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MaxScale/include/maxscale/session.h
Johan Wikman aa11c960b1 2.3.20 Update change date
2020-06-05 09:31:45 +03:00

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/*
* Copyright (c) 2018 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: 2024-06-02
*
* 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
/**
* @file include/maxscale/session.h - The public session interface
*/
#include <maxscale/cdefs.h>
#include <time.h>
#include <maxbase/atomic.h>
#include <maxbase/jansson.h>
#include <maxscale/dcb.h>
#include <maxscale/buffer.h>
#include <maxscale/log.h>
MXS_BEGIN_DECLS
struct dcb;
struct service;
struct mxs_filter_def;
struct mxs_filter;
struct mxs_filter_session;
struct mxs_router_session;
struct server;
typedef enum
{
SESSION_STATE_ALLOC, /*< for all sessions */
SESSION_STATE_READY, /*< for router session */
SESSION_STATE_ROUTER_READY, /*< for router session */
SESSION_STATE_STOPPING, /*< session and router are being closed */
SESSION_STATE_LISTENER, /*< for listener session */
SESSION_STATE_LISTENER_STOPPED, /*< for listener session */
SESSION_STATE_TO_BE_FREED, /*< ready to be freed as soon as there are no references */
SESSION_STATE_FREE, /*< for all sessions */
SESSION_STATE_DUMMY /*< dummy session for consistency */
} mxs_session_state_t;
#define STRSESSIONSTATE(s) \
((s) == SESSION_STATE_ALLOC ? "SESSION_STATE_ALLOC" \
: ((s) == SESSION_STATE_READY ? "SESSION_STATE_READY" \
: ((s) \
== SESSION_STATE_ROUTER_READY \
? "SESSION_STATE_ROUTER_READY" \
: ((s) \
== \
SESSION_STATE_STOPPING \
? \
"SESSION_STATE_STOPPING" \
: (( \
s) \
== \
SESSION_STATE_LISTENER \
? \
"SESSION_STATE_LISTENER" \
: (( \
s) \
== \
SESSION_STATE_LISTENER_STOPPED \
? \
"SESSION_STATE_LISTENER_STOPPED" \
: (( \
s) \
== \
SESSION_STATE_TO_BE_FREED \
? \
"SESSION_STATE_TO_BE_FREED" \
: (( \
s) \
== \
SESSION_STATE_FREE \
? \
"SESSION_STATE_TO_BE_FREE" \
: (( \
s) \
== \
SESSION_STATE_DUMMY \
? \
"SESSION_STATE_DUMMY" \
: \
"SESSION_STATE_UNKNOWN")))))))))
typedef enum
{
SESSION_TRX_INACTIVE_BIT = 0x01, /* 0b00001 */
SESSION_TRX_ACTIVE_BIT = 0x02, /* 0b00010 */
SESSION_TRX_READ_ONLY_BIT = 0x04, /* 0b00100 */
SESSION_TRX_READ_WRITE_BIT = 0x08, /* 0b01000 */
SESSION_TRX_ENDING_BIT = 0x10, /* 0b10000*/
} session_trx_state_bit_t;
typedef enum
{
/*< There is no on-going transaction. */
SESSION_TRX_INACTIVE = SESSION_TRX_INACTIVE_BIT,
/*< A transaction is active. */
SESSION_TRX_ACTIVE = SESSION_TRX_ACTIVE_BIT,
/*< An explicit READ ONLY transaction is active. */
SESSION_TRX_READ_ONLY = (SESSION_TRX_ACTIVE_BIT | SESSION_TRX_READ_ONLY_BIT),
/*< An explicit READ WRITE transaction is active. */
SESSION_TRX_READ_WRITE = (SESSION_TRX_ACTIVE_BIT | SESSION_TRX_READ_WRITE_BIT),
/*< An explicit READ ONLY transaction is ending. */
SESSION_TRX_READ_ONLY_ENDING = (SESSION_TRX_ENDING_BIT | SESSION_TRX_READ_ONLY),
/*< An explicit READ WRITE transaction is ending. */
SESSION_TRX_READ_WRITE_ENDING = (SESSION_TRX_ENDING_BIT | SESSION_TRX_READ_WRITE),
} mxs_session_trx_state_t;
typedef enum
{
SESSION_DUMP_STATEMENTS_NEVER,
SESSION_DUMP_STATEMENTS_ON_CLOSE,
SESSION_DUMP_STATEMENTS_ON_ERROR,
} session_dump_statements_t;
/**
* The session statistics structure
*/
typedef struct
{
time_t connect; /**< Time when the session was started */
} MXS_SESSION_STATS;
/**
* The downstream element in the filter chain. This may refer to
* another filter or to a router.
