1451 lines
47 KiB
Go
1451 lines
47 KiB
Go
// Copyright 2015 The etcd Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package raft
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import (
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"bytes"
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"errors"
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"fmt"
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"math"
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"math/rand"
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"sort"
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"strings"
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"sync"
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"time"
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pb "github.com/coreos/etcd/raft/raftpb"
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)
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// None is a placeholder node ID used when there is no leader.
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const None uint64 = 0
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const noLimit = math.MaxUint64
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// Possible values for StateType.
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const (
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StateFollower StateType = iota
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StateCandidate
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StateLeader
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StatePreCandidate
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numStates
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)
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type ReadOnlyOption int
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const (
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// ReadOnlySafe guarantees the linearizability of the read only request by
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// communicating with the quorum. It is the default and suggested option.
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ReadOnlySafe ReadOnlyOption = iota
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// ReadOnlyLeaseBased ensures linearizability of the read only request by
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// relying on the leader lease. It can be affected by clock drift.
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// If the clock drift is unbounded, leader might keep the lease longer than it
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// should (clock can move backward/pause without any bound). ReadIndex is not safe
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// in that case.
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ReadOnlyLeaseBased
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)
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// Possible values for CampaignType
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const (
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// campaignPreElection represents the first phase of a normal election when
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// Config.PreVote is true.
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campaignPreElection CampaignType = "CampaignPreElection"
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// campaignElection represents a normal (time-based) election (the second phase
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// of the election when Config.PreVote is true).
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campaignElection CampaignType = "CampaignElection"
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// campaignTransfer represents the type of leader transfer
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campaignTransfer CampaignType = "CampaignTransfer"
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)
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// ErrProposalDropped is returned when the proposal is ignored by some cases,
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// so that the proposer can be notified and fail fast.
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var ErrProposalDropped = errors.New("raft proposal dropped")
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// lockedRand is a small wrapper around rand.Rand to provide
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// synchronization. Only the methods needed by the code are exposed
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// (e.g. Intn).
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type lockedRand struct {
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mu sync.Mutex
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rand *rand.Rand
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}
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func (r *lockedRand) Intn(n int) int {
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r.mu.Lock()
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v := r.rand.Intn(n)
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r.mu.Unlock()
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return v
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}
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var globalRand = &lockedRand{
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rand: rand.New(rand.NewSource(time.Now().UnixNano())),
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}
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// CampaignType represents the type of campaigning
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// the reason we use the type of string instead of uint64
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// is because it's simpler to compare and fill in raft entries
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type CampaignType string
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// StateType represents the role of a node in a cluster.
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type StateType uint64
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var stmap = [...]string{
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"StateFollower",
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"StateCandidate",
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"StateLeader",
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"StatePreCandidate",
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}
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func (st StateType) String() string {
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return stmap[uint64(st)]
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}
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// Config contains the parameters to start a raft.
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type Config struct {
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// ID is the identity of the local raft. ID cannot be 0.
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ID uint64
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// peers contains the IDs of all nodes (including self) in the raft cluster. It
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// should only be set when starting a new raft cluster. Restarting raft from
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// previous configuration will panic if peers is set. peer is private and only
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// used for testing right now.
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peers []uint64
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// learners contains the IDs of all learner nodes (including self if the
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// local node is a learner) in the raft cluster. learners only receives
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// entries from the leader node. It does not vote or promote itself.
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learners []uint64
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// ElectionTick is the number of Node.Tick invocations that must pass between
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// elections. That is, if a follower does not receive any message from the
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// leader of current term before ElectionTick has elapsed, it will become
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// candidate and start an election. ElectionTick must be greater than
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// HeartbeatTick. We suggest ElectionTick = 10 * HeartbeatTick to avoid
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// unnecessary leader switching.
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ElectionTick int
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// HeartbeatTick is the number of Node.Tick invocations that must pass between
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// heartbeats. That is, a leader sends heartbeat messages to maintain its
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// leadership every HeartbeatTick ticks.
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HeartbeatTick int
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// Storage is the storage for raft. raft generates entries and states to be
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// stored in storage. raft reads the persisted entries and states out of
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// Storage when it needs. raft reads out the previous state and configuration
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// out of storage when restarting.
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Storage Storage
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// Applied is the last applied index. It should only be set when restarting
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// raft. raft will not return entries to the application smaller or equal to
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// Applied. If Applied is unset when restarting, raft might return previous
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// applied entries. This is a very application dependent configuration.
