hp_rprev.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:3k
- /* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult 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; either version 2 of the License, or
- (at your option) any later version.
- 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 "heapdef.h"
- /* Read prev record for key */
- int heap_rprev(HP_INFO *info, byte *record)
- {
- byte *pos;
- HP_SHARE *share=info->s;
- HP_KEYDEF *keyinfo;
- DBUG_ENTER("heap_rprev");
- if (info->lastinx < 0)
- DBUG_RETURN(my_errno=HA_ERR_WRONG_INDEX);
- keyinfo = share->keydef + info->lastinx;
- if (keyinfo->algorithm == HA_KEY_ALG_BTREE)
- {
- heap_rb_param custom_arg;
- if (info->last_pos)
- pos = tree_search_next(&keyinfo->rb_tree, &info->last_pos,
- offsetof(TREE_ELEMENT, right),
- offsetof(TREE_ELEMENT, left));
- else
- {
- custom_arg.keyseg = keyinfo->seg;
- custom_arg.key_length = keyinfo->length;
- custom_arg.search_flag = SEARCH_SAME;
- pos = tree_search_key(&keyinfo->rb_tree, info->lastkey, info->parents,
- &info->last_pos, info->last_find_flag, &custom_arg);
- }
- if (pos)
- {
- memcpy(&pos, pos + (*keyinfo->get_key_length)(keyinfo, pos),
- sizeof(byte*));
- info->current_ptr = pos;
- }
- else
- {
- my_errno = HA_ERR_KEY_NOT_FOUND;
- }
- }
- else
- {
- if (info->current_ptr || (info->update & HA_STATE_NEXT_FOUND))
- {
- if ((info->update & HA_STATE_DELETED))
- pos= hp_search(info, share->keydef + info->lastinx, info->lastkey, 3);
- else
- pos= hp_search(info, share->keydef + info->lastinx, info->lastkey, 2);
- }
- else
- {
- pos=0; /* Read next after last */
- my_errno=HA_ERR_KEY_NOT_FOUND;
- }
- }
- if (!pos)
- {
- info->update=HA_STATE_PREV_FOUND; /* For heap_rprev */
- if (my_errno == HA_ERR_KEY_NOT_FOUND)
- my_errno=HA_ERR_END_OF_FILE;
- DBUG_RETURN(my_errno);
- }
- memcpy(record,pos,(size_t) share->reclength);
- info->update=HA_STATE_AKTIV | HA_STATE_PREV_FOUND;
- DBUG_RETURN(0);
- }