VOL-1691 Fix openolt adapter getting stuck while registartion with core

Change-Id: Ide8131f325bc15f1b909e14d7af6ee9bcd6b3b5b
diff --git a/vendor/go.etcd.io/etcd/raft/tracker/tracker.go b/vendor/go.etcd.io/etcd/raft/tracker/tracker.go
new file mode 100644
index 0000000..4b3396f
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/tracker/tracker.go
@@ -0,0 +1,259 @@
+// Copyright 2019 The etcd 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.
+
+package tracker
+
+import (
+	"fmt"
+	"sort"
+
+	"go.etcd.io/etcd/raft/quorum"
+)
+
+// Config reflects the configuration tracked in a ProgressTracker.
+type Config struct {
+	Voters quorum.JointConfig
+	// Learners is a set of IDs corresponding to the learners active in the
+	// current configuration.
+	//
+	// Invariant: Learners and Voters does not intersect, i.e. if a peer is in
+	// either half of the joint config, it can't be a learner; if it is a
+	// learner it can't be in either half of the joint config. This invariant
+	// simplifies the implementation since it allows peers to have clarity about
+	// its current role without taking into account joint consensus.
+	Learners map[uint64]struct{}
+	// TODO(tbg): when we actually carry out joint consensus changes and turn a
+	// voter into a learner, we cannot add the learner when entering the joint
+	// state. This is because this would violate the invariant that the inter-
+	// section of voters and learners is empty. For example, assume a Voter is
+	// removed and immediately re-added as a learner (or in other words, it is
+	// demoted).
+	//
+	// Initially, the configuration will be
+	//
+	//   voters:   {1 2 3}
+	//   learners: {}
+	//
+	// and we want to demote 3. Entering the joint configuration, we naively get
+	//
+	//   voters:   {1 2} & {1 2 3}
+	//   learners: {3}
+	//
+	// but this violates the invariant (3 is both voter and learner). Instead,
+	// we have
+	//
+	//   voters:   {1 2} & {1 2 3}
+	//   learners: {}
+	//   next_learners: {3}
+	//
+	// Where 3 is now still purely a voter, but we are remembering the intention
+	// to make it a learner upon transitioning into the final configuration:
+	//
+	//   voters:   {1 2}
+	//   learners: {3}
+	//   next_learners: {}
+	//
+	// Note that next_learners is not used while adding a learner that is not
+	// also a voter in the joint config. In this case, the learner is added
+	// to Learners right away when entering the joint configuration, so that it
+	// is caught up as soon as possible.
+	//
+	// NextLearners        map[uint64]struct{}
+}
+
+func (c *Config) String() string {
+	if len(c.Learners) == 0 {
+		return fmt.Sprintf("voters=%s", c.Voters)
+	}
+	return fmt.Sprintf(
+		"voters=%s learners=%s",
+		c.Voters, quorum.MajorityConfig(c.Learners).String(),
+	)
+}
+
+// ProgressTracker tracks the currently active configuration and the information
+// known about the nodes and learners in it. In particular, it tracks the match
+// index for each peer which in turn allows reasoning about the committed index.
+type ProgressTracker struct {
+	Config
+
+	Progress map[uint64]*Progress
+
+	Votes map[uint64]bool
+
+	MaxInflight int
+}
+
+// MakeProgressTracker initializes a ProgressTracker.
+func MakeProgressTracker(maxInflight int) ProgressTracker {
+	p := ProgressTracker{
+		MaxInflight: maxInflight,
+		Config: Config{
+			Voters: quorum.JointConfig{
+				quorum.MajorityConfig{},
+				// TODO(tbg): this will be mostly empty, so make it a nil pointer
+				// in the common case.
+				quorum.MajorityConfig{},
+			},
+			Learners: map[uint64]struct{}{},
+		},
+		Votes:    map[uint64]bool{},
+		Progress: map[uint64]*Progress{},
+	}
+	return p
+}
+
+// IsSingleton returns true if (and only if) there is only one voting member
+// (i.e. the leader) in the current configuration.
+func (p *ProgressTracker) IsSingleton() bool {
+	return len(p.Voters[0]) == 1 && len(p.Voters[1]) == 0
+}
+
+type matchAckIndexer map[uint64]*Progress
+
+var _ quorum.AckedIndexer = matchAckIndexer(nil)
+
+// AckedIndex implements IndexLookuper.
+func (l matchAckIndexer) AckedIndex(id uint64) (quorum.Index, bool) {
+	pr, ok := l[id]
+	if !ok {
+		return 0, false
+	}
+	return quorum.Index(pr.Match), true
+}
+
+// Committed returns the largest log index known to be committed based on what
+// the voting members of the group have acknowledged.
