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64 lines
1.6 KiB
C++
64 lines
1.6 KiB
C++
/*
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* Copyright (C) 2018-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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#pragma once
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#include "utils/digest_algorithm.hh"
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#include "utils/hashing.hh"
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#include "utils/xx_hasher.hh"
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#include <type_traits>
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#include <variant>
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namespace query {
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struct noop_hasher {
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void update(const char* ptr, size_t length) noexcept { }
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std::array<uint8_t, 16> finalize_array() { return std::array<uint8_t, 16>(); };
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};
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class digester final {
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std::variant<noop_hasher, xx_hasher> _impl;
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public:
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explicit digester(digest_algorithm algo) {
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switch (algo) {
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case digest_algorithm::xxHash:
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_impl = xx_hasher();
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break;
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case digest_algorithm ::none:
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_impl = noop_hasher();
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break;
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}
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}
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template<typename T, typename... Args>
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void feed_hash(const T& value, Args&&... args) {
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// FIXME uncomment the noexcept marking once clang bug 50994 is fixed or gcc compilation is turned on
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std::visit([&] (auto& hasher) /* noexcept(noexcept(::feed_hash(hasher, value, args...))) */ -> void {
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::feed_hash(hasher, value, std::forward<Args>(args)...);
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}, _impl);
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};
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std::array<uint8_t, 16> finalize_array() {
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return std::visit([&] (auto& hasher) {
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return hasher.finalize_array();
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}, _impl);
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}
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};
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using default_hasher = xx_hasher;
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template<typename Hasher>
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using using_hash_of_hash = std::negation<std::is_same<Hasher, noop_hasher>>;
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template<typename Hasher>
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inline constexpr bool using_hash_of_hash_v = using_hash_of_hash<Hasher>::value;
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}
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