mysql5/mysql-5.7.27/sql/rpl_table_access.cc

/* Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.

   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 St, Fifth Floor, Boston, MA
   02110-1301 USA */

#include "rpl_table_access.h"

#include "handler.h"     // ha_rollback_trans
#include "log.h"         // sql_print_warning
#include "sql_base.h"    // close_thread_tables
#include "sql_class.h"   // THD
#include "sql_lex.h"     // Query_tables_list
#include "table.h"       // TABLE_LIST


bool System_table_access::open_table(THD* thd, const LEX_STRING dbstr,
                                     const LEX_STRING tbstr,
                                     uint max_num_field,
                                     enum thr_lock_type lock_type,
                                     TABLE** table,
                                     Open_tables_backup* backup)
{
  TABLE_LIST tables;
  Query_tables_list query_tables_list_backup;

  DBUG_ENTER("System_table_access::open_table");
  before_open(thd);

  /*
    We need to use new Open_tables_state in order not to be affected
    by LOCK TABLES/prelocked mode.
    Also in order not to break execution of current statement we also
    have to backup/reset/restore Query_tables_list part of LEX, which
    is accessed and updated in the process of opening and locking
    tables.
  */
  thd->lex->reset_n_backup_query_tables_list(&query_tables_list_backup);
  thd->reset_n_backup_open_tables_state(backup);

  tables.init_one_table(dbstr.str, dbstr.length, tbstr.str, tbstr.length,
                        tbstr.str, lock_type);

  tables.open_strategy= TABLE_LIST::OPEN_IF_EXISTS;

  if (!open_n_lock_single_table(thd, &tables, tables.lock_type, m_flags))
  {
    close_thread_tables(thd);
    thd->restore_backup_open_tables_state(backup);
    thd->lex->restore_backup_query_tables_list(&query_tables_list_backup);
    if (thd->is_operating_gtid_table_implicitly)
      sql_print_warning("Gtid table is not ready to be used. Table '%s.%s' "
                        "cannot be opened.", dbstr.str, tbstr.str);
    else
      my_error(ER_NO_SUCH_TABLE, MYF(0), dbstr.str, tbstr.str);
    DBUG_RETURN(true);
  }

  if (tables.table->s->fields < max_num_field)
  {
    /*
      Safety: this can only happen if someone started the server and then
      altered the table.
    */
    ha_rollback_trans(thd, false);
    close_thread_tables(thd);
    thd->restore_backup_open_tables_state(backup);
    thd->lex->restore_backup_query_tables_list(&query_tables_list_backup);
    my_error(ER_COL_COUNT_DOESNT_MATCH_CORRUPTED_V2, MYF(0),
             tables.table->s->db.str, tables.table->s->table_name.str,
             max_num_field, tables.table->s->fields);
    DBUG_RETURN(true);
  }

  thd->lex->restore_backup_query_tables_list(&query_tables_list_backup);

  *table= tables.table;
  tables.table->use_all_columns();
  DBUG_RETURN(false);
}


bool System_table_access::close_table(THD *thd, TABLE* table,
                                      Open_tables_backup *backup,
                                      bool error, bool need_commit)
{
  Query_tables_list query_tables_list_backup;
  bool res= false;

  DBUG_ENTER("System_table_access::close_table");

  if (table)
  {
    if (error)
      res= ha_rollback_trans(thd, false);
    else
    {
      /*
        To make the commit not to block with global read lock set
        "ignore_global_read_lock" flag to true.
       */
      res= ha_commit_trans(thd, false, true);
    }
    if (need_commit)
    {
      if (error)
        res= ha_rollback_trans(thd, true) || res;
      else
      {
        /*
          To make the commit not to block with global read lock set
          "ignore_global_read_lock" flag to true.
         */
        res= ha_commit_trans(thd, true, true) || res;
      }
    }
    /*
      In order not to break execution of current statement we have to
      backup/reset/restore Query_tables_list part of LEX, which is
      accessed and updated in the process of closing tables.
    */
    thd->lex->reset_n_backup_query_tables_list(&query_tables_list_backup);
    close_thread_tables(thd);
    thd->lex->restore_backup_query_tables_list(&query_tables_list_backup);
    thd->restore_backup_open_tables_state(backup);
  }

  DBUG_EXECUTE_IF("simulate_flush_commit_error", {res= true;});
  DBUG_RETURN(res);
}


THD *System_table_access::create_thd()
{
  THD *thd= NULL;
  thd= new THD;
  thd->thread_stack= (char*) &thd;
  thd->store_globals();
  thd->security_context()->skip_grants();

  return(thd);
}


void System_table_access::drop_thd(THD *thd)
{
  DBUG_ENTER("System_table_access::drop_thd");

  delete thd;
  my_thread_set_THR_THD(NULL);

  DBUG_VOID_RETURN;
}