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|
/*****************************************************************************
Copyright (c) 1996, 2016, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2015, 2021, MariaDB Corporation.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file include/trx0trx.h
The transaction
Created 3/26/1996 Heikki Tuuri
*******************************************************/
#ifndef trx0trx_h
#define trx0trx_h
#include "trx0types.h"
#include "lock0types.h"
#include "que0types.h"
#include "mem0mem.h"
#include "trx0xa.h"
#include "ut0vec.h"
#include "fts0fts.h"
#include "read0types.h"
#include <vector>
#include <set>
// Forward declaration
struct mtr_t;
class FlushObserver;
struct rw_trx_hash_element_t;
/******************************************************************//**
Set detailed error message for the transaction. */
void
trx_set_detailed_error(
/*===================*/
trx_t* trx, /*!< in: transaction struct */
const char* msg); /*!< in: detailed error message */
/*************************************************************//**
Set detailed error message for the transaction from a file. Note that the
file is rewinded before reading from it. */
void
trx_set_detailed_error_from_file(
/*=============================*/
trx_t* trx, /*!< in: transaction struct */
FILE* file); /*!< in: file to read message from */
/****************************************************************//**
Retrieves the error_info field from a trx.
@return the error info */
UNIV_INLINE
const dict_index_t*
trx_get_error_info(
/*===============*/
const trx_t* trx); /*!< in: trx object */
/** @return an allocated transaction */
trx_t *trx_create();
/** At shutdown, frees a transaction object. */
void trx_free_at_shutdown(trx_t *trx);
/** Disconnect a prepared transaction from MySQL.
@param[in,out] trx transaction */
void trx_disconnect_prepared(trx_t *trx);
/** Initialize (resurrect) transactions at startup. */
dberr_t trx_lists_init_at_db_start();
/*************************************************************//**
Starts the transaction if it is not yet started. */
void
trx_start_if_not_started_xa_low(
/*============================*/
trx_t* trx, /*!< in/out: transaction */
bool read_write); /*!< in: true if read write transaction */
/*************************************************************//**
Starts the transaction if it is not yet started. */
void
trx_start_if_not_started_low(
/*=========================*/
trx_t* trx, /*!< in/out: transaction */
bool read_write); /*!< in: true if read write transaction */
/*************************************************************//**
Starts a transaction for internal processing. */
void
trx_start_internal_low(
/*===================*/
trx_t* trx); /*!< in/out: transaction */
/** Starts a read-only transaction for internal processing.
@param[in,out] trx transaction to be started */
void
trx_start_internal_read_only_low(
trx_t* trx);
#ifdef UNIV_DEBUG
#define trx_start_if_not_started_xa(t, rw) \
do { \
(t)->start_line = __LINE__; \
(t)->start_file = __FILE__; \
trx_start_if_not_started_xa_low((t), rw); \
} while (false)
#define trx_start_if_not_started(t, rw) \
do { \
(t)->start_line = __LINE__; \
(t)->start_file = __FILE__; \
trx_start_if_not_started_low((t), rw); \
} while (false)
#define trx_start_internal(t) \
do { \
(t)->start_line = __LINE__; \
(t)->start_file = __FILE__; \
trx_start_internal_low((t)); \
} while (false)
#define trx_start_internal_read_only(t) \
do { \
(t)->start_line = __LINE__; \
(t)->start_file = __FILE__; \
trx_start_internal_read_only_low(t); \
} while (false)
#else
#define trx_start_if_not_started(t, rw) \
trx_start_if_not_started_low((t), rw)
#define trx_start_internal(t) \
trx_start_internal_low((t))
#define trx_start_internal_read_only(t) \
trx_start_internal_read_only_low(t)
#define trx_start_if_not_started_xa(t, rw) \
trx_start_if_not_started_xa_low((t), (rw))
#endif /* UNIV_DEBUG */
/*************************************************************//**
Starts the transaction for a DDL operation. */
void
trx_start_for_ddl_low(
/*==================*/
trx_t* trx, /*!< in/out: transaction */
trx_dict_op_t op); /*!< in: dictionary operation type */
#ifdef UNIV_DEBUG
#define trx_start_for_ddl(t, o) \
do { \
ut_ad((t)->start_file == 0); \
(t)->start_line = __LINE__; \
(t)->start_file = __FILE__; \
trx_start_for_ddl_low((t), (o)); \
} while (0)
#else
#define trx_start_for_ddl(t, o) \
trx_start_for_ddl_low((t), (o))
#endif /* UNIV_DEBUG */
/**********************************************************************//**
Does the transaction commit for MySQL.
@return DB_SUCCESS or error number */
dberr_t
trx_commit_for_mysql(
/*=================*/
trx_t* trx); /*!< in/out: transaction */
/** XA PREPARE a transaction.
