foundationdb/fdbserver/DBCoreState.h

/*
 * DBCoreState.h
 *
 * This source file is part of the FoundationDB open source project
 *
 * Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef FDBSERVER_DBCORESTATE_H
#define FDBSERVER_DBCORESTATE_H

#include <set>
#include <vector>

#include "fdbclient/FDBTypes.h"
#include "fdbrpc/ReplicationPolicy.h"
#include "fdbserver/LogSystemConfig.h"
#include "fdbserver/MasterInterface.h"

class LogSet;
struct OldLogData;

// This structure is stored persistently in CoordinatedState and must be versioned carefully!
// It records a synchronous replication topology which can be used in the absence of faults (or under a limited
//   number of failures, in the case of less than full write quorums) to durably commit transactions.  When faults or
//   configuration changes require the topology to be changed, (a read quorum of) the old topology is locked, a new
//   topology is constructed, and then committed to this coordinated state before becoming active.  This process
//   is called 'recovery'.
// At the moment, transaction logs are replicated but not partitioned, so the topology is as simple as a list of
//   transaction log replicas and the write quorum that was used to commit to them.  The read quorum required to
//   ensure durability of locking and recovery is therefore tLogWriteAntiQuorum + 1.
struct CoreTLogSet {
	std::vector<UID> tLogs;
	int32_t tLogWriteAntiQuorum; // The write anti quorum previously used to write to tLogs, which might be different from the anti quorum suggested by the current configuration going forward!
	int32_t tLogReplicationFactor; // The replication factor previously used to write to tLogs, which might be different from the current configuration
	std::vector< LocalityData > tLogLocalities; // Stores the localities of the log servers
	Reference<IReplicationPolicy> tLogPolicy;
	bool isLocal;
	int8_t locality;
	Version startVersion;
	std::vector<std::vector<int>> satelliteTagLocations;
	TLogVersion tLogVersion;

	CoreTLogSet() : tLogWriteAntiQuorum(0), tLogReplicationFactor(0), isLocal(true), locality(tagLocalityUpgraded), startVersion(invalidVersion) {}
	explicit CoreTLogSet(const LogSet& logset);

	bool operator==(CoreTLogSet const& rhs) const {
		return tLogs == rhs.tLogs && tLogWriteAntiQuorum == rhs.tLogWriteAntiQuorum &&
		       tLogReplicationFactor == rhs.tLogReplicationFactor && isLocal == rhs.isLocal &&
		       satelliteTagLocations == rhs.satelliteTagLocations && locality == rhs.locality &&
		       startVersion == rhs.startVersion &&
		       ((!tLogPolicy && !rhs.tLogPolicy) ||
		        (tLogPolicy && rhs.tLogPolicy && (tLogPolicy->info() == rhs.tLogPolicy->info())));
	}

	template <class Archive>
	void serialize(Archive& ar) {
		serializer(ar, tLogs, tLogWriteAntiQuorum, tLogReplicationFactor, tLogPolicy, tLogLocalities, isLocal, locality, startVersion, satelliteTagLocations);
		if (ar.isDeserializing && !ar.protocolVersion().hasTLogVersion()) {
			tLogVersion = TLogVersion::V2;
		} else {
			serializer(ar, tLogVersion);
		}
	}
};

struct OldTLogCoreData {
	std::vector<CoreTLogSet> tLogs;
	int32_t logRouterTags;
	int32_t txsTags;
	Version epochBegin, epochEnd;
	std::set<int8_t> pseudoLocalities;
	LogEpoch epoch;

	OldTLogCoreData() : epochBegin(0), epochEnd(0), logRouterTags(0), txsTags(0), epoch(0) {}
	explicit OldTLogCoreData(const OldLogData&);

	bool operator==(const OldTLogCoreData& rhs) const {
		return tLogs == rhs.tLogs && logRouterTags == rhs.logRouterTags && txsTags == rhs.txsTags &&
		       epochBegin == rhs.epochBegin && epochEnd == rhs.epochEnd && pseudoLocalities == rhs.pseudoLocalities &&
		       epoch == rhs.epoch;
	}

