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Diffstat (limited to 'src/common/bloom_filter.hpp')
| -rw-r--r-- | src/common/bloom_filter.hpp | 585 |
1 files changed, 585 insertions, 0 deletions
diff --git a/src/common/bloom_filter.hpp b/src/common/bloom_filter.hpp new file mode 100644 index 000000000..639516fe4 --- /dev/null +++ b/src/common/bloom_filter.hpp @@ -0,0 +1,585 @@ +// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- +// vim: ts=8 sw=2 smarttab + +/* + ******************************************************************* + * * + * Open Bloom Filter * + * * + * Author: Arash Partow - 2000 * + * 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 most current version * + * of the Boost Software License, Version 1.0 * + * http://www.opensource.org/licenses/bsl1.0.html * + * * + ******************************************************************* +*/ + + +#ifndef COMMON_BLOOM_FILTER_HPP +#define COMMON_BLOOM_FILTER_HPP + +#include <cmath> + +#include "include/encoding.h" +#include "include/mempool.h" + +static const unsigned char bit_mask[CHAR_BIT] = { + 0x01, //00000001 + 0x02, //00000010 + 0x04, //00000100 + 0x08, //00001000 + 0x10, //00010000 + 0x20, //00100000 + 0x40, //01000000 + 0x80 //10000000 +}; + +class bloom_filter +{ +protected: + + using bloom_type = unsigned int; + using cell_type = unsigned char; + using table_type = mempool::bloom_filter::vector<cell_type>; + + std::vector<bloom_type> salt_; ///< vector of salts + table_type bit_table_; ///< bit map + std::size_t salt_count_; ///< number of salts + std::size_t table_size_; ///< bit table size in bytes + std::size_t insert_count_; ///< insertion count + std::size_t target_element_count_; ///< target number of unique insertions + std::size_t random_seed_; ///< random seed + +public: + + bloom_filter() + : salt_count_(0), + table_size_(0), + insert_count_(0), + target_element_count_(0), + random_seed_(0) + {} + + bloom_filter(const std::size_t& predicted_inserted_element_count, + const double& false_positive_probability, + const std::size_t& random_seed) + : insert_count_(0), + target_element_count_(predicted_inserted_element_count), + random_seed_((random_seed) ? random_seed : 0xA5A5A5A5) + { + ceph_assert(false_positive_probability > 0.0); + std::tie(salt_count_, table_size_) = + find_optimal_parameters(predicted_inserted_element_count, + false_positive_probability); + init(); + } + + bloom_filter(const std::size_t& salt_count, + std::size_t table_size, + const std::size_t& random_seed, + std::size_t target_element_count) + : salt_count_(salt_count), + table_size_(table_size), + insert_count_(0), + target_element_count_(target_element_count), + random_seed_((random_seed) ? random_seed : 0xA5A5A5A5) + { + init(); + } + + void init() { + generate_unique_salt(); + bit_table_.resize(table_size_, static_cast<unsigned char>(0x00)); + } + + bloom_filter(const bloom_filter& filter) + { + this->operator=(filter); + } + + bloom_filter& operator = (const bloom_filter& filter) + { + if (this != &filter) { + salt_count_ = filter.salt_count_; + table_size_ = filter.table_size_; + insert_count_ = filter.insert_count_; + target_element_count_ = filter.target_element_count_; + random_seed_ = filter.random_seed_; + bit_table_ = filter.bit_table_; + salt_ = filter.salt_; + } + return *this; + } + + virtual ~bloom_filter() = default; + + inline bool operator!() const + { + return (0 == table_size_); + } + + inline void clear() + { + std::fill(bit_table_.begin(), bit_table_.end(), + static_cast<unsigned char>(0x00)); + insert_count_ = 0; + } + + /** + * insert a u32 into the set + * + * NOTE: the internal hash is weak enough that consecutive inputs do + * not achieve the desired fpp. Well-mixed values should be used + * here (e.g., put rjhash(x) into the filter instead of just x). + * + * @param val integer value to insert + */ + inline void insert(uint32_t val) { + for (auto salt : salt_) { + auto [bit_index, bit] = compute_indices(hash_ap(val, salt)); + bit_table_[bit_index >> 3] |= bit_mask[bit]; + } + ++insert_count_; + } + + inline