*/
struct mxs_filter;
struct mxs_filter_session;
// These are more convenient types
typedef int32_t (* DOWNSTREAMFUNC)(struct mxs_filter* instance,
struct mxs_filter_session* session,
GWBUF* response);
typedef int32_t (* UPSTREAMFUNC)(struct mxs_filter* instance,
struct mxs_filter_session* session,
GWBUF* response);
typedef struct mxs_downstream
{
struct mxs_filter* instance;
struct mxs_filter_session* session;
DOWNSTREAMFUNC routeQuery;
} MXS_DOWNSTREAM;
/**
* The upstream element in the filter chain. This may refer to
* another filter or to the protocol implementation.
*/
typedef struct mxs_upstream
{
struct mxs_filter* instance;
struct mxs_filter_session* session;
UPSTREAMFUNC clientReply;
} MXS_UPSTREAM;
/* Specific reasons why a session was closed */
typedef enum
{
SESSION_CLOSE_NONE = 0, // No special reason
SESSION_CLOSE_TIMEOUT, // Connection timed out
SESSION_CLOSE_HANDLEERROR_FAILED, // Router returned an error from handleError
SESSION_CLOSE_ROUTING_FAILED, // Router closed DCB
SESSION_CLOSE_KILLED, // Killed by another connection
SESSION_CLOSE_TOO_MANY_CONNECTIONS, // Too many connections
} session_close_t;
/**
* Handler function for MaxScale specific session variables.
*
* Note that the provided value string is exactly as it appears in
* the received SET-statement. Only leading and trailing whitespace
* has been removed. The handler must itself parse the value string.
*
* @param context Context provided when handler was registered.
* @param name The variable that is being set. Note that it
* will always be in all lower-case irrespective
* of the case used when registering.
* @param value_begin The beginning of the value as specified in the
* "set @maxscale.x.y = VALUE" statement.
* @param value_end One past the end of the VALUE.
*
* @return NULL if successful, otherwise a dynamically allocated string
* containing an end-user friendly error message.
*/
typedef char* (* session_variable_handler_t)(void* context,
const char* name,
const char* value_begin,
const char* value_end);
/**
* The session status block
*
* A session status block is created for each user (client) connection
* to the database, it links the descriptors, routing implementation
* and originating service together for the client session.
*
* Note that the first few fields (up to and including "entry_is_ready") must
* precisely match the LIST_ENTRY structure defined in the list manager.
*/
typedef struct session
{
mxs_session_state_t state; /*< Current descriptor state */
uint64_t ses_id; /*< Unique session identifier */
struct dcb* client_dcb; /*< The client connection */
struct mxs_router_session* router_session; /*< The router instance data */
MXS_SESSION_STATS stats; /*< Session statistics */
struct service* service; /*< The service this session is using */
MXS_DOWNSTREAM head; /*< Head of the filter chain */
MXS_UPSTREAM tail; /*< The tail of the filter chain */
int refcount; /*< Reference count on the session */
mxs_session_trx_state_t trx_state; /*< The current transaction state. */
bool autocommit; /*< Whether autocommit is on. */
intptr_t client_protocol_data; /*< Owned and managed by the client protocol. */
bool qualifies_for_pooling; /**< Whether this session qualifies for the connection
* pool */
struct
{
MXS_UPSTREAM up; /*< Upward component to receive buffer. */
GWBUF* buffer; /*< Buffer to deliver to up. */
} response; /*< Shortcircuited response */
session_close_t close_reason; /*< Reason why the session was closed */
bool load_active; /*< Data streaming state (for LOAD DATA LOCAL INFILE) */
} MXS_SESSION;
/**
* A filter that terminates the request processing and delivers a response
* directly should specify the response using this function. After having
* called this function, the module must not deliver the request further
* in the request processing pipeline.
*
* @param session The session.
* @param up The filter that should receive the response.
* @param buffer The response.
*/
void session_set_response(MXS_SESSION* session, const MXS_UPSTREAM* up, GWBUF* buffer);
/**
* Function to be used by protocol module for routing incoming data
* to the first component in the pipeline of filters and a router.
