/***************************************************************************** Copyright (c) 1996, 2017, Oracle and/or its affiliates. All Rights Reserved. Copyright (c) 2016, 2019, 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 trx/trx0roll.cc Transaction rollback Created 3/26/1996 Heikki Tuuri *******************************************************/ #include "trx0roll.h" #include #include #include "fsp0fsp.h" #include "lock0lock.h" #include "mach0data.h" #include "pars0pars.h" #include "que0que.h" #include "row0mysql.h" #include "row0undo.h" #include "srv0mon.h" #include "srv0start.h" #include "trx0rec.h" #include "trx0rseg.h" #include "trx0sys.h" #include "trx0trx.h" #include "trx0undo.h" /** true if trx_rollback_all_recovered() thread is active */ bool trx_rollback_is_active; /** In crash recovery, the current trx to be rolled back; NULL otherwise */ const trx_t* trx_roll_crash_recv_trx; /** Finish transaction rollback. @param[in,out] trx transaction @return whether the rollback was completed normally @retval false if the rollback was aborted by shutdown */ static bool trx_rollback_finish(trx_t* trx) { trx->mod_tables.clear(); bool finished = trx->error_state == DB_SUCCESS; if (UNIV_LIKELY(finished)) { trx_commit(trx); } else { ut_a(trx->error_state == DB_INTERRUPTED); ut_ad(!srv_is_being_started); ut_a(!srv_undo_sources); ut_ad(srv_fast_shutdown); ut_d(trx->in_rollback = false); if (trx_undo_t*& undo = trx->rsegs.m_redo.old_insert) { UT_LIST_REMOVE(trx->rsegs.m_redo.rseg->old_insert_list, undo); ut_free(undo); undo = NULL; } if (trx_undo_t*& undo = trx->rsegs.m_redo.undo) { UT_LIST_REMOVE(trx->rsegs.m_redo.rseg->undo_list, undo); ut_free(undo); undo = NULL; } if (trx_undo_t*& undo = trx->rsegs.m_noredo.undo) { UT_LIST_REMOVE(trx->rsegs.m_noredo.rseg->undo_list, undo); ut_free(undo); undo = NULL; } trx_commit_low(trx, NULL); } trx->lock.que_state = TRX_QUE_RUNNING; return finished; } /*******************************************************************//** Rollback a transaction used in MySQL. */ static void trx_rollback_to_savepoint_low( /*==========================*/ trx_t* trx, /*!< in: transaction handle */ trx_savept_t* savept) /*!< in: pointer to savepoint undo number, if partial rollback requested, or NULL for complete rollback */ { que_thr_t* thr; mem_heap_t* heap; roll_node_t* roll_node; heap = mem_heap_create(512); roll_node = roll_node_create(heap); if (savept != NULL) { roll_node->savept = savept; check_trx_state(trx); } else { assert_trx_nonlocking_or_in_list(trx); } trx->error_state = DB_SUCCESS; if (trx->has_logged_or_recovered()) { ut_ad(trx->rsegs.m_redo.rseg != 0 || trx->rsegs.m_noredo.rseg != 0); thr = pars_complete_graph_for_exec(roll_node, trx, heap, NULL); ut_a(thr == que_fork_start_command( static_cast(que_node_get_parent(thr)))); que_run_threads(thr); ut_a(roll_node->undo_thr != NULL); que_run_threads(roll_node->undo_thr); /* Free the memory reserved by the undo graph. */ que_graph_free(static_cast( roll_node->undo_thr->common.parent)); } if (savept == NULL) { trx_rollback_finish(trx); MONITOR_INC(MONITOR_TRX_ROLLBACK); } else { ut_a(trx->error_state == DB_SUCCESS); const undo_no_t limit = savept->least_undo_no; for (trx_mod_tables_t::iterator i = trx->mod_tables.begin(); i != trx->mod_tables.end(); ) { trx_mod_tables_t::iterator j = i++; ut_ad(j->second.valid()); if (j->second.rollback(limit)) { trx->mod_tables.erase(j); } } trx->lock.que_state = TRX_QUE_RUNNING; MONITOR_INC(MONITOR_TRX_ROLLBACK_SAVEPOINT); } mem_heap_free(heap); /* There might be work for utility threads.