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Applied uint64
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// MaxSizePerMsg limits the max size of each append message. Smaller value
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// lowers the raft recovery cost(initial probing and message lost during normal
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// operation). On the other side, it might affect the throughput during normal
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// replication. Note: math.MaxUint64 for unlimited, 0 for at most one entry per
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// message.
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MaxSizePerMsg uint64
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// MaxInflightMsgs limits the max number of in-flight append messages during
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// optimistic replication phase. The application transportation layer usually
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// has its own sending buffer over TCP/UDP. Setting MaxInflightMsgs to avoid
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// overflowing that sending buffer. TODO (xiangli): feedback to application to
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// limit the proposal rate?
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MaxInflightMsgs int
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// CheckQuorum specifies if the leader should check quorum activity. Leader
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// steps down when quorum is not active for an electionTimeout.
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CheckQuorum bool
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// PreVote enables the Pre-Vote algorithm described in raft thesis section
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// 9.6. This prevents disruption when a node that has been partitioned away
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// rejoins the cluster.
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PreVote bool
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// ReadOnlyOption specifies how the read only request is processed.
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//
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// ReadOnlySafe guarantees the linearizability of the read only request by
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// communicating with the quorum. It is the default and suggested option.
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//
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// ReadOnlyLeaseBased ensures linearizability of the read only request by
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// relying on the leader lease. It can be affected by clock drift.
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// If the clock drift is unbounded, leader might keep the lease longer than it
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// should (clock can move backward/pause without any bound). ReadIndex is not safe
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// in that case.
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// CheckQuorum MUST be enabled if ReadOnlyOption is ReadOnlyLeaseBased.
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ReadOnlyOption ReadOnlyOption
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// Logger is the logger used for raft log. For multinode which can host
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// multiple raft group, each raft group can have its own logger
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Logger Logger
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// DisableProposalForwarding set to true means that followers will drop
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// proposals, rather than forwarding them to the leader. One use case for
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// this feature would be in a situation where the Raft leader is used to
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// compute the data of a proposal, for example, adding a timestamp from a
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// hybrid logical clock to data in a monotonically increasing way. Forwarding
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// should be disabled to prevent a follower with an inaccurate hybrid
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// logical clock from assigning the timestamp and then forwarding the data
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// to the leader.
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DisableProposalForwarding bool
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}
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func (c *Config) validate() error {
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if c.ID == None {
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return errors.New("cannot use none as id")
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}
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if c.HeartbeatTick <= 0 {
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return errors.New("heartbeat tick must be greater than 0")
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}
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if c.ElectionTick <= c.HeartbeatTick {
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return errors.New("election tick must be greater than heartbeat tick")
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}
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if c.Storage == nil {
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return errors.New("storage cannot be nil")
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}
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if c.MaxInflightMsgs <= 0 {
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return errors.New("max inflight messages must be greater than 0")
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}
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if c.Logger == nil {
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c.Logger = raftLogger
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}
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if c.ReadOnlyOption == ReadOnlyLeaseBased && !c.CheckQuorum {
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return errors.New("CheckQuorum must be enabled when ReadOnlyOption is ReadOnlyLeaseBased")
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}
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return nil
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}
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type raft struct {
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id uint64
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Term uint64
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Vote uint64
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readStates []ReadState
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// the log
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raftLog *raftLog
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maxInflight int
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maxMsgSize uint64
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prs map[uint64]*Progress
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learnerPrs map[uint64]*Progress
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state StateType
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// isLearner is true if the local raft node is a learner.
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isLearner bool
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votes map[uint64]bool
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msgs []pb.Message
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// the leader id
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lead uint64
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// leadTransferee is id of the leader transfer target when its value is not zero.
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// Follow the procedure defined in raft thesis 3.10.
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leadTransferee uint64
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// Only one conf change may be pending (in the log, but not yet
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// applied) at a time. This is enforced via pendingConfIndex, which
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// is set to a value >= the log index of the latest pending
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// configuration change (if any). Config changes are only allowed to
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// be proposed if the leader's applied index is greater than this
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// value.
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pendingConfIndex uint64
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readOnly *readOnly
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// number of ticks since it reached last electionTimeout when it is leader
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// or candidate.
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// number of ticks since it reached last electionTimeout or received a
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// valid message from current leader when it is a follower.
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electionElapsed int
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// number of ticks since it reached last heartbeatTimeout.
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// only leader keeps heartbeatElapsed.
