mirror of
https://github.com/MariaDB/server.git
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423 lines
9.6 KiB
C
423 lines
9.6 KiB
C
/* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB
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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; either version 2 of the License, or
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(at your option) any later version.
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* The hash functions used for saveing keys */
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#include "heapdef.h"
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#include <m_ctype.h>
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/* Search after a record based on a key */
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/* Sets info->current_ptr to found record */
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/* next_flag: Search=0, next=1, prev =2, same =3 */
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byte *_hp_search(HP_INFO *info, HP_KEYDEF *keyinfo, const byte *key,
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uint nextflag)
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{
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reg1 HASH_INFO *pos,*prev_ptr;
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int flag;
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uint old_nextflag;
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HP_SHARE *share=info->s;
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DBUG_ENTER("_hp_search");
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old_nextflag=nextflag;
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flag=1;
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prev_ptr=0;
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if (share->records)
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{
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pos=hp_find_hash(&keyinfo->block,_hp_mask(_hp_hashnr(keyinfo,key),
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share->blength,share->records));
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do
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{
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if (!_hp_key_cmp(keyinfo,pos->ptr_to_rec,key))
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{
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switch (nextflag) {
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case 0: /* Search after key */
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DBUG_PRINT("exit",("found key at %d",pos->ptr_to_rec));
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info->current_hash_ptr=pos;
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DBUG_RETURN(info->current_ptr= pos->ptr_to_rec);
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case 1: /* Search next */
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if (pos->ptr_to_rec == info->current_ptr)
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nextflag=0;
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break;
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case 2: /* Search previous */
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if (pos->ptr_to_rec == info->current_ptr)
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{
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my_errno=HA_ERR_KEY_NOT_FOUND; /* If gpos == 0 */
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info->current_hash_ptr=prev_ptr;
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DBUG_RETURN(info->current_ptr=prev_ptr ? prev_ptr->ptr_to_rec : 0);
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}
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prev_ptr=pos; /* Prev. record found */
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break;
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case 3: /* Search same */
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if (pos->ptr_to_rec == info->current_ptr)
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{
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info->current_hash_ptr=pos;
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DBUG_RETURN(info->current_ptr);
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}
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}
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}
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if (flag)
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{
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flag=0; /* Reset flag */
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if (hp_find_hash(&keyinfo->block,
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_hp_mask(_hp_rec_hashnr(keyinfo,pos->ptr_to_rec),
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share->blength,share->records)) != pos)
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break; /* Wrong link */
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}
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}
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while ((pos=pos->next_key));
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}
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my_errno=HA_ERR_KEY_NOT_FOUND;
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if (nextflag == 2 && ! info->current_ptr)
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{
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/* Do a previous from end */
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info->current_hash_ptr=prev_ptr;
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DBUG_RETURN(info->current_ptr=prev_ptr ? prev_ptr->ptr_to_rec : 0);
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}
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if (old_nextflag && nextflag)
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my_errno=HA_ERR_RECORD_CHANGED; /* Didn't find old record */
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DBUG_PRINT("exit",("Error: %d",my_errno));
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info->current_hash_ptr=0;
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DBUG_RETURN((info->current_ptr= 0));
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}
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/*
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Search next after last read; Assumes that the table hasn't changed
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since last read !