*/ srv_active_wake_master_thread(); MONITOR_DEC(MONITOR_TRX_ACTIVE); } /*******************************************************************//** Rollback a transaction to a given savepoint or do a complete rollback. @return error code or DB_SUCCESS */ dberr_t trx_rollback_to_savepoint( /*======================*/ trx_t* trx, /*!< in: transaction handle */ trx_savept_t* savept) /*!< in: pointer to savepoint undo number, if partial rollback requested, or NULL for complete rollback */ { #ifdef WITH_WSREP if (savept == NULL && wsrep_on(trx->mysql_thd)) { wsrep_handle_SR_rollback(NULL, trx->mysql_thd); } #endif /* WITH_WSREP */ ut_ad(!trx_mutex_own(trx)); trx_start_if_not_started_xa(trx, true); trx_rollback_to_savepoint_low(trx, savept); return(trx->error_state); } /*******************************************************************//** Rollback a transaction used in MySQL. @return error code or DB_SUCCESS */ static dberr_t trx_rollback_for_mysql_low( /*=======================*/ trx_t* trx) /*!< in/out: transaction */ { trx->op_info = "rollback"; /* If we are doing the XA recovery of prepared transactions, then the transaction object does not have an InnoDB session object, and we set a dummy session that we use for all MySQL transactions. */ trx_rollback_to_savepoint_low(trx, NULL); trx->op_info = ""; return(trx->error_state); } /** Rollback a transaction used in MySQL @param[in, out] trx transaction @return error code or DB_SUCCESS */ dberr_t trx_rollback_for_mysql(trx_t* trx) { /* We are reading trx->state without holding trx_sys.mutex here, because the rollback should be invoked for a running active MySQL transaction (or recovered prepared transaction) that is associated with the current thread. */ switch (trx->state) { case TRX_STATE_NOT_STARTED: trx->will_lock = 0; ut_ad(trx->mysql_thd); return(DB_SUCCESS); case TRX_STATE_ACTIVE: ut_ad(trx->mysql_thd); assert_trx_nonlocking_or_in_list(trx); return(trx_rollback_for_mysql_low(trx)); case TRX_STATE_PREPARED: case TRX_STATE_PREPARED_RECOVERED: ut_ad(!trx_is_autocommit_non_locking(trx)); if (trx->rsegs.m_redo.undo || trx->rsegs.m_redo.old_insert) { /* Change the undo log state back from TRX_UNDO_PREPARED to TRX_UNDO_ACTIVE so that if the system gets killed, recovery will perform the rollback. */ ut_ad(!trx->rsegs.m_redo.undo || trx->rsegs.m_redo.undo->rseg == trx->rsegs.m_redo.rseg); ut_ad(!trx->rsegs.m_redo.old_insert || trx->rsegs.m_redo.old_insert->rseg == trx->rsegs.m_redo.rseg); mtr_t mtr; mtr.start(); mutex_enter(&trx->rsegs.m_redo.rseg->mutex); if (trx_undo_t* undo = trx->rsegs.m_redo.undo) { trx_undo_set_state_at_prepare(trx, undo, true, &mtr); } if (trx_undo_t* undo = trx->rsegs.m_redo.old_insert) { trx_undo_set_state_at_prepare(trx, undo, true, &mtr); } mutex_exit(&trx->rsegs.m_redo.rseg->mutex); /* Persist the XA ROLLBACK, so that crash recovery will replay the rollback in case the redo log gets applied past this point. */ mtr.commit(); ut_ad(mtr.commit_lsn() > 0); } #ifdef ENABLED_DEBUG_SYNC if (trx->mysql_thd == NULL) { /* We could be executing XA ROLLBACK after XA PREPARE and a server restart. */ } else if (!trx->has_logged_persistent()) { /* innobase_close_connection() may roll back a transaction that did not generate any persistent undo log. The DEBUG_SYNC would cause an assertion failure for a disconnected thread. NOTE: InnoDB will not know about the XID if no persistent undo log was generated. */ } else { DEBUG_SYNC_C("trx_xa_rollback"); } #endif /* ENABLED_DEBUG_SYNC */ return(trx_rollback_for_mysql_low(trx)); case TRX_STATE_COMMITTED_IN_MEMORY: check_trx_state(trx); break; } ut_error; return(DB_CORRUPTION); } /*******************************************************************//** Rollback the latest SQL statement for MySQL. @return error code or DB_SUCCESS */ dberr_t trx_rollback_last_sql_stat_for_mysql( /*=================================*/ trx_t* trx) /*!