forked from blue/lmdbal
99 lines
3.5 KiB
C++
99 lines
3.5 KiB
C++
/*
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* LMDB Abstraction Layer.
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* Copyright (C) 2023 Yury Gubich <blue@macaw.me>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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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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*
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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, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "storagecommon.h"
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/**
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* \brief A functiion to actually open <a class="el" href="http://www.lmdb.tech/doc/group__mdb.html#gadbe68a06c448dfb62da16443d251a78b">MDB_dbi</a> storage
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*
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* \tparam K type of keys in opening storage
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*
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* \param[in] transaction - lmdb transaction to call <a class="el" href="http://www.lmdb.tech/doc/group__mdb.html#gac08cad5b096925642ca359a6d6f0562a">mdb_dbi_open</a>, must be a writable transaction!
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* \param[in] duplicates - true if key duplicates are allowed (false by default)
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*
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* \returns MDB_SUCCESS if everything went smooth or MDB_<error> -like error code
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*
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* This is a way to optimise database using MDB_INTEGERKEY flag,
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* when the key is actually kind of an integer
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* This infrastructure also allowes us to customize mdb_dbi_open call in the future
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*/
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template<class K, class V>
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inline int LMDBAL::StorageCommon::makeStorage(MDB_txn* transaction, bool duplicates) {
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unsigned int flags = MDB_CREATE;
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if constexpr (std::is_integral<K>::value)
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flags |= MDB_INTEGERKEY;
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if (duplicates) {
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flags |= MDB_DUPSORT;
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if constexpr (std::is_scalar<V>::value)
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flags |= MDB_DUPFIXED;
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if constexpr (
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std::is_same<V, uint32_t>::value ||
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std::is_same<V, int32_t>::value ||
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std::is_same<V, uint64_t>::value ||
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std::is_same<V, int64_t>::value
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) //for some reason lmdb breaks if it's not one of these types in MDB_DUPFIXED mode
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flags |= MDB_INTEGERDUP;
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}
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return _mdbOpen(transaction, flags);
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}
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/**
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* \brief A method to cast a value (which can be a value or a key) to string.
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*
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* This function is mainly used in exceptions, to report which key was duplicated or not found.
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* You can define your own specializations to this function in case std::to_string doesn't cover your case
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*
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* \param[in] value a value that should be converted to string
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* \returns a string presentation of value
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*/
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template<class T>
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inline std::string LMDBAL::StorageCommon::toString(const T& value) {
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return std::to_string(value);
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}
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/**
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* \brief A method to cast a value (which can be a value or a key) to string.
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*
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* QString spectialization
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*
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* \param[in] value a value that should be converted to string
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* \returns a string presentation of value
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*/
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template<>
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inline std::string LMDBAL::StorageCommon::toString(const QString& value) {
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return value.toStdString();
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}
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/**
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* \brief A method to cast a value (which can be a value or a key) to string.
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*
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* std::string spectialization
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*
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* \param[in] value a value that should be converted to string
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* \returns a string presentation of value
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*/
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template<>
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inline std::string LMDBAL::StorageCommon::toString(const std::string& value) {
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return value;
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}
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