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*/
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byte *_hp_search_next(HP_INFO *info, HP_KEYDEF *keyinfo, const byte *key,
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HASH_INFO *pos)
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{
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DBUG_ENTER("_hp_search_next");
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while ((pos= pos->next_key))
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{
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if (!_hp_key_cmp(keyinfo,pos->ptr_to_rec,key))
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{
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info->current_hash_ptr=pos;
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DBUG_RETURN (info->current_ptr= pos->ptr_to_rec);
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}
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}
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my_errno=HA_ERR_KEY_NOT_FOUND;
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DBUG_PRINT("exit",("Error: %d",my_errno));
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info->current_hash_ptr=0;
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DBUG_RETURN ((info->current_ptr= 0));
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}
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/* Calculate pos according to keys */
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ulong _hp_mask(ulong hashnr, ulong buffmax, ulong maxlength)
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{
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if ((hashnr & (buffmax-1)) < maxlength) return (hashnr & (buffmax-1));
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return (hashnr & ((buffmax >> 1) -1));
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}
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/* Change link from pos to new_link */
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void _hp_movelink(HASH_INFO *pos, HASH_INFO *next_link, HASH_INFO *newlink)
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{
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HASH_INFO *old_link;
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do
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{
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old_link=next_link;
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}
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while ((next_link=next_link->next_key) != pos);
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old_link->next_key=newlink;
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return;
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}
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#ifndef NEW_HASH_FUNCTION
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/* Calc hashvalue for a key */
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ulong _hp_hashnr(register HP_KEYDEF *keydef, register const byte *key)
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{
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register ulong nr=1, nr2=4;
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HP_KEYSEG *seg,*endseg;
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for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
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{
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uchar *pos=(uchar*) key;
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key+=seg->length;
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if (seg->null_bit)
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{
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key++; /* Skipp null byte */
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if (*pos) /* Found null */
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{
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nr^= (nr << 1) | 1;
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continue;
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}
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pos++;
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}
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if (seg->type == HA_KEYTYPE_TEXT)
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{
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for (; pos < (uchar*) key ; pos++)
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{
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nr^=(ulong) ((((uint) nr & 63)+nr2) *
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((uint) my_sort_order[(uint) *pos])) + (nr << 8);
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nr2+=3;
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}
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}
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else
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{
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for (; pos < (uchar*) key ; pos++)
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{
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nr^=(ulong) ((((uint) nr & 63)+nr2)*((uint) *pos)) + (nr << 8);
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nr2+=3;
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}
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}
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}
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return((ulong) nr);
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}
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/* Calc hashvalue for a key in a record */
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ulong _hp_rec_hashnr(register HP_KEYDEF *keydef, register const byte *rec)
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{
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register ulong nr=1, nr2=4;
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HP_KEYSEG *seg,*endseg;
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for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
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{
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uchar *pos=(uchar*) rec+seg->start,*end=pos+seg->length;
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if (seg->null_bit)
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{
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if (rec[seg->null_pos] & seg->null_bit)
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{
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nr^= (nr << 1) | 1;
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continue;
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}
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}
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if (seg->type == HA_KEYTYPE_TEXT)
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{
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for (; pos < end ; pos++)
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{
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nr^=(ulong) ((((uint) nr & 63)+nr2)*
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((uint) my_sort_order[(uint) *pos]))+ (nr << 8);
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nr2+=3;
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}
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}
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else
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{
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for (; pos < end ; pos++)
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{
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nr^=(ulong) ((((uint) nr & 63)+nr2)*((uint) *pos))+ (nr << 8);
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nr2+=3;
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}
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}
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}
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return((ulong) nr);
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}
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#else
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/*
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* Fowler/Noll/Vo hash
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*
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* The basis of the hash algorithm was taken from an idea sent by email to the
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* IEEE Posix P1003.2 mailing list from Phong Vo (kpv@research.att.com) and
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* Glenn Fowler (gsf@research.att.com). Landon Curt Noll (chongo@toad.com)
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* later improved on their algorithm.
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*
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* The magic is in the interesting relationship between the special prime
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* 16777619 (2^24 + 403) and 2^32 and 2^8.
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*
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* This hash produces the fewest collisions of any function that we've seen so
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* far, and works well on both numbers and strings.