@param[in,out] trx transaction to prepare */
void trx_prepare_for_mysql(trx_t* trx);
/**********************************************************************//**
This function is used to find number of prepared transactions and
their transaction objects for a recovery.
@return number of prepared transactions */
int
trx_recover_for_mysql(
/*==================*/
XID* xid_list, /*!< in/out: prepared transactions */
uint len); /*!< in: number of slots in xid_list */
/** Look up an X/Open distributed transaction in XA PREPARE state.
@param[in] xid X/Open XA transaction identifier
@return transaction on match (the trx_t::xid will be invalidated);
note that the trx may have been committed before the caller acquires
trx_t::mutex
@retval NULL if no match */
trx_t* trx_get_trx_by_xid(const XID* xid);
/**********************************************************************//**
If required, flushes the log to disk if we called trx_commit_for_mysql()
with trx->flush_log_later == TRUE. */
void
trx_commit_complete_for_mysql(
/*==========================*/
trx_t* trx); /*!< in/out: transaction */
/**********************************************************************//**
Marks the latest SQL statement ended. */
void
trx_mark_sql_stat_end(
/*==================*/
trx_t* trx); /*!< in: trx handle */
/****************************************************************//**
Prepares a transaction for commit/rollback. */
void
trx_commit_or_rollback_prepare(
/*===========================*/
trx_t* trx); /*!< in/out: transaction */
/*********************************************************************//**
Creates a commit command node struct.
@return own: commit node struct */
commit_node_t*
trx_commit_node_create(
/*===================*/
mem_heap_t* heap); /*!< in: mem heap where created */
/***********************************************************//**
Performs an execution step for a commit type node in a query graph.
@return query thread to run next, or NULL */
que_thr_t*
trx_commit_step(
/*============*/
que_thr_t* thr); /*!< in: query thread */
/**********************************************************************//**
Prints info about a transaction.
Caller must hold trx_sys.mutex. */
void
trx_print_low(
/*==========*/
FILE* f,
/*!< in: output stream */
const trx_t* trx,
/*!< in: transaction */
ulint max_query_len,
/*!< in: max query length to print,
or 0 to use the default max length */
ulint n_rec_locks,
/*!< in: lock_number_of_rows_locked(&trx->lock) */
ulint n_trx_locks,
/*!< in: length of trx->lock.trx_locks */
ulint heap_size);
/*!< in: mem_heap_get_size(trx->lock.lock_heap) */
/**********************************************************************//**
Prints info about a transaction.
The caller must hold lock_sys.mutex and trx_sys.mutex.
When possible, use trx_print() instead. */
void
trx_print_latched(
/*==============*/
FILE* f, /*!< in: output stream */
const trx_t* trx, /*!< in: transaction */
ulint max_query_len); /*!< in: max query length to print,
or 0 to use the default max length */
/**********************************************************************//**
Prints info about a transaction.
Acquires and releases lock_sys.mutex. */
void
trx_print(
/*======*/
FILE* f, /*!< in: output stream */
const trx_t* trx, /*!< in: transaction */
ulint max_query_len); /*!< in: max query length to print,
or 0 to use the default max length */
/**********************************************************************//**
Determine if a transaction is a dictionary operation.
@return dictionary operation mode */
UNIV_INLINE
enum trx_dict_op_t
trx_get_dict_operation(
/*===================*/
const trx_t* trx) /*!< in: transaction */
MY_ATTRIBUTE((warn_unused_result));
/**********************************************************************//**
Flag a transaction a dictionary operation. */
UNIV_INLINE
void
trx_set_dict_operation(
/*===================*/
trx_t* trx, /*!< in/out: transaction */
enum trx_dict_op_t op); /*!< in: operation, not
TRX_DICT_OP_NONE */
/**********************************************************************//**
Determines if a transaction is in the given state.
The caller must hold trx_sys.mutex, or it must be the thread
that is serving a running transaction.
A running RW transaction must be in trx_sys.rw_trx_hash.
@return TRUE if trx->state == state */
UNIV_INLINE
bool
trx_state_eq(
/*=========*/
const trx_t* trx, /*!< in: transaction */
trx_state_t state, /*!< in: state;
if state != TRX_STATE_NOT_STARTED
asserts that
trx->state != TRX_STATE_NOT_STARTED */
bool relaxed = false)
/*!< in: whether to allow
trx->state == TRX_STATE_NOT_STARTED
after an error has been reported */
MY_ATTRIBUTE((nonnull, warn_unused_result));
/**********************************************************************//**
Determines if the currently running transaction has been interrupted.
