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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 <memory>
#include "mongo/base/status.h"
#include "mongo/base/status_with.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/repl/optime.h"
#include "mongo/db/repl/replication_consistency_markers.h"
#include "mongo/db/repl/replication_recovery.h"
#include "mongo/platform/mutex.h"
namespace mongo {
class OperationContext;
class ServiceContext;
namespace repl {
class StorageInterface;
/**
* This class represents the current replication process state that is used during the replication
* of operations from the sync source to the current node.
*
* For example, the rollback ID, which is persisted to storage, is cached here for the purposes of
* filling in the metadata for the find/getMore queries used to tail the oplog on the sync source.
*
* This class DOES NOT hold any information related to the consensus protocol.
*/
class ReplicationProcess {
ReplicationProcess(const ReplicationProcess&) = delete;
ReplicationProcess& operator=(const ReplicationProcess&) = delete;
public:
static const int kUninitializedRollbackId = -1;
// Operation Context binding.
static ReplicationProcess* get(ServiceContext* service);
static ReplicationProcess* get(ServiceContext& service);
static ReplicationProcess* get(OperationContext* opCtx);
static void set(ServiceContext* service, std::unique_ptr<ReplicationProcess> process);
ReplicationProcess(StorageInterface* storageInterface,
std::unique_ptr<ReplicationConsistencyMarkers> consistencyMarkers,
std::unique_ptr<ReplicationRecovery> recovery);
virtual ~ReplicationProcess() = default;
/**
* Rollback ID is an increasing counter of how many rollbacks have occurred on this server.
*/
Status refreshRollbackID(OperationContext* opCtx);
int getRollbackID() const;
Status initializeRollbackID(OperationContext* opCtx);
Status incrementRollbackID(OperationContext* opCtx);
/**
* Returns an object used for operating on the documents that maintain replication consistency.
*/
ReplicationConsistencyMarkers* getConsistencyMarkers();
/**
* Returns an object used to recover from the oplog on startup or rollback.
*/
ReplicationRecovery* getReplicationRecovery();
private:
// All member variables are labeled with one of the following codes indicating the
// synchronization rules for accessing them.
//
// (R) Read-only in concurrent operation; no synchronization required.
// (S) Self-synchronizing; access in any way from any context.
// (M) Reads and writes guarded by _mutex.
// Guards access to member variables.
mutable Mutex _mutex = MONGO_MAKE_LATCH("ReplicationProcess::_mutex");
// Used to access the storage layer.
StorageInterface* const _storageInterface; // (R)
// Used for operations on documents that maintain replication consistency.
std::unique_ptr<ReplicationConsistencyMarkers> _consistencyMarkers; // (S)
std::unique_ptr<ReplicationRecovery> _recovery; // (S)
// Rollback ID. This is a cached copy of the persisted value in the local.system.rollback.id
// collection.
int _rbid; // (M)
};
} // namespace repl
} // namespace mongo
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