Revision d1bb46dfe8bc7efe6257b5ce222c04bfe8aedaab authored by Ryan Wick on 10 May 2018, 23:16:07 UTC, committed by Ryan Wick on 10 May 2018, 23:16:07 UTC
1 parent 260bb4d
bloom_filter.h
/*
*********************************************************************
* *
* Open Bloom Filter *
* *
* Author: Arash Partow - 2000 *
* URL: http://www.partow.net *
* URL: http://www.partow.net/programming/hashfunctions/index.html *
* *
* Copyright notice: *
* Free use of the Open Bloom Filter Library is permitted under the *
* guidelines and in accordance with the MIT License. *
* http://www.opensource.org/licenses/MIT *
* *
*********************************************************************
*/
#ifndef INCLUDE_BLOOM_FILTER_HPP
#define INCLUDE_BLOOM_FILTER_HPP
#include <algorithm>
#include <cmath>
#include <cstddef>
#include <cstdlib>
#include <iterator>
#include <limits>
#include <string>
#include <vector>
static const std::size_t bits_per_char = 0x08; // 8 bits in 1 char(unsigned)
static const unsigned char bit_mask[bits_per_char] = {
0x01, //00000001
0x02, //00000010
0x04, //00000100
0x08, //00001000
0x10, //00010000
0x20, //00100000
0x40, //01000000
0x80 //10000000
};
class bloom_parameters
{
public:
bloom_parameters()
: minimum_size(1),
maximum_size(std::numeric_limits<unsigned long long int>::max()),
minimum_number_of_hashes(1),
maximum_number_of_hashes(std::numeric_limits<unsigned int>::max()),
projected_element_count(10000),
false_positive_probability(1.0 / projected_element_count),
random_seed(0xA5A5A5A55A5A5A5AULL)
{}
virtual ~bloom_parameters()
{}
inline bool operator!()
{
return (minimum_size > maximum_size) ||
(minimum_number_of_hashes > maximum_number_of_hashes) ||
(minimum_number_of_hashes < 1) ||
(0 == maximum_number_of_hashes) ||
(0 == projected_element_count) ||
(false_positive_probability < 0.0) ||
(std::numeric_limits<double>::infinity() == std::abs(false_positive_probability)) ||
(0 == random_seed) ||
(0xFFFFFFFFFFFFFFFFULL == random_seed);
}
// Allowable min/max size of the bloom filter in bits
unsigned long long int minimum_size;
unsigned long long int maximum_size;
// Allowable min/max number of hash functions
unsigned int minimum_number_of_hashes;
unsigned int maximum_number_of_hashes;
// The approximate number of elements to be inserted
// into the bloom filter, should be within one order
// of magnitude. The default is 10000.
unsigned long long int projected_element_count;
// The approximate false positive probability expected
// from the bloom filter. The default is assumed to be
// the reciprocal of the projected_element_count.
double false_positive_probability;
unsigned long long int random_seed;
struct optimal_parameters_t
{
optimal_parameters_t()
: number_of_hashes(0),
table_size(0)
{}
unsigned int number_of_hashes;
unsigned long long int table_size;
};
optimal_parameters_t optimal_parameters;
virtual bool compute_optimal_parameters()
{
/*
Note:
The following will attempt to find the number of hash functions
and minimum amount of storage bits required to construct a bloom
filter consistent with the user defined false positive probability
and estimated element insertion count.
