/***********************************************************//**
Fetches an undo log record and does the undo for the recorded operation.
If none left, or a partial rollback completed, returns control to the
parent node, which is always a query thread node.
@return DB_SUCCESS if operation successfully completed, else error code */
static
ulint
row_undo(
/*=====*/
undo_node_t* node, /*!< in: row undo node */
que_thr_t* thr) /*!< in: query thread */
{
ulint err;
trx_t* trx;
roll_ptr_t roll_ptr;
ibool locked_data_dict;
ut_ad(node && thr);
trx = node->trx;
if (node->state == UNDO_NODE_FETCH_NEXT) {
node->undo_rec = trx_roll_pop_top_rec_of_trx(trx,
trx->roll_limit,
&roll_ptr,
node->heap);
if (!node->undo_rec) {
/* Rollback completed for this query thread */
thr->run_node = que_node_get_parent(node);
return(DB_SUCCESS);
}
node->roll_ptr = roll_ptr;
node->undo_no = trx_undo_rec_get_undo_no(node->undo_rec);
if (trx_undo_roll_ptr_is_insert(roll_ptr)) {
node->state = UNDO_NODE_INSERT;
} else {
node->state = UNDO_NODE_MODIFY;
}
} else if (node->state == UNDO_NODE_PREV_VERS) {
/* Undo should be done to the same clustered index record
again in this same rollback, restoring the previous version */
roll_ptr = node->new_roll_ptr;
node->undo_rec = trx_undo_get_undo_rec_low(roll_ptr,
node->heap);
node->roll_ptr = roll_ptr;
node->undo_no = trx_undo_rec_get_undo_no(node->undo_rec);
if (trx_undo_roll_ptr_is_insert(roll_ptr)) {
node->state = UNDO_NODE_INSERT;
} else {
node->state = UNDO_NODE_MODIFY;
}
}
/* Prevent DROP TABLE etc. while we are rolling back this row.
If we are doing a TABLE CREATE or some other dictionary operation,
then we already have dict_operation_lock locked in x-mode. Do not
try to lock again, because that would cause a hang. */
locked_data_dict = (trx->dict_operation_lock_mode == 0);
if (locked_data_dict) {
row_mysql_freeze_data_dictionary(trx);
}
if (node->state == UNDO_NODE_INSERT) {
err = row_undo_ins(node);
node->state = UNDO_NODE_FETCH_NEXT;
} else {
ut_ad(node->state == UNDO_NODE_MODIFY);
err = row_undo_mod(node, thr);
}
if (locked_data_dict) {
row_mysql_unfreeze_data_dictionary(trx);
}
/* Do some cleanup */
btr_pcur_close(&(node->pcur));
mem_heap_empty(node->heap);
thr->run_node = node;
return(err);
}
/***********************************************************//**
Parses the row reference and other info in a modify undo log record.
@return TRUE if purge operation required: NOTE that then the CALLER
must unfreeze data dictionary! */
static
ibool
row_purge_parse_undo_rec(
/*=====================*/
purge_node_t* node, /*!< in: row undo node */
ibool* updated_extern,
/*!< out: TRUE if an externally stored field
was updated */
que_thr_t* thr) /*!< in: query thread */
{
dict_index_t* clust_index;
byte* ptr;
trx_t* trx;
undo_no_t undo_no;
table_id_t table_id;
trx_id_t trx_id;
roll_ptr_t roll_ptr;
ulint info_bits;
ulint type;
ut_ad(node && thr);
trx = thr_get_trx(thr);
ptr = trx_undo_rec_get_pars(
node->undo_rec, &type, &node->cmpl_info,
updated_extern, &undo_no, &table_id);
node->rec_type = type;
if (type == TRX_UNDO_UPD_DEL_REC && !(*updated_extern)) {
return(FALSE);
}
ptr = trx_undo_update_rec_get_sys_cols(ptr, &trx_id, &roll_ptr,
&info_bits);
node->table = NULL;
if (type == TRX_UNDO_UPD_EXIST_REC
&& node->cmpl_info & UPD_NODE_NO_ORD_CHANGE
&& !(*updated_extern)) {
/* Purge requires no changes to indexes: we may return */
return(FALSE);
}
/* Prevent DROP TABLE etc. from running when we are doing the purge
for this row */
row_mysql_freeze_data_dictionary(trx);
mutex_enter(&(dict_sys->mutex));
node->table = dict_table_get_on_id_low(table_id);
mutex_exit(&(dict_sys->mutex));
if (node->table == NULL) {
/* The table has been dropped: no need to do purge */
err_exit:
row_mysql_unfreeze_data_dictionary(trx);
return(FALSE);
}
if (node->table->ibd_file_missing) {
/* We skip purge of missing .ibd files */
node->table = NULL;
goto err_exit;
}
clust_index = dict_table_get_first_index(node->table);
if (clust_index == NULL) {
/* The table was corrupt in the data dictionary */
goto err_exit;
}
ptr = trx_undo_rec_get_row_ref(ptr, clust_index, &(node->ref),
node->heap);
ptr = trx_undo_update_rec_get_update(ptr, clust_index, type, trx_id,
roll_ptr, info_bits, trx,
node->heap, &(node->update));
/* Read to the partial row the fields that occur in indexes */
if (!(node->cmpl_info & UPD_NODE_NO_ORD_CHANGE)) {
ptr = trx_undo_rec_get_partial_row(
ptr, clust_index, &node->row,
type == TRX_UNDO_UPD_DEL_REC,
node->heap);
}
return(TRUE);
}
