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/**
* 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 "mongo/base/status.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/record_id.h"
#include "mongo/db/repl/optime.h"
namespace mongo {
class DBClientConnection;
class NamespaceString;
class OperationContext;
namespace repl {
class OplogInterface;
class ReplicationCoordinator;
class RollbackSource;
/**
* Initiates the rollback process.
* This function assumes the preconditions for undertaking rollback have already been met;
* we have ops in our oplog that our sync source does not have, and we are not currently
* PRIMARY.
* The rollback procedure is:
* - find the common point between this node and its sync source
* - undo operations by fetching all documents affected, then replaying
* the sync source's oplog until we reach the time in the oplog when we fetched the last
* document.
* This function can throw exceptions on failures.
* This function runs a command on the sync source to detect if the sync source rolls back
* while our rollback is in progress.
*
* @param txn Used to read and write from this node's databases
* @param localOplog reads the oplog on this server.
* @param rollbackSource interface for sync source:
* provides oplog; and
* supports fetching documents and copying collections.
* @param replCoord Used to track the rollback ID and to change the follower state
*
* If requiredRBID is supplied, we error if the upstream node has a different RBID (ie it rolled
* back) after fetching any information from it.
*
* Failures: If a Status with code UnrecoverableRollbackError is returned, the caller must exit
* fatally. All other errors should be considered recoverable regardless of whether reported as a
* status or exception.
*/
Status syncRollback(OperationContext* txn,
const OplogInterface& localOplog,
const RollbackSource& rollbackSource,
boost::optional<int> requiredRBID,
ReplicationCoordinator* replCoord);
/**
* This namespace contains internal details of the rollback system. It is only exposed in a header
* for unittesting. Nothing here should be used outside of rs_rollback.cpp or its unittest.
*/
namespace rollback_internal {
struct DocID {
BSONObj ownedObj;
const char* ns;
BSONElement _id;
bool operator<(const DocID& other) const;
bool operator==(const DocID& other) const;
static DocID minFor(const char* ns) {
auto obj = BSON("" << MINKEY);
return {obj, ns, obj.firstElement()};
}
static DocID maxFor(const char* ns) {
auto obj = BSON("" << MAXKEY);
return {obj, ns, obj.firstElement()};
}
};
struct FixUpInfo {
// note this is a set -- if there are many $inc's on a single document we need to rollback,
// we only need to refetch it once.
std::set<DocID> docsToRefetch;
// Key is collection namespace. Value is name of index to drop.
std::multimap<std::string, std::string> indexesToDrop;
std::set<std::string> collectionsToDrop;
std::set<std::string> collectionsToResyncData;
std::set<std::string> collectionsToResyncMetadata;
OpTime commonPoint;
RecordId commonPointOurDiskloc;
int rbid; // remote server's current rollback sequence #
void removeAllDocsToRefetchFor(const std::string& collection);
void removeRedundantOperations();
};
// Indicates that rollback cannot complete and the server must abort.
class RSFatalException : public std::exception {
public:
RSFatalException(std::string m = "replica set fatal exception") : msg(m) {}
virtual const char* what() const throw() {
return msg.c_str();
}
private:
std::string msg;
};
Status updateFixUpInfoFromLocalOplogEntry(FixUpInfo& fixUpInfo, const BSONObj& ourObj);
} // namespace rollback_internal
} // namespace repl
} // namespace mongo
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