*/
if (!(*this))
return false;
double min_m = std::numeric_limits<double>::infinity();
double min_k = 0.0;
double k = 1.0;
while (k < 1000.0)
{
const double numerator = (- k * projected_element_count);
const double denominator = std::log(1.0 - std::pow(false_positive_probability, 1.0 / k));
const double curr_m = numerator / denominator;
if (curr_m < min_m)
{
min_m = curr_m;
min_k = k;
}
k += 1.0;
}
optimal_parameters_t& optp = optimal_parameters;
optp.number_of_hashes = static_cast<unsigned int>(min_k);
optp.table_size = static_cast<unsigned long long int>(min_m);
optp.table_size += (((optp.table_size % bits_per_char) != 0) ? (bits_per_char - (optp.table_size % bits_per_char)) : 0);
if (optp.number_of_hashes < minimum_number_of_hashes)
optp.number_of_hashes = minimum_number_of_hashes;
else if (optp.number_of_hashes > maximum_number_of_hashes)
optp.number_of_hashes = maximum_number_of_hashes;
if (optp.table_size < minimum_size)
optp.table_size = minimum_size;
else if (optp.table_size > maximum_size)
optp.table_size = maximum_size;
return true;
}
};
class bloom_filter
{
protected:
typedef unsigned int bloom_type;
typedef unsigned char cell_type;
typedef std::vector<unsigned char> table_type;
public:
bloom_filter()
: salt_count_(0),
table_size_(0),
projected_element_count_(0),
inserted_element_count_ (0),
random_seed_(0),
desired_false_positive_probability_(0.0)
{}
bloom_filter(const bloom_parameters& p)
: projected_element_count_(p.projected_element_count),
inserted_element_count_(0),
random_seed_((p.random_seed * 0xA5A5A5A5) + 1),
desired_false_positive_probability_(p.false_positive_probability)
{
salt_count_ = p.optimal_parameters.number_of_hashes;
table_size_ = p.optimal_parameters.table_size;
generate_unique_salt();
bit_table_.resize(table_size_ / bits_per_char, static_cast<unsigned char>(0x00));
}
bloom_filter(const bloom_filter& filter)
{
this->operator=(filter);
}
inline bool operator == (const bloom_filter& f) const
{
if (this != &f)
{
return
(salt_count_ == f.salt_count_ ) &&
(table_size_ == f.table_size_ ) &&
(bit_table_.size() == f.bit_table_.size() ) &&
(projected_element_count_ == f.projected_element_count_ ) &&
(inserted_element_count_ == f.inserted_element_count_ ) &&
(random_seed_ == f.random_seed_ ) &&
(desired_false_positive_probability_ == f.desired_false_positive_probability_) &&
(salt_ == f.salt_ ) &&
(bit_table_ == f.bit_table_ ) ;
}
else
return true;
}
inline bool operator != (const bloom_filter& f) const
{
return !operator==(f);
}
inline bloom_filter& operator = (const bloom_filter& f)
{
if (this != &f)
{
salt_count_ = f.salt_count_;
table_size_ = f.table_size_;
bit_table_ = f.bit_table_;
salt_ = f.salt_;
projected_element_count_ = f.projected_element_count_;
inserted_element_count_ = f.inserted_element_count_;
random_seed_ = f.random_seed_;
desired_false_positive_probability_ = f.desired_false_positive_probability_;
}
return *this;
}
virtual ~bloom_filter()
{}
inline bool operator!() const
{
return (0 == table_size_);
}
inline void clear()
{
std::fill(bit_table_.begin(), bit_table_.end(), static_cast<unsigned char>(0x00));
inserted_element_count_ = 0;
}
inline void insert(const unsigned char* key_begin, const std::size_t& length)
{
std::size_t bit_index = 0;
std::size_t bit = 0;
for (std::size_t i = 0; i < salt_.size(); ++i)
{
compute_indices(hash_ap(key_begin, length, salt_[i]), bit_index, bit);
bit_table_[bit_index / bits_per_char] |= bit_mask[bit];
}
++inserted_element_count_;
}
template <typename T>
inline void insert(const T& t)
{
// Note: T must be a C++ POD type.