@return true if interrupted */
bool
trx_is_interrupted(
/*===============*/
const trx_t* trx); /*!< in: transaction */
/*******************************************************************//**
Calculates the "weight" of a transaction. The weight of one transaction
is estimated as the number of altered rows + the number of locked rows.
@param t transaction
@return transaction weight */
#define TRX_WEIGHT(t) ((t)->undo_no + UT_LIST_GET_LEN((t)->lock.trx_locks))
/*******************************************************************//**
Compares the "weight" (or size) of two transactions. Transactions that
have edited non-transactional tables are considered heavier than ones
that have not.
@return true if weight(a) >= weight(b) */
bool
trx_weight_ge(
/*==========*/
const trx_t* a, /*!< in: the transaction to be compared */
const trx_t* b); /*!< in: the transaction to be compared */
/* Maximum length of a string that can be returned by
trx_get_que_state_str(). */
#define TRX_QUE_STATE_STR_MAX_LEN 12 /* "ROLLING BACK" */
/*******************************************************************//**
Retrieves transaction's que state in a human readable string. The string
should not be free()'d or modified.
@return string in the data segment */
UNIV_INLINE
const char*
trx_get_que_state_str(
/*==================*/
const trx_t* trx); /*!< in: transaction */
/** Retreieves the transaction ID.
In a given point in time it is guaranteed that IDs of the running
transactions are unique. The values returned by this function for readonly
transactions may be reused, so a subsequent RO transaction may get the same ID
as a RO transaction that existed in the past. The values returned by this
function should be used for printing purposes only.
@param[in] trx transaction whose id to retrieve
@return transaction id */
UNIV_INLINE
trx_id_t
trx_get_id_for_print(
const trx_t* trx);
/** Create the trx_t pool */
void
trx_pool_init();
/** Destroy the trx_t pool */
void
trx_pool_close();
/**
Set the transaction as a read-write transaction if it is not already
tagged as such.
@param[in,out] trx Transaction that needs to be "upgraded" to RW from RO */
void
trx_set_rw_mode(
trx_t* trx);
/**
Transactions that aren't started by the MySQL server don't set
the trx_t::mysql_thd field. For such transactions we set the lock
wait timeout to 0 instead of the user configured value that comes
from innodb_lock_wait_timeout via trx_t::mysql_thd.
@param trx transaction
@return lock wait timeout in seconds */
#define trx_lock_wait_timeout_get(t) \
((t)->mysql_thd != NULL \
? thd_lock_wait_timeout((t)->mysql_thd) \
: 0)
typedef std::vector<ib_lock_t*, ut_allocator<ib_lock_t*> > lock_list;
/*******************************************************************//**
Latching protocol for trx_lock_t::que_state. trx_lock_t::que_state
captures the state of the query thread during the execution of a query.
This is different from a transaction state. The query state of a transaction
can be updated asynchronously by other threads. The other threads can be
system threads, like the timeout monitor thread or user threads executing
other queries. Another thing to be mindful of is that there is a delay between
when a query thread is put into LOCK_WAIT state and before it actually starts
waiting. Between these two events it is possible that the query thread is
granted the lock it was waiting for, which implies that the state can be changed
asynchronously.
All these operations take place within the context of locking. Therefore state
changes within the locking code must acquire both the lock mutex and the
trx->mutex when changing trx->lock.que_state to TRX_QUE_LOCK_WAIT or
trx->lock.wait_lock to non-NULL but when the lock wait ends it is sufficient
to only acquire the trx->mutex.
To query the state either of the mutexes is sufficient within the locking
code and no mutex is required when the query thread is no longer waiting. */
/** The locks and state of an active transaction. Protected by
lock_sys.mutex, trx->mutex or both. */
struct trx_lock_t {
ulint n_active_thrs; /*!< number of active query threads */
trx_que_t que_state; /*!< valid when trx->state
== TRX_STATE_ACTIVE: TRX_QUE_RUNNING,
TRX_QUE_LOCK_WAIT, ... */
lock_t* wait_lock; /*!< if trx execution state is
TRX_QUE_LOCK_WAIT, this points to
the lock request, otherwise this is
NULL; set to non-NULL when holding
both trx->mutex and lock_sys.mutex;
set to NULL when holding
lock_sys.mutex; readers should
hold lock_sys.mutex, except when
they are holding trx->mutex and
wait_lock==NULL */
ib_uint64_t deadlock_mark; /*!< A mark field that is initialized
to and checked against lock_mark_counter
by lock_deadlock_recursive(). */
bool was_chosen_as_deadlock_victim;
/*!< when the transaction decides to
wait for a lock, it sets this to false;
if another transaction chooses this
transaction as a victim in deadlock
resolution, it sets this to true.
