mi_rnext_same.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 "myisamdef.h"
- #include "rt_index.h"
- /*
- 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, byte *buf)
- {
- int error;
- uint inx,not_used[2];
- MI_KEYDEF *keyinfo;
- DBUG_ENTER("mi_rnext_same");
- if ((int) (inx=info->lastinx) < 0 || info->lastpos == HA_OFFSET_ERROR)
- DBUG_RETURN(my_errno=HA_ERR_WRONG_INDEX);
- keyinfo=info->s->keyinfo+inx;
- if (fast_mi_readinfo(info))
- DBUG_RETURN(my_errno);
- if (info->s->concurrent_insert)
- rw_rdlock(&info->s->key_root_lock[inx]);
-
- switch (keyinfo->key_alg)
- {
- #ifdef HAVE_RTREE_KEYS
- case HA_KEY_ALG_RTREE:
- if ((error=rtree_find_next(info,inx,
- myisam_read_vec[info->last_key_func])))
- {
- error=1;
- my_errno=HA_ERR_END_OF_FILE;
- info->lastpos= HA_OFFSET_ERROR;
- break;
- }
- break;
- #endif
- 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;
- my_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)
- break;
- }
- }
- 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 | HA_STATE_RNEXT_SAME;
- if (error)
- {
- if (my_errno == HA_ERR_KEY_NOT_FOUND)
- 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_RETURN(my_errno);
- } /* mi_rnext */