ -213,8 +214,8 @@ public:
     }
 
 private:
-    reply_state_t m_reply_state;
+    reply_state_t    m_reply_state;
-    HandleMap     m_ps_handles;
+    BackendHandleMap m_ps_handles; /**< Internal ID to backend PS handle mapping */
 };
 
 /** Prepared statement ID to type maps for text protocols */
@@ -295,7 +296,8 @@ struct ROUTER_CLIENT_SES
     ResponseMap               sescmd_responses; /**< Response to each session command */
     uint64_t                  sent_sescmd; /**< ID of the last sent session command*/
     uint64_t                  recv_sescmd; /**< ID of the most recently completed session command */
-    PSManager                 ps_manager;   /**< Prepared statement manager*/
+    PSManager                 ps_manager;  /**< Prepared statement manager*/
+    ClientHandleMap           ps_handles;  /**< Client PS handle to internal ID mapping */
     skygw_chk_t               rses_chk_tail;
 };
 

server/modules/routing/readwritesplit/rwsplit_ps.cc

@@ -126,6 +126,7 @@ uint32_t PSManager::get_type(uint64_t id) const
         MXS_WARNING("Using unknown prepared statement with ID %lu", id);
     }
 
+    ss_dassert(rval != QUERY_TYPE_UNKNOWN);
     return rval;
 }
 

server/modules/routing/readwritesplit/rwsplit_route_stmt.cc

@@ -148,6 +148,18 @@ bool route_single_stmt(ROUTER_INSTANCE *inst, ROUTER_CLIENT_SES *rses,
             std::string id = extract_text_ps_id(querybuf);
             qtype = rses->ps_manager.get_type(id);
         }
+        else if (command == MYSQL_COM_STMT_EXECUTE)
+        {
+            uint32_t id = mxs_mysql_extract_execute(querybuf);
+            ClientHandleMap::iterator it = rses->ps_handles.find(id);
+
+            if (it != rses->ps_handles.end())
+            {
+                char *qtypestr = qc_typemask_to_string(rses->ps_manager.get_type(it->second));
+                MXS_INFO("Client handle %u maps to %lu of type %s", id, it->second, qtypestr);
+                MXS_FREE(qtypestr);
+            }
+        }
 
         route_target = get_route_target(rses, qtype, querybuf->hint);
     }

server/modules/routing/readwritesplit/rwsplit_session_cmd.cc

@@ -38,15 +38,14 @@ void process_sescmd_response(ROUTER_CLIENT_SES* rses, SRWBackend& backend,
             gwbuf_copy_data(*ppPacket, MYSQL_HEADER_LEN, 1, &cmd);
             uint8_t command = backend->next_session_command()->get_command();
             uint64_t id = backend->complete_session_command();
+            MXS_PS_RESPONSE resp = {};
 
             if (command == MYSQL_COM_STMT_PREPARE)
             {
-                MXS_PS_RESPONSE resp;
+                // This should never fail or the backend protocol is broken
-
+                ss_debug(bool b = )mxs_mysql_extract_ps_response(*ppPacket, &resp);
-                if (mxs_mysql_extract_ps_response(*ppPacket, &resp))
+                ss_dassert(b);
-                {
+                backend->add_ps_handle(id, resp.id);
-                    backend->add_ps_handle(id, resp.id);
-                }
             }
 
             if (rses->recv_sescmd < rses->sent_sescmd &&
@@ -60,6 +59,12 @@ void process_sescmd_response(ROUTER_CLIENT_SES* rses, SRWBackend& backend,
                 /** Store the master's response so that the slave responses can
                  * be compared to it */
                 rses->sescmd_responses[id] = cmd;
+
+                if (command == MYSQL_COM_STMT_PREPARE)
+                {
+                    /** Map the returned response to the internal ID */
+                    rses->ps_handles[resp.id] = id;
+                }
             }
             else
             {