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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
*
* Copyright (C) 2008 Sun Microsystems, Inc.
*
* 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; version 2 of the License.
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
/* The hash functions used for saving keys */
/* One of key_length or key_length_offset must be given */
/* Key length of 0 isn't allowed */
#include <config.h>
#include <drizzled/my_hash.h>
#include <drizzled/charset.h>
#include <vector>
namespace drizzled {
const uint32_t NO_RECORD= UINT32_MAX;
const int LOWFIND= 1;
const int LOWUSED= 2;
const int HIGHFIND= 4;
const int HIGHUSED= 8;
static uint32_t hash_mask(uint32_t hashnr, uint32_t buffmax, uint32_t maxlength);
static void movelink(HASH_LINK *array, uint32_t pos, uint32_t next_link, uint32_t newlink);
static int hashcmp(const HASH *hash, HASH_LINK *pos, const unsigned char *key, size_t length);
static uint32_t calc_hash(const HASH *hash, const unsigned char *key, size_t length)
{
uint32_t nr1=1, nr2=4;
hash->charset->coll->hash_sort(hash->charset, key,length, &nr1, &nr2);
return nr1;
}
#define dynamic_element(array,array_index,type) ((type)((array)->buffer) +(array_index))
void
_hash_init(HASH *hash,uint32_t growth_size, const charset_info_st * const charset,
uint32_t size, size_t key_offset, size_t key_length,
hash_get_key get_key,
hash_free_key free_element, uint32_t flags)
{
hash->records=0;
hash->array.init(sizeof(HASH_LINK), size, growth_size);
hash->key_offset=key_offset;
hash->key_length=key_length;
hash->blength=1;
hash->get_key=get_key;
hash->free=free_element;
hash->flags=flags;
hash->charset=charset;
}
/*
Call hash->free on all elements in hash.
SYNOPSIS
hash_free_elements()
hash hash table
NOTES:
Sets records to 0
*/
static inline void hash_free_elements(HASH *hash)
{
if (hash->free)
{
HASH_LINK *data=dynamic_element(&hash->array,0,HASH_LINK*);
HASH_LINK *end= data + hash->records;
while (data < end)
(*hash->free)((data++)->data);
}
hash->records=0;
}
/*
Free memory used by hash.
SYNOPSIS
hash_free()
hash the hash to delete elements of
NOTES: Hash can't be reused without calling hash_init again.
*/
void hash_free(HASH *hash)
{
hash_free_elements(hash);
hash->free= 0;
hash->array.free();
}
/* some helper functions */
/*
This function is char* instead of unsigned char* as HPUX11 compiler can't
handle inline functions that are not defined as native types
*/
static inline char*
hash_key(const HASH *hash, const unsigned char *record, size_t *length,
bool first)
{
if (hash->get_key)
return (char*) (*hash->get_key)(record,length,first);
*length=hash->key_length;
return (char*) record+hash->key_offset;
}
/* Calculate pos according to keys */
static uint32_t hash_mask(uint32_t hashnr,uint32_t buffmax,uint32_t maxlength)
{
if ((hashnr & (buffmax-1)) < maxlength) return (hashnr & (buffmax-1));
return (hashnr & ((buffmax >> 1) -1));
}
static uint32_t hash_rec_mask(const HASH *hash, HASH_LINK *pos,
uint32_t buffmax, uint32_t maxlength)
{
size_t length;
unsigned char *key= (unsigned char*) hash_key(hash,pos->data,&length,0);
return hash_mask(calc_hash(hash,key,length),buffmax,maxlength);
}
static
inline
unsigned int rec_hashnr(HASH *hash,const unsigned char *record)
{
size_t length;
unsigned char *key= (unsigned char*) hash_key(hash,record,&length,0);
return calc_hash(hash,key,length);
}
unsigned char* hash_search(const HASH *hash, const unsigned char *key,
size_t length)
{
HASH_SEARCH_STATE state;
return hash_first(hash, key, length, &state);
}
/*
Search after a record based on a key
NOTE
Assigns the number of the found record to HASH_SEARCH_STATE state
*/
unsigned char* hash_first(const HASH *hash, const unsigned char *key,
size_t length,
HASH_SEARCH_STATE *current_record)
{
HASH_LINK *pos;
uint32_t flag,idx;
flag=1;
if (hash->records)
{
idx=hash_mask(calc_hash(hash,key,length ? length : hash->key_length),
hash->blength,hash->records);
do
{
pos= dynamic_element(&hash->array,idx,HASH_LINK*);
if (!hashcmp(hash,pos,key,length))
{
*current_record= idx;
return (pos->data);
}
if (flag)
{
/* Reset flag */
flag=0;
if (hash_rec_mask(hash,pos,hash->blength,hash->records) != idx)
/* Wrong link */
break;
}
}
while ((idx=pos->next) != NO_RECORD);
}
*current_record= NO_RECORD;
return 0;
}
/* Change link from pos to new_link */
static void movelink(HASH_LINK *array, uint32_t find,
uint32_t next_link, uint32_t newlink)
{
HASH_LINK *old_link;
do
{
old_link=array+next_link;
}
while ((next_link=old_link->next) != find);
old_link->next= newlink;
return;
}
/*
Compare a key in a record to a whole key. Return 0 if identical
SYNOPSIS
hashcmp()
hash hash table
pos position of hash record to use in comparison
key key for comparison
length length of key
NOTES:
If length is 0, comparison is done using the length of the
record being compared against.