insert(reinterpret_cast<const unsigned char*>(&t),sizeof(T));
}
inline void insert(const std::string& key)
{
insert(reinterpret_cast<const unsigned char*>(key.data()),key.size());
}
inline void insert(const char* data, const std::size_t& length)
{
insert(reinterpret_cast<const unsigned char*>(data),length);
}
template <typename InputIterator>
inline void insert(const InputIterator begin, const InputIterator end)
{
InputIterator itr = begin;
while (end != itr)
{
insert(*(itr++));
}
}
inline virtual bool contains(const unsigned char* key_begin, const std::size_t length) const
{
std::size_t bit_index = 0;
std::size_t bit = 0;
for (std::size_t i = 0; i < salt_.size(); ++i)
{
compute_indices(hash_ap(key_begin, length, salt_[i]), bit_index, bit);
if ((bit_table_[bit_index / bits_per_char] & bit_mask[bit]) != bit_mask[bit])
{
return false;
}
}
return true;
}
template <typename T>
inline bool contains(const T& t) const
{
return contains(reinterpret_cast<const unsigned char*>(&t),static_cast<std::size_t>(sizeof(T)));
}
inline bool contains(const std::string& key) const
{
return contains(reinterpret_cast<const unsigned char*>(key.c_str()),key.size());
}
inline bool contains(const char* data, const std::size_t& length) const
{
return contains(reinterpret_cast<const unsigned char*>(data),length);
}
template <typename InputIterator>
inline InputIterator contains_all(const InputIterator begin, const InputIterator end) const
{
InputIterator itr = begin;
while (end != itr)
{
if (!contains(*itr))
{
return itr;
}
++itr;
}
return end;
}
template <typename InputIterator>
inline InputIterator contains_none(const InputIterator begin, const InputIterator end) const
{
InputIterator itr = begin;
while (end != itr)
{
if (contains(*itr))
{
return itr;
}
++itr;
}
return end;
}
inline virtual unsigned long long int size() const
{
return table_size_;
}
inline unsigned long long int element_count() const
{
return inserted_element_count_;
}
inline double effective_fpp() const
{
/*
Note:
The effective false positive probability is calculated using the
designated table size and hash function count in conjunction with
the current number of inserted elements - not the user defined
predicated/expected number of inserted elements.
*/
return std::pow(1.0 - std::exp(-1.0 * salt_.size() * inserted_element_count_ / size()), 1.0 * salt_.size());
}
inline bloom_filter& operator &= (const bloom_filter& f)
{
/* intersection */
if (
(salt_count_ == f.salt_count_ ) &&
(table_size_ == f.table_size_ ) &&
(random_seed_ == f.random_seed_)
)
{
for (std::size_t i = 0; i < bit_table_.size(); ++i)
{
bit_table_[i] &= f.bit_table_[i];
}
}
return *this;
}
inline bloom_filter& operator |= (const bloom_filter& f)
{
/* union */
if (
(salt_count_ == f.salt_count_ ) &&
(table_size_ == f.table_size_ ) &&
(random_seed_ == f.random_seed_)
)
{
for (std::size_t i = 0; i < bit_table_.size(); ++i)
{
bit_table_[i] |= f.bit_table_[i];
}
}
return *this;
}
inline bloom_filter& operator ^= (const bloom_filter& f)
{
/* difference */
if (
(salt_count_ == f.salt_count_ ) &&
(table_size_ == f.table_size_ ) &&
(random_seed_ == f.random_seed_)
)
{
for (std::size_t i = 0; i < bit_table_.size(); ++i)
{
bit_table_[i] ^= f.bit_table_[i];
}
}
return *this;
}
inline const cell_type* table() const
{
return bit_table_.data();
}
inline std::size_t hash_count()
{
return salt_.size();
}
protected:
inline virtual void compute_indices(const bloom_type& hash, std::size_t& bit_index, std::size_t& bit) const
{
bit_index = hash % table_size_;
bit = bit_index % bits_per_char;
}
void generate_unique_salt()
{
/*
Note:
A distinct hash function need not be implementation-wise
distinct. In the current implementation "seeding" a common
hash function with different values seems to be adequate.