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*/
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ulong _hp_hashnr(register HP_KEYDEF *keydef, register const byte *key)
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{
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register ulong nr=0;
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HP_KEYSEG *seg,*endseg;
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for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
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{
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uchar *pos=(uchar*) key;
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key+=seg->length;
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if (seg->null_bit)
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{
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key++;
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if (*pos)
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{
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nr^= (nr << 1) | 1;
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continue;
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}
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pos++;
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}
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if (seg->type == HA_KEYTYPE_TEXT)
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{
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for (; pos < (uchar*) key ; pos++)
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{
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nr *=16777619;
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nr ^=((uint) my_sort_order[(uint) *pos]);
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}
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}
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else
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{
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for ( ; pos < (uchar*) key ; pos++)
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{
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nr *=16777619;
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nr ^=(uint) *pos;
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}
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}
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}
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return((ulong) nr);
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}
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/* Calc hashvalue for a key in a record */
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ulong _hp_rec_hashnr(register HP_KEYDEF *keydef, register const byte *rec)
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{
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register ulong nr=0;
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HP_KEYSEG *seg,*endseg;
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for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
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{
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uchar *pos=(uchar*) rec+seg->start,*end=pos+seg->length;
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if (seg->null_bit)
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{
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if (rec[seg->null_pos] & seg->null_bit)
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{
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nr^= (nr << 1) | 1;
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continue;
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}
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}
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if (seg->type == HA_KEYTYPE_TEXT)
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{
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for ( ; pos < end ; pos++)
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{
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nr *=16777619;
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nr ^=(uint) my_sort_order[(uint) *pos];
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}
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}
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else
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{
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for ( ; pos < end ; pos++)
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{
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nr *=16777619;
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nr ^=(uint) *pos;
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}
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}
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}
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return((ulong) nr);
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}
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#endif
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/* Compare keys for two records. Returns 0 if they are identical */
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int _hp_rec_key_cmp(HP_KEYDEF *keydef, const byte *rec1, const byte *rec2)
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{
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HP_KEYSEG *seg,*endseg;
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for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
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{
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if (seg->null_bit)
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{
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if ((rec1[seg->null_pos] & seg->null_bit) !=
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(rec2[seg->null_pos] & seg->null_bit))
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return 1;
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if (rec1[seg->null_pos] & seg->null_bit)
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continue;
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}
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if (seg->type == HA_KEYTYPE_TEXT)
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{
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if (my_sortcmp(rec1+seg->start,rec2+seg->start,seg->length))
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return 1;
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}
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else
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{
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if (bcmp(rec1+seg->start,rec2+seg->start,seg->length))
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return 1;
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}
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}
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return 0;
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}
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/* Compare a key in a record to a whole key */
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int _hp_key_cmp(HP_KEYDEF *keydef, const byte *rec, const byte *key)
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{
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HP_KEYSEG *seg,*endseg;
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for (seg=keydef->seg,endseg=seg+keydef->keysegs ;
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seg < endseg ;
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key+= (seg++)->length)
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{
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if (seg->null_bit)
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{
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int found_null=test(rec[seg->null_pos] & seg->null_bit);
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if (found_null != (int) *key++)
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return 1;
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if (found_null)
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continue;
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}
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if (seg->type == HA_KEYTYPE_TEXT)
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{
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if (my_sortcmp(rec+seg->start,key,seg->length))
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return 1;
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}
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else
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{
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if (bcmp(rec+seg->start,key,seg->length))
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return 1;
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}
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}
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return 0;
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}
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/* Copy a key from a record to a keybuffer */
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void _hp_make_key(HP_KEYDEF *keydef, byte *key, const byte *rec)
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{
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HP_KEYSEG *seg,*endseg;
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for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
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{
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if (seg->null_bit)
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*key++= test(rec[seg->null_pos] & seg->null_bit);
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memcpy(key,rec+seg->start,(size_t) seg->length);
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key+=seg->length;
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}
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}
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/*
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Test if any of the key parts are NULL.
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Return:
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1 if any of the key parts was NULL
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0 otherwise
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*/
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my_bool hp_if_null_in_key(HP_KEYDEF *keydef, const byte *record)
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{
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HP_KEYSEG *seg,*endseg;
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for (seg=keydef->seg,endseg=seg+keydef->keysegs ; seg < endseg ; seg++)
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{
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if (seg->null_bit && (record[seg->null_pos] & seg->null_bit))
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return 1;
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}
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return 0;
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}
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