68 lines
3.0 KiB
C++
68 lines
3.0 KiB
C++
/*
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* LeaderElection.h
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef FDBSERVER_LEADERELECTION_H
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#define FDBSERVER_LEADERELECTION_H
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#pragma once
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#include "fdbrpc/fdbrpc.h"
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#include "fdbrpc/Locality.h"
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class ServerCoordinators;
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template <class LeaderInterface>
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Future<Void> tryBecomeLeader( ServerCoordinators const& coordinators,
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LeaderInterface const& proposedInterface,
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Reference<AsyncVar<Optional<LeaderInterface>>> const& outKnownLeader,
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bool hasConnected,
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Reference<AsyncVar<ProcessClass>> const& asyncProcessClass);
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// Participates in the given coordination group's leader election process, nominating the given
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// LeaderInterface (presumed to be a local interface) as leader. The leader election process is
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// "sticky" - once a leader becomes leader, as long as its communications with other processes are
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// good it will remain leader. The outKnownLeader variable is updated to reflect a best guess of
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// the current leader. If the proposed interface becomes the leader, the outKnownLeader will be
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// set to the proposedInterface, and then if it is displaced by another leader, the return value will
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// eventually be set. If the return value is cancelled, the candidacy or leadership of the proposedInterface
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// will eventually end.
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Future<Void> changeLeaderCoordinators( ServerCoordinators const& coordinators, Value const& forwardingInfo );
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// Inform all the coordinators that they have been replaced with a new connection string
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#pragma region Implementation
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Future<Void> tryBecomeLeaderInternal( ServerCoordinators const& coordinators, Value const& proposedSerializedInterface, Reference<AsyncVar<Value>> const& outSerializedLeader, bool const& hasConnected, Reference<AsyncVar<ProcessClass>> const& asyncProcessClass );
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template <class LeaderInterface>
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Future<Void> tryBecomeLeader( ServerCoordinators const& coordinators,
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LeaderInterface const& proposedInterface,
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Reference<AsyncVar<Optional<LeaderInterface>>> const& outKnownLeader,
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bool hasConnected,
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Reference<AsyncVar<ProcessClass>> const& asyncProcessClass)
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{
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Reference<AsyncVar<Value>> serializedInfo( new AsyncVar<Value> );
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Future<Void> m = tryBecomeLeaderInternal( coordinators, BinaryWriter::toValue(proposedInterface, IncludeVersion()), serializedInfo, hasConnected, asyncProcessClass );
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return m || asyncDeserialize( serializedInfo, outKnownLeader );
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}
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#pragma endregion
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#endif
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