Protected by trx->mutex. */
time_t wait_started; /*!< lock wait started at this time,
protected only by lock_sys.mutex */
que_thr_t* wait_thr; /*!< query thread belonging to this
trx that is in QUE_THR_LOCK_WAIT
state. For threads suspended in a
lock wait, this is protected by
lock_sys.mutex. Otherwise, this may
only be modified by the thread that is
serving the running transaction. */
#ifdef WITH_WSREP
bool was_chosen_as_wsrep_victim;
/*!< high priority wsrep thread has
marked this trx to abort */
#endif /* WITH_WSREP */
/** Pre-allocated record locks */
struct {
ib_lock_t lock; byte pad[256];
} rec_pool[8];
/** Pre-allocated table locks */
ib_lock_t table_pool[8];
/** Next available rec_pool[] entry */
unsigned rec_cached;
/** Next available table_pool[] entry */
unsigned table_cached;
mem_heap_t* lock_heap; /*!< memory heap for trx_locks;
protected by lock_sys.mutex */
trx_lock_list_t trx_locks; /*!< locks requested by the transaction;
insertions are protected by trx->mutex
and lock_sys.mutex; removals are
protected by lock_sys.mutex */
lock_list table_locks; /*!< All table locks requested by this
transaction, including AUTOINC locks */
/** List of pending trx_t::evict_table() */
UT_LIST_BASE_NODE_T(dict_table_t) evicted_tables;
bool cancel; /*!< true if the transaction is being
rolled back either via deadlock
detection or due to lock timeout. The
caller has to acquire the trx_t::mutex
in order to cancel the locks. In
lock_trx_table_locks_remove() we
check for this cancel of a transaction's
locks and avoid reacquiring the trx
mutex to prevent recursive deadlocks.
Protected by both the lock sys mutex
and the trx_t::mutex. */
ulint n_rec_locks; /*!< number of rec locks in this trx */
};
/** Logical first modification time of a table in a transaction */
class trx_mod_table_time_t
{
/** First modification of the table */
undo_no_t first;
/** First modification of a system versioned column */
undo_no_t first_versioned;
/** Magic value signifying that a system versioned column of a
table was never modified in a transaction. */
static const undo_no_t UNVERSIONED = IB_ID_MAX;
public:
/** Constructor
@param[in] rows number of modified rows so far */
trx_mod_table_time_t(undo_no_t rows)
: first(rows), first_versioned(UNVERSIONED) {}
#ifdef UNIV_DEBUG
/** Validation
@param[in] rows number of modified rows so far
@return whether the object is valid */
bool valid(undo_no_t rows = UNVERSIONED) const
{
return first <= first_versioned && first <= rows;
}
#endif /* UNIV_DEBUG */
/** @return if versioned columns were modified */
bool is_versioned() const { return first_versioned != UNVERSIONED; }
/** After writing an undo log record, set is_versioned() if needed
@param[in] rows number of modified rows so far */
void set_versioned(undo_no_t rows)
{
ut_ad(!is_versioned());
first_versioned = rows;
ut_ad(valid());
}
/** Invoked after partial rollback
@param[in] limit number of surviving modified rows
@return whether this should be erased from trx_t::mod_tables */
bool rollback(undo_no_t limit)
{
ut_ad(valid());
if (first >= limit) {
return true;
}
if (first_versioned < limit && is_versioned()) {
first_versioned = UNVERSIONED;
}
return false;
}
};
/** Collection of persistent tables and their first modification
in a transaction.
We store pointers to the table objects in memory because
we know that a table object will not be destroyed while a transaction
that modified it is running. */
typedef std::map<
dict_table_t*, trx_mod_table_time_t,
std::less<dict_table_t*>,
ut_allocator<std::pair<dict_table_t* const, trx_mod_table_time_t> > >
trx_mod_tables_t;
/** The transaction handle
Normally, there is a 1:1 relationship between a transaction handle
(trx) and a session (client connection). One session is associated
with exactly one user transaction. There are some exceptions to this:
* For DDL operations, a subtransaction is allocated that modifies the
data dictionary tables. Lock waits and deadlocks are prevented by
acquiring the dict_sys.latch before starting the subtransaction
and releasing it after committing the subtransaction.
* The purge system uses a special transaction that is not associated
with any session.
* If the system crashed or it was quickly shut down while there were
transactions in the ACTIVE or PREPARED state, these transactions would
no longer be associated with a session when the server is restarted.
A session may be served by at most one thread at a time. The serving
thread of a session might change in some MySQL implementations.
Therefore we do not have os_thread_get_curr_id() assertions in the code.
Normally, only the thread that is currently associated with a running
transaction may access (read and modify) the trx object, and it may do
so without holding any mutex. The following are exceptions to this:
* trx_rollback_recovered() may access resurrected (connectionless)
transactions (state == TRX_STATE_ACTIVE && is_recovered)
while the system is already processing new user transactions (!is_recovered).
