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// kv_engine.h
/**
* Copyright (C) 2014 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <string>
#include <vector>
#include "mongo/base/status.h"
#include "mongo/base/string_data.h"
#include "mongo/db/catalog/collection_options.h"
namespace mongo {
class IndexDescriptor;
class OperationContext;
class RecordStore;
class RecoveryUnit;
class SortedDataInterface;
class KVEngine {
public:
virtual RecoveryUnit* newRecoveryUnit() = 0;
// ---------
/**
* Caller takes ownership
* Having multiple out for the same ns is a rules violation;
* Calling on a non-created ident is invalid and may crash.
*/
virtual RecordStore* getRecordStore( OperationContext* opCtx,
StringData ns,
StringData ident,
const CollectionOptions& options ) = 0;
virtual SortedDataInterface* getSortedDataInterface( OperationContext* opCtx,
StringData ident,
const IndexDescriptor* desc ) = 0;
//
// The create and drop methods on KVEngine are not transactional. Transactional semantics
// are provided by the KVStorageEngine code that calls these. For example, drop will be
// called if a create is rolled back. A higher-level drop operation will only propagate to a
// drop call on the KVEngine once the WUOW commits. Therefore drops will never be rolled
// back and it is safe to immediately reclaim storage.
//
virtual Status createRecordStore( OperationContext* opCtx,
StringData ns,
StringData ident,
const CollectionOptions& options ) = 0;
virtual Status createSortedDataInterface( OperationContext* opCtx,
StringData ident,
const IndexDescriptor* desc ) = 0;
virtual int64_t getIdentSize( OperationContext* opCtx,
StringData ident ) = 0;
virtual Status repairIdent( OperationContext* opCtx,
StringData ident ) = 0;
virtual Status dropIdent( OperationContext* opCtx,
StringData ident ) = 0;
// optional
virtual int flushAllFiles( bool sync ) { return 0; }
virtual bool isDurable() const = 0;
/**
* This must not change over the lifetime of the engine.
*/
virtual bool supportsDocLocking() const = 0;
/**
* Returns true if storage engine supports --directoryperdb.
* See:
* http://docs.mongodb.org/manual/reference/program/mongod/#cmdoption--directoryperdb
*/
virtual bool supportsDirectoryPerDB() const = 0;
virtual Status okToRename( OperationContext* opCtx,
StringData fromNS,
StringData toNS,
StringData ident,
const RecordStore* originalRecordStore ) const {
return Status::OK();
}
virtual bool hasIdent(OperationContext* opCtx, StringData ident) const = 0;
virtual std::vector<std::string> getAllIdents( OperationContext* opCtx ) const = 0;
/**
* This method will be called before there is a clean shutdown. Storage engines should
* override this method if they have clean-up to do that is different from unclean shutdown.
* MongoDB will not call into the storage subsystem after calling this function.
*
* There is intentionally no uncleanShutdown().
*/
virtual void cleanShutdown() = 0;
/**
* The destructor will never be called from mongod, but may be called from tests.
* Engines may assume that this will only be called in the case of clean shutdown, even if
* cleanShutdown() hasn't been called.
*/
virtual ~KVEngine() {}
};
}
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