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bloom_filter.c
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bloom_filter.c
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#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define BLK_SZ 250000
#define BLK_NMEMB 8
#define MAXP 46337 /* prime, and 46337*46337 < 2147483647 */
/* Used to create 8 different hash functions */
int b[8];
int v0[256];
int v1[256];
int v2[256];
int v3[256];
int v4[256];
int v5[256];
int v6[256];
int v7[256];
typedef struct bloom {
char block0[BLK_SZ];
char block1[BLK_SZ];
char block2[BLK_SZ];
char block3[BLK_SZ];
char block4[BLK_SZ];
char block5[BLK_SZ];
char block6[BLK_SZ];
char block7[BLK_SZ];
} bf_t;
void sample_string_A(char *s, long i) {
s[0] = (char) (1 + (i % 254));
s[1] = (char) (1 + ((i / 254) % 254));
s[2] = (char) (1 + (((i / 254) / 254) % 254));
s[3] = 'a';
s[4] = 'b';
s[5] = (char) (1 + ((i * (i - 3)) % 217));
s[6] = (char) (1 + ((17 * i + 129) % 233));
s[7] = '\0';
}
void sample_string_B(char *s, long i) {
s[0] = (char) (1 + (i % 254));
s[1] = (char) (1 + ((i / 254) % 254));
s[2] = (char) (1 + (((i / 254) / 254) % 254));
s[3] = 'a';
s[4] = (char) (1 + ((i * (i - 3)) % 217));
s[5] = (char) (1 + ((17 * i + 129) % 233));
s[6] = '\0';
}
void sample_string_C(char *s, long i) {
s[0] = (char) (1 + (i % 254));
s[1] = (char) (1 + ((i / 254) % 254));
s[2] = 'a';
s[3] = (char) (1 + ((i * (i - 3)) % 217));
s[4] = (char) (1 + ((17 * i + 129) % 233));
s[5] = '\0';
}
void sample_string_D(char *s, long i) {
s[0] = (char) (1 + (i % 254));
s[1] = (char) (1 + ((i / 254) % 254));
s[2] = (char) (1 + (((i / 254) / 254) % 254));
s[3] = 'b';
s[4] = 'b';
s[5] = (char) (1 + ((i * (i - 3)) % 217));
s[6] = (char) (1 + ((17 * i + 129) % 233));
s[7] = '\0';
}
void sample_string_E(char *s, long i) {
s[0] = (char) (1 + (i % 254));
s[1] = (char) (1 + ((i / 254) % 254));
s[2] = (char) (1 + (((i / 254) / 254) % 254));
s[3] = 'a';
s[4] = (char) (2 + ((i * (i - 3)) % 217));
s[5] = (char) (1 + ((17 * i + 129) % 233));
s[6] = '\0';
}
int blk_num = 0;
int universalhashfunction(char *string, int size, int sum, int *a) {
char *key = string;
int m = 0;
int index = 0;
while (*key != '\0') {
m = a[index];
index++;
sum += ((m) * ((int) *key));
key += 1;
}
return (sum % size);
}
void set_bit(char *blk, int k) {
int i = k / 8;
int pos = k % 8;
unsigned int flag = 1;
blk_num++;
flag = flag << pos;
blk[i] = blk[i] | flag;
}
int get_bit(char *blk, int k) {
int i = k / 8;
int pos = k % 8;
blk_num++;
unsigned int flag = 1;
flag = flag << pos;
if (blk[i] & flag) {
return 1;
} else {
return 0;
}
}
bf_t *create_bf() {
bf_t *block = (bf_t*) calloc(BLK_SZ * 8, sizeof(char));
int i = 0;
for (i = 0; i < 8; i++) {
b[i] = rand() % MAXP;
}
for (i = 0; i < 256; i++) {
v0[i] = rand() % MAXP;
}
for (i = 0; i < 256; i++) {
v1[i] = rand() % MAXP;
}
for (i = 0; i < 256; i++) {
v2[i] = rand() % MAXP;
}
for (i = 0; i < 256; i++) {
v3[i] = rand() % MAXP;
}
for (i = 0; i < 256; i++) {
v4[i] = rand() % MAXP;
}
for (i = 0; i < 256; i++) {
v5[i] = rand() % MAXP;
}
for (i = 0; i < 256; i++) {
v6[i] = rand() % MAXP;
}
for (i = 0; i < 256; i++) {
v7[i] = rand() % MAXP;
}
return block;
}
void insert_bf(bf_t *block, char *s) {
// (*bloom).block0[3] = 14;
int hash = 0;
int size = 2000000;
int i = 0;
blk_num = 0;
// printf("block first starts %d\n",index);
for (i = 0; i < 8; i++) {
if (i == 0) {
hash = universalhashfunction(s, size, b[i], v0);
} else if (i == 1) {
hash = universalhashfunction(s, size, b[i], v1);
} else if (i == 2) {
hash = universalhashfunction(s, size, b[i], v2);
} else if (i == 3) {
hash = universalhashfunction(s, size, b[i], v3);
