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b7a52e81e2
A client will always try to connect all coordinators. This commit let Status track the number of connected coordinators for each client. This allows us to do canary in coordinators. For example, when we switch from non-TLS to TLS, we can switch 1 coordinator from non-TLS to TLS. This can help check if a client has the ability to connect through TLS. We can make the non-TLS to TLS switch for each coordinators one by one. This avoid the risk of losing connection in the switch.
51 lines
2.2 KiB
C++
51 lines
2.2 KiB
C++
/*
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* MonitorLeader.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 FDBCLIENT_MONITORLEADER_H
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#define FDBCLIENT_MONITORLEADER_H
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#pragma once
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#include "fdbclient/FDBTypes.h"
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#include "fdbclient/CoordinationInterface.h"
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#define CLUSTER_FILE_ENV_VAR_NAME "FDB_CLUSTER_FILE"
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class ClientCoordinators;
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template <class LeaderInterface>
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Future<Void> monitorLeader( Reference<ClusterConnectionFile> const& connFile, Reference<AsyncVar<Optional<LeaderInterface>>> const& outKnownLeader, Reference<AsyncVar<int>> connectedCoordinatorsNum );
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// Monitors the given coordination group's leader election process and provides a best current guess
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// of the current leader. If a leader is elected for long enough and communication with a quorum of
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// coordinators is possible, eventually outKnownLeader will be that leader's interface.
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#pragma region Implementation
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Future<Void> monitorLeaderInternal( Reference<ClusterConnectionFile> const& connFile, Reference<AsyncVar<Value>> const& outSerializedLeaderInfo, Reference<AsyncVar<int>> const& connectedCoordinatorsNum );
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template <class LeaderInterface>
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Future<Void> monitorLeader( Reference<ClusterConnectionFile> const& connFile, Reference<AsyncVar<Optional<LeaderInterface>>> const& outKnownLeader, Reference<AsyncVar<int>> connectedCoordinatorsNum ) {
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Reference<AsyncVar<Value>> serializedInfo( new AsyncVar<Value> );
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Future<Void> m = monitorLeaderInternal( connFile, serializedInfo, connectedCoordinatorsNum );
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return m || asyncDeserialize( serializedInfo, outKnownLeader );
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}
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#pragma endregion
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#endif |