adbd666991
This commit introduces safe session references that can be handled without holding locks. This allows the safe searching of sessions with the unique ID of the session. Remove the use of raw pointers passed as strings. Change the comments of the argument types and add more details to the parsing function documentation.
363 lines
12 KiB
C
363 lines
12 KiB
C
#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/bsl.
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*
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* Change Date: 2019-07-01
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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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/**
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* @file session.h
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*
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* @verbatim
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* Revision History
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*
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* Date Who Description
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* 01-06-2013 Mark Riddoch Initial implementation
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* 14-06-2013 Massimiliano Pinto Added void *data to session
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* for session specific data
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* 01-07-2013 Massimiliano Pinto Removed backends pointer
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* from struct session
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* 02-09-2013 Massimiliano Pinto Added session ref counter
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* 29-05-2014 Mark Riddoch Support for filter mechanism
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* added
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* 20-02-2015 Markus Mäkelä Added session timeouts
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* 27/06/2016 Martin Brampton Modify session struct for list manager
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*
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* @endverbatim
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*/
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#include <maxscale/cdefs.h>
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#include <time.h>
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#include <maxscale/atomic.h>
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#include <maxscale/buffer.h>
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#include <maxscale/spinlock.h>
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#include <maxscale/resultset.h>
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#include <maxscale/log_manager.h>
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MXS_BEGIN_DECLS
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struct dcb;
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struct service;
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struct filter_def;
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/**
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* The session statistics structure
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*/
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typedef struct
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{
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time_t connect; /**< Time when the session was started */
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} SESSION_STATS;
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#define SESSION_STATS_INIT {0}
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typedef enum
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{
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SESSION_STATE_ALLOC, /*< for all sessions */
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SESSION_STATE_READY, /*< for router session */
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SESSION_STATE_ROUTER_READY, /*< for router session */
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SESSION_STATE_STOPPING, /*< session and router are being closed */
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SESSION_STATE_LISTENER, /*< for listener session */
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SESSION_STATE_LISTENER_STOPPED, /*< for listener session */
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SESSION_STATE_TO_BE_FREED, /*< ready to be freed as soon as there are no references */
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SESSION_STATE_FREE, /*< for all sessions */
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SESSION_STATE_DUMMY /*< dummy session for consistency */
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} session_state_t;
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typedef enum
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{
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SESSION_TRX_INACTIVE_BIT = 1, /* 0b0001 */
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SESSION_TRX_ACTIVE_BIT = 2, /* 0b0010 */
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SESSION_TRX_READ_ONLY_BIT = 4, /* 0b0100 */
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SESSION_TRX_READ_WRITE_BIT = 8, /* 0b1000 */
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} session_trx_state_bit_t;
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typedef enum
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{
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/*< There is no on-going transaction. */
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SESSION_TRX_INACTIVE = SESSION_TRX_INACTIVE_BIT,
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/*< A transaction is active. */
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SESSION_TRX_ACTIVE = SESSION_TRX_ACTIVE_BIT,
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/*< An explicit READ ONLY transaction is active. */
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SESSION_TRX_READ_ONLY = (SESSION_TRX_ACTIVE_BIT | SESSION_TRX_READ_ONLY_BIT),
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/*< An explicit READ WRITE transaction is active. */
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SESSION_TRX_READ_WRITE = (SESSION_TRX_ACTIVE_BIT | SESSION_TRX_READ_WRITE_BIT)
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} session_trx_state_t;
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/**
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* Convert transaction state to string representation.
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*
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* @param state A transaction state.
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* @return String representation of the state.
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*/
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const char* session_trx_state_to_string(session_trx_state_t state);
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/**
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* The downstream element in the filter chain. This may refer to
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* another filter or to a router.
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*/
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typedef struct
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{
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void *instance;
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void *session;
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int (*routeQuery)(void *instance, void *session, GWBUF *request);
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} DOWNSTREAM;
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#define DOWNSTREAM_INIT {0}
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/**
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* The upstream element in the filter chain. This may refer to
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* another filter or to the protocol implementation.
