MXS-2485 Add suport for split query packets (from client side)

maxutils/maxsql/include/maxsql/packet_tracker.hh

@@ -22,21 +22,36 @@ namespace maxsql
 
 class ComResponse;
 
-// Minimal class to track the lifetime of a query.
 // TODO add documentation
 class PacketTracker
 {
 public:
+    // The State reflects the response status. For the unlikely event that the query is split, but
+    // no response is expected, the tracker may still be waiting for packets from the client while
+    // m_state = Done. The function expecting_more_packets() would return true in this case.
+    // TODO, maybe, rename to ResponseState.
     enum class State {FirstPacket, Field, FieldEof, Row,
                       ComFieldList, ComStatistics, ComStmtFetch,
                       Done, ErrorPacket, Error};
 
     PacketTracker() = default;
+
     explicit PacketTracker(GWBUF* pQuery);      // Track this query
 
-    void  update(GWBUF* pPacket);       // Update as packets are received.
+    PacketTracker(const PacketTracker&) = delete;
+    PacketTracker& operator=(const PacketTracker&) = delete;
+
+    PacketTracker(PacketTracker&&) = default;
+    PacketTracker& operator=(PacketTracker&&) = default;
+
+    bool update_request(GWBUF* pPacket);        // Updates the query (must be a split packet)
+    void update_response(GWBUF* pPacket);       // Update as response packets are received.
+
+    bool expecting_request_packets() const;
+    bool expecting_response_packets() const;
+    bool expecting_more_packets() const;
+
     State state() const;
-    bool  expecting_more_packets() const;
 
 private:
     // State functions.
@@ -47,12 +62,12 @@ private:
     State com_field_list(const ComResponse& response);
     State com_statistics(const ComResponse& response);
     State com_stmt_fetch(const ComResponse& response);
-
-    State expect_no_more(const ComResponse& response);          // states: Done, ErrorPacket, Error
+    State expect_no_response_packets(const ComResponse& response);      // states: Done, ErrorPacket,  Error
 
     State m_state = State::Error;
-    bool  m_client_packet_internal = false;
-    bool  m_server_packet_internal = false;
+    bool  m_client_com_packet_internal = false;
+    bool  m_server_com_packet_internal = false;
+    bool  m_expect_more_split_query_packets = false;
 
     int m_command;
     int m_total_fields;