MXS-1703 Add convenience function + class for querying and storing results

An object of the class is returned as an auto_ptr to simplify memory management.

server/modules/monitor/mariadbmon/utilities.cc

@@ -113,3 +113,81 @@ string monitored_servers_to_string(const ServerVector& array)
     }
     return rval;
 }
+
+QueryResult::QueryResult(MYSQL_RES* resultset)
+    : m_resultset(resultset)
+    , m_columns(-1)
+    , m_rowdata(NULL)
+    , m_current_row(-1)
+{
+    if (m_resultset)
+    {
+        m_columns = mysql_num_fields(m_resultset);
+        MYSQL_FIELD* field_info = mysql_fetch_fields(m_resultset);
+        for (int64_t column_index = 0; column_index < m_columns; column_index++)
+        {
+            string key(field_info[column_index].name);
+            // TODO: Think of a way to handle duplicate names nicely. Currently this should only be used
+            // for known queries.
+            ss_dassert(m_col_indexes.count(key) == 0);
+            m_col_indexes[key] = column_index;
+        }
+    }
+}
+
+QueryResult::~QueryResult()
+{
+    if (m_resultset)
+    {
+        mysql_free_result(m_resultset);
+    }
+}
+
+bool QueryResult::next_row()
+{
+    m_rowdata = mysql_fetch_row(m_resultset);
+    if (m_rowdata != NULL)
+    {
+        m_current_row++;
+        return true;
+    }
+    return false;
+}
+
+int64_t QueryResult::get_row_index() const
+{
+    return m_current_row;
+}
+
+int64_t QueryResult::get_column_count() const
+{
+    return m_columns;
+}
+
+int64_t QueryResult::get_col_index(const string& col_name) const
+{
+    auto iter = m_col_indexes.find(col_name);
+    return (iter != m_col_indexes.end()) ? iter->second : -1;
+}
+
+string QueryResult::get_string(int64_t column_ind) const
+{
+    ss_dassert(column_ind < m_columns);
+    char* data = m_rowdata[column_ind];
+    return data ? data : "";
+}
+
+int64_t QueryResult::get_int(int64_t column_ind) const
+{
+    ss_dassert(column_ind < m_columns);
+    char* data = m_rowdata[column_ind];
+    errno = 0; // strtoll sets this
+    return data ? strtoll(data, NULL, 10) : 0;
+}
+
+bool QueryResult::get_bool(int64_t column_ind) const
+{
+    ss_dassert(column_ind < m_columns);
+    char* data = m_rowdata[column_ind];
+    return data ? (strcmp(data,"Y") == 0 || strcmp(data, "1") == 0) : false;
+}