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// 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package raft
import (
pb ""
// ErrStepLocalMsg is returned when try to step a local raft message
var ErrStepLocalMsg = errors.New("raft: cannot step raft local message")
// ErrStepPeerNotFound is returned when try to step a response message
// but there is no peer found in raft.prs for that node.
var ErrStepPeerNotFound = errors.New("raft: cannot step as peer not found")
// RawNode is a thread-unsafe Node.
// The methods of this struct correspond to the methods of Node and are described
// more fully there.
type RawNode struct {
raft *raft
prevSoftSt *SoftState
prevHardSt pb.HardState
// NewRawNode instantiates a RawNode from the given configuration.
// See Bootstrap() for bootstrapping an initial state; this replaces the former
// 'peers' argument to this method (with identical behavior). However, It is
// recommended that instead of calling Bootstrap, applications bootstrap their
// state manually by setting up a Storage that has a first index > 1 and which
// stores the desired ConfState as its InitialState.
func NewRawNode(config *Config) (*RawNode, error) {
r := newRaft(config)
rn := &RawNode{
raft: r,
rn.prevSoftSt = r.softState()
rn.prevHardSt = r.hardState()
return rn, nil
// Tick advances the internal logical clock by a single tick.
func (rn *RawNode) Tick() {
// TickQuiesced advances the internal logical clock by a single tick without
// performing any other state machine processing. It allows the caller to avoid
// periodic heartbeats and elections when all of the peers in a Raft group are
// known to be at the same state. Expected usage is to periodically invoke Tick
// or TickQuiesced depending on whether the group is "active" or "quiesced".
// WARNING: Be very careful about using this method as it subverts the Raft
// state machine. You should probably be using Tick instead.
func (rn *RawNode) TickQuiesced() {
// Campaign causes this RawNode to transition to candidate state.
func (rn *RawNode) Campaign() error {
return rn.raft.Step(pb.Message{
Type: pb.MsgHup,
// Propose proposes data be appended to the raft log.
func (rn *RawNode) Propose(data []byte) error {
return rn.raft.Step(pb.Message{
Type: pb.MsgProp,
Entries: []pb.Entry{
{Data: data},
// ProposeConfChange proposes a config change. See (Node).ProposeConfChange for
// details.
func (rn *RawNode) ProposeConfChange(cc pb.ConfChangeI) error {
m, err := confChangeToMsg(cc)
if err != nil {
return err
return rn.raft.Step(m)
// ApplyConfChange applies a config change to the local node.
func (rn *RawNode) ApplyConfChange(cc pb.ConfChangeI) *pb.ConfState {
cs := rn.raft.applyConfChange(cc.AsV2())
return &cs
// Step advances the state machine using the given message.
func (rn *RawNode) Step(m pb.Message) error {
// ignore unexpected local messages receiving over network
if IsLocalMsg(m.Type) {
return ErrStepLocalMsg
if pr := rn.raft.prs.Progress[m.From]; pr != nil || !IsResponseMsg(m.Type) {
return rn.raft.Step(m)
return ErrStepPeerNotFound
// Ready returns the outstanding work that the application needs to handle. This
// includes appending and applying entries or a snapshot, updating the HardState,
// and sending messages. The returned Ready() *must* be handled and subsequently
// passed back via Advance().
func (rn *RawNode) Ready() Ready {
rd := rn.readyWithoutAccept()
return rd
// readyWithoutAccept returns a Ready. This is a read-only operation, i.e. there
// is no obligation that the Ready must be handled.
func (rn *RawNode) readyWithoutAccept() Ready {
return newReady(rn.raft, rn.prevSoftSt, rn.prevHardSt)
// acceptReady is called when the consumer of the RawNode has decided to go
// ahead and handle a Ready. Nothing must alter the state of the RawNode between
// this call and the prior call to Ready().
func (rn *RawNode) acceptReady(rd Ready) {
if rd.SoftState != nil {
rn.prevSoftSt = rd.SoftState
if len(rd.ReadStates) != 0 {
rn.raft.readStates = nil
rn.raft.msgs = nil
// HasReady called when RawNode user need to check if any Ready pending.
// Checking logic in this method should be consistent with Ready.containsUpdates().
func (rn *RawNode) HasReady() bool {
r := rn.raft
if !r.softState().equal(rn.prevSoftSt) {
return true
if hardSt := r.hardState(); !IsEmptyHardState(hardSt) && !isHardStateEqual(hardSt, rn.prevHardSt) {
return true
if r.raftLog.unstable.snapshot != nil && !IsEmptySnap(*r.raftLog.unstable.snapshot) {
return true
if len(r.msgs) > 0 || len(r.raftLog.unstableEntries()) > 0 || r.raftLog.hasNextEnts() {
return true
if len(r.readStates) != 0 {
return true
return false
// Advance notifies the RawNode that the application has applied and saved progress in the
// last Ready results.
func (rn *RawNode) Advance(rd Ready) {
if !IsEmptyHardState(rd.HardState) {
rn.prevHardSt = rd.HardState
// Status returns the current status of the given group. This allocates, see
// BasicStatus and WithProgress for allocation-friendlier choices.
func (rn *RawNode) Status() Status {
status := getStatus(rn.raft)
return status
// BasicStatus returns a BasicStatus. Notably this does not contain the
// Progress map; see WithProgress for an allocation-free way to inspect it.
func (rn *RawNode) BasicStatus() BasicStatus {
return getBasicStatus(rn.raft)
// ProgressType indicates the type of replica a Progress corresponds to.
type ProgressType byte
const (
// ProgressTypePeer accompanies a Progress for a regular peer replica.
ProgressTypePeer ProgressType = iota
// ProgressTypeLearner accompanies a Progress for a learner replica.
// WithProgress is a helper to introspect the Progress for this node and its
// peers.
func (rn *RawNode) WithProgress(visitor func(id uint64, typ ProgressType, pr tracker.Progress)) {
rn.raft.prs.Visit(func(id uint64, pr *tracker.Progress) {
typ := ProgressTypePeer
if pr.IsLearner {
typ = ProgressTypeLearner
p := *pr
p.Inflights = nil
visitor(id, typ, p)
// ReportUnreachable reports the given node is not reachable for the last send.
func (rn *RawNode) ReportUnreachable(id uint64) {
_ = rn.raft.Step(pb.Message{Type: pb.MsgUnreachable, From: id})
// ReportSnapshot reports the status of the sent snapshot.
func (rn *RawNode) ReportSnapshot(id uint64, status SnapshotStatus) {
rej := status == SnapshotFailure
_ = rn.raft.Step(pb.Message{Type: pb.MsgSnapStatus, From: id, Reject: rej})
// TransferLeader tries to transfer leadership to the given transferee.
func (rn *RawNode) TransferLeader(transferee uint64) {
_ = rn.raft.Step(pb.Message{Type: pb.MsgTransferLeader, From: transferee})
// ReadIndex requests a read state. The read state will be set in ready.
// Read State has a read index. Once the application advances further than the read
// index, any linearizable read requests issued before the read request can be
// processed safely. The read state will have the same rctx attached.
func (rn *RawNode) ReadIndex(rctx []byte) {
_ = rn.raft.Step(pb.Message{Type: pb.MsgReadIndex, Entries: []pb.Entry{{Data: rctx}}})