~drizzle-trunk/drizzle/development

/* Copyright (C) 2000-2004 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "myisamdef.h"

	/*

	   Read next row with the same key as previous read

	   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(MI_INFO *info, uchar *buf, int inx)

{

  int error,changed;

  uint flag;

  int res= 0;

  if ((inx = _mi_check_index(info,inx)) < 0)

    return(my_errno);

  flag=SEARCH_BIGGER;				/* Read next */

  if (info->lastpos == HA_OFFSET_ERROR && info->update & HA_STATE_PREV_FOUND)

    flag=0;					/* Read first */

  if (fast_mi_readinfo(info))

    return(my_errno);

  if (info->s->concurrent_insert)

    rw_rdlock(&info->s->key_root_lock[inx]);

  changed=_mi_test_if_changed(info);

  if (!flag)

  {

    switch(info->s->keyinfo[inx].key_alg){

    case HA_KEY_ALG_BTREE:

    default:

      error=_mi_search_first(info,info->s->keyinfo+inx,

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

      break;

    }

  }

  else

  {

    switch (info->s->keyinfo[inx].key_alg) {

    case HA_KEY_ALG_BTREE:

    default:

      if (!changed)

	error= _mi_search_next(info,info->s->keyinfo+inx,info->lastkey,

			       info->lastkey_length,flag,

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

      else

	error= _mi_search(info,info->s->keyinfo+inx,info->lastkey,

			  USE_WHOLE_KEY,flag, info->s->state.key_root[inx]);

    }

  }

  if (!error)

  {

    while ((info->s->concurrent_insert &&

            info->lastpos >= info->state->data_file_length) ||

           (info->index_cond_func &&

           !(res= mi_check_index_cond(info, inx, buf))))

    {

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

      if  ((error=_mi_search_next(info,info->s->keyinfo+inx,

                                  info->lastkey,

                                  info->lastkey_length,

                                  SEARCH_BIGGER,

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

        break;

    }

    if (!error && res == 2)

    {

      if (info->s->concurrent_insert)

        rw_unlock(&info->s->key_root_lock[inx]);

      info->lastpos= HA_OFFSET_ERROR;

      return(my_errno= HA_ERR_END_OF_FILE);

    }

  }

  if (info->s->concurrent_insert)

    rw_unlock(&info->s->key_root_lock[inx]);

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

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

  info->update|= HA_STATE_NEXT_FOUND;

  if (error)

  {

    if (my_errno == HA_ERR_KEY_NOT_FOUND)

      my_errno=HA_ERR_END_OF_FILE;

  }

  else if (!buf)

  {

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

  }

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

  {

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

    return(0);

  }

  return(my_errno);

} /* mi_rnext */