*
* @param session The session.
* @param buffer A buffer.
*
* @return True, if the routing should continue, false otherwise.
*/
bool session_route_query(MXS_SESSION* session, GWBUF* buffer);
/**
* Function to be used by the router module to route the replies to
* the first element in the pipeline of filters and a protocol.
*
* @param session The session.
* @param buffer A buffer.
*
* @return True, if the routing should continue, false otherwise.
*/
bool session_route_reply(MXS_SESSION* session, GWBUF* buffer);
/**
* A convenience macro that can be used by the protocol modules to route
* the incoming data to the first element in the pipeline of filters and
* routers.
*/
#define MXS_SESSION_ROUTE_QUERY(sess, buf) session_route_query(sess, buf)
/**
* A convenience macro that can be used by the router modules to route
* the replies to the first element in the pipeline of filters and
* the protocol.
*/
#define MXS_SESSION_ROUTE_REPLY(sess, buf) session_route_reply(sess, buf)
/**
* Allocate a new session for a new client of the specified service.
*
* Create the link to the router session by calling the newSession
* entry point of the router using the router instance of the
* service this session is part of.
*
* @param service The service this connection was established by
* @param client_dcb The client side DCB
* @return The newly created session or NULL if an error occurred
*/
MXS_SESSION* session_alloc(struct service*, struct dcb*);
/**
* A version of session_alloc() which takes the session id number as parameter.
* The id should have been generated with session_get_next_id().
*
* @param service The service this connection was established by
* @param client_dcb The client side DCB
* @param id Id for the new session.
* @return The newly created session or NULL if an error occurred
*/
MXS_SESSION* session_alloc_with_id(struct service*, struct dcb*, uint64_t);
MXS_SESSION* session_set_dummy(struct dcb*);
static inline bool session_is_dummy(MXS_SESSION* session)
{
return session->state == SESSION_STATE_DUMMY;
}
const char* session_get_remote(const MXS_SESSION*);
const char* session_get_user(const MXS_SESSION*);
/**
* Convert transaction state to string representation.
*
* @param state A transaction state.
* @return String representation of the state.
*/
const char* session_trx_state_to_string(mxs_session_trx_state_t state);
/**
* Get the transaction state of the session.
*
* Note that this tells only the state of @e explicitly started transactions.
* That is, if @e autocommit is OFF, which means that there is always an
* active transaction that is ended with an explicit COMMIT or ROLLBACK,
* at which point a new transaction is started, this function will still
* return SESSION_TRX_INACTIVE, unless a transaction has explicitly been
* started with START TRANSACTION.
*
* Likewise, if @e autocommit is ON, which means that every statement is
* executed in a transaction of its own, this will return false, unless a
* transaction has explicitly been started with START TRANSACTION.
*
* @note The return value is valid only if either a router or a filter
* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
*
* @param ses The MXS_SESSION object.
* @return The transaction state.
*/
mxs_session_trx_state_t session_get_trx_state(const MXS_SESSION* ses);
/**
* Set the transaction state of the session.
*
* NOTE: Only the protocol object may call this.
*
* @param ses The MXS_SESSION object.
* @param new_state The new transaction state.
*
* @return The previous transaction state.
*/
mxs_session_trx_state_t session_set_trx_state(MXS_SESSION* ses, mxs_session_trx_state_t new_state);
/**
* Tells whether an explicit READ ONLY transaction is active.
*
* @see session_get_trx_state
*
* @note The return value is valid only if either a router or a filter
* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
*
* @return True if an explicit READ ONLY transaction is active,
* false otherwise.
*/
static inline bool session_trx_is_read_only(const MXS_SESSION* ses)
{
return ses->trx_state == SESSION_TRX_READ_ONLY || ses->trx_state == SESSION_TRX_READ_ONLY_ENDING;
}
/**
* Tells whether an explicit READ WRITE transaction is active.
*
* @see session_get_trx_state
*
* @note The return value is valid only if either a router or a filter
* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
*
* @return True if an explicit READ WRITE transaction is active,
* false otherwise.
*/
static inline bool session_trx_is_read_write(const MXS_SESSION* ses)
{
return ses->trx_state == SESSION_TRX_READ_WRITE || ses->trx_state == SESSION_TRX_READ_WRITE_ENDING;
}
/**
* Tells whether a transaction is ending.