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heartbeatElapsed int
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checkQuorum bool
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preVote bool
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heartbeatTimeout int
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electionTimeout int
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// randomizedElectionTimeout is a random number between
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// [electiontimeout, 2 * electiontimeout - 1]. It gets reset
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// when raft changes its state to follower or candidate.
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randomizedElectionTimeout int
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disableProposalForwarding bool
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tick func()
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step stepFunc
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logger Logger
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}
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func newRaft(c *Config) *raft {
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if err := c.validate(); err != nil {
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panic(err.Error())
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}
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raftlog := newLog(c.Storage, c.Logger)
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hs, cs, err := c.Storage.InitialState()
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if err != nil {
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panic(err) // TODO(bdarnell)
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}
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peers := c.peers
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learners := c.learners
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if len(cs.Nodes) > 0 || len(cs.Learners) > 0 {
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if len(peers) > 0 || len(learners) > 0 {
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// TODO(bdarnell): the peers argument is always nil except in
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// tests; the argument should be removed and these tests should be
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// updated to specify their nodes through a snapshot.
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panic("cannot specify both newRaft(peers, learners) and ConfState.(Nodes, Learners)")
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}
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peers = cs.Nodes
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learners = cs.Learners
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}
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r := &raft{
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id: c.ID,
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lead: None,
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isLearner: false,
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raftLog: raftlog,
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maxMsgSize: c.MaxSizePerMsg,
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maxInflight: c.MaxInflightMsgs,
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prs: make(map[uint64]*Progress),
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learnerPrs: make(map[uint64]*Progress),
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electionTimeout: c.ElectionTick,
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heartbeatTimeout: c.HeartbeatTick,
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logger: c.Logger,
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checkQuorum: c.CheckQuorum,
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preVote: c.PreVote,
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readOnly: newReadOnly(c.ReadOnlyOption),
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disableProposalForwarding: c.DisableProposalForwarding,
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}
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for _, p := range peers {
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r.prs[p] = &Progress{Next: 1, ins: newInflights(r.maxInflight)}
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}
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for _, p := range learners {
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if _, ok := r.prs[p]; ok {
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panic(fmt.Sprintf("node %x is in both learner and peer list", p))
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}
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r.learnerPrs[p] = &Progress{Next: 1, ins: newInflights(r.maxInflight), IsLearner: true}
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if r.id == p {
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r.isLearner = true
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}
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}
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if !isHardStateEqual(hs, emptyState) {
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r.loadState(hs)
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}
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if c.Applied > 0 {
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raftlog.appliedTo(c.Applied)
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}
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r.becomeFollower(r.Term, None)
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var nodesStrs []string
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for _, n := range r.nodes() {
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nodesStrs = append(nodesStrs, fmt.Sprintf("%x", n))
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}
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r.logger.Infof("newRaft %x [peers: [%s], term: %d, commit: %d, applied: %d, lastindex: %d, lastterm: %d]",
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r.id, strings.Join(nodesStrs, ","), r.Term, r.raftLog.committed, r.raftLog.applied, r.raftLog.lastIndex(), r.raftLog.lastTerm())
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return r
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}
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func (r *raft) hasLeader() bool { return r.lead != None }
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func (r *raft) softState() *SoftState { return &SoftState{Lead: r.lead, RaftState: r.state} }
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func (r *raft) hardState() pb.HardState {
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return pb.HardState{
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Term: r.Term,
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Vote: r.Vote,
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Commit: r.raftLog.committed,
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}
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}
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func (r *raft) quorum() int { return len(r.prs)/2 + 1 }
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func (r *raft) nodes() []uint64 {
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nodes := make([]uint64, 0, len(r.prs))
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for id := range r.prs {
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nodes = append(nodes, id)
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}
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sort.Sort(uint64Slice(nodes))
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return nodes
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}
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func (r *raft) learnerNodes() []uint64 {
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nodes := make([]uint64, 0, len(r.learnerPrs))
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for id := range r.learnerPrs {
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nodes = append(nodes, id)
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}
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sort.Sort(uint64Slice(nodes))
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return nodes
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}
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// send persists state to stable storage and then sends to its mailbox.
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func (r *raft) send(m pb.Message) {
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m.From = r.id
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if m.Type == pb.MsgVote || m.Type == pb.MsgVoteResp || m.Type == pb.MsgPreVote || m.Type == pb.MsgPreVoteResp {
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if m.Term == 0 {
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// All {pre-,}campaign messages need to have the term set when
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// sending.
