beedb/include/storage/manager.h

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/*------------------------------------------------------------------------------*
* Architecture & Implementation of DBMS *
*------------------------------------------------------------------------------*
* Copyright 2022 Databases and Information Systems Group TU Dortmund *
* Visit us at *
* http://dbis.cs.tu-dortmund.de/cms/en/home/ *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR *
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, *
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR *
* OTHER DEALINGS IN THE SOFTWARE. *
* *
* Authors: *
* Maximilian Berens <maximilian.berens@tu-dortmund.de> *
* Roland Kühn <roland.kuehn@cs.tu-dortmund.de> *
* Jan Mühlig <jan.muehlig@tu-dortmund.de> *
*------------------------------------------------------------------------------*
*/
#pragma once
#include "page.h"
#include <atomic>
#include <cstddef>
#include <cstdint>
#include <fstream>
#include <string>
namespace beedb::storage
{
/**
* The StorageManager grants access to the data written to the disk.
*/
class Manager
{
public:
explicit Manager(const std::string &file_name);
~Manager();
/**
* Copy a page from disk to memory.
*
* @param page_id Id of the page.
* @param buffer Location where to store the data in memory.
*/
void read(Page::id_t page_id, std::byte *buffer);
/**
* Write the page from memory to disk.
*
* @param page_id Page to be written.
* @param data Location in memory of the data to write to disk.
*/
void write(Page::id_t page_id, const std::byte *data);
/**
* Allocates a new page in the disk file and extends the
* file by the new allocated page.
*
* @return Id of the new allocated page.
*/
template <typename P> Page::id_t allocate()
{
const auto page_id = this->_count_pages.fetch_add(1);
P page;
this->write(page_id, page.data());
return page_id;
}
/**
* @return Number of pages stored in the disk file.
*/
[[nodiscard]] std::size_t count_pages() const
{
return _count_pages;
}
private:
std::atomic_size_t _count_pages = 0u;
std::fstream _storage_file;
};
} // namespace beedb::storage