* trx_print_low() may access transactions not associated with the current
thread. The caller must be holding lock_sys.mutex.
* When a transaction handle is in the trx_sys.trx_list, some of its fields
must not be modified without holding trx->mutex.
* The locking code (in particular, lock_deadlock_recursive() and
lock_rec_convert_impl_to_expl()) will access transactions associated
to other connections. The locks of transactions are protected by
lock_sys.mutex (insertions also by trx->mutex). */
/** Represents an instance of rollback segment along with its state variables.*/
struct trx_undo_ptr_t {
trx_rseg_t* rseg; /*!< rollback segment assigned to the
transaction, or NULL if not assigned
yet */
trx_undo_t* undo; /*!< pointer to the undo log, or
NULL if nothing logged yet */
};
/** An instance of temporary rollback segment. */
struct trx_temp_undo_t {
/** temporary rollback segment, or NULL if not assigned yet */
trx_rseg_t* rseg;
/** pointer to the undo log, or NULL if nothing logged yet */
trx_undo_t* undo;
};
/** Rollback segments assigned to a transaction for undo logging. */
struct trx_rsegs_t {
/** undo log ptr holding reference to a rollback segment that resides in
system/undo tablespace used for undo logging of tables that needs
to be recovered on crash. */
trx_undo_ptr_t m_redo;
/** undo log for temporary tables; discarded immediately after
transaction commit/rollback */
trx_temp_undo_t m_noredo;
};
struct trx_t {
private:
/**
Count of references.
We can't release the locks nor commit the transaction until this reference
is 0. We can change the state to TRX_STATE_COMMITTED_IN_MEMORY to signify
that it is no longer "active".
*/
Atomic_counter<int32_t> n_ref;
public:
TrxMutex mutex; /*!< Mutex protecting the fields
state and lock (except some fields
of lock, which are protected by
lock_sys.mutex) */
trx_id_t id; /*!< transaction id */
trx_id_t no; /*!< transaction serialization number:
max trx id shortly before the
transaction is moved to
COMMITTED_IN_MEMORY state.
Protected by trx_sys_t::mutex
when trx is in rw_trx_hash. Initially
set to TRX_ID_MAX. */
/** State of the trx from the point of view of concurrency control
and the valid state transitions.
Possible states:
TRX_STATE_NOT_STARTED
TRX_STATE_ACTIVE
TRX_STATE_PREPARED
TRX_STATE_PREPARED_RECOVERED (special case of TRX_STATE_PREPARED)
TRX_STATE_COMMITTED_IN_MEMORY (alias below COMMITTED)
Valid state transitions are:
Regular transactions:
* NOT_STARTED -> ACTIVE -> COMMITTED -> NOT_STARTED
Auto-commit non-locking read-only:
* NOT_STARTED -> ACTIVE -> NOT_STARTED
XA (2PC):
* NOT_STARTED -> ACTIVE -> PREPARED -> COMMITTED -> NOT_STARTED
Recovered XA:
* NOT_STARTED -> PREPARED -> COMMITTED -> (freed)
Recovered XA followed by XA ROLLBACK:
* NOT_STARTED -> PREPARED -> ACTIVE -> COMMITTED -> (freed)
XA (2PC) (shutdown or disconnect before ROLLBACK or COMMIT):
* NOT_STARTED -> PREPARED -> (freed)
Disconnected XA can become recovered:
* ... -> ACTIVE -> PREPARED (connected) -> PREPARED (disconnected)
Disconnected means from mysql e.g due to the mysql client disconnection.
Latching and various transaction lists membership rules:
XA (2PC) transactions are always treated as non-autocommit.
Transitions to ACTIVE or NOT_STARTED occur when transaction
is not in rw_trx_hash (no trx_sys.mutex needed).
Autocommit non-locking read-only transactions move between states
without holding any mutex. They are not in rw_trx_hash.
All transactions, unless they are determined to be ac-nl-ro,
explicitly tagged as read-only or read-write, will first be put
on the read-only transaction list. Only when a !read-only transaction
in the read-only list tries to acquire an X or IX lock on a table
do we remove it from the read-only list and put it on the read-write
list. During this switch we assign it a rollback segment.
When a transaction is NOT_STARTED, it can be in trx_list. It cannot be
in rw_trx_hash.
ACTIVE->PREPARED->COMMITTED is only possible when trx is in rw_trx_hash.
The transition ACTIVE->PREPARED is protected by trx_sys.mutex.
ACTIVE->COMMITTED is possible when the transaction is in
rw_trx_hash.
