mirror of https://gitee.com/bigwinds/arangodb
99 lines
2.8 KiB
C++
99 lines
2.8 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2016 by EMC Corporation, All Rights Reserved
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is EMC Corporation
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///
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/// @author Andrey Abramov
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/// @author Vasiliy Nabatchikov
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////////////////////////////////////////////////////////////////////////////////
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#include <chrono>
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#include "MurmurHash/MurmurHash3.h"
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#include "integer.hpp"
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#include "string.hpp"
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// -----------------------------------------------------------------------------
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// --SECTION-- hash function
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// -----------------------------------------------------------------------------
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NS_LOCAL
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inline uint32_t get_seed() {
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auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(
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std::chrono::high_resolution_clock::now().time_since_epoch()
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);
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return static_cast<uint32_t>(ms.count());
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}
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template<typename T>
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inline size_t get_hash(const T* value, size_t size) {
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static const auto seed = get_seed();
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size_t length = std::min(size, size_t(irs::integer_traits<int>::const_max));
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uint32_t code;
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// hash as much as possible if length greater than std::numeric_limits<int>::max
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MurmurHash3_x86_32(value, int(length), seed, &code);
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return code;
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}
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NS_END
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NS_ROOT
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/* -------------------------------------------------------------------
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* basic_string_ref
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* ------------------------------------------------------------------*/
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#if defined(_MSC_VER) && defined(IRESEARCH_DLL)
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template class IRESEARCH_API basic_string_ref<char>;
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template class IRESEARCH_API basic_string_ref<byte_type>;
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#endif
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NS_BEGIN(hash_utils)
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size_t hash(const std::string& value) {
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return get_hash(value.c_str(), value.size());
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}
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size_t hash(const bstring& value) {
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return get_hash(value.c_str(), value.size());
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}
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size_t hash(const char* value) {
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return get_hash(value, std::char_traits<char>::length(value) * sizeof(char));
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}
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size_t hash(const wchar_t* value) {
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return get_hash(value, std::char_traits<wchar_t>::length(value) * sizeof(wchar_t));
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}
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size_t hash(const bytes_ref& value) {
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return get_hash(value.c_str(), value.size());
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}
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size_t hash(const string_ref& value) {
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return get_hash(value.c_str(), value.size());
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}
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NS_END // detail
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NS_END
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