void insert(const unsigned char* key_begin, const std::size_t& length) + { + for (auto salt : salt_) { + auto [bit_index, bit] = compute_indices(hash_ap(key_begin, length, salt)); + bit_table_[bit_index >> 3] |= bit_mask[bit]; + } + ++insert_count_; + } + + inline void insert(const std::string& key) + { + insert(reinterpret_cast<const unsigned char*>(key.c_str()),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++)); + } + } + + /** + * check if a u32 is contained by set + * + * NOTE: the internal hash is weak enough that consecutive inputs do + * not achieve the desired fpp. Well-mixed values should be used + * here (e.g., put rjhash(x) into the filter instead of just x). + * + * @param val integer value to query + * @returns true if value is (probably) in the set, false if it definitely is not + */ + inline virtual bool contains(uint32_t val) const + { + if (table_size_ == 0) { + return false; + } + for (auto salt : salt_) { + auto [bit_index, bit] = compute_indices(hash_ap(val, salt)); + if ((bit_table_[bit_index >> 3] & bit_mask[bit]) != bit_mask[bit]) { + return false; + } + } + return true; + } + + inline virtual bool contains(const unsigned char* key_begin, const std::size_t length) const + { + if (table_size_ == 0) { + return false; + } + for (auto salt : salt_) { + auto [bit_index, bit] = compute_indices(hash_ap(key_begin, length, salt)); + if ((bit_table_[bit_index >> 3] & bit_mask[bit]) != bit_mask[bit]) { + return false; + } + } + return true; + } + + 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 std::size_t size() const + { + return table_size_ * CHAR_BIT; + } + + inline std::size_t element_count() const + { + return insert_count_; + } + + inline bool is_full() const + { + return insert_count_ >= target_element_count_; + } + + /* + * density of bits set. inconvenient units, but: + * .3 = ~50% target insertions + * .5 = 100% target insertions, "perfectly full" + * .75 = 200% target insertions + * 1.0 = all bits set... infinite insertions + */ + double density() const; + + virtual inline double approx_unique_element_count() const { + // this is not a very good estimate; a better solution should have + // some asymptotic behavior as density() approaches 1.0. + return (double)target_element_count_ * 2.0 * density(); + } + + 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() * insert_count_ / size()), 1.0 * salt_.size()); + } + + inline const cell_type* table() const + { + return bit_table_.data(); + } + +protected: + + virtual std::pair<size_t /* bit_index */, + size_t /* bit */> + compute_indices(const bloom_type& hash) const + { + size_t bit_index = hash % (table_size_ << 3); + size_t bit = bit_index & 7; + return {bit_index, bit}; + } + + 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 (unsigned int 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()] + 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); + } + } + } + } + + static std::pair<std::size_t /* salt_count */, + std::size_t /* table_size */> + find_optimal_parameters(std::size_t target_insert_count, + double target_fpp) + { + /* + 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. + */ + + double min_m = std::numeric_limits<double>::infinity(); + double min_k = 0.0; + double curr_m = 0.0; + double k = 1.0; + while (k < 1000.0) + { + double numerator = (- k * target_insert_count); + double denominator = std::log(1.0 - std::pow(target_fpp, 1.0 / k)); + curr_m = numerator / denominator; + + if (curr_m < min_m) + { + min_m = curr_m; + min_k = k; + } + k += 1.0; + } + + size_t salt_count = static_cast<std::size_t>(min_k); + size_t t = static_cast<std::size_t>(min_m); + t += (((t & 7) != 0) ? (CHAR_BIT - (t & 7)) : 0); + size_t table_size = t >> 3; + return {salt_count, table_size}; + } + + inline bloom_type hash_ap(uint32_t val, bloom_type hash) const + { + hash ^= (hash << 7) ^ ((val & 0xff000000) >> 24) * (hash >> 3); + hash ^= (~((hash << 11) + (((val & 0xff0000) >> 16) ^ (hash >> 5)))); + hash ^= (hash << 7) ^ ((val & 0xff00) >> 8) * (hash >> 3); + hash ^= (~((hash << 11) + (((val & 0xff)) ^ (hash >> 5)))); + return hash; + } + + inline bloom_type hash_ap(const unsigned char* begin, std::size_t remaining_length, bloom_type hash) const + { + const unsigned char* itr = begin; + + while (remaining_length >= 4) + { + hash ^= (hash << 7) ^ (*itr++) * (hash >> 3); + hash ^= (~((hash << 11) + ((*itr++) ^ (hash >> 5)))); + hash ^= (hash << 7) ^ (*itr++) * (hash >> 3); + hash ^= (~((hash << 11) + ((*itr++) ^ (hash >> 5)))); + remaining_length -= 4; + } + + while (remaining_length >= 2) + { + hash ^= (hash << 7) ^ (*itr++) * (hash >> 3); + hash ^= (~((hash << 11) + ((*itr++) ^ (hash >> 5)))); + remaining_length -= 2; + } + + if (remaining_length) + { + hash ^= (hash << 7) ^ (*itr) * (hash >> 3); + } + + return hash; + } + +public: + void encode(ceph::buffer::list& bl) const; + void decode(ceph::buffer::list::const_iterator& bl); + void dump(ceph::Formatter *f) const; + static void generate_test_instances(std::list<bloom_filter*>& ls); +}; +WRITE_CLASS_ENCODER(bloom_filter) + + +class compressible_bloom_filter : public bloom_filter +{ +public: + + compressible_bloom_filter() : bloom_filter() {} + + compressible_bloom_filter(const std::size_t& predicted_element_count, + const double& false_positive_probability, + const std::size_t& random_seed) + : bloom_filter(predicted_element_count, false_positive_probability, random_seed) + { + size_list.push_back(table_size_); + } + + compressible_bloom_filter(const std::size_t& salt_count, + std::size_t table_size, + const std::size_t& random_seed, + std::size_t target_count) + : bloom_filter(salt_count, table_size, random_seed, target_count) + { + size_list.push_back(table_size_); + } + + inline std::size_t size() const override + { + return size_list.back() * CHAR_BIT; + } + + inline bool compress(const double& target_ratio) + { + if (bit_table_.empty()) + return false; + + if ((0.0 >= target_ratio) || (target_ratio >= 1.0)) + { + return false; + } + + std::size_t original_table_size = size_list.back(); + std::size_t new_table_size = static_cast<std::size_t>(size_list.back() * target_ratio); + + if ((!new_table_size) || (new_table_size >= original_table_size)) + { + return false; + } + + table_type tmp(new_table_size); + std::copy(bit_table_.begin(), bit_table_.begin() + new_table_size, tmp.begin()); + auto itr = bit_table_.begin() + new_table_size; + auto end = bit_table_.begin() + original_table_size; + auto itr_tmp = tmp.begin(); + auto itr_end = tmp.begin() + new_table_size; + while (end != itr) { + *(itr_tmp++) |= (*itr++); + if (itr_tmp == itr_end) { + itr_tmp = tmp.begin(); + } + } + std::swap(bit_table_, tmp); + size_list.push_back(new_table_size); + table_size_ = new_table_size; + + return true; + } + + inline double approx_unique_element_count() const override { + // this is not a very good estimate; a better solution should have + // some asymptotic behavior as density() approaches 1.0. + // + // the compress() correction is also bad; it tends to under-estimate. + return (double)target_element_count_ * 2.0 * density() * (double)size_list.back() / (double)size_list.front(); + } + +private: + + std::pair<size_t /* bit_index */, + size_t /* bit */> + compute_indices(const bloom_type& hash) const final + { + size_t bit_index = hash; + for (auto size : size_list) { + bit_index %= size << 3; + } + size_t bit = bit_index & 7; + return {bit_index, bit}; + } + + std::vector<std::size_t> size_list; +public: + void encode(ceph::bufferlist& bl) const; + void decode(ceph::bufferlist::const_iterator& bl); + void dump(ceph::Formatter *f) const; + static void generate_test_instances(std::list<compressible_bloom_filter*>& ls); +}; +WRITE_CLASS_ENCODER(compressible_bloom_filter) + +#endif + + +/* + Note 1: + If it can be guaranteed that CHAR_BIT will be of the form 2^n then + the following optimization can be used: + + bit_table_[bit_index >> n] |= bit_mask[bit_index & (CHAR_BIT - 1)]; + + Note 2: + For performance reasons where possible when allocating memory it should + be aligned (aligned_alloc) according to the architecture being used. +*/ |