foundationdb/fdbclient/CoordinationInterface.h

/*
 * CoordinationInterface.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 FDBCLIENT_COORDINATIONINTERFACE_H
#define FDBCLIENT_COORDINATIONINTERFACE_H
#pragma once

#include "fdbclient/FDBTypes.h"
#include "fdbrpc/fdbrpc.h"
#include "fdbrpc/Locality.h"
#include "fdbclient/CommitProxyInterface.h"
#include "fdbclient/ClusterInterface.h"

const int MAX_CLUSTER_FILE_BYTES = 60000;

constexpr UID WLTOKEN_CLIENTLEADERREG_GETLEADER(-1, 2);
constexpr UID WLTOKEN_CLIENTLEADERREG_OPENDATABASE(-1, 3);

constexpr UID WLTOKEN_PROTOCOL_INFO(-1, 10);

// The coordinator interface as exposed to clients
struct ClientLeaderRegInterface {
	RequestStream<struct GetLeaderRequest> getLeader;
	RequestStream<struct OpenDatabaseCoordRequest> openDatabase;

	ClientLeaderRegInterface() {}
	ClientLeaderRegInterface(NetworkAddress remote);
	ClientLeaderRegInterface(INetwork* local);

	bool operator==(const ClientLeaderRegInterface& rhs) const {
		return getLeader == rhs.getLeader && openDatabase == rhs.openDatabase;
	}
};

class ClusterConnectionString {
public:
	ClusterConnectionString() {}
	ClusterConnectionString(std::string const& connectionString);
	ClusterConnectionString(vector<NetworkAddress>, Key);
	vector<NetworkAddress> const& coordinators() const { return coord; }
	Key clusterKey() const { return key; }
	Key clusterKeyName() const {
		return keyDesc;
	} // Returns the "name" or "description" part of the clusterKey (the part before the ':')
	std::string toString() const;
	static std::string getErrorString(std::string const& source, Error const& e);

private:
	void parseKey(std::string const& key);

	vector<NetworkAddress> coord;
	Key key, keyDesc;
};

class ClusterConnectionFile : NonCopyable, public ReferenceCounted<ClusterConnectionFile> {
public:
	ClusterConnectionFile() {}
	// Loads and parses the file at 'path', throwing errors if the file cannot be read or the format is invalid.
	//
	// The format of the file is: description:id@[addrs]+
	//  The description and id together are called the "key"
	//
	// The following is enforced about the format of the file:
	//  - The key must contain one (and only one) ':' character
	//  - The description contains only allowed characters (a-z, A-Z, 0-9, _)
	//  - The ID contains only allowed characters (a-z, A-Z, 0-9)
	//  - At least one address is specified
	//  - There is no address present more than once
	explicit ClusterConnectionFile(std::string const& path);
	explicit ClusterConnectionFile(ClusterConnectionString const& cs) : cs(cs), setConn(false) {}
	explicit ClusterConnectionFile(std::string const& filename, ClusterConnectionString const& contents);

	// returns <resolved name, was default file>
	static std::pair<std::string, bool> lookupClusterFileName(std::string const& filename);
	// get a human readable error message describing the error returned from the constructor
	static std::string getErrorString(std::pair<std::string, bool> const& resolvedFile, Error const& e);

	ClusterConnectionString const& getConnectionString() const;
	bool writeFile();
	void setConnectionString(ClusterConnectionString const&);
	std::string const& getFilename() const {
		ASSERT(filename.size());
		return filename;
	}
	bool canGetFilename() const { return filename.size() != 0; }
	bool fileContentsUpToDate() const;
	bool fileContentsUpToDate(ClusterConnectionString& fileConnectionString) const;
	void notifyConnected();

private:
	ClusterConnectionString cs;
	std::string filename;
	bool setConn;
};

struct LeaderInfo {
	constexpr static FileIdentifier file_identifier = 8338794;
	// The first 7 bits of changeID represent cluster controller process class fitness, the lower the better
	UID changeID;
	static const uint64_t changeIDMask = ~(uint64_t(0b1111111) << 57);
	Value serializedInfo;
	bool forward; // If true, serializedInfo is a connection string instead!

