~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 <drizzled/server_includes.h>

#include <drizzled/error.h>

#include <drizzled/table_list.h>

#include <drizzled/session.h>

#include <drizzled/lock.h>

#include "drizzled/rename.h"

static TableList *rename_tables(Session *session, TableList *table_list,

                                bool skip_error);

static TableList *reverse_table_list(TableList *table_list);

/*

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

  second entry is the new name.

*/

bool drizzle_rename_tables(Session *session, TableList *table_list)

{

  bool error= true;

  TableList *ren_table= NULL;

  /*

    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 (session->inTransaction())

  {

    my_message(ER_LOCK_OR_ACTIVE_TRANSACTION, ER(ER_LOCK_OR_ACTIVE_TRANSACTION), MYF(0));

    return true;

  }

  if (wait_if_global_read_lock(session,0,1))

    return true;

  pthread_mutex_lock(&LOCK_open); /* Rename table lock for exclusive access */

  if (lock_table_names_exclusively(session, table_list))

  {

    pthread_mutex_unlock(&LOCK_open);

    goto err;

  }

  error= false;

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

  {

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

    TableList *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(session, table, 1);

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

    table_list= reverse_table_list(table_list);

    error= true;

  }

  /*

    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 (!error)

  {

    write_bin_log(session, true, session->query, session->query_length);

    session->my_ok();

  }

  pthread_mutex_lock(&LOCK_open); /* unlock all tables held */

  unlock_table_names(table_list, NULL);

  pthread_mutex_unlock(&LOCK_open);

err:

  start_waiting_global_read_lock(session);

  return error;

}

/*

  reverse table list

  SYNOPSIS

    reverse_table_list()

    table_list pointer to table _list

  RETURN

    pointer to new (reversed) list

*/

static TableList *reverse_table_list(TableList *table_list)

{

  TableList *prev= NULL;

  while (table_list)

  {

    TableList *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()

      session               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

      skip_error        Whether to skip error

  DESCRIPTION

    Rename a single table or a view.

  RETURN

    false     Ok

    true      rename failed

*/

static bool

do_rename(Session *session, TableList *ren_table, const char *new_db, const char *new_table_name, bool skip_error)

{

  bool rc= true;

  const char *new_alias, *old_alias;

  {

    old_alias= ren_table->table_name;

    new_alias= new_table_name;

  }

  StorageEngine *engine= NULL;

  drizzled::message::Table table_proto;

  char path[FN_REFLEN];

  size_t length;

  length= build_table_filename(path, sizeof(path),

                               ren_table->db, old_alias, false);

  if (StorageEngine::getTableProto(path, &table_proto)!= EEXIST)

  {

    my_error(ER_NO_SUCH_TABLE, MYF(0), ren_table->db, old_alias);

    return true;

  }

  engine= ha_resolve_by_name(session, table_proto.engine().name());

  length= build_table_filename(path, sizeof(path),

                               new_db, new_alias, false);

  if (StorageEngine::getTableProto(path, NULL)!=ENOENT)

  {

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

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

  }

  rc= mysql_rename_table(engine,

                         ren_table->db, old_alias,

                         new_db, new_alias, 0);

  if (rc && !skip_error)

    return true;

  return false;

}

/*

  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()

      session               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 TableList *

rename_tables(Session *session, TableList *table_list, bool skip_error)

{

  TableList *ren_table, *new_table;

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

  {

    new_table= ren_table->next_local;

    if (do_rename(session, ren_table, new_table->db, new_table->table_name, skip_error))

      return(ren_table);

  }

  return(0);

}