MXS-1538: Remove unnecessary copying of schema information

The schema related information was copied for each row. A shared pointer
to the data can be used to remove the repeated copying of the values.

connectors/cdc-connector/cdc_connector.cpp

@@ -156,6 +156,7 @@ template <> void Closer<struct addrinfo*>::close(struct addrinfo* ai)
 {
     freeaddrinfo(ai);
 }
+
 template <> void Closer<int>::close(int fd)
 {
     close(fd);
@@ -307,8 +308,8 @@ static inline bool is_schema(json_t* json)
 
 void Connection::process_schema(json_t* json)
 {
-    ValueList keys;
-    ValueList types;
+    SValueVector keys(std::make_shared<ValueVector>());
+    SValueVector types(std::make_shared<ValueVector>());
 
     json_t* arr = json_object_get(json, "fields");
     size_t i;
@@ -338,22 +339,22 @@ void Connection::process_schema(json_t* json)
             }
         }
 
-        keys.push_back(nameval);
-        types.push_back(typeval);
+        keys->push_back(nameval);
+        types->push_back(typeval);
     }
 
-    m_keys.swap(keys);
-    m_types.swap(types);
+    m_keys = keys;
+    m_types = types;
 }
 
-Row Connection::process_row(json_t* js)
+SRow Connection::process_row(json_t* js)
 {
-    ValueList values;
-    values.reserve(m_keys.size());
+    ValueVector values;
+    values.reserve(m_keys->size());
     m_error.clear();
 
-    for (ValueList::iterator it = m_keys.begin();
-         it != m_keys.end(); it++)
+    for (ValueVector::iterator it = m_keys->begin();
+         it != m_keys->end(); it++)
     {
         json_t* v = json_object_get(js, it->c_str());
 
@@ -369,20 +370,20 @@ Row Connection::process_row(json_t* js)
         }
     }
 
-    Row rval;
+    SRow rval;
 
     if (m_error.empty())
     {
-        rval = Row(new InternalRow(m_keys, m_types, values));
+        rval = SRow(new Row(m_keys, m_types, values));
     }
 
     return rval;
 }
 
-Row Connection::read()
+SRow Connection::read()
 {
     m_error.clear();
-    Row rval;
+    SRow rval;
     std::string row;
 
     if (m_first_row)

connectors/cdc-connector/cdc_connector.h

@@ -1,3 +1,4 @@
+#pragma once
 /* Copyright (c) 2017, MariaDB Corporation. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ -32,10 +33,11 @@ namespace CDC
 const char* TIMEOUT = "Request timed out";
 
 // The typedef for the Row type
-class InternalRow;
-typedef std::shared_ptr<InternalRow> Row;
+class Row;
+typedef std::shared_ptr<Row> SRow;
 
-typedef std::vector<std::string> ValueList;
+typedef std::vector<std::string> ValueVector;
+typedef std::shared_ptr<ValueVector> SValueVector;
 typedef std::map<std::string, std::string> ValueMap;
 
 // A class that represents a CDC connection
@@ -78,7 +80,7 @@ public:
      *
      * @see InternalRow
      */
-    Row read();
+    SRow read();
 
     /**
      * Explicitly close the connection
@@ -116,9 +118,9 @@ public:
     {
         ValueMap fields;
 
-        for (size_t i = 0; i < m_keys.size(); i++)
+        for (size_t i = 0; i < m_keys->size(); i++)
         {
-            fields[m_keys[i]] = m_types[i];
+            fields[(*m_keys)[i]] = (*m_types)[i];
         }
 
         return fields;
@@ -132,19 +134,19 @@ private:
     std::string m_password;
     std::string m_error;
     std::string m_schema;
-    ValueList m_keys;
-    ValueList m_types;
+    SValueVector m_keys;
+    SValueVector m_types;
     int m_timeout;
     std::vector<char> m_buffer;
     std::vector<char>::iterator m_buf_ptr;
-    Row m_first_row;
+    SRow m_first_row;
     bool m_connected;
 
     bool do_auth();
     bool do_registration();
     bool read_row(std::string& dest);
     void process_schema(json_t* json);
-    Row process_row(json_t*);
+    SRow process_row(json_t*);
     bool is_error(const char* str);
 
     // Lower-level functions
@@ -154,11 +156,11 @@ private:
 };
 
 // Internal representation of a row, used via the Row type
-class InternalRow
+class Row
 {
-    InternalRow(const InternalRow&) = delete;
-    InternalRow& operator=(const InternalRow&) = delete;
-    InternalRow() = delete;
+    Row(const Row&) = delete;
+    Row& operator=(const Row&) = delete;
+    Row() = delete;
 public:
 
     /**
@@ -180,7 +182,7 @@ public:
      */
     const std::string& value(size_t i) const
     {
-        return m_values[i];
+        return m_values.at(i);
     }
 
     /**
@@ -192,8 +194,8 @@ public:
      */
     const std::string& value(const std::string& str) const
     {
-        ValueList::const_iterator it = std::find(m_keys.begin(), m_keys.end(), str);
-        return m_values[it - m_keys.begin()];
+        ValueVector::const_iterator it = std::find(m_keys->begin(), m_keys->end(), str);
+        return m_values.at(it - m_keys->begin());
     }
 
     /**
@@ -219,7 +221,7 @@ public:
      */
     const std::string& key(size_t i) const
     {
-        return m_keys[i];
+        return m_keys->at(i);
     }
 
     /**
@@ -229,24 +231,24 @@ public:
      */
     const std::string& type(size_t i) const
     {
-        return m_types[i];
+        return m_types->at(i);
     }
 
-    ~InternalRow()
+    ~Row()
     {
     }
 
 private:
-    ValueList m_keys;
-    ValueList m_types;
-    ValueList m_values;
+    SValueVector m_keys;
+    SValueVector m_types;
+    ValueVector m_values;
 
     // Only a Connection should construct an InternalRow
     friend class Connection;
 
-    InternalRow(const ValueList& keys,
-                const ValueList& types,
-                ValueList& values):
+    Row(SValueVector& keys,
+        SValueVector& types,
+        ValueVector& values):
         m_keys(keys),
         m_types(types)
     {

maxscale-system-test/cdc_datatypes/cdc_datatypes.cpp

@@ -182,7 +182,7 @@ bool run_test(TestConnections& test)
             {
                 for (int j = 0; test_set[x].values[j]; j++)
                 {
-                    CDC::Row row;
+                    CDC::SRow row;
 
                     if ((row = conn.read()))
                     {