< in/out: transaction */ { dberr_t err; /* We are reading trx->state without holding trx_sys.mutex here, because the statement rollback should be invoked for a running active MySQL transaction that is associated with the current thread. */ ut_ad(trx->mysql_thd); switch (trx->state) { case TRX_STATE_NOT_STARTED: return(DB_SUCCESS); case TRX_STATE_ACTIVE: assert_trx_nonlocking_or_in_list(trx); trx->op_info = "rollback of SQL statement"; err = trx_rollback_to_savepoint( trx, &trx->last_sql_stat_start); if (trx->fts_trx != NULL) { fts_savepoint_rollback_last_stmt(trx); } /* The following call should not be needed, but we play it safe: */ trx_mark_sql_stat_end(trx); trx->op_info = ""; return(err); case TRX_STATE_PREPARED: case TRX_STATE_PREPARED_RECOVERED: case TRX_STATE_COMMITTED_IN_MEMORY: /* The statement rollback is only allowed on an ACTIVE transaction, not a PREPARED or COMMITTED one. */ break; } ut_error; return(DB_CORRUPTION); } /*******************************************************************//** Search for a savepoint using name. @return savepoint if found else NULL */ static trx_named_savept_t* trx_savepoint_find( /*===============*/ trx_t* trx, /*!< in: transaction */ const char* name) /*!< in: savepoint name */ { trx_named_savept_t* savep; for (savep = UT_LIST_GET_FIRST(trx->trx_savepoints); savep != NULL; savep = UT_LIST_GET_NEXT(trx_savepoints, savep)) { if (0 == ut_strcmp(savep->name, name)) { return(savep); } } return(NULL); } /*******************************************************************//** Frees a single savepoint struct. */ static void trx_roll_savepoint_free( /*=====================*/ trx_t* trx, /*!< in: transaction handle */ trx_named_savept_t* savep) /*!< in: savepoint to free */ { UT_LIST_REMOVE(trx->trx_savepoints, savep); ut_free(savep->name); ut_free(savep); } /*******************************************************************//** Frees savepoint structs starting from savep. */ void trx_roll_savepoints_free( /*=====================*/ trx_t* trx, /*!< in: transaction handle */ trx_named_savept_t* savep) /*!< in: free all savepoints starting with this savepoint i*/ { while (savep != NULL) { trx_named_savept_t* next_savep; next_savep = UT_LIST_GET_NEXT(trx_savepoints, savep); trx_roll_savepoint_free(trx, savep); savep = next_savep; } } /*******************************************************************//** Rolls back a transaction back to a named savepoint. Modifications after the savepoint are undone but InnoDB does NOT release the corresponding locks which are stored in memory. If a lock is 'implicit', that is, a new inserted row holds a lock where the lock information is carried by the trx id stored in the row, these locks are naturally released in the rollback. Savepoints which were set after this savepoint are deleted. @return if no savepoint of the name found then DB_NO_SAVEPOINT, otherwise DB_SUCCESS */ static MY_ATTRIBUTE((nonnull, warn_unused_result)) dberr_t trx_rollback_to_savepoint_for_mysql_low( /*====================================*/ trx_t* trx, /*!< in/out: transaction */ trx_named_savept_t* savep, /*!< in/out: savepoint */ int64_t* mysql_binlog_cache_pos) /*!