Transitions to COMMITTED are protected by trx_t::mutex. */
trx_state_t state;
#ifdef WITH_WSREP
/** whether wsrep_on(mysql_thd) held at the start of transaction */
bool wsrep;
bool is_wsrep() const { return UNIV_UNLIKELY(wsrep); }
/** true, if BF thread is performing unique secondary index scanning */
bool wsrep_UK_scan;
bool is_wsrep_UK_scan() const { return UNIV_UNLIKELY(wsrep_UK_scan); }
#else /* WITH_WSREP */
bool is_wsrep() const { return false; }
#endif /* WITH_WSREP */
ReadView read_view; /*!< consistent read view used in the
transaction, or NULL if not yet set */
trx_lock_t lock; /*!< Information about the transaction
locks and state. Protected by
lock_sys.mutex (insertions also
by trx_t::mutex). */
/* These fields are not protected by any mutex. */
/** false=normal transaction, true=recovered (must be rolled back)
or disconnected transaction in XA PREPARE STATE.
This field is accessed by the thread that owns the transaction,
without holding any mutex.
There is only one foreign-thread access in trx_print_low()
and a possible race condition with trx_disconnect_prepared(). */
bool is_recovered;
const char* op_info; /*!< English text describing the
current operation, or an empty
string */
ulint isolation_level;/*!< TRX_ISO_REPEATABLE_READ, ... */
bool check_foreigns; /*!< normally TRUE, but if the user
wants to suppress foreign key checks,
(in table imports, for example) we
set this FALSE */
/*------------------------------*/
/* MySQL has a transaction coordinator to coordinate two phase
commit between multiple storage engines and the binary log. When
an engine participates in a transaction, it's responsible for
registering itself using the trans_register_ha() API. */
bool is_registered; /* This flag is set to true after the
transaction has been registered with
the coordinator using the XA API, and
is set to false after commit or
rollback. */
/** whether this is holding the prepare mutex */
bool active_commit_ordered;
/*------------------------------*/
bool check_unique_secondary;
/*!< normally TRUE, but if the user
wants to speed up inserts by
suppressing unique key checks
for secondary indexes when we decide
if we can use the insert buffer for
them, we set this FALSE */
bool flush_log_later;/* In 2PC, we hold the
prepare_commit mutex across
both phases. In that case, we
defer flush of the logs to disk
until after we release the
mutex. */
bool must_flush_log_later;/*!< set in commit()
if flush_log_later was
set and redo log was written;
in that case we will
flush the log in
trx_commit_complete_for_mysql() */
ulint duplicates; /*!< TRX_DUP_IGNORE | TRX_DUP_REPLACE */
trx_dict_op_t dict_operation; /**< @see enum trx_dict_op_t */
/* Fields protected by the srv_conc_mutex. */
bool declared_to_be_inside_innodb;
/*!< this is TRUE if we have declared
this transaction in
srv_conc_enter_innodb to be inside the
InnoDB engine */
ib_uint32_t n_tickets_to_enter_innodb;
/*!< this can be > 0 only when
declared_to_... is TRUE; when we come
to srv_conc_innodb_enter, if the value
here is > 0, we decrement this by 1 */
ib_uint32_t dict_operation_lock_mode;
/*!< 0, RW_S_LATCH, or RW_X_LATCH:
the latch mode trx currently holds
on dict_sys.latch. Protected
by dict_sys.latch. */
/** wall-clock time of the latest transition to TRX_STATE_ACTIVE;
used for diagnostic purposes only */
time_t start_time;
/** microsecond_interval_timer() of transaction start */
ulonglong start_time_micro;
lsn_t commit_lsn; /*!< lsn at the time of the commit */
table_id_t table_id; /*!< Table to drop iff dict_operation
== TRX_DICT_OP_TABLE, or 0. */
/*------------------------------*/
THD* mysql_thd; /*!< MySQL thread handle corresponding
to this trx, or NULL */
const char* mysql_log_file_name;
/*!< if MySQL binlog is used, this field
contains a pointer to the latest file
name; this is NULL if binlog is not
used */
ulonglong mysql_log_offset;
/*!< if MySQL binlog is used, this
field contains the end offset of the
binlog entry */
/*------------------------------*/
ib_uint32_t n_mysql_tables_in_use; /*!< number of Innobase tables
used in the processing of the current
SQL statement in MySQL */
ib_uint32_t mysql_n_tables_locked;
/*!< how many tables the current SQL
statement uses, except those
in consistent read */
/*------------------------------*/
UT_LIST_NODE_T(trx_t) trx_list; /*!< list of all transactions;
protected by trx_sys.mutex */
/*------------------------------*/
dberr_t error_state; /*!< 0 if no error, otherwise error
number; NOTE That ONLY the thread
doing the transaction is allowed to
set this field: this is NOT protected
by any mutex */
const dict_index_t*error_info; /*!< if the error number indicates a
duplicate key error, a pointer to
