foundationdb/fdbclient/MonitorLeader.h

/*
 * MonitorLeader.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_MONITORLEADER_H
#define FDBCLIENT_MONITORLEADER_H
#pragma once

#include "fdbclient/FDBTypes.h"
#include "fdbclient/CoordinationInterface.h"
#include "fdbclient/ClusterInterface.h"
#include "fdbclient/MasterProxyInterface.h"

#define CLUSTER_FILE_ENV_VAR_NAME "FDB_CLUSTER_FILE"

class ClientCoordinators;

struct ClientStatusInfo {
	Key traceLogGroup;
	Standalone<VectorRef<ClientVersionRef>> versions;
	Standalone<VectorRef<StringRef>> issues;

	ClientStatusInfo() {}
	ClientStatusInfo(Key const& traceLogGroup, Standalone<VectorRef<ClientVersionRef>> versions, Standalone<VectorRef<StringRef>> issues) : traceLogGroup(traceLogGroup), versions(versions), issues(issues) {}
};

struct ClientData {
	std::map<NetworkAddress, ClientStatusInfo> clientStatusInfoMap;
	Reference<AsyncVar<CachedSerialization<ClientDBInfo>>> clientInfo;

	OpenDatabaseRequest getRequest();

	ClientData() : clientInfo( new AsyncVar<CachedSerialization<ClientDBInfo>>( CachedSerialization<ClientDBInfo>() ) ) {}
};

template <class LeaderInterface>
Future<Void> monitorLeader( Reference<ClusterConnectionFile> const& connFile, Reference<AsyncVar<Optional<LeaderInterface>>> const& outKnownLeader );
// Monitors the given coordination group's leader election process and provides a best current guess
// of the current leader.  If a leader is elected for long enough and communication with a quorum of
// coordinators is possible, eventually outKnownLeader will be that leader's interface.

Future<Void> monitorLeaderForProxies( Value const& key, vector<NetworkAddress> const& coordinators, ClientData* const& clientData );

Future<Void> monitorProxies( Reference<AsyncVar<Reference<ClusterConnectionFile>>> const& connFile, Reference<AsyncVar<ClientDBInfo>> const& clientInfo, Standalone<VectorRef<ClientVersionRef>> const& supportedVersions, Key const& traceLogGroup );

#pragma region Implementation

Future<Void> monitorLeaderInternal( Reference<ClusterConnectionFile> const& connFile, Reference<AsyncVar<Value>> const& outSerializedLeaderInfo );

template <class LeaderInterface>
struct LeaderDeserializer {
	Future<Void> operator()(const Reference<AsyncVar<Value>>& serializedInfo,
							const Reference<AsyncVar<Optional<LeaderInterface>>>& outKnownLeader) {
		return asyncDeserialize(serializedInfo, outKnownLeader, FLOW_KNOBS->USE_OBJECT_SERIALIZER);
	}
};

Future<Void> asyncDeserializeClusterInterface(const Reference<AsyncVar<Value>>& serializedInfo,
											  const Reference<AsyncVar<Optional<ClusterInterface>>>& outKnownLeader);

template <>
struct LeaderDeserializer<ClusterInterface> {
	Future<Void> operator()(const Reference<AsyncVar<Value>>& serializedInfo,
							const Reference<AsyncVar<Optional<ClusterInterface>>>& outKnownLeader) {
		return asyncDeserializeClusterInterface(serializedInfo, outKnownLeader);
	}
};

template <class LeaderInterface>
Future<Void> monitorLeader(Reference<ClusterConnectionFile> const& connFile,
						   Reference<AsyncVar<Optional<LeaderInterface>>> const& outKnownLeader) {
	LeaderDeserializer<LeaderInterface> deserializer;
	Reference<AsyncVar<Value>> serializedInfo( new AsyncVar<Value> );
	Future<Void> m = monitorLeaderInternal( connFile, serializedInfo );
	return m || deserializer( serializedInfo, outKnownLeader );
}

#pragma endregion

#endif