~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2009 Sun Microsystems

 *

 *  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; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  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 <drizzled/server_includes.h>

#include <drizzled/show.h>

#include <drizzled/lock.h>

#include <drizzled/session.h>

#include <drizzled/statement/rename_table.h>

namespace drizzled

{

bool statement::RenameTable::execute()

{

  TableList *first_table= (TableList *) session->lex->select_lex.table_list.first;

  TableList *all_tables= session->lex->query_tables;

  assert(first_table == all_tables && first_table != 0);

  TableList *table;

  for (table= first_table; table; table= table->next_local->next_local)

  {

    TableList old_list, new_list;

    /*

       we do not need initialize old_list and new_list because we will

       come table[0] and table->next[0] there

     */

    old_list= table[0];

    new_list= table->next_local[0];

  }

  if (! session->endActiveTransaction() || renameTables(first_table))

  {

    return true;

  }

  return false;

}

bool statement::RenameTable::renameTables(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;

  ren_table= renameTablesInList(table_list, 0);

  if (ren_table)

  {

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

    TableList *table;

    /* Reverse the table list */

    table_list= reverseTableList(table_list);

    /* Find the last renamed table */

    for (table= table_list;

         table->next_local != ren_table;

         table= table->next_local->next_local) 

    { /* do nothing */ }

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

    /* Revert to old names */

    renameTablesInList(table, 1);

    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, 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;

}

TableList *statement::RenameTable::reverseTableList(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;

}

bool statement::RenameTable::rename(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;

  }

  plugin::StorageEngine *engine= NULL;

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

  {

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

    return true;

  }

  engine= plugin::StorageEngine::findByName(session, table_proto.engine().name());

  length= build_table_filename(path, sizeof(path),

                               new_db, new_alias, false);

  if (plugin::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;

}

TableList *statement::RenameTable::renameTablesInList(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 (rename(ren_table, new_table->db, new_table->table_name, skip_error))

      return ren_table;

  }

  return 0;

} 

} /* namespace drizzled */