Add session command class

The class abstracts the session commands and the lists of session commands
using standard library containers.

server/modules/routing/schemarouter/session_command.hh

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#pragma once
+
+#include <list>
+#include <string>
+
+#include <maxscale/buffer.hh>
+
+using namespace maxscale;
+
+class SessionCommand;
+typedef std::list<SessionCommand> SessionCommandList;
+
+class SessionCommand
+{
+public:
+    /**
+     * @brief Mark reply as received
+     */
+    void mark_reply_received();
+
+    /**
+     * @brief Check if the session command has received a reply
+     * @return True if the reply is already received
+     */
+    bool is_reply_received() const;
+
+    /**
+     * @brief Creates a copy of the internal buffer
+     * @return A copy of the internal buffer
+     */
+    Buffer copy_buffer() const;
+
+    /**
+     * @brief Create a new session command
+     *
+     * @param buffer The buffer containing the command. Note that the ownership
+     *               of @c buffer is transferred to this object.
+     */
+    SessionCommand(GWBUF *buffer);
+
+    ~SessionCommand();
+
+    /**
+     * @brief Debug function for printing session commands
+     *
+     * @return String representation of the object
+     */
+    std::string to_string();
+
+private:
+    Buffer m_buffer; /**< The buffer containing the command */
+    bool   m_replySent; /**< Whether the session command reply has been sent */
+
+    SessionCommand();
+    SessionCommand& operator = (const SessionCommand& command);
+};