< out: the MySQL binlog cache position corresponding to this savepoint; MySQL needs this information to remove the binlog entries of the queries executed after the savepoint */ { dberr_t err; ut_ad(trx_state_eq(trx, TRX_STATE_ACTIVE)); ut_ad(trx->mysql_thd); /* Free all savepoints strictly later than savep. */ trx_roll_savepoints_free( trx, UT_LIST_GET_NEXT(trx_savepoints, savep)); *mysql_binlog_cache_pos = savep->mysql_binlog_cache_pos; trx->op_info = "rollback to a savepoint"; err = trx_rollback_to_savepoint(trx, &savep->savept); /* Store the current undo_no of the transaction so that we know where to roll back if we have to roll back the next SQL statement: */ trx_mark_sql_stat_end(trx); trx->op_info = ""; #ifdef WITH_WSREP trx->lock.was_chosen_as_wsrep_victim = FALSE; #endif return(err); } /*******************************************************************//** Rolls back a transaction back to a named savepoint. Modifications after the savepoint are undone but InnoDB does NOT release the corresponding locks which are stored in memory. If a lock is 'implicit', that is, a new inserted row holds a lock where the lock information is carried by the trx id stored in the row, these locks are naturally released in the rollback. Savepoints which were set after this savepoint are deleted. @return if no savepoint of the name found then DB_NO_SAVEPOINT, otherwise DB_SUCCESS */ dberr_t trx_rollback_to_savepoint_for_mysql( /*================================*/ trx_t* trx, /*!< in: transaction handle */ const char* savepoint_name, /*!< in: savepoint name */ int64_t* mysql_binlog_cache_pos) /*!< out: the MySQL binlog cache position corresponding to this savepoint; MySQL needs this information to remove the binlog entries of the queries executed after the savepoint */ { trx_named_savept_t* savep; /* We are reading trx->state without holding trx_sys.mutex here, because the savepoint rollback should be invoked for a running active MySQL transaction that is associated with the current thread. */ ut_ad(trx->mysql_thd); savep = trx_savepoint_find(trx, savepoint_name); if (savep == NULL) { return(DB_NO_SAVEPOINT); } switch (trx->state) { case TRX_STATE_NOT_STARTED: ib::error() << "Transaction has a savepoint " << savep->name << " though it is not started"; return(DB_ERROR); case TRX_STATE_ACTIVE: return(trx_rollback_to_savepoint_for_mysql_low( trx, savep, mysql_binlog_cache_pos)); case TRX_STATE_PREPARED: case TRX_STATE_PREPARED_RECOVERED: case TRX_STATE_COMMITTED_IN_MEMORY: /* The savepoint rollback is only allowed on an ACTIVE transaction, not a PREPARED or COMMITTED one. */ break; } ut_error; return(DB_CORRUPTION); } /*******************************************************************//** Creates a named savepoint. If the transaction is not yet started, starts it. If there is already a savepoint of the same name, this call erases that old savepoint and replaces it with a new. Savepoints are deleted in a transaction commit or rollback. @return always DB_SUCCESS */ dberr_t trx_savepoint_for_mysql( /*====================*/ trx_t* trx, /*!< in: transaction handle */ const char* savepoint_name, /*!< in: savepoint name */ int64_t binlog_cache_pos) /*!