Drizzled Public API Documentation

mi_rprev.cc
1 /* Copyright (C) 2000-2001, 2004 MySQL AB
2 
3  This program is free software; you can redistribute it and/or modify
4  it under the terms of the GNU General Public License as published by
5  the Free Software Foundation; version 2 of the License.
6 
7  This program is distributed in the hope that it will be useful,
8  but WITHOUT ANY WARRANTY; without even the implied warranty of
9  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10  GNU General Public License for more details.
11 
12  You should have received a copy of the GNU General Public License
13  along with this program; if not, write to the Free Software
14  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
15 
16 #include "myisam_priv.h"
17 
18  /*
19  Read previous row with the same key as previous read
20  One may have done a write, update or delete of the previous row.
21  NOTE! Even if one changes the previous row, the next read is done
22  based on the position of the last used key!
23  */
24 
25 int mi_rprev(MI_INFO *info, unsigned char *buf, int inx)
26 {
27  int error,changed;
28  register uint32_t flag;
29  MYISAM_SHARE *share=info->s;
30 
31  if ((inx = _mi_check_index(info,inx)) < 0)
32  return(errno);
33  flag=SEARCH_SMALLER; /* Read previous */
34  if (info->lastpos == HA_OFFSET_ERROR && info->update & HA_STATE_NEXT_FOUND)
35  flag=0; /* Read last */
36 
37  if (fast_mi_readinfo(info))
38  return(errno);
39  changed=_mi_test_if_changed(info);
40  if (!flag)
41  error=_mi_search_last(info, share->keyinfo+inx,
42  share->state.key_root[inx]);
43  else if (!changed)
44  error=_mi_search_next(info,share->keyinfo+inx,info->lastkey,
45  info->lastkey_length,flag,
46  share->state.key_root[inx]);
47  else
48  error=_mi_search(info,share->keyinfo+inx,info->lastkey,
49  USE_WHOLE_KEY, flag, share->state.key_root[inx]);
50 
51  if (share->concurrent_insert)
52  {
53  if (!error)
54  {
55  while (info->lastpos >= info->state->data_file_length)
56  {
57  /* Skip rows that are inserted by other threads since we got a lock */
58  if ((error=_mi_search_next(info,share->keyinfo+inx,info->lastkey,
59  info->lastkey_length,
60  SEARCH_SMALLER,
61  share->state.key_root[inx])))
62  break;
63  }
64  }
65  }
66  info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);
67  info->update|= HA_STATE_PREV_FOUND;
68  if (error)
69  {
70  if (errno == drizzled::HA_ERR_KEY_NOT_FOUND)
71  errno= drizzled::HA_ERR_END_OF_FILE;
72  }
73  else if (!buf)
74  {
75  return(info->lastpos==HA_OFFSET_ERROR ? errno : 0);
76  }
77  else if (!(*info->read_record)(info,info->lastpos,buf))
78  {
79  info->update|= HA_STATE_AKTIV; /* Record is read */
80  return(0);
81  }
82  return(errno);
83 } /* mi_rprev */