Move Backend and SessionCommand classes to the core
Using the same implementation of the Backend and SessionCommand classes in both schemarouter and readwritesplit will prevent duplication of code. This commit only splits the generic parts of the class to a Backend class which the schemarouter then extends. The session commands for both routers are similar so they require no special handling.
This commit is contained in:
Markus Mäkelä
195
include/maxscale/backend.hh
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195
include/maxscale/backend.hh
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#pragma once
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/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2020-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#include <maxscale/cppdefs.hh>
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#include <list>
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#include <tr1/memory>
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#include <maxscale/service.h>
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#include <maxscale/session_command.hh>
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namespace maxscale
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{
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/**
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* The state of the backend server reference
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*/
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enum bref_state
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{
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BREF_IN_USE = 0x01,
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BREF_WAITING_RESULT = 0x02, /**< for session commands only */
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BREF_QUERY_ACTIVE = 0x04, /**< for other queries */
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BREF_CLOSED = 0x08,
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};
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class Backend
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{
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Backend(const Backend&);
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Backend& operator =(const Backend&);
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public:
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/**
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* @brief Create new Backend
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*
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* @param ref Server reference used by this backend
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*/
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Backend(SERVER_REF* ref);
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virtual ~Backend();
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/**
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* @brief Execute the next session command in the queue
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*
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* @return True if the command was executed successfully
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*/
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bool execute_session_command();
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/**
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* @brief Add a new session command to the tail of the command queue
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*
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* @param buffer Session command to add
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* @param sequence Sequence identifier of this session command, returned when
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* the session command is completed
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*/
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void add_session_command(GWBUF* buffer, uint64_t sequence);
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/**
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* @brief Mark the current session command as successfully executed
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*
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* This should be called when the response to the command is received
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*
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* @return The sequence identifier for this session command
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*/
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uint64_t complete_session_command();
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/**
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* @brief Check if backend has session commands
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*
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* @return True if backend has session commands
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*/
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size_t session_command_count() const;
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/**
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* @brief Clear state
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*
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* @param state State to clear
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*/
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void clear_state(enum bref_state state);
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/**
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* @brief Set state
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*
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* @param state State to set
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*/
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void set_state(enum bref_state state);
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/**
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* @brief Get pointer to server reference
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*
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* @return Pointer to server reference
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*/
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SERVER_REF* backend() const;
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/**
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* @brief Create a new connection
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*
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* @param session The session to which the connection is linked
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*
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* @return True if connection was successfully created
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*/
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bool connect(MXS_SESSION* session);
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/**
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* @brief Close the backend
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*
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* This will close all active connections created by the backend.
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*/
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void close();
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/**
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* @brief Get a pointer to the internal DCB
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*
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* @return Pointer to internal DCB
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*/
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DCB* dcb() const;
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/**
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* @brief Write data to the backend server
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*
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* @param buffer Buffer containing the data to write
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*
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* @return True if data was written successfully
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*/
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bool write(GWBUF* buffer);
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/**
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* @brief Store a command
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*
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* The command is stored and executed once the session can execute
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* the next command.
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*
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* @param buffer Buffer to store
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*/
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void store_command(GWBUF* buffer);
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/**
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* @brief Write the stored command to the backend server
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*
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* @return True if command was written successfully
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*/
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bool write_stored_command();
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/**
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* @brief Check if backend is in use
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*
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* @return True if backend is in use
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*/
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bool in_use() const;
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/**
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* @brief Check if backend is waiting for a result
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*
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* @return True if backend is waiting for a result
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*/
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bool is_waiting_result() const;
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/**
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* @brief Check if a query is active
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*
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* @return True if a query is active
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*/
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bool is_query_active() const;
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/**
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* @brief Check if the backend is closed
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*
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* @return True if the backend is closed
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*/
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bool is_closed() const;
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private:
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bool m_closed; /**< True if a connection has been opened and closed */
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SERVER_REF* m_backend; /**< Backend server */
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DCB* m_dcb; /**< Backend DCB */
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int m_num_result_wait; /**< Number of not yet received results */
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mxs::Buffer m_pending_cmd; /**< Pending commands */
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int m_state; /**< State of the backend */
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SessionCommandList m_session_commands; /**< List of session commands that are
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* to be executed on this backend server */
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};
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typedef std::tr1::shared_ptr<Backend> SBackend;
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typedef std::list<SBackend> BackendList;
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}
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90
include/maxscale/session_command.hh
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90
include/maxscale/session_command.hh
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@ -0,0 +1,90 @@
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#pragma once
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/*
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* Copyright (c) 2016 MariaDB Corporation Ab
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file and at www.mariadb.com/bsl11.
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*
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* Change Date: 2020-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2 or later of the General
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* Public License.
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*/
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#include <maxscale/cppdefs.hh>
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#include <tr1/memory>
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#include <list>
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#include <string>
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#include <maxscale/buffer.hh>
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namespace maxscale
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{
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class SessionCommand
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{
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SessionCommand(const SessionCommand&);
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SessionCommand& operator=(const SessionCommand&);
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public:
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/**
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* @brief Mark reply as received
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*/
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void mark_reply_received();
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/**
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* @brief Check if the session command has received a reply
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* @return True if the reply is already received
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*/
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bool is_reply_received() const;
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/**
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* @brief Get the command type of the session command
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*
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* @return The type of the command
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*/
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uint8_t get_command() const;
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/**
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* @brief Get the position of this session command
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*
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* @return The position of the session command
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*/
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uint64_t get_position() const;
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/**
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* @brief Creates a copy of the internal buffer
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* @return A copy of the internal buffer
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*/
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mxs::Buffer copy_buffer() const;
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/**
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* @brief Create a new session command
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*
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* @param buffer The buffer containing the command. Note that the ownership
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* of @c buffer is transferred to this object.
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* @param id A unique position identifier used to track replies
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*/
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SessionCommand(GWBUF *buffer, uint64_t id);
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~SessionCommand();
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/**
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* @brief Debug function for printing session commands
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*
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* @return String representation of the object
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*/
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std::string to_string();
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private:
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mxs::Buffer m_buffer; /**< The buffer containing the command */
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uint8_t m_command; /**< The command being executed */
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uint64_t m_pos; /**< Unique position identifier */
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bool m_reply_sent; /**< Whether the session command reply has been sent */
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};
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typedef std::tr1::shared_ptr<SessionCommand> SSessionCommand;
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typedef std::list<SSessionCommand> SessionCommandList;
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}
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