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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <boost/filesystem/path.hpp>
#include <cstddef>
#include <cstdint>
#include <fstream>
#include <vector>
#include "mongo/base/status.h"
#include "mongo/db/ftdc/compressor.h"
#include "mongo/db/jsobj.h"
namespace mongo {
/**
* Manages writing to an append only archive file, and an interim file.
* - The archive file is designed to write complete metric chunks.
* - The interim file writes smaller chunks in case of process failure.
*
* Note: This class never reads from the interim file. It is the callers responsibility to check
* for unclean shutdown as this file. An unclean shutdown will mean there is valid data in the
* interim file. If the shutdown is clean, the interim file will contain zeros as the leading
* 8 bytes instead of a valid BSON length.
*
* The chunks in the archive stream will have better compression since it compresses larger chunks
* of data.
*
* File format is compatible with mongodump as it is just a sequential series of bson documents
*
* File rotation and cleanup is not handled by this class.
*/
class FTDCFileWriter {
FTDCFileWriter(const FTDCFileWriter&) = delete;
FTDCFileWriter& operator=(const FTDCFileWriter&) = delete;
public:
FTDCFileWriter(const FTDCConfig* config) : _config(config), _compressor(_config) {}
~FTDCFileWriter();
/**
* Open both an archive file, and interim file.
*/
Status open(const boost::filesystem::path& file);
/**
* Write a BSON document as a metadata type to the archive log.
*/
Status writeMetadata(const BSONObj& metadata, Date_t date);
/**
* Write a sample to interim and/or archive log as needed.
*/
Status writeSample(const BSONObj& sample, Date_t date);
/**
* Close all the files and shutdown cleanly by zeroing the beginning of the interim file.
*/
Status close();
/**
* Get the size of data written to file. Size of file after file is closed due to effects of
* compression may be different.
*/
std::size_t getSize() const {
return _size + _sizeInterim;
}
public:
/**
* Test hook that closes the files without moving interim results to the archive log.
* Note: OS Buffers are still flushes correctly though.
*/
void closeWithoutFlushForTest();
private:
/**
* Flush all changes to disk.
*/
Status flush(const boost::optional<ConstDataRange>&, Date_t date);
/**
* Write a buffer to the beginning of the interim file.
*/
Status writeInterimFileBuffer(ConstDataRange buf);
/**
* Append a buffer to the archive file.
*/
Status writeArchiveFileBuffer(ConstDataRange buf);
private:
// Config
const FTDCConfig* const _config;
// Archive file name
boost::filesystem::path _archiveFile;
// Interim file name
boost::filesystem::path _interimFile;
// Interim temp file name
boost::filesystem::path _interimTempFile;
// Append only archive stream
std::ofstream _archiveStream;
// FTDC compressor
FTDCCompressor _compressor;
// Size of archive file
std::size_t _size{0};
// Size of interim file
std::size_t _sizeInterim{0};
};
} // namespace mongo
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