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/* Copyright (C) 2003 MySQL AB
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 Street, Fifth Floor, Boston, MA 02110-1301, USA */
#ifndef NdbLinHash_H
#define NdbLinHash_H
#include <ndb_types.h>
#define SEGMENTSIZE 64
#define SEGMENTLOGSIZE 6
#define DIRECTORYSIZE 64
#define DIRINDEX(adress) ((adress) >> SEGMENTLOGSIZE)
#define SEGINDEX(adress) ((adress) & (SEGMENTSIZE-1))
#if !defined(MAXLOADFCTR)
#define MAXLOADFCTR 2
#endif
#if !defined(MINLOADFCTR)
#define MINLOADFCTR (MAXLOADFCTR/2)
#endif
template<class C>
class NdbElement_t {
public:
NdbElement_t();
~NdbElement_t();
Uint32 len;
Uint32 hash;
Uint32 localkey1;
Uint32 *str;
NdbElement_t<C> *next;
C* theData;
private:
NdbElement_t(const NdbElement_t<C> & aElement_t);
NdbElement_t & operator = (const NdbElement_t<C> & aElement_t);
};
template <class C>
class NdbLinHash {
public:
NdbLinHash();
~NdbLinHash();
void createHashTable(void);
void releaseHashTable(void);
int insertKey(const char * str, Uint32 len, Uint32 lkey1, C* data);
C *deleteKey(const char * str, Uint32 len);
C* getData(const char *, Uint32);
Uint32* getKey(const char *, Uint32);
void shrinkTable(void);
void expandHashTable(void);
Uint32 Hash(const char *str, Uint32 len);
Uint32 Hash(Uint32 h);
NdbElement_t<C> * getNext(NdbElement_t<C> * curr);
private:
void getBucket(Uint32 hash, int * dirindex, int * segindex);
struct Segment_t {
NdbElement_t<C> * elements[SEGMENTSIZE];
};
Uint32 p; /*bucket to be split*/
Uint32 max; /*max is the upper bound*/
Int32 slack; /*number of insertions before splits*/
Segment_t * directory[DIRECTORYSIZE];
NdbLinHash(const NdbLinHash<C> & aLinHash);
NdbLinHash<C> & operator = (const NdbLinHash<C> & aLinHash);
};
// All template methods must be inline
template <class C>
inline
NdbLinHash<C>::NdbLinHash() {
}
template <class C>
inline
NdbLinHash<C>::NdbLinHash(const NdbLinHash<C>& aLinHash)
{
}
template <class C>
inline
NdbLinHash<C>::~NdbLinHash()
{
}
template <class C>
inline
Uint32
NdbLinHash<C>::Hash( const char* str, Uint32 len )
{
Uint32 h = 0;
while(len >= 4){
h = (h << 5) + h + str[0];
h = (h << 5) + h + str[1];
h = (h << 5) + h + str[2];
h = (h << 5) + h + str[3];
len -= 4;
str += 4;
}
while(len > 0){
h = (h << 5) + h + *str++;
len--;
}
return h;
}
template <class C>
inline
Uint32
NdbLinHash<C>::Hash( Uint32 h ){
return h;
}
template <class C>
inline
NdbElement_t<C>::NdbElement_t() :
len(0),
hash(0),
localkey1(0),
str(NULL),
next(NULL),
theData(NULL)
{
}
template <class C>
inline
NdbElement_t<C>::~NdbElement_t()
{
delete []str;
}
/* Initialize the hashtable HASH_T */
template <class C>
inline
void
NdbLinHash<C>::createHashTable() {
p = 0;
max = SEGMENTSIZE - 1;
slack = SEGMENTSIZE * MAXLOADFCTR;
directory[0] = new Segment_t();
int i;
/* The first segment cleared before used */
for(i = 0; i < SEGMENTSIZE; i++ )
directory[0]->elements[i] = 0;
/* clear the rest of the directory */
for(i = 1; i < DIRECTORYSIZE; i++)
directory[i] = 0;
}
template <class C>
inline
void
NdbLinHash<C>::getBucket(Uint32 hash, int * dir, int * seg){
Uint32 adress = hash & max;
if(adress < p)
adress = hash & (2 * max + 1);
* dir = DIRINDEX(adress);
* seg = SEGINDEX(adress);
}
template <class C>
inline
Int32
NdbLinHash<C>::insertKey( const char* str, Uint32 len, Uint32 lkey1, C* data )
{
const Uint32 hash = Hash(str, len);
int dir, seg;
getBucket(hash, &dir, &seg);
NdbElement_t<C> **chainp = &directory[dir]->elements[seg];
/**
* Check if the string already are in the hash table
* chain=chainp will copy the contents of HASH_T into chain
*/
NdbElement_t<C> * oldChain = 0;
NdbElement_t<C> * chain;
for(chain = *chainp; chain != 0; chain = chain->next){
if(chain->len == len && !memcmp(chain->str, str, len))
return -1; /* Element already exists */
else
oldChain = chain;
}
/* New entry */
chain = new NdbElement_t<C>();
chain->len = len;
chain->hash = hash;
chain->localkey1 = lkey1;
chain->next = 0;
chain->theData = data;
len++; // Null terminated
chain->str = new Uint32[((len + 3) >> 2)];
memcpy( &chain->str[0], str, len);
if (oldChain != 0)
oldChain->next = chain;
else
*chainp = chain;
#if 0
if(--(slack) < 0)
expandHashTable();
#endif
return chain->localkey1;
}
template <class C>
inline
Uint32*
NdbLinHash<C>::getKey( const char* str, Uint32 len )