RETURN
= 0 key of record == key
!= 0 key of record != key
*/
static int hashcmp(const HASH *hash, HASH_LINK *pos, const unsigned char *key,
size_t length)
{
size_t rec_keylength;
unsigned char *rec_key= (unsigned char*) hash_key(hash, pos->data,
&rec_keylength,1);
return ((length && length != rec_keylength) ||
my_strnncoll(hash->charset, rec_key, rec_keylength,
key, rec_keylength));
}
/* Write a hash-key to the hash-index */
bool my_hash_insert(HASH *info,const unsigned char *record)
{
int flag;
size_t idx;
uint32_t halfbuff,hash_nr,first_index;
unsigned char *ptr_to_rec=NULL,*ptr_to_rec2=NULL;
HASH_LINK *data,*empty,*gpos=NULL,*gpos2=NULL,*pos;
if (HASH_UNIQUE & info->flags)
{
unsigned char *key= (unsigned char*) hash_key(info, record, &idx, 1);
if (hash_search(info, key, idx))
/* Duplicate entry */
return true;
}
flag=0;
empty=(HASH_LINK*)info->array.alloc();
data=dynamic_element(&info->array,0,HASH_LINK*);
halfbuff= info->blength >> 1;
idx= first_index= info->records-halfbuff;
/* If some records */
if (idx != info->records)
{
do
{
pos=data+idx;
hash_nr=rec_hashnr(info,pos->data);
/* First loop; Check if ok */
if (flag == 0)
if (hash_mask(hash_nr,info->blength,info->records) != first_index)
break;
if (!(hash_nr & halfbuff))
{
/* Key will not move */
if (!(flag & LOWFIND))
{
if (flag & HIGHFIND)
{
flag=LOWFIND | HIGHFIND;
/* key shall be moved to the current empty position */
gpos=empty;
ptr_to_rec=pos->data;
/* This place is now free */
empty=pos;
}
else
{
/* key isn't changed */
flag=LOWFIND | LOWUSED;
gpos=pos;
ptr_to_rec=pos->data;
}
}
else
{
if (!(flag & LOWUSED))
{
/* Change link of previous LOW-key */
gpos->data=ptr_to_rec;
gpos->next= (uint32_t) (pos-data);
flag= (flag & HIGHFIND) | (LOWFIND | LOWUSED);
}
gpos=pos;
ptr_to_rec=pos->data;
}
}
else
{
/* key will be moved */
if (!(flag & HIGHFIND))
{
flag= (flag & LOWFIND) | HIGHFIND;
/* key shall be moved to the last (empty) position */
gpos2 = empty; empty=pos;
ptr_to_rec2=pos->data;
}
else
{
if (!(flag & HIGHUSED))
{
/* Change link of previous hash-key and save */
gpos2->data=ptr_to_rec2;
gpos2->next=(uint32_t) (pos-data);
flag= (flag & LOWFIND) | (HIGHFIND | HIGHUSED);
}
gpos2=pos;
ptr_to_rec2=pos->data;
}
}
}
while ((idx=pos->next) != NO_RECORD);
if ((flag & (LOWFIND | LOWUSED)) == LOWFIND)
{
gpos->data=ptr_to_rec;
gpos->next=NO_RECORD;
}
if ((flag & (HIGHFIND | HIGHUSED)) == HIGHFIND)
{
gpos2->data=ptr_to_rec2;
gpos2->next=NO_RECORD;
}
}
/* Check if we are at the empty position */
idx=hash_mask(rec_hashnr(info,record),info->blength,info->records+1);
pos=data+idx;
if (pos == empty)
{
pos->data=(unsigned char*) record;
pos->next=NO_RECORD;
}
else
{
/* Check if more records in same hash-nr family */
empty[0]=pos[0];
gpos=data+hash_rec_mask(info,pos,info->blength,info->records+1);
if (pos == gpos)
{
pos->data=(unsigned char*) record;
pos->next=(uint32_t) (empty - data);
}
else
{
pos->data=(unsigned char*) record;
pos->next=NO_RECORD;
movelink(data,(uint32_t) (pos-data),(uint32_t) (gpos-data),(uint32_t) (empty-data));
}
}
if (++info->records == info->blength)
info->blength+= info->blength;
return 0;
}
} /* namespace drizzled */
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