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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 "mongo/rpc/metadata/oplog_query_metadata.h"
#include "mongo/util/net/hostandport.h"
#include "mongo/util/time_support.h"
namespace mongo {
class OperationContext;
class Timestamp;
namespace rpc {
class ReplSetMetadata;
class OplogQueryMetadata;
} // namespace rpc
namespace repl {
class OpTime;
struct SyncSourceResolverResponse;
enum class ChangeSyncSourceAction {
kContinueSyncing,
kStopSyncingAndDropLastBatchIfPresent,
kStopSyncingAndEnqueueLastBatch
};
inline std::ostream& operator<<(std::ostream& os, const ChangeSyncSourceAction action) {
switch (action) {
case ChangeSyncSourceAction::kContinueSyncing:
os << "kContinueSyncing";
break;
case ChangeSyncSourceAction::kStopSyncingAndDropLastBatchIfPresent:
os << "kStopSyncingAndDropLastBatchIfPresent";
break;
case ChangeSyncSourceAction::kStopSyncingAndEnqueueLastBatch:
os << "kStopSyncingAndEnqueueLastBatch";
break;
}
return os;
}
/**
* Manage list of viable and blocked sync sources that we can replicate from.
*/
class SyncSourceSelector {
SyncSourceSelector(const SyncSourceSelector&) = delete;
SyncSourceSelector& operator=(const SyncSourceSelector&) = delete;
public:
SyncSourceSelector() = default;
virtual ~SyncSourceSelector() = default;
/**
* Clears the list of sync sources we have denylisted.
*/
virtual void clearSyncSourceDenylist() = 0;
/**
* Chooses a viable sync source, or, if none available, returns empty HostAndPort.
*/
virtual HostAndPort chooseNewSyncSource(const OpTime& lastOpTimeFetched) = 0;
/**
* Denylists choosing 'host' as a sync source until time 'until'.
*/
virtual void denylistSyncSource(const HostAndPort& host, Date_t until) = 0;
/**
* Determines if a new sync source should be chosen, if a better candidate sync source is
* available. If the current sync source's last optime (visibleOpTime or appliedOpTime of
* metadata under protocolVersion 1, but pulled from the MemberData in protocolVersion 0)
* is more than _maxSyncSourceLagSecs behind any syncable source, this function returns true.
* If we are running in ProtocolVersion 1, our current sync source is not primary, has no sync
* source and only has data up to "myLastOpTime", returns true.
*
* "now" is used to skip over currently denylisted sync sources.
*/
virtual ChangeSyncSourceAction shouldChangeSyncSource(
const HostAndPort& currentSource,
const rpc::ReplSetMetadata& replMetadata,
const rpc::OplogQueryMetadata& oqMetadata,
const OpTime& previousOpTimeFetched,
const OpTime& lastOpTimeFetched) const = 0;
/*
* Determines if a new sync source should be chosen when an error occures during fetching,
* without attempting retries on the same sync source.
* Because metadata is not available, checks are a subset of those in shouldChangeSyncSource.
*/
virtual ChangeSyncSourceAction shouldChangeSyncSourceOnError(
const HostAndPort& currentSource, const OpTime& lastOpTimeFetched) const = 0;
};
} // namespace repl
} // namespace mongo
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