Make variables of Backend private

The variables are no longer directly manipulated by the session level
code.

server/modules/routing/schemarouter/schemarouter.cc

@@ -21,9 +21,7 @@ Backend::Backend(SERVER_REF *ref):
     m_closed(false),
     m_backend(ref),
     m_dcb(NULL),
-    m_map_queue(NULL),
     m_mapped(false),
-    m_num_mapping_eof(0),
     m_num_result_wait(0),
     m_state(0)
 {
@@ -37,8 +35,6 @@ Backend::~Backend()
     {
         close();
     }
-
-    gwbuf_free(m_map_queue);
 }
 
 void Backend::close()
@@ -71,9 +67,9 @@ void Backend::close()
     }
 }
 
-bool Backend::execute_sescmd()
+bool Backend::execute_session_command()
 {
-    if (is_closed() || m_session_commands.size() == 0)
+    if (is_closed() || !session_command_count())
     {
         return false;
     }
@@ -82,13 +78,6 @@ bool Backend::execute_sescmd()
 
     int rc = 0;
 
-    /** Return if there are no pending ses commands */
-    if (m_session_commands.size() == 0)
-    {
-        MXS_INFO("Cursor had no pending session commands.");
-        return false;
-    }
-
     SessionCommandList::iterator iter = m_session_commands.begin();
     GWBUF *buffer = iter->copy_buffer().release();
 
@@ -114,6 +103,23 @@ bool Backend::execute_sescmd()
     return rc == 1;
 }
 
+void Backend::add_session_command(GWBUF* buffer, uint64_t sequence)
+{
+    m_session_commands.push_back(SessionCommand(buffer, sequence));
+}
+
+uint64_t Backend::complete_session_command()
+{
+    uint64_t rval = m_session_commands.front().get_position();
+    m_session_commands.pop_front();
+    return rval;
+}
+
+size_t Backend::session_command_count() const
+{
+    return m_session_commands.size();
+}
+
 void Backend::clear_state(enum bref_state state)
 {
     if (state != BREF_WAITING_RESULT)
@@ -213,6 +219,11 @@ bool Backend::is_closed() const
     return m_state & BREF_CLOSED;
 }
 
+void Backend::set_mapped(bool value)
+{
+    m_mapped = value;
+}
+
 bool Backend::is_mapped() const
 {
     return m_mapped;

server/modules/routing/schemarouter/schemarouter.hh

@@ -127,11 +127,36 @@ public:
     ~Backend();
 
     /**
-     * @brief Execute the next session command
+     * @brief Execute the next session command in the queue
      *
      * @return True if the command was executed successfully
      */
-    bool execute_sescmd();
+    bool execute_session_command();
+
+    /**
+     * @brief Add a new session command to the tail of the command queue
+     *
+     * @param buffer   Session command to add
+     * @param sequence Sequence identifier of this session command, returned when
+     *                 the session command is completed
+     */
+    void add_session_command(GWBUF* buffer, uint64_t sequence);
+
+    /**
+     * @brief Mark the current session command as successfully executed
+     *
+     * This should be called when the response to the command is received
+     *
+     * @return The sequence identifier for this session command
+     */
+    uint64_t complete_session_command();
+
+    /**
+     * @brief Check if backend has session commands
+     *
+     * @return True if backend has session commands
+     */
+    size_t session_command_count() const;
 
     /**
      * @brief Clear state
@@ -231,6 +256,13 @@ public:
      */
     bool is_closed() const;
 
+    /**
+     * @brief Set the mapping state of the backend
+     *
+     * @param value Value to set
+     */
+    void set_mapped(bool value);
+
     /**
      * @brief Check if the backend has been mapped
      *
@@ -242,11 +274,7 @@ private:
     bool               m_closed;           /**< True if a connection has been opened and closed */
     SERVER_REF*        m_backend;          /**< Backend server */
     DCB*               m_dcb;              /**< Backend DCB */
-
-public:
-    GWBUF*             m_map_queue;
     bool               m_mapped;           /**< Whether the backend has been mapped */
-    int                m_num_mapping_eof;
     int                m_num_result_wait;  /**< Number of not yet received results */
     Buffer             m_pending_cmd;      /**< Pending commands */
     int                m_state;            /**< State of the backend */

server/modules/routing/schemarouter/schemaroutersession.cc

@@ -426,7 +426,7 @@ int32_t SchemaRouterSession::routeQuery(GWBUF* pPacket)
 