{
const Uint32 tHash = Hash(str, len);
int dir, seg;
getBucket(tHash, &dir, &seg);
NdbElement_t<C> ** keyp = &directory[dir]->elements[seg];
/*Check if the string are in the hash table*/
for(NdbElement_t<C> * key = *keyp; key != 0; key = key->next ) {
if(key->len == len && !memcmp(key->str, str, len)) {
return &key->localkey1;
}
}
return NULL ; /* The key was not found */
}
template <class C>
inline
C*
NdbLinHash<C>::getData( const char* str, Uint32 len ){
const Uint32 tHash = Hash(str, len);
int dir, seg;
getBucket(tHash, &dir, &seg);
NdbElement_t<C> ** keyp = &directory[dir]->elements[seg];
/*Check if the string are in the hash table*/
for(NdbElement_t<C> * key = *keyp; key != 0; key = key->next ) {
if(key->len == len && !memcmp(key->str, str, len)) {
return key->theData;
}
}
return NULL ; /* The key was not found */
}
template <class C>
inline
C *
NdbLinHash<C>::deleteKey ( const char* str, Uint32 len){
const Uint32 hash = Hash(str, len);
int dir, seg;
getBucket(hash, &dir, &seg);
NdbElement_t<C> *oldChain = 0;
NdbElement_t<C> **chainp = &directory[dir]->elements[seg];
for(NdbElement_t<C> * chain = *chainp; chain != 0; chain = chain->next){
if(chain->len == len && !memcmp(chain->str, str, len)){
C *data= chain->theData;
if (oldChain == 0) {
* chainp = chain->next;
} else {
oldChain->next = chain->next;
}
delete chain;
return data;
} else {
oldChain = chain;
}
}
return 0; /* Element doesn't exist */
}
template <class C>
inline
void
NdbLinHash<C>::releaseHashTable( void ){
NdbElement_t<C>* tNextElement;
NdbElement_t<C>* tElement;
//Traverse the whole directory structure
for(int countd = 0; countd < DIRECTORYSIZE;countd++ ){
if (directory[countd] != 0) {
//Traverse whole hashtable
for(int counts = 0; counts < SEGMENTSIZE; counts++ )
if (directory[countd]->elements[counts] != 0) {
tElement = directory[countd]->elements[counts];
//Delete all elements even those who is linked
do {
tNextElement = tElement->next;
delete tElement;
tElement = tNextElement;
} while (tNextElement != 0);
}
delete directory[countd];
}
}
}
template <class C>
inline
void
NdbLinHash<C>::shrinkTable( void )
{
Segment_t *lastseg;
NdbElement_t<C> **chainp;
Uint32 oldlast = p + max;
if( oldlast == 0 )
return;
// Adjust the state variables.
if( p == 0 ) {
max >>= 1;
p = max;
}
else
--(p);
// Update slack after shrink.
slack -= MAXLOADFCTR;
// Insert the chain oldlast at the end of chain p.
chainp = &directory[DIRINDEX(p)]->elements[SEGINDEX(p)];
while( *chainp != 0 ) {
chainp = &((*chainp)->next);
lastseg = directory[DIRINDEX(oldlast)];
*chainp = lastseg->elements[SEGINDEX(oldlast)];
// If necessary free last segment.
if( SEGINDEX(oldlast) == 0)
delete lastseg;
}
}
template <class C>
inline
void
NdbLinHash<C>::expandHashTable( void )
{
NdbElement_t<C> **oldbucketp, *chain, *headofold, *headofnew, *next;
Uint32 maxp = max + 1;
Uint32 newadress = maxp + p;
// Still room in the adress space?
if( newadress >= DIRECTORYSIZE * SEGMENTSIZE ) {
return;
}
// If necessary, create a new segment.
if( SEGINDEX(newadress) == 0 )
directory[DIRINDEX(newadress)] = new Segment_t();
// Locate the old (to be split) bucket.
oldbucketp = &directory[DIRINDEX(p)]->elements[SEGINDEX(p)];
// Adjust the state variables.
p++;
if( p > max ) {
max = 2 *max + 1;
p = 0;
}
// Update slack after expandation.
slack += MAXLOADFCTR;
// Relocate records to the new bucket.
headofold = 0;
headofnew = 0;
for( chain = *oldbucketp; chain != 0; chain = next ) {
next = chain->next;
if( chain->hash & maxp ) {
chain->next = headofnew;
headofnew = chain;
}
else {
chain->next = headofold;
headofold = chain;
}
}
*oldbucketp = headofold;
directory[DIRINDEX(newadress)]->elements[SEGINDEX(newadress)] = headofnew;
}
template <class C>
inline
NdbElement_t<C> *
NdbLinHash<C>::getNext(NdbElement_t<C> * curr){
if(curr != 0 && curr->next != 0)
return curr->next;
int dir = 0, seg = 0;
int counts;
if(curr != 0)
{
getBucket(curr->hash, &dir, &seg);
counts = seg + 1;
}
else
{
counts = 0;
}
for(int countd = dir; countd < DIRECTORYSIZE;countd++ ){
if (directory[countd] != 0) {
for(; counts < SEGMENTSIZE; counts++ ){
if (directory[countd]->elements[counts] != 0) {
return directory[countd]->elements[counts];
}
}
}
counts = 0;
}
return 0;
}
#endif
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