3619e86271
git-svn-id: svn+ssh://svn.corp.yahoo.com/yahoo/yrl/labs/pnuts/code/logstore@1232 8dad8b1f-cf64-0410-95b6-bcf113ffbcfe
102 lines
3 KiB
C++
102 lines
3 KiB
C++
/*
|
|
* check_bloomFilter.c
|
|
*
|
|
* Created on: Oct 2, 2010
|
|
* Author: sears
|
|
*/
|
|
#include <stasis/util/hashFunctions.h>
|
|
#include <bloomFilter.h>
|
|
#include <assert.h>
|
|
#include <stdio.h>
|
|
#include <sys/time.h>
|
|
#include <stasis/crc32.h>
|
|
|
|
/*
|
|
* This file can test CRC and FNV-1 based hash functions. Based on early experiments:
|
|
*
|
|
* CRC32 insert/lookup: 11/13 seconds, 1.1% false positive
|
|
* FNV-1 insert/lookup: 8/9 seconds, 2.8% false positive
|
|
*
|
|
* Expected false positive rate is 1%.
|
|
*/
|
|
|
|
static uint64_t hash_a(const char* a, int len) {
|
|
return stasis_crc32(a,len,0xcafebabe);
|
|
}
|
|
|
|
static uint64_t hash_b(const char* a, int len) {
|
|
return stasis_crc32(a,len,0xdeadbeef);
|
|
}
|
|
static uint64_t hash_a_fnv(const char* a, int len) {
|
|
return stasis_util_hash_fnv_1_uint32_t((const byte*)a, len);
|
|
}
|
|
static uint64_t hash_b_fnv(const char* a, int len) {
|
|
return stasis_util_hash_fnv_1_uint64_t((const byte*)a, len);
|
|
}
|
|
|
|
static char * malloc_random_string(int group) {
|
|
char * str = 0;
|
|
int strlen = 0;
|
|
while(!strlen) strlen = 128 + (rand() & 127);
|
|
str = (char*)malloc(strlen + 1);
|
|
str[0] = group;
|
|
|
|
for(int i = 1; i < strlen; i++) {
|
|
str[i] = (rand() & 128) + 1;
|
|
}
|
|
str[strlen] = 0;
|
|
return str;
|
|
}
|
|
|
|
int main(int argc, char * argv[]) {
|
|
(void)hash_a; (void)hash_b;
|
|
(void)hash_a_fnv; (void)hash_b_fnv;
|
|
|
|
const int num_inserts = 1000000;
|
|
char ** strings = (char**)malloc(num_inserts * sizeof(char*));
|
|
uint64_t sum_strlen = 0;
|
|
struct timeval start, stop;
|
|
gettimeofday(&start, 0);
|
|
printf("seed: %lld\n", (long long)start.tv_sec);
|
|
srand(start.tv_sec);
|
|
for(int i = 0; i < num_inserts; i++) {
|
|
strings[i] = malloc_random_string(1);
|
|
sum_strlen += strlen(strings[i]);
|
|
}
|
|
gettimeofday(&stop,0);
|
|
printf("Generated strings in %d seconds. Mean string length: %f\n", (int)(stop.tv_sec - start.tv_sec), (double)(sum_strlen)/(double)num_inserts);
|
|
|
|
bloom_filter_t * bf = bloom_filter_create(hash_a, hash_b, num_inserts, 0.01);
|
|
bloom_filter_print_stats(bf);
|
|
gettimeofday(&start, 0);
|
|
for(int i = 0; i < num_inserts; i++) {
|
|
bloom_filter_insert(bf,strings[i], strlen(strings[i]));
|
|
}
|
|
gettimeofday(&stop, 0);
|
|
printf("Inserted strings in %d seconds.\n", (int)(stop.tv_sec - start.tv_sec));
|
|
|
|
gettimeofday(&start, 0);
|
|
for(int i = 0; i < num_inserts; i++) {
|
|
assert(bloom_filter_lookup(bf, strings[i], strlen(strings[i])));
|
|
}
|
|
gettimeofday(&stop, 0);
|
|
printf("Looked up strings in %d seconds.\n", (int)(stop.tv_sec - start.tv_sec));
|
|
bloom_filter_print_stats(bf);
|
|
|
|
uint64_t false_positives = 0;
|
|
gettimeofday(&start, 0);
|
|
for(int i = 0; i < num_inserts; i++) {
|
|
char * str = malloc_random_string(2);
|
|
if(bloom_filter_lookup(bf, str, strlen(str))) {
|
|
false_positives ++;
|
|
}
|
|
assert(bloom_filter_lookup(bf, strings[i], strlen(strings[i])));
|
|
free(str);
|
|
}
|
|
gettimeofday(&stop, 0);
|
|
printf("Generated and looked up non-existant strings in %d seconds\n"
|
|
"false positive rate was %lf\n", (int)(stop.tv_sec - start.tv_sec),
|
|
((double)false_positives)/(double)num_inserts);
|
|
|
|
return 0;
|
|
}
|