/* Copyright (c) 2000, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   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, version 2.0, 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 "myisamdef.h"

#include "rt_index.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;
  uint update_mask= HA_STATE_NEXT_FOUND;
  DBUG_ENTER("mi_rnext");

  if ((inx = _mi_check_index(info,inx)) < 0)
    DBUG_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))
    DBUG_RETURN(my_errno());
  if (info->s->concurrent_insert)
    mysql_rwlock_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_RTREE:
      error=rtree_get_first(info,inx,info->lastkey_length);
      break;
    case HA_KEY_ALG_BTREE:
    default:
      error=_mi_search_first(info,info->s->keyinfo+inx,
			   info->s->state.key_root[inx]);
      break;
    }
    /*
      "search first" failed. This means we have no pivot for
      "search next", or in other words MI_INFO::lastkey is
      likely uninitialized.

      Normally SQL layer would never request "search next" if
      "search first" failed. But HANDLER may do anything.

      As mi_rnext() without preceding mi_rkey()/mi_rfirst()
      equals to mi_rfirst(), we must restore original state
      as if failing mi_rfirst() was not called.
    */
    if (error)
      update_mask|= HA_STATE_PREV_FOUND;
  }
  else
  {
    switch (info->s->keyinfo[inx].key_alg) {
    case HA_KEY_ALG_RTREE:
      /*
	Note that rtree doesn't support that the table
	may be changed since last call, so we do need
	to skip rows inserted by other threads like in btree
      */
      error= rtree_get_next(info,inx,info->lastkey_length);
      break;
    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 that are either inserted by other threads since
         we got a lock or do not match pushed index conditions
      */
      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)
        mysql_rwlock_unlock(&info->s->key_root_lock[inx]);
      info->lastpos= HA_OFFSET_ERROR;
      set_my_errno(HA_ERR_END_OF_FILE);
      DBUG_RETURN(HA_ERR_END_OF_FILE);
    }
  }
  
  if (info->s->concurrent_insert)
  {
    if (!error)
    {
      while (info->lastpos >= info->state->data_file_length)
      {
	/* 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;
      }
    }
    mysql_rwlock_unlock(&info->s->key_root_lock[inx]);
  }
	/* Don't clear if database-changed */
  info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);
  info->update|= update_mask;

  if (error)
  {
    if (my_errno() == HA_ERR_KEY_NOT_FOUND)
      set_my_errno(HA_ERR_END_OF_FILE);
  }
  else if (!buf)
  {
    DBUG_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 */
    DBUG_RETURN(0);
  }
  DBUG_PRINT("error",("Got error: %d,  errno: %d",error, my_errno()));
  DBUG_RETURN(my_errno());
} /* mi_rnext */
