~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2006 MySQL AB

   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 "myisam_priv.h"

using namespace drizzled;

	/*

	   Read next row with the same key as previous read, but abort if

	   the key changes.

	   One may have done a write, update or delete of the previous row.

	   NOTE! Even if one changes the previous row, the next read is done

	   based on the position of the last used key!

	*/

int mi_rnext_same(MI_INFO *info, unsigned char *buf)

{

  int error;

  uint32_t inx,not_used[2];

  MI_KEYDEF *keyinfo;

  if ((int) (inx=info->lastinx) < 0 || info->lastpos == HA_OFFSET_ERROR)

    return(errno=HA_ERR_WRONG_INDEX);

  keyinfo=info->s->keyinfo+inx;

  if (fast_mi_readinfo(info))

    return(errno);

  switch (keyinfo->key_alg)

  {

    case HA_KEY_ALG_BTREE:

    default:

      if (!(info->update & HA_STATE_RNEXT_SAME))

      {

        /* First rnext_same; Store old key */

        memcpy(info->lastkey2,info->lastkey,info->last_rkey_length);

      }

      for (;;)

      {

        if ((error=_mi_search_next(info,keyinfo,info->lastkey,

			       info->lastkey_length,SEARCH_BIGGER,

			       info->s->state.key_root[inx])))

          break;

        if (ha_key_cmp(keyinfo->seg, info->lastkey, info->lastkey2,

                       info->last_rkey_length, SEARCH_FIND, not_used))

        {

          error=1;

          errno=HA_ERR_END_OF_FILE;

          info->lastpos= HA_OFFSET_ERROR;

          break;

        }

        /* Skip rows that are inserted by other threads since we got a lock */

        if (info->lastpos < info->state->data_file_length &&

            (!info->index_cond_func || mi_check_index_cond(info, inx, buf)))

          break;

      }

  }

  /* Don't clear if database-changed */

  info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);

  info->update|= HA_STATE_NEXT_FOUND | HA_STATE_RNEXT_SAME;

  if (error)

  {

    if (errno == HA_ERR_KEY_NOT_FOUND)

      errno=HA_ERR_END_OF_FILE;

  }

  else if (!buf)

  {

    return(info->lastpos==HA_OFFSET_ERROR ? errno : 0);

  }

  else if (!(*info->read_record)(info,info->lastpos,buf))

  {

    info->update|= HA_STATE_AKTIV;		/* Record is read */

    return(0);

  }

  return(errno);

} /* mi_rnext_same */