Update to kube v1.17

Signed-off-by: Humble Chirammal <hchiramm@redhat.com>

vendor/go.etcd.io/etcd/raft/tracker/progress.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"
+	"strings"
+)
+
+// Progress represents a follower’s progress in the view of the leader. Leader
+// maintains progresses of all followers, and sends entries to the follower
+// based on its progress.
+//
+// NB(tbg): Progress is basically a state machine whose transitions are mostly
+// strewn around `*raft.raft`. Additionally, some fields are only used when in a
+// certain State. All of this isn't ideal.
+type Progress struct {
+	Match, Next uint64
+	// State defines how the leader should interact with the follower.
+	//
+	// When in StateProbe, leader sends at most one replication message
+	// per heartbeat interval. It also probes actual progress of the follower.
+	//
+	// When in StateReplicate, leader optimistically increases next
+	// to the latest entry sent after sending replication message. This is
+	// an optimized state for fast replicating log entries to the follower.
+	//
+	// When in StateSnapshot, leader should have sent out snapshot
+	// before and stops sending any replication message.
+	State StateType
+
+	// PendingSnapshot is used in StateSnapshot.
+	// If there is a pending snapshot, the pendingSnapshot will be set to the
+	// index of the snapshot. If pendingSnapshot is set, the replication process of
+	// this Progress will be paused. raft will not resend snapshot until the pending one
+	// is reported to be failed.
+	PendingSnapshot uint64
+
+	// RecentActive is true if the progress is recently active. Receiving any messages
+	// from the corresponding follower indicates the progress is active.
+	// RecentActive can be reset to false after an election timeout.
+	//
+	// TODO(tbg): the leader should always have this set to true.
+	RecentActive bool
+
+	// ProbeSent is used while this follower is in StateProbe. When ProbeSent is
+	// true, raft should pause sending replication message to this peer until
+	// ProbeSent is reset. See ProbeAcked() and IsPaused().
+	ProbeSent bool
+
+	// Inflights is a sliding window for the inflight messages.
+	// Each inflight message contains one or more log entries.
+	// The max number of entries per message is defined in raft config as MaxSizePerMsg.
+	// Thus inflight effectively limits both the number of inflight messages
+	// and the bandwidth each Progress can use.
+	// When inflights is Full, no more message should be sent.
+	// When a leader sends out a message, the index of the last
+	// entry should be added to inflights. The index MUST be added
+	// into inflights in order.
+	// When a leader receives a reply, the previous inflights should
+	// be freed by calling inflights.FreeLE with the index of the last
+	// received entry.
+	Inflights *Inflights
+
+	// IsLearner is true if this progress is tracked for a learner.
+	IsLearner bool
+}
+
+// ResetState moves the Progress into the specified State, resetting ProbeSent,
+// PendingSnapshot, and Inflights.
+func (pr *Progress) ResetState(state StateType) {
+	pr.ProbeSent = false
+	pr.PendingSnapshot = 0
+	pr.State = state
+	pr.Inflights.reset()
+}
+
+func max(a, b uint64) uint64 {
+	if a > b {
+		return a
+	}
+	return b
+}
+
+func min(a, b uint64) uint64 {
+	if a > b {
+		return b
+	}
+	return a
+}
+
+// ProbeAcked is called when this peer has accepted an append. It resets
+// ProbeSent to signal that additional append messages should be sent without
+// further delay.
+func (pr *Progress) ProbeAcked() {
+	pr.ProbeSent = false
+}
+
+// BecomeProbe transitions into StateProbe. Next is reset to Match+1 or,
+// optionally and if larger, the index of the pending snapshot.
+func (pr *Progress) BecomeProbe() {
+	// If the original state is StateSnapshot, progress knows that
+	// the pending snapshot has been sent to this peer successfully, then
+	// probes from pendingSnapshot + 1.
+	if pr.State == StateSnapshot {
+		pendingSnapshot := pr.PendingSnapshot
+		pr.ResetState(StateProbe)
+		pr.Next = max(pr.Match+1, pendingSnapshot+1)
+	} else {
+		pr.ResetState(StateProbe)
+		pr.Next = pr.Match + 1
+	}
+}
+
+// BecomeReplicate transitions into StateReplicate, resetting Next to Match+1.
+func (pr *Progress) BecomeReplicate() {
+	pr.ResetState(StateReplicate)
+	pr.Next = pr.Match + 1
+}
+
+// BecomeSnapshot moves the Progress to StateSnapshot with the specified pending
+// snapshot index.
