/bloomfileter/bloom.c

#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <syslog.h>

#include "log.h"
#include "bloom.h"
#include "bits.h"

#define DICT_INITIAL_SIZE 16
#define LONG_MAX_SIZE 0x01FFFFFF


static u_int32 get_next_size(u_int32 size)
{
	u_int32 i = DICT_INITIAL_SIZE;

	while(1)
	{
		if(i>size)
			return i;		
		i*=2;
	}	
}
static u_int32 dict_func1(const char *str, u_int32 len)
{
	u_int32 hash = 5381;
	while(len--)
		hash = ((hash << 5) + hash) + (*str++);
	return hash;
}

static u_int32 dict_func2(const char *str, u_int32 len)
{
	u_int32 hash = 0;
	while(*str)
		hash = (*str++) + (hash << 6) + (hash << 16) - hash;
	return hash&0x7fffffff;
}

static u_int32 dict_func3(const char *str, u_int32 len)
{
	u_int32 a = 0x5c6b7;
	u_int32 b = 0xf8c9;

	u_int32 hash = 0;
	while(*str)
	{
		hash = hash*a + (*str++);
		a *= b;
	}
	return hash&0x7fffffff;
}	

static u_int32 dict_func4(const char *str, u_int32 len)
{
	u_int32 hash = 0x4e67c6a7;

	while(*str)
		hash = (hash << 5) + (*str++) + (hash >> 2);

	return hash&0x7fffffff;
}

u_int32 init_bloom(PBloom p_bloom, u_int32 size, double error_rate)
{

	p_bloom->func1 = dict_func1;
	p_bloom->func2 = dict_func2;
	p_bloom->func3 = dict_func3;
	p_bloom->func4 = dict_func4;

	p_bloom->error_rate = error_rate;
	
	u_int32 actual_size = (u_int32)size*(log(1/error_rate));
	
#ifdef _DEBUG_MODE
	
	write_log(LOG_DEBUG, NULL,
			  "size:%u actual size:%u Max size:%u error_rate:%g\n", 
			  size, 
		      actual_size,
		      LONG_MAX_SIZE,
			  error_rate);
#endif
	
	if(actual_size>size)
	{
		if(actual_size<=LONG_MAX_SIZE)
		{
			p_bloom->size = get_next_size(actual_size);
			p_bloom->size_mask = p_bloom->size - 1;
		}
		else
		{
			p_bloom->size_mask = p_bloom->size = actual_size;
		}
	}
	else
		return SIZE_OVERFLOW_ERROR;
		


	p_bloom->bit_size = (p_bloom->size)*sizeof(u_int32)*8;

#ifdef _DEBUG_MODE
	write_log(LOG_DEBUG, NULL,
			  "size:%u  bit_size(HEX FORMAT):%x\n", 
			  p_bloom->size, 
		      p_bloom->bit_size);
#endif

	p_bloom->map = (u_int32*)malloc((p_bloom->size)*sizeof(u_int32));
	
	if(p_bloom->map==NULL)
		return CREATE_BLOOM_ERROR;

	memset((void*)p_bloom->map, 0x00, (p_bloom->size)*sizeof(u_int32));
	return SUCCESS;
}


u_int32 add_ele(PBloom p_bloom, const char *str)
{
	if(str==NULL||p_bloom==NULL)
		return NULL_POINTER;
	
	u_int32 hash1 = (p_bloom->func1(str, strlen(str)))%p_bloom->bit_size;
	u_int32 hash2 = (p_bloom->func2(str, strlen(str)))%p_bloom->bit_size;
	u_int32 hash3 = (p_bloom->func3(str, strlen(str)))%p_bloom->bit_size;
	u_int32 hash4 = (p_bloom->func4(str, strlen(str)))%p_bloom->bit_size;
	
#ifdef _DEBUG_MODE
	write_log(LOG_DEBUG, NULL, "HASH1:%u\tHASH2:%u\tHASH3:%u\tHASH4:%u\n", hash1, hash2, hash3, hash4);
#endif

	if(p_bloom->size_mask==p_bloom->size)
	{
		set_bits(&p_bloom->map[((u_int32)(hash1/32))%p_bloom->size_mask], hash1%32, BITS_ONE);
		set_bits(&p_bloom->map[((u_int32)(hash2/32))%p_bloom->size_mask], hash2%32, BITS_ONE);
		set_bits(&p_bloom->map[((u_int32)(hash3/32))%p_bloom->size_mask], hash3%32, BITS_ONE);
		set_bits(&p_bloom->map[((u_int32)(hash4/32))%p_bloom->size_mask], hash4%32, BITS_ONE);
	}
	else
	{
		set_bits(&p_bloom->map[((u_int32)(hash1/32))&p_bloom->size_mask], hash1%32, BITS_ONE);
		set_bits(&p_bloom->map[((u_int32)(hash2/32))&p_bloom->size_mask], hash2%32, BITS_ONE);
		set_bits(&p_bloom->map[((u_int32)(hash3/32))&p_bloom->size_mask], hash3%32, BITS_ONE);
		set_bits(&p_bloom->map[((u_int32)(hash4/32))&p_bloom->size_mask], hash4%32, BITS_ONE);
	}

	
	return SUCCESS;
}

u_int32 check_ele(PBloom p_bloom, const char *str)
{
	if(str==NULL||p_bloom==NULL)
		return NULL_POINTER;
	
	u_int32 hash1 = (p_bloom->func1(str, strlen(str)))%p_bloom->bit_size;
	u_int32 hash2 = (p_bloom->func2(str, strlen(str)))%p_bloom->bit_size;
	u_int32 hash3 = (p_bloom->func3(str, strlen(str)))%p_bloom->bit_size;
	u_int32 hash4 = (p_bloom->func4(str, strlen(str)))%p_bloom->bit_size;

	int val = is_bit_zero(&p_bloom->map[(u_int32)(hash1/32)],hash1%32);
	if(val==0)
		return NOT_EXIST;
	val = is_bit_zero(&p_bloom->map[(u_int32)(hash2/32)],hash2%32);
	if(val==0)
		return NOT_EXIST;
	val = is_bit_zero(&p_bloom->map[(u_int32)(hash3/32)],hash3%32);
	if(val==0)
		return NOT_EXIST;
	val = is_bit_zero(&p_bloom->map[(u_int32)(hash4/32)],hash4%32);
	if(val==0)
		return NOT_EXIST;	
	return EXIST;
}

void clean_bloom(PBloom p_bloom)
{
	if(p_bloom==NULL)
		return;
	
	memset(p_bloom->map, 0x00, (p_bloom->size)*sizeof(u_int32));
}


void destroy_bloom(PBloom p_Bloom)
{
	free(p_Bloom->map);
}