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*/
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typedef struct
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{
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void *instance;
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void *session;
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int (*clientReply)(void *instance, void *session, GWBUF *response);
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int (*error)(void *instance, void *session, void *);
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} UPSTREAM;
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#define UPSTREAM_INIT {0}
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/**
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* Structure used to track the filter instances and sessions of the filters
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* that are in use within a session.
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*/
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typedef struct
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{
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struct filter_def *filter;
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void *instance;
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void *session;
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} SESSION_FILTER;
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#define SESSION_FILTER_INIT {0}
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/**
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* Filter type for the sessionGetList call
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*/
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typedef enum
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{
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SESSION_LIST_ALL,
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SESSION_LIST_CONNECTION
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} SESSIONLISTFILTER;
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/**
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* The session status block
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*
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* A session status block is created for each user (client) connection
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* to the database, it links the descriptors, routing implementation
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* and originating service together for the client session.
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*
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* Note that the first few fields (up to and including "entry_is_ready") must
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* precisely match the LIST_ENTRY structure defined in the list manager.
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*/
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typedef struct session
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{
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skygw_chk_t ses_chk_top;
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SPINLOCK ses_lock;
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session_state_t state; /*< Current descriptor state */
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size_t ses_id; /*< Unique session identifier */
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int enabled_log_priorities; /*< Bitfield of enabled syslog priorities */
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struct dcb *client_dcb; /*< The client connection */
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void *router_session; /*< The router instance data */
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SESSION_STATS stats; /*< Session statistics */
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struct service *service; /*< The service this session is using */
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int n_filters; /*< Number of filter sessions */
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SESSION_FILTER *filters; /*< The filters in use within this session */
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DOWNSTREAM head; /*< Head of the filter chain */
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UPSTREAM tail; /*< The tail of the filter chain */
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int refcount; /*< Reference count on the session */
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bool ses_is_child; /*< this is a child session */
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session_trx_state_t trx_state; /*< The current transaction state. */
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bool autocommit; /*< Whether autocommit is on. */
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skygw_chk_t ses_chk_tail;
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} SESSION;
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#define SESSION_INIT {.ses_chk_top = CHK_NUM_SESSION, .ses_lock = SPINLOCK_INIT, \
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.stats = SESSION_STATS_INIT, .head = DOWNSTREAM_INIT, .tail = UPSTREAM_INIT, \
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.state = SESSION_STATE_ALLOC, .ses_chk_tail = CHK_NUM_SESSION}
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#define SESSION_PROTOCOL(x, type) DCB_PROTOCOL((x)->client_dcb, type)
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/**
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* A convenience macro that can be used by the protocol modules to route
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* the incoming data to the first element in the pipeline of filters and
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* routers.
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*/
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#define SESSION_ROUTE_QUERY(sess, buf) \
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((sess)->head.routeQuery)((sess)->head.instance, \
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(sess)->head.session, (buf))
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/**
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* A convenience macro that can be used by the router modules to route
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* the replies to the first element in the pipeline of filters and
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* the protocol.
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*/
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#define SESSION_ROUTE_REPLY(sess, buf) \
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((sess)->tail.clientReply)((sess)->tail.instance, \
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(sess)->tail.session, (buf))
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SESSION *session_alloc(struct service *, struct dcb *);
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SESSION *session_set_dummy(struct dcb *);
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bool session_free(SESSION *);
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int session_isvalid(SESSION *);
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int session_reply(void *inst, void *session, GWBUF *data);
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char *session_get_remote(SESSION *);
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char *session_getUser(SESSION *);
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void printAllSessions();
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void printSession(SESSION *);
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void dprintSessionList(DCB *pdcb);
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void dprintAllSessions(struct dcb *);
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void dprintSession(struct dcb *, SESSION *);
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void dListSessions(struct dcb *);
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char *session_state(session_state_t);
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bool session_link_dcb(SESSION *, struct dcb *);
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void session_enable_log_priority(SESSION* ses, int priority);
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void session_disable_log_priority(SESSION* ses, int priority);
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RESULTSET *sessionGetList(SESSIONLISTFILTER);
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/**
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* Get the transaction state of the session.
