~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_SELECT_SEND_H

#define DRIZZLED_SELECT_SEND_H

#include <drizzled/plugin/client.h>

#include <drizzled/plugin/transactional_storage_engine.h>

namespace drizzled

{

class select_send :public select_result {

  /**

    True if we have sent result set metadata to the client.

    In this case the client always expects us to end the result

    set with an eof or error packet

  */

  bool is_result_set_started;

public:

  select_send() :is_result_set_started(false) {}

  bool send_eof()

  {

    /*

      We may be passing the control from mysqld to the client: release the

      InnoDB adaptive hash S-latch to avoid thread deadlocks if it was reserved

      by session

    */

    plugin::TransactionalStorageEngine::releaseTemporaryLatches(session);

    /* Unlock tables before sending packet to gain some speed */

    if (session->lock)

    {

      mysql_unlock_tables(session, session->lock);

      session->lock= 0;

    }

    session->my_eof();

    is_result_set_started= 0;

    return false;

  }

  bool send_fields(List<Item> &list)

  {

    bool res;

    if (! (res= session->client->sendFields(&list)))

      is_result_set_started= 1;

    return res;

  }

  void abort()

  {

    return;

  }

  /**

    Cleanup an instance of this class for re-use

    at next execution of a prepared statement/

    stored procedure statement.

  */

  virtual void cleanup()

  {

    is_result_set_started= false;

  }

  /* Send data to client. Returns 0 if ok */

  bool send_data(List<Item> &items)

  {

    if (unit->offset_limit_cnt)

    {						// using limit offset,count

      unit->offset_limit_cnt--;

      return false;

    }

    /*

      We may be passing the control from mysqld to the client: release the

      InnoDB adaptive hash S-latch to avoid thread deadlocks if it was reserved

      by session

    */

    plugin::TransactionalStorageEngine::releaseTemporaryLatches(session);

    List_iterator_fast<Item> li(items);

    char buff[MAX_FIELD_WIDTH];

    String buffer(buff, sizeof(buff), &my_charset_bin);

    Item *item;

    while ((item=li++))

    {

      if (item->send(session->client, &buffer))

      {

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

        break;

      }

    }

    session->sent_row_count++;

    if (session->is_error())

      return true;

    return session->client->flush();

  }

};

} /* namespace drizzled */

#endif /* DRIZZLED_SELECT_SEND_H */