*
* @see session_get_trx_state
*
* @note The return value is valid only if either a router or a filter
* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
*
* @return True if a transaction that was active is ending either via COMMIT or ROLLBACK.
*/
static inline bool session_trx_is_ending(const MXS_SESSION* ses)
{
return ses->trx_state & SESSION_TRX_ENDING_BIT;
}
/**
* Tells whether autocommit is ON or not.
*
* Note that the returned value effectively only tells the last value
* of the statement "set autocommit=...".
*
* That is, if the statement "set autocommit=1" has been executed, then
* even if a transaction has been started, which implicitly will cause
* autocommit to be set to 0 for the duration of the transaction, this
* function will still return true.
*
* Note also that by default autocommit is ON.
*
* @see session_get_trx_state
*
* @return True if autocommit has been set ON, false otherwise.
*/
static inline bool session_is_autocommit(const MXS_SESSION* ses)
{
return ses->autocommit;
}
/**
* Tells whether a transaction is active.
*
* @see session_get_trx_state
*
* @note The return value is valid only if either a router or a filter
* has declared that it needs RCAP_TYPE_TRANSACTION_TRACKING.
*
* @return True if a transaction is active, false otherwise.
*/
static inline bool session_trx_is_active(const MXS_SESSION* ses)
{
return !session_is_autocommit(ses) || (ses->trx_state & SESSION_TRX_ACTIVE_BIT);
}
/**
* Sets the autocommit state of the session.
*
* NOTE: Only the protocol object may call this.
*
* @param enable True if autocommit is enabled, false otherwise.
* @return The previous state.
*/
static inline bool session_set_autocommit(MXS_SESSION* ses, bool autocommit)
{
bool prev_autocommit = ses->autocommit;
ses->autocommit = autocommit;
return prev_autocommit;
}
/**
* @brief Get a session reference by ID
*
* This creates an additional reference to a session whose unique ID matches @c id.
*
* @param id Unique session ID
* @return Reference to a MXS_SESSION or NULL if the session was not found
*
* @note The caller must free the session reference by calling session_put_ref
*/
MXS_SESSION* session_get_by_id(uint64_t id);
/**
* Get the next available unique (assuming no overflow) session id number.
*
* @return An unused session id.
*/
uint64_t session_get_next_id();
/**
* @brief Close a session
*
* Calling this function will start the session shutdown process. The shutdown
* closes all related backend DCBs by calling the closeSession entry point
* of the router session.
*
* @param session The session to close
*/
void session_close(MXS_SESSION* session);
/**
* @brief Release a session reference
*
* This function is public only because the tee-filter uses it.
*
* @param session Session reference to release
*/
void session_put_ref(MXS_SESSION* session);
/**
* @brief Convert a session to JSON
*
* @param session Session to convert
* @param host Hostname of this server
*
* @return New JSON object or NULL on error
*/
json_t* session_to_json(const MXS_SESSION* session, const char* host);
/**
* @brief Convert all sessions to JSON
*
* @param host Hostname of this server
*
* @return A JSON array with all sessions
*/
json_t* session_list_to_json(const char* host);
/**
* Qualify the session for connection pooling
*
* @param session Session to qualify
*/
void session_qualify_for_pool(MXS_SESSION* session);
/**
* Check if the session qualifies for connection pooling
*
* @param session
*/
bool session_valid_for_pool(const MXS_SESSION* session);
/**
* @brief Return the session of the dcb currently being processed
* by the calling thread.
*
* @return A session, or NULL if the calling thread is not currently handling
* a dcb or if the calling thread is not a polling/worker thread.
**/
MXS_SESSION* session_get_current();
/**
* @brief Return the id of the session of the dcb currently being processed
* by the calling thread.
*
* @return The id of the current session or 0 if there is no current session.
**/
uint64_t session_get_current_id();
/**
* @brief Add new MaxScale specific user variable to the session.
*
* The name of the variable must be of the following format:
*
* "@maxscale\.[a-zA-Z_]+(\.[a-zA-Z_])*"
*
* e.g. "@maxscale.cache.enabled". A strong suggestion is that the first
* sub-scope is the same as the module name of the component registering the
* variable. The sub-scope "core" is reserved by MaxScale.
*
* The variable name will be converted to all lowercase when added.
*
* @param session The session in question.
* @param name The name of the variable, must start with "@MAXSCALE.".
* @param handler The handler function for the variable.