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*
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* Note that this tells only the state of @e explicitly started transactions.
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* That is, if @e autocommit is OFF, which means that there is always an
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* active transaction that is ended with an explicit COMMIT or ROLLBACK,
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* at which point a new transaction is started, this function will still
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* return SESSION_TRX_INACTIVE, unless a transaction has explicitly been
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* started with START TRANSACTION.
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*
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* Likewise, if @e autocommit is ON, which means that every statement is
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* executed in a transaction of its own, this will return false, unless a
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* transaction has explicitly been started with START TRANSACTION.
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*
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* @note The return value is valid only if either a router or a filter
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* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
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*
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* @param ses The SESSION object.
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* @return The transaction state.
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*/
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session_trx_state_t session_get_trx_state(const SESSION* ses);
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/**
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* Set the transaction state of the session.
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*
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* NOTE: Only the protocol object may call this.
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*
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* @param ses The SESSION object.
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* @param new_state The new transaction state.
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*
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* @return The previous transaction state.
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*/
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session_trx_state_t session_set_trx_state(SESSION* ses, session_trx_state_t new_state);
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/**
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* Tells whether an explicit transaction is active.
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*
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* @see session_get_trx_state
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*
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* @note The return value is valid only if either a router or a filter
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* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
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*
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* @return True if a transaction is active, false otherwise.
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*/
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static inline bool session_trx_is_active(const SESSION* ses)
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{
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return ses->trx_state & SESSION_TRX_ACTIVE_BIT;
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}
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/**
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* Tells whether an explicit READ ONLY transaction is active.
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*
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* @see session_get_trx_state
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*
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* @note The return value is valid only if either a router or a filter
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* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
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*
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* @return True if an explicit READ ONLY transaction is active,
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* false otherwise.
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*/
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static inline bool session_trx_is_read_only(const SESSION* ses)
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{
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return ses->trx_state == SESSION_TRX_READ_ONLY;
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}
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/**
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* Tells whether an explicit READ WRITE transaction is active.
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*
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* @see session_get_trx_state
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*
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* @note The return value is valid only if either a router or a filter
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* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
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*
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* @return True if an explicit READ WRITE transaction is active,
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* false otherwise.
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*/
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static inline bool session_trx_is_read_write(const SESSION* ses)
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{
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return ses->trx_state == SESSION_TRX_READ_WRITE;
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}
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/**
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* Tells whether autocommit is ON or not.
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*
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* Note that the returned value effectively only tells the last value
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* of the statement "set autocommit=...".
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*
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* That is, if the statement "set autocommit=1" has been executed, then
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* even if a transaction has been started, which implicitly will cause
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* autocommit to be set to 0 for the duration of the transaction, this
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* function will still return true.
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*
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* Note also that by default autocommit is ON.
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*
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* @see session_get_trx_state
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*
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* @return True if autocommit has been set ON, false otherwise.
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*/
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static inline bool session_is_autocommit(const SESSION* ses)
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{
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return ses->autocommit;
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}
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/**
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* Sets the autocommit state of the session.
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*
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* NOTE: Only the protocol object may call this.
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*
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* @param enable True if autocommit is enabled, false otherwise.
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* @return The previous state.
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*/
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static inline bool session_set_autocommit(SESSION* ses, bool autocommit)
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{
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bool prev_autocommit = ses->autocommit;
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ses->autocommit = autocommit;
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return prev_autocommit;
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}
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/**
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* @brief Get a session reference by ID
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*
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* This creates an additional reference to a session whose unique ID matches @c id.
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*
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* @param id Unique session ID
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* @return Reference to a SESSION or NULL if the session was not found
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*
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* @note The caller must free the session reference by passing it to the
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* @c session_put_ref function
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*/
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SESSION* session_get_ref(int id);
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/**
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* @brief Release a session reference
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*
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* @param session Session reference to release
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*/
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void session_put_ref(SESSION *session);
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MXS_END_DECLS
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