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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 <boost/optional.hpp>
#include <fstream>
#include <stddef.h>
#include <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/status.h"
#include "mongo/base/status_with.h"
#include "mongo/db/ftdc/decompressor.h"
#include "mongo/db/ftdc/util.h"
#include "mongo/db/jsobj.h"
namespace mongo {
/**
* Reads a file, either an archive stream or interim file
*
* Does not recover interim files into archive files.
*/
class FTDCFileReader {
MONGO_DISALLOW_COPYING(FTDCFileReader);
public:
FTDCFileReader() : _state(State::kNeedsDoc) {}
~FTDCFileReader();
/**
* Open the specified file
*/
Status open(const boost::filesystem::path& file);
/**
* Returns true if their are more records in the file.
* Returns false if the end of the file has been reached.
* Return other error codes if the file is corrupt.
*/
StatusWith<bool> hasNext();
/**
* Returns the next document.
* Metadata documents are unowned.
* Metric documents are owned.
*/
std::tuple<FTDCBSONUtil::FTDCType, const BSONObj&, Date_t> next();
private:
/**
* Read a document from the file. If the file is corrupt, returns an appropriate status.
*/
StatusWith<BSONObj> readDocument();
private:
FTDCDecompressor _decompressor;
/**
* Internal state of file reading state machine.
*
* +--------------+ +--------------+
* +> | kNeedsDoc | <--> | kMetadataDoc |
* | +--------------+ +--------------+
* |
* | +----------+
* | v |
* | +--------------+
* +> | kMetricChunk |
* +--------------+
*/
enum class State {
/**
* Indicates that we need to read another document from disk
*/
kNeedsDoc,
/**
* Indicates that are processing a metric chunk, and have one or more documents to return.
*/
kMetricChunk,
/**
* Indicates that we need to read another document from disk
*/
kMetadataDoc,
};
State _state{State::kNeedsDoc};
// Current position in the _docs array.
std::size_t _pos{0};
// Current set of metrics documents
std::vector<BSONObj> _docs;
// _id of current metadata or metric chunk
Date_t _dateId;
// Current metadata document - unowned
BSONObj _metadata;
// Parent document
BSONObj _parent;
// Buffer of data read from disk
std::vector<char> _buffer;
// File name
boost::filesystem::path _file;
// Size of file on disk
std::size_t _fileSize{0};
// Input file stream
std::ifstream _stream;
};
} // namespace mongo
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