* @param context Context that will be passed to the handler function.
*
* @return True, if the variable could be added, false otherwise.
*/
bool session_add_variable(MXS_SESSION* session,
const char* name,
session_variable_handler_t handler,
void* context);
/**
* @brief Remove MaxScale specific user variable from the session.
*
* With this function a particular MaxScale specific user variable
* can be removed. Note that it is *not* mandatory to remove a
* variable when a session is closed, but have to be done in case
* the context object must manually be deleted.
*
* @param session The session in question.
* @param name The name of the variable.
* @param context On successful return, if non-NULL, the context object
* that was provided when the variable was added.
*
* @return True, if the variable existed, false otherwise.
*/
bool session_remove_variable(MXS_SESSION* session,
const char* name,
void** context);
/**
* @brief Set value of maxscale session variable.
*
* @param session The session.
* @param name_begin Should point to the beginning of the variable name.
* @param name_end Should point one past the end of the variable name.
* @param value_begin Should point to the beginning of the value.
* @param value_end Should point one past the end of the value.
*
* @return NULL if successful, otherwise a dynamically allocated string
* containing an end-user friendly error message.
*
* @note Should only be called from the protocol module that scans
* incoming statements.
*/
char* session_set_variable_value(MXS_SESSION* session,
const char* name_begin,
const char* name_end,
const char* value_begin,
const char* value_end);
/**
* @brief Specify how many statements each session should retain for
* debugging purposes.
*
* @param n The number of statements.
*/
void session_set_retain_last_statements(uint32_t n);
/**
* Get retain_last_statements
*/
uint32_t session_get_retain_last_statements();
/**
* @brief Retain provided statement, if configured to do so.
*
* @param session The session.
* @param buffer Buffer assumed to contain a full statement.
*/
void session_retain_statement(MXS_SESSION* session, GWBUF* buffer);
/**
* @brief Book a server response for the statement currently being handled.
*
* @param session The session.
* @param server The server having returned a response.
* @param final_response True if this was the final server to respond,
* false otherwise.
*/
void session_book_server_response(MXS_SESSION* session, struct server* server, bool final_response);
/**
* @brief Reset the server bookkeeping for the current statement.
*
* To be called, e.g., after a transaction is rolled back (possibly with
* results having been reported) and before it is replayed.
*
* @param session The session.
*/
void session_reset_server_bookkeeping(MXS_SESSION* session);
/**
* @brief Dump the last statements, if statements have been retained.
*
* @param session The session.
*/
void session_dump_statements(MXS_SESSION* pSession);
/**
* @brief Specify whether statements should be dumped or not.
*
* @param value Whether and when to dump statements.
*/
void session_set_dump_statements(session_dump_statements_t value);
/**
* @brief Returns in what contexts statements should be dumped.
*
* @return Whether and when to dump statements.
*/
session_dump_statements_t session_get_dump_statements();
/**
* String version of session_get_dump_statements
*/
const char* session_get_dump_statements_str();
void session_set_session_trace(uint32_t value);
uint32_t session_get_session_trace();
const char* session_get_session_log(MXS_SESSION* pSession);
void session_append_log(MXS_SESSION* pSession, const char* log);
void session_dump_log(MXS_SESSION* pSession);
/**
* @brief Route the query again after a delay
*
* @param session The current Session
* @param down The downstream component, either a filter or a router
* @param buffer The buffer to route
* @param seconds Number of seconds to wait before routing the query. Use 0 for immediate re-routing.
*
* @return True if queuing of the query was successful
*/
bool session_delay_routing(MXS_SESSION* session, MXS_DOWNSTREAM down, GWBUF* buffer, int seconds);
/**
* Cast the session's router as a MXS_DOWNSTREAM object
*
* @param session The session to use
*
* @return The router cast as MXS_DOWNSTREAM
*/
MXS_DOWNSTREAM router_as_downstream(MXS_SESSION* session);
/**
* Get the reason why a session was closed
*
* @param session Session to inspect
*
* @return String representation of the reason why the session was closed. If
* the session was closed normally, an empty string is returned.
*/
const char* session_get_close_reason(const MXS_SESSION* session);
static inline void session_set_load_active(MXS_SESSION* session, bool value)
{
session->load_active = value;
}
static inline bool session_is_load_active(const MXS_SESSION* session)
{
return session->load_active;
}
MXS_END_DECLS
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