114 lines
4.0 KiB
C
114 lines
4.0 KiB
C
/*
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* Copyright (c) 2019 TAOS Data, Inc. <cli@taosdata.com>
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*
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* This program is free software: you can use, redistribute, and/or modify
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* it under the terms of the GNU Affero General Public License, version 3
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* or later ("AGPL"), as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _TD_LIBS_SYNC_RAFT_PROGRESS_TRACKER_H
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#define _TD_LIBS_SYNC_RAFT_PROGRESS_TRACKER_H
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#include "sync_type.h"
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#include "sync_raft_quorum_joint.h"
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#include "sync_raft_progress.h"
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struct SSyncRaftProgressTrackerConfig {
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SSyncRaftQuorumJointConfig voters;
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/**
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* autoLeave is true if the configuration is joint and a transition to the
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* incoming configuration should be carried out automatically by Raft when
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* this is possible. If false, the configuration will be joint until the
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* application initiates the transition manually.
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**/
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bool autoLeave;
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/**
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* Learners is a set of IDs corresponding to the learners active in the
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* current configuration.
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*
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* Invariant: Learners and Voters does not intersect, i.e. if a peer is in
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* either half of the joint config, it can't be a learner; if it is a
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* learner it can't be in either half of the joint config. This invariant
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* simplifies the implementation since it allows peers to have clarity about
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* its current role without taking into account joint consensus.
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**/
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SyncNodeId learners[TSDB_MAX_REPLICA];
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/**
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* When we turn a voter into a learner during a joint consensus transition,
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* we cannot add the learner directly when entering the joint state. This is
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* because this would violate the invariant that the intersection of
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* voters and learners is empty. For example, assume a Voter is removed and
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* immediately re-added as a learner (or in other words, it is demoted):
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*
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* Initially, the configuration will be
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*
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* voters: {1 2 3}
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* learners: {}
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*
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* and we want to demote 3. Entering the joint configuration, we naively get
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*
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* voters: {1 2} & {1 2 3}
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* learners: {3}
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*
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* but this violates the invariant (3 is both voter and learner). Instead,
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* we get
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*
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* voters: {1 2} & {1 2 3}
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* learners: {}
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* next_learners: {3}
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*
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* Where 3 is now still purely a voter, but we are remembering the intention
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* to make it a learner upon transitioning into the final configuration:
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*
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* voters: {1 2}
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* learners: {3}
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* next_learners: {}
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*
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* Note that next_learners is not used while adding a learner that is not
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* also a voter in the joint config. In this case, the learner is added
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* right away when entering the joint configuration, so that it is caught up
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* as soon as possible.
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**/
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SyncNodeId learnersNext[TSDB_MAX_REPLICA];
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};
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struct SSyncRaftProgressTracker {
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SSyncRaftProgressTrackerConfig config;
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SSyncRaftProgress progressMap[TSDB_MAX_REPLICA];
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SyncRaftVoteResult votes[TSDB_MAX_REPLICA];
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int maxInflight;
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};
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SSyncRaftProgressTracker* syncRaftOpenProgressTracker();
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void syncRaftResetVotes(SSyncRaftProgressTracker*);
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typedef void (*visitProgressFp)(int i, SSyncRaftProgress* progress, void* arg);
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void syncRaftProgressVisit(SSyncRaftProgressTracker*, visitProgressFp visit, void* arg);
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/**
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* syncRaftRecordVote records that the node with the given id voted for this Raft
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* instance if v == true (and declined it otherwise).
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**/
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void syncRaftRecordVote(SSyncRaftProgressTracker* tracker, int i, bool grant);
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/**
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* syncRaftTallyVotes returns the number of granted and rejected Votes, and whether the
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* election outcome is known.
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**/
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SyncRaftVoteResult syncRaftTallyVotes(SSyncRaftProgressTracker* tracker, int* rejected, int *granted);
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#endif /* _TD_LIBS_SYNC_RAFT_PROGRESS_TRACKER_H */
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