+func (pr *Progress) BecomeSnapshot(snapshoti uint64) {
+	pr.ResetState(StateSnapshot)
+	pr.PendingSnapshot = snapshoti
+}
+
+// MaybeUpdate is called when an MsgAppResp arrives from the follower, with the
+// index acked by it. The method returns false if the given n index comes from
+// an outdated message. Otherwise it updates the progress and returns true.
+func (pr *Progress) MaybeUpdate(n uint64) bool {
+	var updated bool
+	if pr.Match < n {
+		pr.Match = n
+		updated = true
+		pr.ProbeAcked()
+	}
+	if pr.Next < n+1 {
+		pr.Next = n + 1
+	}
+	return updated
+}
+
+// OptimisticUpdate signals that appends all the way up to and including index n
+// are in-flight. As a result, Next is increased to n+1.
+func (pr *Progress) OptimisticUpdate(n uint64) { pr.Next = n + 1 }
+
+// MaybeDecrTo adjusts the Progress to the receipt of a MsgApp rejection. The
+// arguments are the index the follower rejected to append to its log, and its
+// last index.
+//
+// Rejections can happen spuriously as messages are sent out of order or
+// duplicated. In such cases, the rejection pertains to an index that the
+// Progress already knows were previously acknowledged, and false is returned
+// without changing the Progress.
+//
+// If the rejection is genuine, Next is lowered sensibly, and the Progress is
+// cleared for sending log entries.
+func (pr *Progress) MaybeDecrTo(rejected, last uint64) bool {
+	if pr.State == StateReplicate {
+		// The rejection must be stale if the progress has matched and "rejected"
+		// is smaller than "match".
+		if rejected <= pr.Match {
+			return false
+		}
+		// Directly decrease next to match + 1.
+		//
+		// TODO(tbg): why not use last if it's larger?
+		pr.Next = pr.Match + 1
+		return true
+	}
+
+	// The rejection must be stale if "rejected" does not match next - 1. This
+	// is because non-replicating followers are probed one entry at a time.
+	if pr.Next-1 != rejected {
+		return false
+	}
+
+	if pr.Next = min(rejected, last+1); pr.Next < 1 {
+		pr.Next = 1
+	}
+	pr.ProbeSent = false
+	return true
+}
+
+// IsPaused returns whether sending log entries to this node has been throttled.
+// This is done when a node has rejected recent MsgApps, is currently waiting
+// for a snapshot, or has reached the MaxInflightMsgs limit. In normal
+// operation, this is false. A throttled node will be contacted less frequently
+// until it has reached a state in which it's able to accept a steady stream of
+// log entries again.
+func (pr *Progress) IsPaused() bool {
+	switch pr.State {
+	case StateProbe:
+		return pr.ProbeSent
+	case StateReplicate:
+		return pr.Inflights.Full()
+	case StateSnapshot:
+		return true
+	default:
+		panic("unexpected state")
+	}
+}
+
+func (pr *Progress) String() string {
+	var buf strings.Builder
+	fmt.Fprintf(&buf, "%s match=%d next=%d", pr.State, pr.Match, pr.Next)
+	if pr.IsLearner {
+		fmt.Fprint(&buf, " learner")
+	}
+	if pr.IsPaused() {
+		fmt.Fprint(&buf, " paused")
+	}
+	if pr.PendingSnapshot > 0 {
+		fmt.Fprintf(&buf, " pendingSnap=%d", pr.PendingSnapshot)
+	}
+	if !pr.RecentActive {
+		fmt.Fprintf(&buf, " inactive")
+	}
+	if n := pr.Inflights.Count(); n > 0 {
+		fmt.Fprintf(&buf, " inflight=%d", n)
+		if pr.Inflights.Full() {
+			fmt.Fprint(&buf, "[full]")
+		}
+	}
+	return buf.String()
+}
+
+// ProgressMap is a map of *Progress.
+type ProgressMap map[uint64]*Progress
+
+// String prints the ProgressMap in sorted key order, one Progress per line.
+func (m ProgressMap) String() string {
+	ids := make([]uint64, 0, len(m))
+	for k := range m {
+		ids = append(ids, k)
+	}
+	sort.Slice(ids, func(i, j int) bool {
+		return ids[i] < ids[j]
+	})
+	var buf strings.Builder
+	for _, id := range ids {
+		fmt.Fprintf(&buf, "%d: %s\n", id, m[id])
+	}
+	return buf.String()
+}