the problematic index is stored here */
ulint error_key_num; /*!< if the index creation fails to a
duplicate key error, a mysql key
number of that index is stored here */
que_t* graph; /*!< query currently run in the session,
or NULL if none; NOTE that the query
belongs to the session, and it can
survive over a transaction commit, if
it is a stored procedure with a COMMIT
WORK statement, for instance */
/*------------------------------*/
UT_LIST_BASE_NODE_T(trx_named_savept_t)
trx_savepoints; /*!< savepoints set with SAVEPOINT ...,
oldest first */
/*------------------------------*/
undo_no_t undo_no; /*!< next undo log record number to
assign; since the undo log is
private for a transaction, this
is a simple ascending sequence
with no gaps; thus it represents
the number of modified/inserted
rows in a transaction */
trx_savept_t last_sql_stat_start;
/*!< undo_no when the last sql statement
was started: in case of an error, trx
is rolled back down to this number */
trx_rsegs_t rsegs; /* rollback segments for undo logging */
undo_no_t roll_limit; /*!< least undo number to undo during
a partial rollback; 0 otherwise */
bool in_rollback; /*!< true when the transaction is
executing a partial or full rollback */
ulint pages_undone; /*!< number of undo log pages undone
since the last undo log truncation */
/*------------------------------*/
ulint n_autoinc_rows; /*!< no. of AUTO-INC rows required for
an SQL statement. This is useful for
multi-row INSERTs */
ib_vector_t* autoinc_locks; /* AUTOINC locks held by this
transaction. Note that these are
also in the lock list trx_locks. This
vector needs to be freed explicitly
when the trx instance is destroyed.
Protected by lock_sys.mutex. */
/*------------------------------*/
bool read_only; /*!< true if transaction is flagged
as a READ-ONLY transaction.
if auto_commit && !will_lock
then it will be handled as a
AC-NL-RO-SELECT (Auto Commit Non-Locking
Read Only Select). A read only
transaction will not be assigned an
UNDO log. */
bool auto_commit; /*!< true if it is an autocommit */
bool will_lock; /*!< set to inform trx_start_low() that
the transaction may acquire locks */
/*------------------------------*/
fts_trx_t* fts_trx; /*!< FTS information, or NULL if
transaction hasn't modified tables
with FTS indexes (yet). */
doc_id_t fts_next_doc_id;/* The document id used for updates */
/*------------------------------*/
ib_uint32_t flush_tables; /*!< if "covering" the FLUSH TABLES",
count of tables being flushed. */
/*------------------------------*/
bool ddl; /*!< true if it is an internal
transaction for DDL */
bool internal; /*!< true if it is a system/internal
transaction background task. This
includes DDL transactions too. Such
transactions are always treated as
read-write. */
/*------------------------------*/
#ifdef UNIV_DEBUG
unsigned start_line; /*!< Track where it was started from */
const char* start_file; /*!< Filename where it was started */
#endif /* UNIV_DEBUG */
XID* xid; /*!< X/Open XA transaction
identification to identify a
transaction branch */
trx_mod_tables_t mod_tables; /*!< List of tables that were modified
by this transaction */
/*------------------------------*/
char* detailed_error; /*!< detailed error message for last
error, or empty. */
private:
/** flush observer used to track flushing of non-redo logged pages
during bulk create index */
FlushObserver* flush_observer;
public:
#ifdef WITH_WSREP
os_event_t wsrep_event; /* event waited for in srv_conc_slot */
#endif /* WITH_WSREP */
rw_trx_hash_element_t *rw_trx_hash_element;
LF_PINS *rw_trx_hash_pins;
ulint magic_n;
/** @return whether any persistent undo log has been generated */
bool has_logged_persistent() const
{
return(rsegs.m_redo.undo);
}
/** @return whether any undo log has been generated */
bool has_logged() const
{
return(has_logged_persistent() || rsegs.m_noredo.undo);
}
/** @return rollback segment for modifying temporary tables */
trx_rseg_t* get_temp_rseg()
{
if (trx_rseg_t* rseg = rsegs.m_noredo.rseg) {
ut_ad(id != 0);
return(rseg);
}
return(assign_temp_rseg());
}
/** Set the innodb_log_optimize_ddl page flush observer
@param[in,out] space tablespace
@param[in,out] stage performance_schema accounting */
void set_flush_observer(fil_space_t* space, ut_stage_alter_t* stage);
/** Remove the flush observer */
void remove_flush_observer();
/** @return the flush observer */
FlushObserver* get_flush_observer() const
{
return flush_observer;
}
/** Transition to committed state, to release implicit locks. */
inline void commit_state();
/** Release any explicit locks of a committing transaction. */
inline void release_locks();
/** Evict a table definition due to the rollback of ALTER TABLE.
