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53 lines
1.6 KiB
C++
53 lines
1.6 KiB
C++
/* Copyright (C) 2021 Mariadb Corporation.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; version 2 of
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the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#pragma once
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#include "hasher.h"
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#include "collation.h"
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namespace utils
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{
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class HashFamily
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{
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public:
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HashFamily(const utils::Hasher_r& h, const uint64_t intermediateHash, const uint64_t len,
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const datatypes::MariaDBHasher& hM)
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: mHasher(h), mMariaDBHasher(hM), mHasher_rHash(intermediateHash), mHasher_rLen(len)
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{
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}
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// Algorithm, seed and factor are taken from this discussion
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// https://stackoverflow.com/questions/1646807/quick-and-simple-hash-code-combinations
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inline uint64_t finalize() const
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{
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return (seed * factor + mHasher.finalize(mHasher_rHash, mHasher_rLen)) * factor +
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mMariaDBHasher.finalize();
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}
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private:
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constexpr static uint64_t seed = 1009ULL;
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constexpr static uint64_t factor = 9176ULL;
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const utils::Hasher_r& mHasher;
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const datatypes::MariaDBHasher& mMariaDBHasher;
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const uint64_t mHasher_rHash;
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const uint32_t mHasher_rLen;
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};
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} // namespace utils
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