+func (p *ProgressTracker) Committed() uint64 {
+	return uint64(p.Voters.CommittedIndex(matchAckIndexer(p.Progress)))
+}
+
+// RemoveAny removes this peer, which *must* be tracked as a voter or learner,
+// from the tracker.
+func (p *ProgressTracker) RemoveAny(id uint64) {
+	_, okPR := p.Progress[id]
+	_, okV1 := p.Voters[0][id]
+	_, okV2 := p.Voters[1][id]
+	_, okL := p.Learners[id]
+
+	okV := okV1 || okV2
+
+	if !okPR {
+		panic("attempting to remove unknown peer %x")
+	} else if !okV && !okL {
+		panic("attempting to remove unknown peer %x")
+	} else if okV && okL {
+		panic(fmt.Sprintf("peer %x is both voter and learner", id))
+	}
+
+	delete(p.Voters[0], id)
+	delete(p.Voters[1], id)
+	delete(p.Learners, id)
+	delete(p.Progress, id)
+}
+
+// InitProgress initializes a new progress for the given node or learner. The
+// node may not exist yet in either form or a panic will ensue.
+func (p *ProgressTracker) InitProgress(id, match, next uint64, isLearner bool) {
+	if pr := p.Progress[id]; pr != nil {
+		panic(fmt.Sprintf("peer %x already tracked as node %v", id, pr))
+	}
+	if !isLearner {
+		p.Voters[0][id] = struct{}{}
+	} else {
+		p.Learners[id] = struct{}{}
+	}
+	p.Progress[id] = &Progress{Next: next, Match: match, Inflights: NewInflights(p.MaxInflight), IsLearner: isLearner}
+}
+
+// Visit invokes the supplied closure for all tracked progresses.
+func (p *ProgressTracker) Visit(f func(id uint64, pr *Progress)) {
+	for id, pr := range p.Progress {
+		f(id, pr)
+	}
+}
+
+// QuorumActive returns true if the quorum is active from the view of the local
+// raft state machine. Otherwise, it returns false.
+func (p *ProgressTracker) QuorumActive() bool {
+	votes := map[uint64]bool{}
+	p.Visit(func(id uint64, pr *Progress) {
+		if pr.IsLearner {
+			return
+		}
+		votes[id] = pr.RecentActive
+	})
+
+	return p.Voters.VoteResult(votes) == quorum.VoteWon
+}
+
+// VoterNodes returns a sorted slice of voters.
+func (p *ProgressTracker) VoterNodes() []uint64 {
+	m := p.Voters.IDs()
+	nodes := make([]uint64, 0, len(m))
+	for id := range m {
+		nodes = append(nodes, id)
+	}
+	sort.Slice(nodes, func(i, j int) bool { return nodes[i] < nodes[j] })
+	return nodes
+}
+
+// LearnerNodes returns a sorted slice of learners.
+func (p *ProgressTracker) LearnerNodes() []uint64 {
+	nodes := make([]uint64, 0, len(p.Learners))
+	for id := range p.Learners {
+		nodes = append(nodes, id)
+	}
+	sort.Slice(nodes, func(i, j int) bool { return nodes[i] < nodes[j] })
+	return nodes
+}
+
+// ResetVotes prepares for a new round of vote counting via recordVote.
+func (p *ProgressTracker) ResetVotes() {
+	p.Votes = map[uint64]bool{}
+}
+
+// RecordVote records that the node with the given id voted for this Raft
+// instance if v == true (and declined it otherwise).
+func (p *ProgressTracker) RecordVote(id uint64, v bool) {
+	_, ok := p.Votes[id]
+	if !ok {
+		p.Votes[id] = v
+	}
+}
+
+// TallyVotes returns the number of granted and rejected Votes, and whether the
+// election outcome is known.
+func (p *ProgressTracker) TallyVotes() (granted int, rejected int, _ quorum.VoteResult) {
+	// Make sure to populate granted/rejected correctly even if the Votes slice
+	// contains members no longer part of the configuration. This doesn't really
+	// matter in the way the numbers are used (they're informational), but might
+	// as well get it right.
+	for id, pr := range p.Progress {
+		if pr.IsLearner {
+			continue
+		}
+		v, voted := p.Votes[id]
+		if !voted {
+			continue
+		}
+		if v {
+			granted++
+		} else {
+			rejected++
+		}
+	}
+	result := p.Voters.VoteResult(p.Votes)
+	return granted, rejected, result
+}