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/**
* Copyright (C) 2017 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 "mongo/db/repl/rollback_common_point_resolver.h"
#include "mongo/db/repl/rollback_impl.h"
namespace mongo {
namespace repl {
/**
* This class implements the RollbackCommonPointResolver::Listener interface. It is owned by
* RollbackImpl and used by RollbackCommonPointResolver to notify RollbackImpl of oplog entries
* on the local and remote oplogs as we look for the common point between both oplogs.
*
* As we scan the local oplog backwards, each oplog entry is validated (to see if it can be rolled
* back by RollbackImpl) and processed by RollbackFixUpInfo (to eventually revert the operation
* described in the oplog entry).
*
* For oplog entries on the remote oplog, we validate each oplog entry to ensure it can be handled
* by RollbackImpl.
*
* When we encounter the common point between the local and remote oplogs, the oplog entry
* corresponding to the common point is recorded by RollbackFixUpInfo.
*
* If a scanned operation cannot be rolled back (for local oplog) or rolled forward (for remote
* oplog), there are two possible outcomes:
*
* 1) If the operation is not recognized (for example, we downgraded and this operation is from a
* more recent version of the server), we immediately shut down with a fatal error and inform
* the user that a full resync of this node is required.
*
* 2) For certain 3.4 operations that RollbackFixUpInfo is not designed to handle, we return a
* IncompatibleRollbackAlgorithm error code to indicate that we have to call rollback() (in
* rs_rollback.cpp) to complete the rollback procedure.
* TODO: This fallback behaviour can be removed in 3.8.
*/
class RollbackImpl::Listener : public RollbackCommonPointResolver::Listener {
public:
Status onLocalOplogEntry(const BSONObj& oplogEntryObj) override;
Status onRemoteOplogEntry(const BSONObj& oplogEntryObj) override;
Status onCommonPoint(
const RollbackCommonPointResolver::RollbackCommonPoint& oplogEntryObj) override;
};
} // namespace repl
} // namespace mongo
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