< in: MySQL binlog cache position corresponding to this connection at the time of the savepoint */ { trx_named_savept_t* savep; trx_start_if_not_started_xa(trx, false); savep = trx_savepoint_find(trx, savepoint_name); if (savep) { /* There is a savepoint with the same name: free that */ UT_LIST_REMOVE(trx->trx_savepoints, savep); ut_free(savep->name); ut_free(savep); } /* Create a new savepoint and add it as the last in the list */ savep = static_cast( ut_malloc_nokey(sizeof(*savep))); savep->name = mem_strdup(savepoint_name); savep->savept = trx_savept_take(trx); savep->mysql_binlog_cache_pos = binlog_cache_pos; UT_LIST_ADD_LAST(trx->trx_savepoints, savep); return(DB_SUCCESS); } /*******************************************************************//** Releases only the named savepoint. Savepoints which were set after this savepoint are left as is. @return if no savepoint of the name found then DB_NO_SAVEPOINT, otherwise DB_SUCCESS */ dberr_t trx_release_savepoint_for_mysql( /*============================*/ trx_t* trx, /*!< in: transaction handle */ const char* savepoint_name) /*!< in: savepoint name */ { trx_named_savept_t* savep; ut_ad(trx_state_eq(trx, TRX_STATE_ACTIVE, true) || trx_state_eq(trx, TRX_STATE_PREPARED, true)); ut_ad(trx->mysql_thd); savep = trx_savepoint_find(trx, savepoint_name); if (savep != NULL) { trx_roll_savepoint_free(trx, savep); } return(savep != NULL ? DB_SUCCESS : DB_NO_SAVEPOINT); } /*******************************************************************//** Determines if this transaction is rolling back an incomplete transaction in crash recovery. @return TRUE if trx is an incomplete transaction that is being rolled back in crash recovery */ ibool trx_is_recv( /*========*/ const trx_t* trx) /*!< in: transaction */ { return(trx == trx_roll_crash_recv_trx); } /*******************************************************************//** Returns a transaction savepoint taken at this point in time. @return savepoint */ trx_savept_t trx_savept_take( /*============*/ trx_t* trx) /*!< in: transaction */ { trx_savept_t savept; savept.least_undo_no = trx->undo_no; return(savept); } /*******************************************************************//** Roll back an active transaction. */ static void trx_rollback_active( /*================*/ trx_t* trx) /*!< in/out: transaction */ { mem_heap_t* heap; que_fork_t* fork; que_thr_t* thr; roll_node_t* roll_node; const trx_id_t trx_id = trx->id; ut_ad(trx_id); heap = mem_heap_create(512); fork = que_fork_create(NULL, NULL, QUE_FORK_RECOVERY, heap); fork->trx = trx; thr = que_thr_create(fork, heap, NULL); roll_node = roll_node_create(heap); thr->child = roll_node; roll_node->common.parent = thr; trx->graph = fork; ut_a(thr == que_fork_start_command(fork)); trx_roll_crash_recv_trx = trx; const bool dictionary_locked = trx_get_dict_operation(trx) != TRX_DICT_OP_NONE; if (dictionary_locked) { row_mysql_lock_data_dictionary(trx); } que_run_threads(thr); ut_a(roll_node->undo_thr != NULL); que_run_threads(roll_node->undo_thr); que_graph_free( static_cast(roll_node->undo_thr->common.parent)); if (UNIV_UNLIKELY(!trx_rollback_finish(trx))) { ut_ad(!dictionary_locked); goto func_exit; } ut_a(trx->lock.que_state == TRX_QUE_RUNNING); if (!dictionary_locked || !trx->table_id) { } else if (dict_table_t* table = dict_table_open_on_id( trx->table_id, TRUE, DICT_TABLE_OP_NORMAL)) { ib::info() << "Dropping table " << table->name << ", with id " << trx->table_id << " in recovery"; dict_table_close_and_drop(trx, table); trx_commit_for_mysql(trx); } ib::info() << "Rolled back recovered transaction " << trx_id; func_exit: if (dictionary_locked) { row_mysql_unlock_data_dictionary(trx); } mem_heap_free(heap); trx_roll_crash_recv_trx = NULL; } struct trx_roll_count_callback_arg { uint32_t n_trx; uint64_t n_rows; trx_roll_count_callback_arg(): n_trx(0), n_rows(0) {} }; static my_bool trx_roll_count_callback(rw_trx_hash_element_t *element, trx_roll_count_callback_arg *arg) { mutex_enter(&element->mutex); if (trx_t *trx= element->trx) { if (trx->is_recovered && trx_state_eq(trx, TRX_STATE_ACTIVE)) { arg->n_trx++; arg->n_rows+= trx->undo_no; } } mutex_exit(&element->mutex); return 0; } /** Report progress when rolling back a row of a recovered transaction. */ void trx_roll_report_progress() { ib_time_t time = ut_time(); mutex_enter(&recv_sys->mutex); bool report = recv_sys->report(time); mutex_exit(&recv_sys->mutex); if (report) { trx_roll_count_callback_arg arg; /* Get number of recovered active transactions and number of rows they modified. Numbers must be accurate, because only this thread is allowed to touch recovered transactions. */ trx_sys.rw_trx_hash.iterate_no_dups( reinterpret_cast (trx_roll_count_callback), &arg); if (arg.n_rows > 0) { service_manager_extend_timeout( INNODB_EXTEND_TIMEOUT_INTERVAL, "To roll back: " UINT32PF " transactions, " UINT64PF " rows", arg.n_trx, arg.n_rows); } ib::info() << "To roll back: " << arg.n_trx << " transactions, " << arg.n_rows << " rows"; } } static my_bool trx_rollback_recovered_callback(rw_trx_hash_element_t *element, std::vector *trx_list) { mutex_enter(&element->mutex); if (trx_t *trx= element->trx) { mutex_enter(&trx->mutex); if (trx->is_recovered && trx_state_eq(trx, TRX_STATE_ACTIVE)) trx_list->push_back(trx); mutex_exit(&trx->mutex); } mutex_exit(&element->mutex); return 0; } /** Rollback any incomplete transactions which were encountered in crash recovery. If the transaction already was committed, then we clean up a possible insert undo log. If the transaction was not yet committed, then we roll it back. Note: For XA recovered transactions, we rely on MySQL to do rollback. They will be in TRX_STATE_PREPARED state. If the server is shutdown and they are still lingering in trx_sys_t::trx_list then the shutdown will hang. @param[in] all true=roll back all recovered active transactions; false=roll back any incomplete dictionary transaction */ void trx_rollback_recovered(bool all) { std::vector trx_list; ut_a(srv_force_recovery < SRV_FORCE_NO_TRX_UNDO); /* Collect list of recovered ACTIVE transaction ids first. Once collected, no other thread is allowed to modify or remove these transactions from rw_trx_hash. */ trx_sys.rw_trx_hash.iterate_no_dups(reinterpret_cast (trx_rollback_recovered_callback), &trx_list); while (!trx_list.empty()) { trx_t *trx= trx_list.back(); trx_list.pop_back(); #ifdef UNIV_DEBUG ut_ad(trx); trx_mutex_enter(trx); ut_ad(trx->is_recovered && trx_state_eq(trx, TRX_STATE_ACTIVE)); trx_mutex_exit(trx); #endif if (!srv_is_being_started && !srv_undo_sources && srv_fast_shutdown) goto discard; if (all || trx_get_dict_operation(trx) != TRX_DICT_OP_NONE) { trx_rollback_active(trx); if (trx->error_state != DB_SUCCESS) { ut_ad(trx->error_state == DB_INTERRUPTED); trx->error_state= DB_SUCCESS; ut_ad(!srv_undo_sources); ut_ad(srv_fast_shutdown); discard: trx_sys.deregister_rw(trx); trx_free_at_shutdown(trx); } else trx_free(trx); } } } /*******************************************************************//** Rollback or clean up any incomplete transactions which were encountered in crash recovery. If the transaction already was committed, then we clean up a possible insert undo log. If the transaction was not yet committed, then we roll it back. Note: this is done in a background thread. @return a dummy parameter */ extern "C" os_thread_ret_t DECLARE_THREAD(trx_rollback_all_recovered)(void*) { my_thread_init(); ut_ad(!srv_read_only_mode); #ifdef