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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/optional.hpp>
#include <memory>
#include <string>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/status.h"
#include "mongo/db/jsobj.h"
namespace mongo {
/**
* This reads and write the storage engine metadata file 'storage.bson'
* in the data directory (See --dbpath).
* 'storage.engine' is the only mandatory field in the BSON metadata file.
* Fields other than 'storage.engine' are ignored.
*/
class StorageEngineMetadata {
MONGO_DISALLOW_COPYING(StorageEngineMetadata);
public:
/**
* Returns a metadata object describing the storage engine that backs the data files
* contained in 'dbpath', and nullptr otherwise.
*/
static std::unique_ptr<StorageEngineMetadata> forPath(const std::string& dbpath);
/**
* Returns the name of the storage engine that backs the data files contained in 'dbpath',
* and none otherwise.
*/
static boost::optional<std::string> getStorageEngineForPath(const std::string& dbpath);
/**
* Sets fields to defaults.
* Use read() load metadata from file.
*/
StorageEngineMetadata(const std::string& dbpath);
virtual ~StorageEngineMetadata();
/**
* Returns name of storage engine in metadata.
*/
const std::string& getStorageEngine() const;
/**
* Returns storage engine options in metadata.
*/
const BSONObj& getStorageEngineOptions() const;
/**
* Sets name of storage engine in metadata.
*/
void setStorageEngine(const std::string& storageEngine);
/**
* Sets storage engine options in metadata.
*/
void setStorageEngineOptions(const BSONObj& storageEngineOptions);
/**
* Resets fields to default values.
*/
void reset();
/**
* Reads metadata from 'storage.bson' in 'dbpath' directory.
*/
Status read();
/**
* Writes metadata to file.
*/
Status write() const;
/**
* Validates a single field in the storage engine options. Currently, only boolean fields are
* supported. If the 'fieldName' does not exist in the 'storage.bson' file and a
* 'defaultValue' is passed in, the 'expectedValue' must match the 'defaultValue'.
*/
template <typename T>
Status validateStorageEngineOption(StringData fieldName,
T expectedValue,
boost::optional<T> defaultValue = boost::none) const;
private:
std::string _dbpath;
std::string _storageEngine;
BSONObj _storageEngineOptions;
};
} // namespace mongo
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