~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2006 MySQL AB

   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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/*

  Atomic rename of table;  RENAME TABLE t1 to t2, tmp to t1 [,...]

*/

#include "mysql_priv.h"

static TABLE_LIST *rename_tables(THD *thd, TABLE_LIST *table_list,

				 bool skip_error);

static TABLE_LIST *reverse_table_list(TABLE_LIST *table_list);

/*

  Every second entry in the table_list is the original name and every

  second entry is the new name.

*/

bool mysql_rename_tables(THD *thd, TABLE_LIST *table_list, bool silent)

{

  bool error= 1;

  TABLE_LIST *ren_table= 0;

  DBUG_ENTER("mysql_rename_tables");

  /*

    Avoid problems with a rename on a table that we have locked or

    if the user is trying to to do this in a transcation context

  */

  if (thd->locked_tables || thd->active_transaction())

  {

    my_message(ER_LOCK_OR_ACTIVE_TRANSACTION,

               ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));

    DBUG_RETURN(1);

  }

  mysql_ha_rm_tables(thd, table_list, FALSE);

  if (wait_if_global_read_lock(thd,0,1))

    DBUG_RETURN(1);

  pthread_mutex_lock(&LOCK_open);

  if (lock_table_names_exclusively(thd, table_list))

  {

    pthread_mutex_unlock(&LOCK_open);

    goto err;

  }

  error=0;

  if ((ren_table=rename_tables(thd,table_list,0)))

  {

    /* Rename didn't succeed;  rename back the tables in reverse order */

    TABLE_LIST *table;

    /* Reverse the table list */

    table_list= reverse_table_list(table_list);

    /* Find the last renamed table */

    for (table= table_list;

	 table->next_local != ren_table ;

	 table= table->next_local->next_local) ;

    table= table->next_local->next_local;		// Skip error table

    /* Revert to old names */

    rename_tables(thd, table, 1);

    /* Revert the table list (for prepared statements) */

    table_list= reverse_table_list(table_list);

    error= 1;

  }

  /*

    An exclusive lock on table names is satisfactory to ensure

    no other thread accesses this table.

    We still should unlock LOCK_open as early as possible, to provide

    higher concurrency - query_cache_invalidate can take minutes to

    complete.

  */

  pthread_mutex_unlock(&LOCK_open);

  /* Lets hope this doesn't fail as the result will be messy */ 

  if (!silent && !error)

  {

    write_bin_log(thd, TRUE, thd->query, thd->query_length);

    my_ok(thd);

  }

  pthread_mutex_lock(&LOCK_open);

  unlock_table_names(thd, table_list, (TABLE_LIST*) 0);

  pthread_mutex_unlock(&LOCK_open);

err:

  start_waiting_global_read_lock(thd);

  DBUG_RETURN(error);

}

/*

  reverse table list

  SYNOPSIS

    reverse_table_list()

    table_list pointer to table _list

  RETURN

    pointer to new (reversed) list

*/

static TABLE_LIST *reverse_table_list(TABLE_LIST *table_list)

{

  TABLE_LIST *prev= 0;

  while (table_list)

  {

    TABLE_LIST *next= table_list->next_local;

    table_list->next_local= prev;

    prev= table_list;

    table_list= next;

  }

  return (prev);

}

/*

  Rename a single table or a view

  SYNPOSIS

    do_rename()

      thd               Thread handle

      ren_table         A table/view to be renamed

      new_db            The database to which the table to be moved to

      new_table_name    The new table/view name

      new_table_alias   The new table/view alias

      skip_error        Whether to skip error

  DESCRIPTION

    Rename a single table or a view.

  RETURN

    false     Ok

    true      rename failed

*/

bool

do_rename(THD *thd, TABLE_LIST *ren_table, char *new_db, char *new_table_name,

          char *new_table_alias, bool skip_error)

{

  int rc= 1;

  char name[FN_REFLEN];

  const char *new_alias, *old_alias;

  enum legacy_db_type table_type;

  DBUG_ENTER("do_rename");

  if (lower_case_table_names == 2)

  {

    old_alias= ren_table->alias;

    new_alias= new_table_alias;

  }

  else

  {

    old_alias= ren_table->table_name;

    new_alias= new_table_name;

  }

  build_table_filename(name, sizeof(name),

                       new_db, new_alias, reg_ext, 0);

  if (!access(name,F_OK))

  {

    my_error(ER_TABLE_EXISTS_ERROR, MYF(0), new_alias);

    DBUG_RETURN(1);			// This can't be skipped

  }

  build_table_filename(name, sizeof(name),

                       ren_table->db, old_alias, reg_ext, 0);

  rc= mysql_rename_table(ha_resolve_by_legacy_type(thd, table_type), 

                               ren_table->db, old_alias,

                               new_db, new_alias, 0);

  if (rc && !skip_error)

    DBUG_RETURN(1);

  DBUG_RETURN(0);

}

/*

  Rename all tables in list; Return pointer to wrong entry if something goes

  wrong.  Note that the table_list may be empty!

*/

/*

  Rename tables/views in the list

  SYNPOSIS

    rename_tables()

      thd               Thread handle

      table_list        List of tables to rename

      skip_error        Whether to skip errors

  DESCRIPTION

    Take a table/view name from and odd list element and rename it to a

    the name taken from list element+1. Note that the table_list may be

    empty.

  RETURN

    false     Ok

    true      rename failed

*/

static TABLE_LIST *

rename_tables(THD *thd, TABLE_LIST *table_list, bool skip_error)

{

  TABLE_LIST *ren_table, *new_table;

  DBUG_ENTER("rename_tables");

  for (ren_table= table_list; ren_table; ren_table= new_table->next_local)

  {

    new_table= ren_table->next_local;

    if (do_rename(thd, ren_table, new_table->db, new_table->table_name,

                  new_table->alias, skip_error))

      DBUG_RETURN(ren_table);

  }

  DBUG_RETURN(0);

}