~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, Inc.

 *  Copyright (C) 2009-2010 Jay Pipes <jaypipes@gmail.com>

 *

 *  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 <config.h>

#include <drizzled/plugin/transactional_storage_engine.h>

#include <drizzled/resource_context.h>

#include <drizzled/session.h>

#include <vector>

#include <algorithm>

#include <functional>

namespace drizzled {

namespace plugin {

static std::vector<TransactionalStorageEngine*> g_engines;

TransactionalStorageEngine::TransactionalStorageEngine(const std::string &name_arg,

                                                       const std::bitset<HTON_BIT_SIZE> &flags_arg)

    : StorageEngine(name_arg, flags_arg)

{

}

void TransactionalStorageEngine::setTransactionReadWrite(Session& session)

{

  ResourceContext& resource_context= session.getResourceContext(*this);

  /*

    When a storage engine method is called, the transaction must

    have been started, unless it's a DDL call, for which the

    storage engine starts the transaction internally, and commits

    it internally, without registering in the ha_list.

    Unfortunately here we can't know know for sure if the engine

    has registered the transaction or not, so we must check.

  */

  if (resource_context.isStarted())

    resource_context.markModifiedData();

}

/**

  @details

  This function should be called when MySQL sends rows of a SELECT result set

  or the EOF mark to the client. It releases a possible adaptive hash index

  S-latch held by session in InnoDB and also releases a possible InnoDB query

  FIFO ticket to enter InnoDB. To save CPU time, InnoDB allows a session to

  keep them over several calls of the InnoDB Cursor interface when a join

  is executed. But when we let the control to pass to the client they have

  to be released because if the application program uses use_result(),

  it may deadlock on the S-latch if the application on another connection

  performs another SQL query. In MySQL-4.1 this is even more important because

  there a connection can have several SELECT queries open at the same time.

  @param session           the thread handle of the current connection

  @return

    always 0

*/

void TransactionalStorageEngine::releaseTemporaryLatches(Session *session)

{

  BOOST_FOREACH(TransactionalStorageEngine* it, g_engines) 

    it->doReleaseTemporaryLatches(session);

}

int TransactionalStorageEngine::notifyStartTransaction(Session *session, start_transaction_option_t options)

{

  if (g_engines.empty())

    return 0;

  std::vector<int> results;

  results.reserve(g_engines.size());

  BOOST_FOREACH(TransactionalStorageEngine* it, g_engines)

    results.push_back(it->startTransaction(session, options));

  return *std::max_element(results.begin(), results.end());

}

bool TransactionalStorageEngine::addPlugin(TransactionalStorageEngine *engine)

{

  g_engines.push_back(engine);

  return StorageEngine::addPlugin(engine);

}

void TransactionalStorageEngine::removePlugin(TransactionalStorageEngine*)

{

  g_engines.clear();

}

} /* namespace plugin */

} /* namespace drizzled */