*/
const unsigned int predef_salt_count = 128;
static const bloom_type predef_salt[predef_salt_count] =
{
0xAAAAAAAA, 0x55555555, 0x33333333, 0xCCCCCCCC,
0x66666666, 0x99999999, 0xB5B5B5B5, 0x4B4B4B4B,
0xAA55AA55, 0x55335533, 0x33CC33CC, 0xCC66CC66,
0x66996699, 0x99B599B5, 0xB54BB54B, 0x4BAA4BAA,
0xAA33AA33, 0x55CC55CC, 0x33663366, 0xCC99CC99,
0x66B566B5, 0x994B994B, 0xB5AAB5AA, 0xAAAAAA33,
0x555555CC, 0x33333366, 0xCCCCCC99, 0x666666B5,
0x9999994B, 0xB5B5B5AA, 0xFFFFFFFF, 0xFFFF0000,
0xB823D5EB, 0xC1191CDF, 0xF623AEB3, 0xDB58499F,
0xC8D42E70, 0xB173F616, 0xA91A5967, 0xDA427D63,
0xB1E8A2EA, 0xF6C0D155, 0x4909FEA3, 0xA68CC6A7,
0xC395E782, 0xA26057EB, 0x0CD5DA28, 0x467C5492,
0xF15E6982, 0x61C6FAD3, 0x9615E352, 0x6E9E355A,
0x689B563E, 0x0C9831A8, 0x6753C18B, 0xA622689B,
0x8CA63C47, 0x42CC2884, 0x8E89919B, 0x6EDBD7D3,
0x15B6796C, 0x1D6FDFE4, 0x63FF9092, 0xE7401432,
0xEFFE9412, 0xAEAEDF79, 0x9F245A31, 0x83C136FC,
0xC3DA4A8C, 0xA5112C8C, 0x5271F491, 0x9A948DAB,
0xCEE59A8D, 0xB5F525AB, 0x59D13217, 0x24E7C331,
0x697C2103, 0x84B0A460, 0x86156DA9, 0xAEF2AC68,
0x23243DA5, 0x3F649643, 0x5FA495A8, 0x67710DF8,
0x9A6C499E, 0xDCFB0227, 0x46A43433, 0x1832B07A,
0xC46AFF3C, 0xB9C8FFF0, 0xC9500467, 0x34431BDF,
0xB652432B, 0xE367F12B, 0x427F4C1B, 0x224C006E,
0x2E7E5A89, 0x96F99AA5, 0x0BEB452A, 0x2FD87C39,
0x74B2E1FB, 0x222EFD24, 0xF357F60C, 0x440FCB1E,
0x8BBE030F, 0x6704DC29, 0x1144D12F, 0x948B1355,
0x6D8FD7E9, 0x1C11A014, 0xADD1592F, 0xFB3C712E,
0xFC77642F, 0xF9C4CE8C, 0x31312FB9, 0x08B0DD79,
0x318FA6E7, 0xC040D23D, 0xC0589AA7, 0x0CA5C075,
0xF874B172, 0x0CF914D5, 0x784D3280, 0x4E8CFEBC,
0xC569F575, 0xCDB2A091, 0x2CC016B4, 0x5C5F4421
};
if (salt_count_ <= predef_salt_count)
{
std::copy(predef_salt,
predef_salt + salt_count_,
std::back_inserter(salt_));
for (std::size_t i = 0; i < salt_.size(); ++i)
{
/*
Note:
This is done to integrate the user defined random seed,
so as to allow for the generation of unique bloom filter
instances.
