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improvement on the hashing of the dictionnary, with visible speed up as

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* dict.c: improvement on the hashing of the dictionnary, with visible
  speed up as the number of strings in the hash increases, work from
  Stefan Behnel
Daniel

svn path=/trunk/; revision=3739
This commit is contained in:
Daniel Veillard 2008-04-22 08:28:50 +00:00
parent dee23485f6
commit e9100a589d
2 changed files with 105 additions and 15 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
Tue Apr 22 10:27:17 CEST 2008 Daniel Veillard <daniel@veillard.com>
* dict.c: improvement on the hashing of the dictionnary, with visible
speed up as the number of strings in the hash increases, work from
Stefan Behnel
Fri Apr 11 14:44:00 CEST 2008 Daniel Veillard <daniel@veillard.com>
* include/libxml/xmlschemas.h xmlschemas.c: added new function

114
dict.c
View File

@ -20,16 +20,30 @@
#include "libxml.h"
#include <string.h>
#include <stdint.h>
#include <libxml/tree.h>
#include <libxml/dict.h>
#include <libxml/xmlmemory.h>
#include <libxml/xmlerror.h>
#include <libxml/globals.h>
#define MAX_HASH_LEN 4
#define MAX_HASH_LEN 3
#define MIN_DICT_SIZE 128
#define MAX_DICT_HASH 8 * 2048
#define xmlDictComputeKey(dict, name, len) \
(((dict)->size == MIN_DICT_SIZE) ? \
xmlDictComputeFastKey(name, len) : \
xmlDictComputeBigKey(name, len, len)) \
#define xmlDictComputeQKey(dict, prefix, name, len) \
(((prefix) == NULL) ? \
(xmlDictComputeKey(dict, name, len)) : \
(((dict)->size == MIN_DICT_SIZE) ? \
xmlDictComputeFastQKey(prefix, name, len) : \
xmlDictComputeBigKey(prefix, xmlStrlen(prefix), \
xmlDictComputeBigKey(name, len, len))))
/* #define ALLOW_REMOVAL */
/* #define DEBUG_GROW */
@ -223,11 +237,80 @@ found_pool:
}
/*
* xmlDictComputeKey:
* Calculate the hash key
* xmlDictComputeBigKey:
*
* Calculate a hash key using a good hash function that works well for
* larger hash table sizes.
*
* Hash function by Paul Hsieh, see
* http://www.azillionmonkeys.com/qed/hash.html
* http://burtleburtle.net/bob/hash/doobs.html
*/
#undef get16bits
#if (defined(__GNUC__) && defined(__i386__)) || defined(__WATCOMC__) \
|| defined(_MSC_VER) || defined (__BORLANDC__) || defined (__TURBOC__)
#define get16bits(d) (*((const uint16_t *) (d)))
#endif
#if !defined (get16bits)
#define get16bits(d) ((((uint32_t)(((const uint8_t *)(d))[1])) << 8)\
+(uint32_t)(((const uint8_t *)(d))[0]) )
#endif
static uint32_t
xmlDictComputeBigKey(const xmlChar* data, int len, uint32_t hash) {
uint32_t tmp;
int rem;
if (len <= 0 || data == NULL) return hash;
rem = len & 3;
len >>= 2;
/* Main loop */
for (;len > 0; len--) {
hash += get16bits (data);
tmp = (get16bits (data+2) << 11) ^ hash;
hash = (hash << 16) ^ tmp;
data += 2*sizeof (uint16_t);
hash += hash >> 11;
}
/* Handle end cases */
switch (rem) {
case 3: hash += get16bits (data);
hash ^= hash << 16;
hash ^= data[sizeof (uint16_t)] << 18;
hash += hash >> 11;
break;
case 2: hash += get16bits (data);
hash ^= hash << 11;
hash += hash >> 17;
break;
case 1: hash += *data;
hash ^= hash << 10;
hash += hash >> 1;
}
/* Force "avalanching" of final 127 bits */
hash ^= hash << 3;
hash += hash >> 5;
hash ^= hash << 4;
hash += hash >> 17;
hash ^= hash << 25;
hash += hash >> 6;
return hash;
}
/*
* xmlDictComputeFastKey:
*
* Calculate a hash key using a fast hash function that works well
* for low hash table fill.
*/
static unsigned long
xmlDictComputeKey(const xmlChar *name, int namelen) {
xmlDictComputeFastKey(const xmlChar *name, int namelen) {
unsigned long value = 0L;
if (name == NULL) return(0);
@ -253,17 +336,18 @@ xmlDictComputeKey(const xmlChar *name, int namelen) {
}
/*
* xmlDictComputeQKey:
* Calculate the hash key
* xmlDictComputeFastQKey:
*
* Calculate a hash key for two strings using a fast hash function
* that works well for low hash table fill.
*
* Neither of the two strings must be NULL.
*/
static unsigned long
xmlDictComputeQKey(const xmlChar *prefix, const xmlChar *name, int len)
xmlDictComputeFastQKey(const xmlChar *prefix, const xmlChar *name, int len)
{
unsigned long value = 0L;
int plen;
if (prefix == NULL)
return(xmlDictComputeKey(name, len));
plen = xmlStrlen(prefix);
if (plen == 0)
@ -435,7 +519,7 @@ xmlDictGrow(xmlDictPtr dict, int size) {
for (i = 0; i < oldsize; i++) {
if (olddict[i].valid == 0)
continue;
key = xmlDictComputeKey(olddict[i].name, olddict[i].len) % dict->size;
key = xmlDictComputeKey(dict, olddict[i].name, olddict[i].len) % dict->size;
memcpy(&(dict->dict[key]), &(olddict[i]), sizeof(xmlDictEntry));
dict->dict[key].next = NULL;
#ifdef DEBUG_GROW
@ -452,7 +536,7 @@ xmlDictGrow(xmlDictPtr dict, int size) {
* put back the entry in the new dict
*/
key = xmlDictComputeKey(iter->name, iter->len) % dict->size;
key = xmlDictComputeKey(dict, iter->name, iter->len) % dict->size;
if (dict->dict[key].valid == 0) {
memcpy(&(dict->dict[key]), iter, sizeof(xmlDictEntry));
dict->dict[key].next = NULL;
@ -570,7 +654,7 @@ xmlDictLookup(xmlDictPtr dict, const xmlChar *name, int len) {
/*
* Check for duplicate and insertion location.
*/
okey = xmlDictComputeKey(name, len);
okey = xmlDictComputeKey(dict, name, len);
key = okey % dict->size;
if (dict->dict[key].valid == 0) {
insert = NULL;
@ -687,7 +771,7 @@ xmlDictExists(xmlDictPtr dict, const xmlChar *name, int len) {
/*
* Check for duplicate and insertion location.
*/
okey = xmlDictComputeKey(name, len);
okey = xmlDictComputeKey(dict, name, len);
key = okey % dict->size;
if (dict->dict[key].valid == 0) {
insert = NULL;
@ -783,7 +867,7 @@ xmlDictQLookup(xmlDictPtr dict, const xmlChar *prefix, const xmlChar *name) {
/*
* Check for duplicate and insertion location.
*/
okey = xmlDictComputeQKey(prefix, name, len);
okey = xmlDictComputeQKey(dict, prefix, name, len);
key = okey % dict->size;
if (dict->dict[key].valid == 0) {
insert = NULL;