	template <class Archive>
	void serialize(Archive& ar) {
		if( ar.protocolVersion().hasTagLocality()) {
			serializer(ar, tLogs, logRouterTags, epochEnd);
		}
		else if(ar.isDeserializing) {
			tLogs.push_back(CoreTLogSet());
			serializer(ar, tLogs[0].tLogs, tLogs[0].tLogWriteAntiQuorum, tLogs[0].tLogReplicationFactor, tLogs[0].tLogPolicy, epochEnd, tLogs[0].tLogLocalities);
			tLogs[0].tLogVersion = TLogVersion::V2;
		}
		if (ar.protocolVersion().hasPseudoLocalities()) {
			serializer(ar, pseudoLocalities);
		}
		if (ar.protocolVersion().hasShardedTxsTags()) {
			serializer(ar, txsTags);
		}
		if (ar.protocolVersion().hasBackupWorker()) {
			serializer(ar, epoch, epochBegin);
		}
	}
};

struct DBCoreState {
	std::vector<CoreTLogSet> tLogs;
	int32_t logRouterTags;
	int32_t txsTags;
	std::vector<OldTLogCoreData> oldTLogData;
	DBRecoveryCount recoveryCount;  // Increases with sequential successful recoveries.
	LogSystemType logSystemType;
	std::set<int8_t> pseudoLocalities;
	
	DBCoreState() : logRouterTags(0), txsTags(0), recoveryCount(0), logSystemType(LogSystemType::empty) {}

	vector<UID> getPriorCommittedLogServers() {
		vector<UID> priorCommittedLogServers;
		for(auto& it : tLogs) {
			for(auto& log : it.tLogs) {
				priorCommittedLogServers.push_back(log);
			}
		}
		for(int i = 0; i < oldTLogData.size(); i++) {
			for(auto& it : oldTLogData[i].tLogs) {
				for(auto& log : it.tLogs) {
					priorCommittedLogServers.push_back(log);
				}
			}
		}
		return priorCommittedLogServers;
	}

	bool isEqual(const DBCoreState& r) const {
		return logSystemType == r.logSystemType && recoveryCount == r.recoveryCount && tLogs == r.tLogs &&
		       oldTLogData == r.oldTLogData && logRouterTags == r.logRouterTags && txsTags == r.txsTags &&
		       pseudoLocalities == r.pseudoLocalities;
	}
	bool operator==(const DBCoreState& rhs) const { return isEqual(rhs); }
	bool operator!=(const DBCoreState& rhs) const { return !isEqual(rhs); }

	template <class Archive>
	void serialize(Archive& ar) {
		ASSERT(ar.protocolVersion().hasMultiGenerationTLog());
		if(ar.protocolVersion().hasTagLocality()) {
			serializer(ar, tLogs, logRouterTags, oldTLogData, recoveryCount, logSystemType);
			if (ar.protocolVersion().hasPseudoLocalities()) {
				serializer(ar, pseudoLocalities);
			}
			if (ar.protocolVersion().hasShardedTxsTags()) {
				serializer(ar, txsTags);
			}
		} else if(ar.isDeserializing) {
			tLogs.push_back(CoreTLogSet());
			serializer(ar, tLogs[0].tLogs, tLogs[0].tLogWriteAntiQuorum, recoveryCount, tLogs[0].tLogReplicationFactor, logSystemType);
			tLogs[0].tLogVersion = TLogVersion::V2;

			uint64_t tLocalitySize = (uint64_t)tLogs[0].tLogLocalities.size();
			serializer(ar, oldTLogData, tLogs[0].tLogPolicy, tLocalitySize);
			if (ar.isDeserializing) {
				tLogs[0].tLogLocalities.reserve(tLocalitySize);
				for (size_t i = 0; i < tLocalitySize; i++) {
					LocalityData locality;
					serializer(ar, locality);
					tLogs[0].tLogLocalities.push_back(locality);
				}

				if(oldTLogData.size()) {
					tLogs[0].startVersion = oldTLogData[0].epochEnd;
					for(int i = 0; i < oldTLogData.size() - 1; i++) {
						oldTLogData[i].tLogs[0].startVersion = oldTLogData[i+1].epochEnd;
					}
				}
			}
		}
	}
};

#endif