*/
salt_[i] = salt_[i] * salt_[(i + 3) % salt_.size()] + static_cast<bloom_type>(random_seed_);
}
}
else
{
std::copy(predef_salt, predef_salt + predef_salt_count, std::back_inserter(salt_));
srand(static_cast<unsigned int>(random_seed_));
while (salt_.size() < salt_count_)
{
bloom_type current_salt = static_cast<bloom_type>(rand()) * static_cast<bloom_type>(rand());
if (0 == current_salt)
continue;
if (salt_.end() == std::find(salt_.begin(), salt_.end(), current_salt))
{
salt_.push_back(current_salt);
}
}
}
}
inline bloom_type hash_ap(const unsigned char* begin, std::size_t remaining_length, bloom_type hash) const
{
const unsigned char* itr = begin;
unsigned int loop = 0;
while (remaining_length >= 8)
{
const unsigned int& i1 = *(reinterpret_cast<const unsigned int*>(itr)); itr += sizeof(unsigned int);
const unsigned int& i2 = *(reinterpret_cast<const unsigned int*>(itr)); itr += sizeof(unsigned int);
hash ^= (hash << 7) ^ i1 * (hash >> 3) ^
(~((hash << 11) + (i2 ^ (hash >> 5))));
remaining_length -= 8;
}
if (remaining_length)
{
if (remaining_length >= 4)
{
const unsigned int& i = *(reinterpret_cast<const unsigned int*>(itr));
if (loop & 0x01)
hash ^= (hash << 7) ^ i * (hash >> 3);
else
hash ^= (~((hash << 11) + (i ^ (hash >> 5))));
++loop;
remaining_length -= 4;
itr += sizeof(unsigned int);
}
if (remaining_length >= 2)
{
const unsigned short& i = *(reinterpret_cast<const unsigned short*>(itr));
if (loop & 0x01)
hash ^= (hash << 7) ^ i * (hash >> 3);
else
hash ^= (~((hash << 11) + (i ^ (hash >> 5))));
++loop;
remaining_length -= 2;
itr += sizeof(unsigned short);
}
if (remaining_length)
{
hash += ((*itr) ^ (hash * 0xA5A5A5A5)) + loop;
}
}
return hash;
}
std::vector<bloom_type> salt_;
std::vector<unsigned char> bit_table_;
unsigned int salt_count_;
unsigned long long int table_size_;
unsigned long long int projected_element_count_;
unsigned long long int inserted_element_count_;
unsigned long long int random_seed_;
double desired_false_positive_probability_;
};
inline bloom_filter operator & (const bloom_filter& a, const bloom_filter& b)
{
bloom_filter result = a;
result &= b;
return result;
}
inline bloom_filter operator | (const bloom_filter& a, const bloom_filter& b)
{
bloom_filter result = a;
result |= b;
return result;
}
inline bloom_filter operator ^ (const bloom_filter& a, const bloom_filter& b)
{
bloom_filter result = a;
result ^= b;
return result;
}
class compressible_bloom_filter : public bloom_filter
{
public:
compressible_bloom_filter(const bloom_parameters& p)
: bloom_filter(p)
{
size_list.push_back(table_size_);
}
inline unsigned long long int size() const
{
return size_list.back();
}
inline bool compress(const double& percentage)
{
if (
(percentage < 0.0) ||
(percentage >= 100.0)
)
{
return false;
}
unsigned long long int original_table_size = size_list.back();
unsigned long long int new_table_size = static_cast<unsigned long long int>((size_list.back() * (1.0 - (percentage / 100.0))));
new_table_size -= new_table_size % bits_per_char;
if (
(bits_per_char > new_table_size) ||
(new_table_size >= original_table_size)
)
{
return false;
}
desired_false_positive_probability_ = effective_fpp();
const unsigned long long int new_tbl_raw_size = new_table_size / bits_per_char;
table_type tmp(new_tbl_raw_size);
std::copy(bit_table_.begin(), bit_table_.begin() + new_tbl_raw_size, tmp.begin());
typedef table_type::iterator itr_t;
itr_t itr = bit_table_.begin() + (new_table_size / bits_per_char);
itr_t end = bit_table_.begin() + (original_table_size / bits_per_char);
itr_t itr_tmp = tmp.begin();
while (end != itr)
{
*(itr_tmp++) |= (*itr++);
}
std::swap(bit_table_, tmp);
size_list.push_back(new_table_size);
return true;
}
private:
inline void compute_indices(const bloom_type& hash, std::size_t& bit_index, std::size_t& bit) const
{
bit_index = hash;
for (std::size_t i = 0; i < size_list.size(); ++i)
{
bit_index %= size_list[i];
}
bit = bit_index % bits_per_char;
}
std::vector<unsigned long long int> size_list;
};
#endif
/*
Note 1:
If it can be guaranteed that bits_per_char will be of the form 2^n then
the following optimization can be used:
bit_table_[bit_index >> n] |= bit_mask[bit_index & (bits_per_char - 1)];
Note 2:
For performance reasons where possible when allocating memory it should
be aligned (aligned_alloc) according to the architecture being used.
*/
Computing file changes ...