@param[in] table_id table identifier */
void evict_table(table_id_t table_id);
private:
/** Mark a transaction committed in the main memory data structures. */
inline void commit_in_memory(const mtr_t *mtr);
public:
/** Commit the transaction. */
void commit();
/** Commit the transaction in a mini-transaction.
@param mtr mini-transaction (if there are any persistent modifications) */
void commit_low(mtr_t *mtr= nullptr);
bool is_referenced() const { return n_ref > 0; }
void reference()
{
#ifdef UNIV_DEBUG
auto old_n_ref=
#endif
n_ref++;
ut_ad(old_n_ref >= 0);
}
void release_reference()
{
#ifdef UNIV_DEBUG
auto old_n_ref=
#endif
n_ref--;
ut_ad(old_n_ref > 0);
}
/** @return whether the table has lock on
mysql.innodb_table_stats and mysql.innodb_index_stats */
bool has_stats_table_lock() const;
/** Free the memory to trx_pools */
void free();
void assert_freed() const
{
ut_ad(state == TRX_STATE_NOT_STARTED);
ut_ad(!id);
ut_ad(!has_logged());
ut_ad(!is_referenced());
ut_ad(!is_wsrep());
#ifdef WITH_WSREP
ut_ad(!lock.was_chosen_as_wsrep_victim);
#endif
ut_ad(!read_view.is_open());
ut_ad(!lock.wait_thr);
ut_ad(UT_LIST_GET_LEN(lock.trx_locks) == 0);
ut_ad(lock.table_locks.empty());
ut_ad(!autoinc_locks || ib_vector_is_empty(autoinc_locks));
ut_ad(UT_LIST_GET_LEN(lock.evicted_tables) == 0);
ut_ad(dict_operation == TRX_DICT_OP_NONE);
}
/** @return whether this is a non-locking autocommit transaction */
bool is_autocommit_non_locking() const { return auto_commit && !will_lock; }
private:
/** Assign a rollback segment for modifying temporary tables.
@return the assigned rollback segment */
trx_rseg_t *assign_temp_rseg();
};
/**
Check if transaction is started.
@param[in] trx Transaction whose state we need to check
@reutrn true if transaction is in state started */
inline bool trx_is_started(const trx_t* trx)
{
return trx->state != TRX_STATE_NOT_STARTED;
}
/* Transaction isolation levels (trx->isolation_level) */
#define TRX_ISO_READ_UNCOMMITTED 0 /* dirty read: non-locking
SELECTs are performed so that
we do not look at a possible
earlier version of a record;
thus they are not 'consistent'
reads under this isolation
level; otherwise like level
2 */
#define TRX_ISO_READ_COMMITTED 1 /* somewhat Oracle-like
isolation, except that in
range UPDATE and DELETE we
must block phantom rows
with next-key locks;
SELECT ... FOR UPDATE and ...
LOCK IN SHARE MODE only lock
the index records, NOT the
gaps before them, and thus
allow free inserting;
each consistent read reads its
own snapshot */
#define TRX_ISO_REPEATABLE_READ 2 /* this is the default;
all consistent reads in the
same trx read the same
snapshot;
full next-key locking used
in locking reads to block
insertions into gaps */
#define TRX_ISO_SERIALIZABLE 3 /* all plain SELECTs are
converted to LOCK IN SHARE
MODE reads */
/* Treatment of duplicate values (trx->duplicates; for example, in inserts).
Multiple flags can be combined with bitwise OR. */
#define TRX_DUP_IGNORE 1U /* duplicate rows are to be updated */
#define TRX_DUP_REPLACE 2U /* duplicate rows are to be replaced */
/** Commit node states */
enum commit_node_state {
COMMIT_NODE_SEND = 1, /*!< about to send a commit signal to
the transaction */
COMMIT_NODE_WAIT /*!< commit signal sent to the transaction,
waiting for completion */
};
/** Commit command node in a query graph */
struct commit_node_t{
que_common_t common; /*!< node type: QUE_NODE_COMMIT */
enum commit_node_state
state; /*!< node execution state */
};
/** Test if trx->mutex is owned. */
#define trx_mutex_own(t) mutex_own(&t->mutex)
/** Acquire the trx->mutex. */
#define trx_mutex_enter(t) do { \
mutex_enter(&t->mutex); \
} while (0)
/** Release the trx->mutex. */
#define trx_mutex_exit(t) do { \
mutex_exit(&t->mutex); \
} while (0)
#include "trx0trx.ic"
#endif
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