UNIV_PFS_THREAD pfs_register_thread(trx_rollback_clean_thread_key); #endif /* UNIV_PFS_THREAD */ if (trx_sys.rw_trx_hash.size()) { ib::info() << "Starting in background the rollback of" " recovered transactions"; trx_rollback_recovered(true); ib::info() << "Rollback of non-prepared transactions" " completed"; } trx_rollback_is_active = false; my_thread_end(); /* We count the number of threads in os_thread_exit(). A created thread should always use that to exit and not use return() to exit. */ os_thread_exit(); OS_THREAD_DUMMY_RETURN; } /****************************************************************//** Builds an undo 'query' graph for a transaction. The actual rollback is performed by executing this query graph like a query subprocedure call. The reply about the completion of the rollback will be sent by this graph. @return own: the query graph */ static que_t* trx_roll_graph_build( /*=================*/ trx_t* trx) /*!< in/out: transaction */ { mem_heap_t* heap; que_fork_t* fork; que_thr_t* thr; ut_ad(trx_mutex_own(trx)); heap = mem_heap_create(512); fork = que_fork_create(NULL, NULL, QUE_FORK_ROLLBACK, heap); fork->trx = trx; thr = que_thr_create(fork, heap, NULL); thr->child = row_undo_node_create(trx, thr, heap); return(fork); } /*********************************************************************//** Starts a rollback operation, creates the UNDO graph that will do the actual undo operation. @return query graph thread that will perform the UNDO operations. */ static que_thr_t* trx_rollback_start( /*===============*/ trx_t* trx, /*!< in: transaction */ undo_no_t roll_limit) /*!< in: rollback to undo no (for partial undo), 0 if we are rolling back the entire transaction */ { ut_ad(trx_mutex_own(trx)); /* Initialize the rollback field in the transaction */ ut_ad(!trx->roll_limit); ut_ad(!trx->in_rollback); trx->roll_limit = roll_limit; trx->in_rollback = true; ut_a(trx->roll_limit <= trx->undo_no); trx->pages_undone = 0; /* Build a 'query' graph which will perform the undo operations */ que_t* roll_graph = trx_roll_graph_build(trx); trx->graph = roll_graph; trx->lock.que_state = TRX_QUE_ROLLING_BACK; return(que_fork_start_command(roll_graph)); } /*********************************************************************//** Creates a rollback command node struct. @return own: rollback node struct */ roll_node_t* roll_node_create( /*=============*/ mem_heap_t* heap) /*!< in: mem heap where created */ { roll_node_t* node; node = static_cast(mem_heap_zalloc(heap, sizeof(*node))); node->state = ROLL_NODE_SEND; node->common.type = QUE_NODE_ROLLBACK; return(node); } /***********************************************************//** Performs an execution step for a rollback command node in a query graph. @return query thread to run next, or NULL */ que_thr_t* trx_rollback_step( /*==============*/ que_thr_t* thr) /*!< in: query thread */ { roll_node_t* node; node = static_cast(thr->run_node); ut_ad(que_node_get_type(node) == QUE_NODE_ROLLBACK); if (thr->prev_node == que_node_get_parent(node)) { node->state = ROLL_NODE_SEND; } if (node->state == ROLL_NODE_SEND) { trx_t* trx; ib_id_t roll_limit; trx = thr_get_trx(thr); trx_mutex_enter(trx); node->state = ROLL_NODE_WAIT; ut_a(node->undo_thr == NULL); roll_limit = node->savept ? node->savept->least_undo_no : 0; trx_commit_or_rollback_prepare(trx); node->undo_thr = trx_rollback_start(trx, roll_limit); trx_mutex_exit(trx); } else { ut_ad(node->state == ROLL_NODE_WAIT); thr->run_node = que_node_get_parent(node); } return(thr); }