Replace session command implementation

The schemarouter now uses the new session commands. It uses a standard
library container to manage the execution and storage of session commands.

The session command history is disabled until a more complete refactoring
can be done.

server/modules/routing/schemarouter/schemarouter.h

@@ -146,25 +146,6 @@ typedef enum rses_property_type_t
         strncmp(s,"LEAST_CURRENT_OPERATIONS", strlen("LEAST_CURRENT_OPERATIONS")) == 0 ?        \
         LEAST_CURRENT_OPERATIONS : UNDEFINED_CRITERIA))))
 
-/**
- * Session variable command
- */
-typedef struct mysql_sescmd_st
-{
-#if defined(SS_DEBUG)
-    skygw_chk_t        my_sescmd_chk_top;
-#endif
-    rses_property_t*   my_sescmd_prop;       /*< Parent property */
-    GWBUF*             my_sescmd_buf;        /*< Query buffer */
-    unsigned char      my_sescmd_packet_type;/*< Packet type */
-    bool               my_sescmd_is_replied; /*< Is cmd replied to client */
-    int      position; /*< Position of this command */
-#if defined(SS_DEBUG)
-    skygw_chk_t        my_sescmd_chk_tail;
-#endif
-} mysql_sescmd_t;
-
-
 /**
  * Property structure
  */
@@ -178,7 +159,6 @@ struct rses_property_st
     rses_property_type_t rses_prop_type; /*< Property type */
     union rses_prop_data
     {
-        mysql_sescmd_t  sescmd; /*< Session commands */
         HASHTABLE*  temp_tables; /*< Hashtable of table names */
     } rses_prop_data;
     rses_property_t*     rses_prop_next; /*< Next property of same type */
@@ -187,21 +167,6 @@ struct rses_property_st
 #endif
 };
 
-typedef struct sescmd_cursor_st
-{
-#if defined(SS_DEBUG)
-    skygw_chk_t        scmd_cur_chk_top;
-#endif
-    SCHEMAROUTER_SESSION* scmd_cur_rses;         /*< pointer to owning router session */
-    rses_property_t**  scmd_cur_ptr_property; /*< address of pointer to owner property */
-    mysql_sescmd_t*    scmd_cur_cmd;          /*< pointer to current session command */
-    bool               scmd_cur_active;       /*< true if command is being executed */
-    int      position; /*< Position of this cursor */
-#if defined(SS_DEBUG)
-    skygw_chk_t        scmd_cur_chk_tail;
-#endif
-} sescmd_cursor_t;
-
 /**
  * Internal structure used to define the set of backend servers we are routing
  * connections to. This provides the storage for routing module specific data
@@ -253,7 +218,6 @@ typedef struct backend_ref_st
     bool            bref_mapped; /*< Whether the backend has been mapped */
     bool            last_sescmd_replied;
     int             bref_num_result_wait; /*< Number of not yet received results */
-    sescmd_cursor_t bref_sescmd_cur; /*< Session command cursor */
     GWBUF*          bref_pending_cmd; /*< For stmt which can't be routed due active sescmd execution */
 
     SessionCommandList session_commands; /**< List of session commands that are
@@ -271,8 +235,6 @@ typedef struct schemarouter_config_st
     int               rw_max_slave_conn_percent;
     int               rw_max_slave_conn_count;
     mxs_target_t      rw_use_sql_variables_in;
-    int max_sescmd_hist;
-    bool disable_sescmd_hist;
     time_t last_refresh; /*< Last time the database list was refreshed */
     double refresh_min_interval; /*< Minimum required interval between refreshes of databases */
     bool refresh_databases; /*< Are databases refreshed when they are not found in the hashtable */
@@ -329,6 +291,9 @@ struct schemarouter_session
     ROUTER_STATS    stats;     /*< Statistics for this router         */
     int             n_sescmd;
     int             pos_generator;
+
+    uint64_t        sent_sescmd;    /**< The latest session command being executed */
+    uint64_t        replied_sescmd; /**< The last session command reply that was sent to the client */
 #if defined(SS_DEBUG)
     skygw_chk_t      rses_chk_tail;
 #endif

server/modules/routing/schemarouter/session_command.cc

@@ -13,6 +13,7 @@
 
 #include "session_command.hh"
 #include <maxscale/modutil.h>
+#include <maxscale/protocol/mysql.h>
 
 void SessionCommand::mark_reply_received()
 {
@@ -24,15 +25,31 @@ bool SessionCommand::is_reply_received() const
     return m_replySent;
 }
 
+uint8_t SessionCommand::get_command() const
+{
+    return m_command;
+}
+
+uint64_t SessionCommand::get_position() const
+{
+    return m_pos;
+}
+
 Buffer SessionCommand::copy_buffer() const
 {
     return m_buffer;
 }
 
-SessionCommand::SessionCommand(GWBUF *buffer):
+SessionCommand::SessionCommand(GWBUF *buffer, uint64_t id):
     m_buffer(buffer),
+    m_command(0),
+    m_pos(id),
     m_replySent(false)
 {
+    if (buffer)
+    {
+        gwbuf_copy_data(buffer, MYSQL_HEADER_LEN, 1, &m_command);
+    }
 }
 
 SessionCommand::~SessionCommand()
@@ -42,15 +59,18 @@ SessionCommand::~SessionCommand()
 std::string SessionCommand::to_string()
 {
     std::string str;
-    
-    GWBUF **buf = &m_buffer;
     char *sql;
     int sql_len;
 
-    if (modutil_extract_SQL(*buf, &sql, &sql_len))
+    /** TODO: Create C++ versions of modutil functions  */
+    GWBUF *buf = m_buffer.release();
+
+    if (modutil_extract_SQL(buf, &sql, &sql_len))
     {
         str.append(sql, sql_len);
     }
 
+    m_buffer.reset(buf);
+
     return str;
 }

server/modules/routing/schemarouter/session_command.hh

@@ -37,6 +37,20 @@ public:
      */
     bool is_reply_received() const;
 
+    /**
+     * @brief Get the command type of the session command
+     *
+     * @return The type of the command
+     */
+    uint8_t get_command() const;
+
+    /**
+     * @brief Get the position of this session command
+     *
+     * @return The position of the session command
+     */
+    uint64_t get_position() const;
+
     /**
      * @brief Creates a copy of the internal buffer
      * @return A copy of the internal buffer
@@ -48,8 +62,9 @@ public:
      *
      * @param buffer The buffer containing the command. Note that the ownership
      *               of @c buffer is transferred to this object.
+     * @param id     A unique position identifier used to track replies
      */
-    SessionCommand(GWBUF *buffer);
+    SessionCommand(GWBUF *buffer, uint64_t id);
 
     ~SessionCommand();
 
@@ -62,6 +77,8 @@ public:
 
 private:
     Buffer   m_buffer;    /**< The buffer containing the command */
+    uint8_t  m_command;   /**< The command being executed */
+    uint64_t m_pos;       /**< Unique position identifier */
     bool     m_replySent; /**< Whether the session command reply has been sent */
 
     SessionCommand();