~drizzle-trunk/drizzle/development

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

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

 *

 *  Copyright (C) 2008 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; 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

 */

#ifndef DRIZZLED_HA_TRX_INFO_H

#define DRIZZLED_HA_TRX_INFO_H

namespace drizzled

{

class Session_TRANS;

namespace plugin

{

class StorageEngine;

}

/**

  Either statement transaction or normal transaction - related

  thread-specific storage engine data.

  If a storage engine participates in a statement/transaction,

  an instance of this class is present in

  session->transaction.{stmt|all}.ha_list. The addition to

  {stmt|all}.ha_list is made by trans_register_ha().

  When it's time to commit or rollback, each element of ha_list

  is used to access storage engine's prepare()/commit()/rollback()

  methods, and also to evaluate if a full two phase commit is

  necessary.

  @sa General description of transaction handling in handler.cc.

*/

class Ha_trx_info

{

public:

  /** Register this storage engine in the given transaction context. */

  void register_ha(Session_TRANS *trans,

                   plugin::StorageEngine *engine_arg);

  /** Clear, prepare for reuse. */

  void reset();

  Ha_trx_info() { reset(); }

  void set_trx_read_write();

  bool is_trx_read_write() const;

  bool is_started() const;

  /** Mark this transaction read-write if the argument is read-write. */

  void coalesce_trx_with(const Ha_trx_info *stmt_trx);

  Ha_trx_info *next() const;

  plugin::StorageEngine *engine() const;

private:

  enum { TRX_READ_ONLY= 0, TRX_READ_WRITE= 1 };

  /** Auxiliary, used for ha_list management */

  Ha_trx_info *m_next;

  /**

    Although a given Ha_trx_info instance is currently always used

    for the same storage engine, 'engine' is not-NULL only when the

    corresponding storage is a part of a transaction.

  */

  plugin::StorageEngine *m_engine;

  /**

    Transaction flags related to this engine.

    Not-null only if this instance is a part of transaction.

    May assume a combination of enum values above.

  */

  unsigned char       m_flags;

};

} /* namespace drizzled */

#endif /* DRIZZLED_HA_TRX_INFO_H */