[VOL-4291] Rw-core updates for gRPC migration
Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/github.com/coreos/etcd/raft/progress.go b/vendor/github.com/coreos/etcd/raft/progress.go
new file mode 100644
index 0000000..ef3787d
--- /dev/null
+++ b/vendor/github.com/coreos/etcd/raft/progress.go
@@ -0,0 +1,284 @@
+// Copyright 2015 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 raft
+
+import "fmt"
+
+const (
+ ProgressStateProbe ProgressStateType = iota
+ ProgressStateReplicate
+ ProgressStateSnapshot
+)
+
+type ProgressStateType uint64
+
+var prstmap = [...]string{
+ "ProgressStateProbe",
+ "ProgressStateReplicate",
+ "ProgressStateSnapshot",
+}
+
+func (st ProgressStateType) String() string { return prstmap[uint64(st)] }
+
+// 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.
+type Progress struct {
+ Match, Next uint64
+ // State defines how the leader should interact with the follower.
+ //
+ // When in ProgressStateProbe, leader sends at most one replication message
+ // per heartbeat interval. It also probes actual progress of the follower.
+ //
+ // When in ProgressStateReplicate, 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 ProgressStateSnapshot, leader should have sent out snapshot
+ // before and stops sending any replication message.
+ State ProgressStateType
+
+ // Paused is used in ProgressStateProbe.
+ // When Paused is true, raft should pause sending replication message to this peer.
+ Paused bool
+ // PendingSnapshot is used in ProgressStateSnapshot.
+ // 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.
+ RecentActive 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.freeTo with the index of the last
+ // received entry.
+ ins *inflights
+
+ // IsLearner is true if this progress is tracked for a learner.
+ IsLearner bool
+}
+
+func (pr *Progress) resetState(state ProgressStateType) {
+ pr.Paused = false
+ pr.PendingSnapshot = 0
+ pr.State = state
+ pr.ins.reset()
+}
+
+func (pr *Progress) becomeProbe() {
+ // If the original state is ProgressStateSnapshot, progress knows that
+ // the pending snapshot has been sent to this peer successfully, then
+ // probes from pendingSnapshot + 1.
+ if pr.State == ProgressStateSnapshot {
+ pendingSnapshot := pr.PendingSnapshot
+ pr.resetState(ProgressStateProbe)
+ pr.Next = max(pr.Match+1, pendingSnapshot+1)
+ } else {
+ pr.resetState(ProgressStateProbe)
+ pr.Next = pr.Match + 1
+ }
+}
+
+func (pr *Progress) becomeReplicate() {
+ pr.resetState(ProgressStateReplicate)
+ pr.Next = pr.Match + 1
+}
+
+func (pr *Progress) becomeSnapshot(snapshoti uint64) {
+ pr.resetState(ProgressStateSnapshot)
+ pr.PendingSnapshot = snapshoti
+}
+
+// maybeUpdate 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.resume()
+ }
+ if pr.Next < n+1 {
+ pr.Next = n + 1
+ }
+ return updated
+}
+
+func (pr *Progress) optimisticUpdate(n uint64) { pr.Next = n + 1 }
+
+// maybeDecrTo returns false if the given to index comes from an out of order message.
+// Otherwise it decreases the progress next index to min(rejected, last) and returns true.
+func (pr *Progress) maybeDecrTo(rejected, last uint64) bool {
+ if pr.State == ProgressStateReplicate {
+ // 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
+ pr.Next = pr.Match + 1
+ return true
+ }
+
+ // the rejection must be stale if "rejected" does not match next - 1
+ if pr.Next-1 != rejected {
+ return false
+ }
+
+ if pr.Next = min(rejected, last+1); pr.Next < 1 {
+ pr.Next = 1
+ }
+ pr.resume()
+ return true
+}
+
+func (pr *Progress) pause() { pr.Paused = true }
+func (pr *Progress) resume() { pr.Paused = false }
+
+// IsPaused returns whether sending log entries to this node has been
+// paused. A node may be paused because it has rejected recent
+// MsgApps, is currently waiting for a snapshot, or has reached the
+// MaxInflightMsgs limit.
+func (pr *Progress) IsPaused() bool {
+ switch pr.State {
+ case ProgressStateProbe:
+ return pr.Paused
+ case ProgressStateReplicate:
+ return pr.ins.full()
+ case ProgressStateSnapshot:
+ return true
+ default:
+ panic("unexpected state")
+ }
+}
+
+func (pr *Progress) snapshotFailure() { pr.PendingSnapshot = 0 }
+
+// needSnapshotAbort returns true if snapshot progress's Match
+// is equal or higher than the pendingSnapshot.
+func (pr *Progress) needSnapshotAbort() bool {
+ return pr.State == ProgressStateSnapshot && pr.Match >= pr.PendingSnapshot
+}
+
+func (pr *Progress) String() string {
+ return fmt.Sprintf("next = %d, match = %d, state = %s, waiting = %v, pendingSnapshot = %d", pr.Next, pr.Match, pr.State, pr.IsPaused(), pr.PendingSnapshot)
+}
+
+type inflights struct {
+ // the starting index in the buffer
+ start int
+ // number of inflights in the buffer
+ count int
+
+ // the size of the buffer
+ size int
+
+ // buffer contains the index of the last entry
+ // inside one message.
+ buffer []uint64
+}
+
+func newInflights(size int) *inflights {
+ return &inflights{
+ size: size,
+ }
+}
+
+// add adds an inflight into inflights
+func (in *inflights) add(inflight uint64) {
+ if in.full() {
+ panic("cannot add into a full inflights")
+ }
+ next := in.start + in.count
+ size := in.size
+ if next >= size {
+ next -= size
+ }
+ if next >= len(in.buffer) {
+ in.growBuf()
+ }
+ in.buffer[next] = inflight
+ in.count++
+}
+
+// grow the inflight buffer by doubling up to inflights.size. We grow on demand
+// instead of preallocating to inflights.size to handle systems which have
+// thousands of Raft groups per process.
+func (in *inflights) growBuf() {
+ newSize := len(in.buffer) * 2
+ if newSize == 0 {
+ newSize = 1
+ } else if newSize > in.size {
+ newSize = in.size
+ }
+ newBuffer := make([]uint64, newSize)
+ copy(newBuffer, in.buffer)
+ in.buffer = newBuffer
+}
+
+// freeTo frees the inflights smaller or equal to the given `to` flight.
+func (in *inflights) freeTo(to uint64) {
+ if in.count == 0 || to < in.buffer[in.start] {
+ // out of the left side of the window
+ return
+ }
+
+ idx := in.start
+ var i int
+ for i = 0; i < in.count; i++ {
+ if to < in.buffer[idx] { // found the first large inflight
+ break
+ }
+
+ // increase index and maybe rotate
+ size := in.size
+ if idx++; idx >= size {
+ idx -= size
+ }
+ }
+ // free i inflights and set new start index
+ in.count -= i
+ in.start = idx
+ if in.count == 0 {
+ // inflights is empty, reset the start index so that we don't grow the
+ // buffer unnecessarily.
+ in.start = 0
+ }
+}
+
+func (in *inflights) freeFirstOne() { in.freeTo(in.buffer[in.start]) }
+
+// full returns true if the inflights is full.
+func (in *inflights) full() bool {
+ return in.count == in.size
+}
+
+// resets frees all inflights.
+func (in *inflights) reset() {
+ in.count = 0
+ in.start = 0
+}