~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 *> vector_of_transactional_engines;

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

                                                       const std::bitset<HTON_BIT_SIZE> &flags_arg)

    : StorageEngine(name_arg, flags_arg)

{

}

TransactionalStorageEngine::~TransactionalStorageEngine()

{

}

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

*/

int TransactionalStorageEngine::releaseTemporaryLatches(Session *session)

{

  std::for_each(vector_of_transactional_engines.begin(), vector_of_transactional_engines.end(),

                std::bind2nd(std::mem_fun(&TransactionalStorageEngine::doReleaseTemporaryLatches),session));

  return 0;

}

struct StartTransactionFunc :public std::unary_function<TransactionalStorageEngine *, int>

{

  Session *session;

  start_transaction_option_t options;

  StartTransactionFunc(Session *in_session, start_transaction_option_t in_options) :

    session(in_session),

    options(in_options)

  {}

  result_type operator()(argument_type engine) const

  {

    return engine->startTransaction(session, options);

  }

};

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

{

  if (vector_of_transactional_engines.empty())

  {

    return 0;

  }

  else

  {

    StartTransactionFunc functor(session, options);

    std::vector<int> results;

    results.reserve(vector_of_transactional_engines.size());

    transform(vector_of_transactional_engines.begin(),

              vector_of_transactional_engines.end(),

              results.begin(),

              functor);

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

  }

}

bool TransactionalStorageEngine::addPlugin(TransactionalStorageEngine *engine)

{

  vector_of_transactional_engines.push_back(engine);

  return StorageEngine::addPlugin(engine);

}

void TransactionalStorageEngine::removePlugin(TransactionalStorageEngine *)

{

  vector_of_transactional_engines.clear();

}

} /* namespace plugin */

} /* namespace drizzled */