54 lines
1.7 KiB
C++
54 lines
1.7 KiB
C++
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/*
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* Copyright (C) 2015-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.1
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*/
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#include "utils/log.hh"
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#include "bloom_filter.hh"
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#include "bloom_calculations.hh"
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#include "utils/assert.hh"
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#include "utils/murmur_hash.hh"
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#include <seastar/core/thread.hh>
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namespace utils {
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static logging::logger filterlog("bloom_filter");
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filter_ptr i_filter::get_filter(int64_t num_elements, double max_false_pos_probability, filter_format fformat) {
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SCYLLA_ASSERT(seastar::thread::running_in_thread());
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if (max_false_pos_probability > 1.0) {
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throw std::invalid_argument(format("Invalid probability {:f}: must be lower than 1.0", max_false_pos_probability));
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}
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if (max_false_pos_probability == 1.0) {
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return std::make_unique<filter::always_present_filter>();
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}
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int buckets_per_element = bloom_calculations::max_buckets_per_element(num_elements);
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auto spec = bloom_calculations::compute_bloom_spec(buckets_per_element, max_false_pos_probability);
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return filter::create_filter(spec.K, num_elements, spec.buckets_per_element, fformat);
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}
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size_t i_filter::get_filter_size(int64_t num_elements, double max_false_pos_probability) {
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if (max_false_pos_probability >= 1.0) {
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return 0;
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}
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int buckets_per_element = bloom_calculations::max_buckets_per_element(num_elements);
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auto spec = bloom_calculations::compute_bloom_spec(buckets_per_element, max_false_pos_probability);
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return filter::get_bitset_size(num_elements, spec.buckets_per_element) / 8;
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}
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hashed_key make_hashed_key(bytes_view b) {
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std::array<uint64_t, 2> h;
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utils::murmur_hash::hash3_x64_128(b, 0, h);
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return { h };
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}
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}
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