	LeaderInfo() : forward(false) {}
	LeaderInfo(UID changeID) : changeID(changeID), forward(false) {}

	bool operator<(LeaderInfo const& r) const { return changeID < r.changeID; }
	bool operator>(LeaderInfo const& r) const { return r < *this; }
	bool operator<=(LeaderInfo const& r) const { return !(*this > r); }
	bool operator>=(LeaderInfo const& r) const { return !(*this < r); }
	bool operator==(LeaderInfo const& r) const { return changeID == r.changeID; }
	bool operator!=(LeaderInfo const& r) const { return !(*this == r); }

	// The first 7 bits of ChangeID represent cluster controller process class fitness, the lower the better
	void updateChangeID(ClusterControllerPriorityInfo info) {
		changeID = UID(((uint64_t)info.processClassFitness << 57) | ((uint64_t)info.isExcluded << 60) |
		                   ((uint64_t)info.dcFitness << 61) | (changeID.first() & changeIDMask),
		               changeID.second());
	}

	// All but the first 7 bits are used to represent process id
	bool equalInternalId(LeaderInfo const& leaderInfo) const {
		return ((changeID.first() & changeIDMask) == (leaderInfo.changeID.first() & changeIDMask)) &&
		       changeID.second() == leaderInfo.changeID.second();
	}

	// Change leader only if
	// 1. the candidate has better process class fitness and the candidate is not the leader
	// 2. the leader process class fitness becomes worse
	bool leaderChangeRequired(LeaderInfo const& candidate) const {
		return ((changeID.first() & ~changeIDMask) > (candidate.changeID.first() & ~changeIDMask) &&
		        !equalInternalId(candidate)) ||
		       ((changeID.first() & ~changeIDMask) < (candidate.changeID.first() & ~changeIDMask) &&
		        equalInternalId(candidate));
	}

	ClusterControllerPriorityInfo getPriorityInfo() const {
		ClusterControllerPriorityInfo info;
		info.processClassFitness = (changeID.first() >> 57) & 7;
		info.isExcluded = (changeID.first() >> 60) & 1;
		info.dcFitness = (changeID.first() >> 61) & 7;
		return info;
	}

	template <class Ar>
	void serialize(Ar& ar) {
		serializer(ar, changeID, serializedInfo, forward);
	}
};

struct GetLeaderRequest {
	constexpr static FileIdentifier file_identifier = 214727;
	Key key;
	UID knownLeader;
	ReplyPromise<Optional<LeaderInfo>> reply;

	GetLeaderRequest() {}
	explicit GetLeaderRequest(Key key, UID kl) : key(key), knownLeader(kl) {}

	template <class Ar>
	void serialize(Ar& ar) {
		serializer(ar, key, knownLeader, reply);
	}
};

struct OpenDatabaseCoordRequest {
	constexpr static FileIdentifier file_identifier = 214728;
	// Sent by the native API to the coordinator to open a database and track client
	//   info changes.  Returns immediately if the current client info id is different from
	//   knownClientInfoID; otherwise returns when it next changes (or perhaps after a long interval)
	Key traceLogGroup;
	Standalone<VectorRef<StringRef>> issues;
	Standalone<VectorRef<ClientVersionRef>> supportedVersions;
	UID knownClientInfoID;
	Key clusterKey;
	vector<NetworkAddress> coordinators;
	ReplyPromise<CachedSerialization<struct ClientDBInfo>> reply;

	template <class Ar>
	void serialize(Ar& ar) {
		serializer(ar, issues, supportedVersions, traceLogGroup, knownClientInfoID, clusterKey, coordinators, reply);
	}
};

class ClientCoordinators {
public:
	vector<ClientLeaderRegInterface> clientLeaderServers;
	Key clusterKey;
	Reference<ClusterConnectionFile> ccf;

	explicit ClientCoordinators(Reference<ClusterConnectionFile> ccf);
	explicit ClientCoordinators(Key clusterKey, std::vector<NetworkAddress> coordinators);
	ClientCoordinators() {}
};

struct ProtocolInfoReply {
	constexpr static FileIdentifier file_identifier = 7784298;
	ProtocolVersion version;
	template <class Ar>
	void serialize(Ar& ar) {
		uint64_t version_ = 0;
		if (Ar::isSerializing) {
			version_ = version.versionWithFlags();
		}
		serializer(ar, version_);
		if (Ar::isDeserializing) {
			version = ProtocolVersion(version_);
		}
	}
};

struct ProtocolInfoRequest {
	constexpr static FileIdentifier file_identifier = 13261233;
	ReplyPromise<ProtocolInfoReply> reply{ PeerCompatibilityPolicy{ RequirePeer::AtLeast,
		                                                            ProtocolVersion::withStableInterfaces() } };
	template <class Ar>
	void serialize(Ar& ar) {
		serializer(ar, reply);
	}
};

#endif