mi_rnext.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:4k
- /* 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
- 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, byte *buf, int inx)
- {
- int error,changed;
- uint flag;
- 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)
- rw_rdlock(&info->s->key_root_lock[inx]);
- changed=_mi_test_if_changed(info);
- if (!flag)
- {
- switch(info->s->keyinfo[inx].key_alg){
- #ifdef HAVE_RTREE_KEYS
- case HA_KEY_ALG_RTREE:
- error=rtree_get_first(info,inx,info->lastkey_length);
- break;
- #endif
- 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) {
- #ifdef HAVE_RTREE_KEYS
- 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;
- #endif
- 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 (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;
- }
- }
- 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)
- {
- 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 */