} else if (i == 4) {
hash = universalhashfunction(s, size, b[i], v4);
} else if (i == 5) {
hash = universalhashfunction(s, size, b[i], v5);
} else if (i == 6) {
hash = universalhashfunction(s, size, b[i], v6);
} else if (i == 7) {
hash = universalhashfunction(s, size, b[i], v7);
}
hash = abs(hash);
if (i == 0) {
set_bit((*block).block0, hash);
} else if (i == 1) {
set_bit((*block).block1, hash);
} else if (i == 2) {
set_bit((*block).block2, hash);
} else if (i == 3) {
set_bit((*block).block3, hash);
} else if (i == 4) {
set_bit((*block).block4, hash);
} else if (i == 5) {
set_bit((*block).block5, hash);
} else if (i == 6) {
set_bit((*block).block6, hash);
} else if (i == 7) {
set_bit((*block).block7, hash);
}
}
}
int is_element(bf_t *block, char *s) {
int result = 0;
int hash = 0;
int size = 2000000;
//printf("checking %s\n",s);
int i = 0;
int f = 0;
blk_num = 0;
for (i = 0; i < 8; i++) {
if (i == 0) {
hash = universalhashfunction(s, size, b[i], v0);
} else if (i == 1) {
hash = universalhashfunction(s, size, b[i], v1);
} else if (i == 2) {
hash = universalhashfunction(s, size, b[i], v2);
} else if (i == 3) {
hash = universalhashfunction(s, size, b[i], v3);
} else if (i == 4) {
hash = universalhashfunction(s, size, b[i], v4);
} else if (i == 5) {
hash = universalhashfunction(s, size, b[i], v5);
} else if (i == 6) {
hash = universalhashfunction(s, size, b[i], v6);
} else if (i == 7) {
hash = universalhashfunction(s, size, b[i], v7);
}
hash = abs(hash);
if (i == 0) {
result = get_bit((*block).block0, hash);
if (result == 0) {
f++;
} else if (result == 1) {
}
} else if (i == 1) {
result = get_bit((*block).block1, hash);
if (result == 0) {
f++;
} else if (result == 1) {
}
} else if (i == 2) {
result = get_bit((*block).block2, hash);
if (result == 0) {
f++;
} else if (result == 1) {
}
} else if (i == 3) {
result = get_bit((*block).block3, hash);
if (result == 0) {
f++;
} else if (result == 1) {
}
} else if (i == 4) {
result = get_bit((*block).block4, hash);
if (result == 0) {
f++;
} else if (result == 1) {
}
} else if (i == 5) {
result = get_bit((*block).block5, hash);
if (result == 0) {
f++;
} else if (result == 1) {
}
} else if (i == 6) {
result = get_bit((*block).block6, hash);
if (result == 0) {
f++;
} else if (result == 1) {
}
} else if (i == 7) {
result = get_bit((*block).block7, hash);
if (result == 0) {
f++;
} else if (result == 1) {
}
}
}
if (f > 0) {
f = 0;
} else if (f == 0) {
f = 1;
}
return f;
}
int main() {
long i, j;
bf_t * bloom;
bloom = create_bf();
printf("Created Filter\n");
for (i = 0; i < 1450000; i++) {
char s[8];
sample_string_A(s, i);
insert_bf(bloom, s);
}
for (i = 0; i < 500000; i++) {
char s[7];
sample_string_B(s, i);
insert_bf(bloom, s);
}
for (i = 0; i < 50000; i++) {
char s[6];
sample_string_C(s, i);
insert_bf(bloom, s);
}
printf("inserted 2,000,000 strings of length 8,7,6.\n");
for (i = 0; i < 1450000; i++) {
char s[8];
sample_string_A(s, i);
if (is_element(bloom, s) != 1) {
printf("found negative error (1)\n");
exit(0);
}
}
for (i = 0; i < 500000; i++) {
char s[7];
sample_string_B(s, i);
if (is_element(bloom, s) != 1) {
printf("found negative error (2)\n");
exit(0);
}
}
for (i = 0; i < 50000; i++) {
char s[6];
sample_string_C(s, i);
if (is_element(bloom, s) != 1) {
printf("found negative error (3)\n");
exit(0);
}
}
j = 0;
for (i = 0; i < 500000; i++) {
char s[8];
sample_string_D(s, i);
if (is_element(bloom, s) != 0)
j += 1;
}
for (i = 0; i < 500000; i++) {
char s[7];
sample_string_E(s, i);
if (is_element(bloom, s) != 0)
j += 1;
}
printf("Found %d positive errors out of 1,000,000 tests.\n", j);
printf("Positive error rate %f\%.\n", (float) j / 10000.0);
return 0;
}