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98 lines
3.1 KiB
C
98 lines
3.1 KiB
C
/* Copyright (c) 2000-2002, 2005-2007 MySQL AB
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Use is subject to license terms
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
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#include "heapdef.h"
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/* Read prev record for key */
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int heap_rprev(HP_INFO *info, uchar *record)
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{
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uchar *pos;
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HP_SHARE *share=info->s;
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HP_KEYDEF *keyinfo;
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DBUG_ENTER("heap_rprev");
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if (info->lastinx < 0)
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DBUG_RETURN(my_errno=HA_ERR_WRONG_INDEX);
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keyinfo = share->keydef + info->lastinx;
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if (keyinfo->algorithm == HA_KEY_ALG_BTREE)
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{
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heap_rb_param custom_arg;
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/* If no active record and last was not deleted */
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if (!(info->update & (HA_STATE_AKTIV | HA_STATE_NO_KEY |
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HA_STATE_DELETED)))
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{
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if (info->update & HA_STATE_PREV_FOUND)
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pos= 0; /* Can't search before first row */
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else
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{
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/* Last was 'next' after last record; search after last record */
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pos= tree_search_edge(&keyinfo->rb_tree, info->parents,
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&info->last_pos, offsetof(TREE_ELEMENT, right));
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}
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}
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else if (info->last_pos)
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pos = tree_search_next(&keyinfo->rb_tree, &info->last_pos,
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offsetof(TREE_ELEMENT, right),
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offsetof(TREE_ELEMENT, left));
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else
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{
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custom_arg.keyseg = keyinfo->seg;
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custom_arg.key_length = keyinfo->length;
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custom_arg.search_flag = SEARCH_SAME;
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info->last_find_flag= HA_READ_KEY_OR_PREV;
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pos = tree_search_key(&keyinfo->rb_tree, info->lastkey, info->parents,
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&info->last_pos, info->last_find_flag, &custom_arg);
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}
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if (pos)
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{
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memcpy(&pos, pos + (*keyinfo->get_key_length)(keyinfo, pos),
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sizeof(uchar*));
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info->current_ptr = pos;
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}
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else
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{
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my_errno = HA_ERR_KEY_NOT_FOUND;
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}
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}
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else
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{
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if (info->current_ptr || (info->update & HA_STATE_NEXT_FOUND))
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{
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if ((info->update & HA_STATE_DELETED))
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pos= hp_search(info, share->keydef + info->lastinx, info->lastkey, 3);
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else
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pos= hp_search(info, share->keydef + info->lastinx, info->lastkey, 2);
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}
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else
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{
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pos=0; /* Read next after last */
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my_errno=HA_ERR_KEY_NOT_FOUND;
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}
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}
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if (!pos)
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{
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info->update=HA_STATE_PREV_FOUND; /* For heap_rprev */
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if (my_errno == HA_ERR_KEY_NOT_FOUND)
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my_errno=HA_ERR_END_OF_FILE;
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DBUG_RETURN(my_errno);
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}
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memcpy(record,pos,(size_t) share->reclength);
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info->update=HA_STATE_AKTIV | HA_STATE_PREV_FOUND;
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DBUG_RETURN(0);
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}
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