         MXS_INFO("Route query to \t%s:%d <", bref->backend()->server->name, bref->backend()->server->port);
 
-        if (bref->m_session_commands.size() > 0)
+        if (bref->session_command_count())
         {
             /** Store current statement if execution of the previous
              * session command hasn't been completed. */
@@ -486,13 +486,14 @@ void SchemaRouterSession::handle_mapping_reply(SBackend& bref, GWBUF** pPacket)
 
 void SchemaRouterSession::process_response(SBackend& bref, GWBUF** ppPacket)
 {
-    if (bref->m_session_commands.size() > 0)
+    if (bref->session_command_count())
     {
         /** We are executing a session command */
         if (GWBUF_IS_TYPE_SESCMD_RESPONSE((*ppPacket)))
         {
-            if (m_replied_sescmd < m_sent_sescmd &&
+            uint64_t id = bref->complete_session_command();
-                bref->m_session_commands.front().get_position() == m_replied_sescmd + 1)
+
+            if (m_replied_sescmd < m_sent_sescmd && id == m_replied_sescmd + 1)
             {
                 /** First reply to this session command, route it to the client */
                 ++m_replied_sescmd;
@@ -504,8 +505,6 @@ void SchemaRouterSession::process_response(SBackend& bref, GWBUF** ppPacket)
                 gwbuf_free(*ppPacket);
                 *ppPacket = NULL;
             }
-
-            bref->m_session_commands.pop_front();
         }
 
         if (*ppPacket)
@@ -572,7 +571,7 @@ void SchemaRouterSession::clientReply(GWBUF* pPacket, DCB* pDcb)
             pPacket = NULL;
         }
 
-        if (bref->execute_sescmd())
+        if (bref->execute_session_command())
         {
             MXS_INFO("Backend %s:%d processed reply and starts to execute active cursor.",
                      bref->backend()->server->name, bref->backend()->server->port);
@@ -732,7 +731,8 @@ bool SchemaRouterSession::route_session_write(GWBUF* querybuf, uint8_t command)
         if ((*it)->in_use())
         {
             GWBUF *buffer = gwbuf_clone(querybuf);
-            (*it)->m_session_commands.push_back(SessionCommand(buffer, m_sent_sescmd));
+
+            (*it)->add_session_command(buffer, m_sent_sescmd);
 
             if (MXS_LOG_PRIORITY_IS_ENABLED(LOG_INFO))
             {
@@ -742,7 +742,7 @@ bool SchemaRouterSession::route_session_write(GWBUF* querybuf, uint8_t command)
                          (*it)->backend()->server->port);
             }
 
-            if ((*it)->m_session_commands.size() == 1)
+            if ((*it)->session_command_count() == 1)
             {
                 /** Only one command, execute it */
                 switch (command)
@@ -757,7 +757,7 @@ bool SchemaRouterSession::route_session_write(GWBUF* querybuf, uint8_t command)
                     break;
                 }
 
-                if ((*it)->execute_sescmd())
+                if ((*it)->execute_session_command())
                 {
                     succp = true;
                 }
@@ -771,7 +771,7 @@ bool SchemaRouterSession::route_session_write(GWBUF* querybuf, uint8_t command)
             }
             else
             {
-                ss_dassert((*it)->m_session_commands.size() > 1);
+                ss_dassert((*it)->session_command_count() > 1);
                 /** The server is already executing a session command */
                 MXS_INFO("Backend %s:%d already executing sescmd.",
                          (*it)->backend()->server->name,