Drizzled Public API Documentation

mi_rnext_same.cc
1 /* Copyright (C) 2000-2006 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 using namespace drizzled;
19 
20  /*
21  Read next row with the same key as previous read, but abort if
22  the key changes.
23  One may have done a write, update or delete of the previous row.
24  NOTE! Even if one changes the previous row, the next read is done
25  based on the position of the last used key!
26  */
27 
28 int mi_rnext_same(MI_INFO *info, unsigned char *buf)
29 {
30  int error;
31  uint32_t inx,not_used[2];
32  MI_KEYDEF *keyinfo;
33 
34  if ((int) (inx=info->lastinx) < 0 || info->lastpos == HA_OFFSET_ERROR)
35  return(errno=HA_ERR_WRONG_INDEX);
36  keyinfo=info->s->keyinfo+inx;
37  if (fast_mi_readinfo(info))
38  return(errno);
39 
40  switch (keyinfo->key_alg)
41  {
42  case HA_KEY_ALG_BTREE:
43  default:
44  if (!(info->update & HA_STATE_RNEXT_SAME))
45  {
46  /* First rnext_same; Store old key */
47  memcpy(info->lastkey2,info->lastkey,info->last_rkey_length);
48  }
49  for (;;)
50  {
51  if ((error=_mi_search_next(info,keyinfo,info->lastkey,
52  info->lastkey_length,SEARCH_BIGGER,
53  info->s->state.key_root[inx])))
54  break;
55  if (ha_key_cmp(keyinfo->seg, info->lastkey, info->lastkey2,
56  info->last_rkey_length, SEARCH_FIND, not_used))
57  {
58  error=1;
59  errno=HA_ERR_END_OF_FILE;
60  info->lastpos= HA_OFFSET_ERROR;
61  break;
62  }
63  /* Skip rows that are inserted by other threads since we got a lock */
64  if (info->lastpos < info->state->data_file_length &&
65  (!info->index_cond_func || mi_check_index_cond(info, inx, buf)))
66  break;
67  }
68  }
69  /* Don't clear if database-changed */
70  info->update&= (HA_STATE_CHANGED | HA_STATE_ROW_CHANGED);
71  info->update|= HA_STATE_NEXT_FOUND | HA_STATE_RNEXT_SAME;
72 
73  if (error)
74  {
75  if (errno == HA_ERR_KEY_NOT_FOUND)
76  errno=HA_ERR_END_OF_FILE;
77  }
78  else if (!buf)
79  {
80  return(info->lastpos==HA_OFFSET_ERROR ? errno : 0);
81  }
82  else if (!(*info->read_record)(info,info->lastpos,buf))
83  {
84  info->update|= HA_STATE_AKTIV; /* Record is read */
85  return(0);
86  }
87  return(errno);
88 } /* mi_rnext_same */