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/* ===========================================================================
*
* PUBLIC DOMAIN NOTICE
* National Center for Biotechnology Information
*
* This software/database is a "United States Government Work" under the
* terms of the United States Copyright Act. It was written as part of
* the author's official duties as a United States Government employee and
* thus cannot be copyrighted. This software/database is freely available
* to the public for use. The National Library of Medicine and the U.S.
* Government have not placed any restriction on its use or reproduction.
*
* Although all reasonable efforts have been taken to ensure the accuracy
* and reliability of the software and data, the NLM and the U.S.
* Government do not and cannot warrant the performance or results that
* may be obtained by using this software or data. The NLM and the U.S.
* Government disclaim all warranties, express or implied, including
* warranties of performance, merchantability or fitness for any particular
* purpose.
*
* Please cite the author in any work or product based on this material.
*
* ===========================================================================
*/
#ifndef __HASHING_HPP__
#define __HASHING_HPP__
#include <bm/bm64.h>
#include <vector>
#include <functional>
#include <openssl/sha.h>
#include <bitset>
using namespace std;
namespace hashing {
using bvector_type = bm::bvector<>;
uint64_t fnv1a(const char* key, std::size_t key_size, size_t hash = 14695981039346656037u)
{
static const std::size_t FnvPrime = 1099511628211u;
unsigned char *bp = (unsigned char *)key;
unsigned char *be = bp + key_size;
while (bp < be) {
hash ^= *bp++;
hash *= FnvPrime;
}
return hash;
}
struct fnv_1a_hash
{
std::size_t operator()(const char* key, std::size_t key_size) const
{
return fnv1a(key, key_size);
}
};
/* copied from https://github.com/explosion/murmurhash/blob/master/murmurhash/MurmurHash2.cpp */
#define BIG_CONSTANT(x) (x##LLU)
uint64_t MurmurHash ( const void * key, int len, uint64_t seed = 0)
{
const uint64_t m = BIG_CONSTANT(0xc6a4a7935bd1e995);
const int r = 47;
uint64_t h = seed ^ (len * m);
const uint64_t * data = (const uint64_t *)key;
const uint64_t * end = data + (len/8);
while(data != end)
{
uint64_t k = *data++;
k *= m;
k ^= k >> r;
k *= m;
h ^= k;
h *= m;
}
const unsigned char * data2 = (const unsigned char*)data;
switch(len & 7)
{
case 7: h ^= ((uint64_t) data2[6]) << 48;
case 6: h ^= ((uint64_t) data2[5]) << 40;
case 5: h ^= ((uint64_t) data2[4]) << 32;
case 4: h ^= ((uint64_t) data2[3]) << 24;
case 3: h ^= ((uint64_t) data2[2]) << 16;
case 2: h ^= ((uint64_t) data2[1]) << 8;
case 1: h ^= ((uint64_t) data2[0]);
h *= m;
};
h ^= h >> r;
h *= m;
h ^= h >> r;
return h;
}
}
class spot_name_filter
{
public:
spot_name_filter() = default;
virtual ~spot_name_filter() = default;
virtual bool seen_before(const char* value, size_t sz) = 0;
virtual size_t memory_used() const = 0;
uint64_t get_name_hash() const { return m_name_hash; }
protected:
uint64_t m_name_hash = 0;
};
class fnv_murmur_filter : public spot_name_filter
{
public:
fnv_murmur_filter() {
for (auto& hb : hash_buckets) {
hb = hashing::bvector_type(bm::BM_GAP, bm::gap_len_table_min<true>::_len);
hb.init();
}
}
virtual bool seen_before(const char* value, size_t sz)
{
bool hits[4];
m_name_hash = hashing::fnv1a(value, sz);
auto murmur_hash = hashing::MurmurHash(value, sz);
uint32_t hash32 = m_name_hash;
hits[0] = (hash32 == bm::id_max || !hash_buckets[0].set_bit_conditional(hash32, true, false));
hash32 = (m_name_hash >> 32);
hits[1] = (hash32 == bm::id_max || !hash_buckets[1].set_bit_conditional(hash32, true, false));
hash32 = murmur_hash;
hits[2] = (hash32 == bm::id_max || !hash_buckets[2].set_bit_conditional(hash32, true, false));
hash32 = (murmur_hash >> 32);
hits[3] = (hash32 == bm::id_max || !hash_buckets[3].set_bit_conditional(hash32, true, false));
return hits[0] && hits[1] && hits[2] && hits[3];
}
size_t memory_used() const override {
size_t memory_used = 0;
for (const auto& hb : hash_buckets) {
hashing::bvector_type::statistics st;
hb.calc_stat(&st);
memory_used += st.memory_used;
}
return memory_used;
}
private:
array<hashing::bvector_type, 4> hash_buckets;
};
template<unsigned char* ShaFunc(const unsigned char *data, size_t count, unsigned char *md_buf), int NUM_BUCKETS>
class sha_filter : public spot_name_filter
{
public:
virtual bool seen_before(const char* value, size_t sz) override
{
m_name_hash = hashing::fnv1a(value, sz);
ShaFunc((const unsigned char*)value, sz, (unsigned char*)m_md_buf.data());
uint8_t hits = 0;
for (int i = 0; i < NUM_BUCKETS; ++i) {
m_hits[i] = hash_buckets[i].test(m_md_buf[i]);
m_hits[i] ? ++hits : hash_buckets[i].set(m_md_buf[i]);
}
return hits == NUM_BUCKETS;
}
size_t memory_used() const override {
return (4294967296/8) * NUM_BUCKETS;
};
private:
array<uint32_t, NUM_BUCKETS> m_md_buf;
array<bool, NUM_BUCKETS> m_hits;
array<std::bitset<4294967296>, NUM_BUCKETS> hash_buckets;
};
class sha1_filter : public sha_filter<SHA1, 5>
{
};
class sha224_filter : public sha_filter<SHA224, 7>
{
};
class sha256_filter : public sha_filter<SHA256, 8>
{
};
#endif // __HASHING_HPP__
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