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