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// - MsgVote: m.Term is the term the node is campaigning for,
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// non-zero as we increment the term when campaigning.
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// - MsgVoteResp: m.Term is the new r.Term if the MsgVote was
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// granted, non-zero for the same reason MsgVote is
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// - MsgPreVote: m.Term is the term the node will campaign,
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// non-zero as we use m.Term to indicate the next term we'll be
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// campaigning for
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// - MsgPreVoteResp: m.Term is the term received in the original
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// MsgPreVote if the pre-vote was granted, non-zero for the
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// same reasons MsgPreVote is
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panic(fmt.Sprintf("term should be set when sending %s", m.Type))
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}
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} else {
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if m.Term != 0 {
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panic(fmt.Sprintf("term should not be set when sending %s (was %d)", m.Type, m.Term))
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}
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// do not attach term to MsgProp, MsgReadIndex
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// proposals are a way to forward to the leader and
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// should be treated as local message.
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// MsgReadIndex is also forwarded to leader.
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if m.Type != pb.MsgProp && m.Type != pb.MsgReadIndex {
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m.Term = r.Term
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}
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}
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r.msgs = append(r.msgs, m)
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}
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func (r *raft) getProgress(id uint64) *Progress {
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if pr, ok := r.prs[id]; ok {
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return pr
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}
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return r.learnerPrs[id]
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}
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// sendAppend sends RPC, with entries to the given peer.
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func (r *raft) sendAppend(to uint64) {
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pr := r.getProgress(to)
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if pr.IsPaused() {
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return
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}
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m := pb.Message{}
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m.To = to
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term, errt := r.raftLog.term(pr.Next - 1)
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ents, erre := r.raftLog.entries(pr.Next, r.maxMsgSize)
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if errt != nil || erre != nil { // send snapshot if we failed to get term or entries
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if !pr.RecentActive {
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r.logger.Debugf("ignore sending snapshot to %x since it is not recently active", to)
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return
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}
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m.Type = pb.MsgSnap
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snapshot, err := r.raftLog.snapshot()
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if err != nil {
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if err == ErrSnapshotTemporarilyUnavailable {
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r.logger.Debugf("%x failed to send snapshot to %x because snapshot is temporarily unavailable", r.id, to)
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return
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}
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panic(err) // TODO(bdarnell)
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}
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if IsEmptySnap(snapshot) {
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panic("need non-empty snapshot")
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}
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m.Snapshot = snapshot
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sindex, sterm := snapshot.Metadata.Index, snapshot.Metadata.Term
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r.logger.Debugf("%x [firstindex: %d, commit: %d] sent snapshot[index: %d, term: %d] to %x [%s]",
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r.id, r.raftLog.firstIndex(), r.raftLog.committed, sindex, sterm, to, pr)
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pr.becomeSnapshot(sindex)
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r.logger.Debugf("%x paused sending replication messages to %x [%s]", r.id, to, pr)
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} else {
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m.Type = pb.MsgApp
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m.Index = pr.Next - 1
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m.LogTerm = term
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m.Entries = ents
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m.Commit = r.raftLog.committed
|
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if n := len(m.Entries); n != 0 {
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switch pr.State {
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// optimistically increase the next when in ProgressStateReplicate
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case ProgressStateReplicate:
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last := m.Entries[n-1].Index
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pr.optimisticUpdate(last)
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pr.ins.add(last)
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case ProgressStateProbe:
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pr.pause()
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default:
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r.logger.Panicf("%x is sending append in unhandled state %s", r.id, pr.State)
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}
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}
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}
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r.send(m)
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}
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|
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// sendHeartbeat sends an empty MsgApp
|
|
func (r *raft) sendHeartbeat(to uint64, ctx []byte) {
|
|
// Attach the commit as min(to.matched, r.committed).
|
|
// When the leader sends out heartbeat message,
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// the receiver(follower) might not be matched with the leader
|
|
// or it might not have all the committed entries.
|
|
// The leader MUST NOT forward the follower's commit to
|
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// an unmatched index.
|
|
commit := min(r.getProgress(to).Match, r.raftLog.committed)
|
|
m := pb.Message{
|
|
To: to,
|
|
Type: pb.MsgHeartbeat,
|
|
Commit: commit,
|
|
Context: ctx,
|
|
}
|
|
|
|
r.send(m)
|
|
}
|
|
|
|
func (r *raft) forEachProgress(f func(id uint64, pr *Progress)) {
|
|
for id, pr := range r.prs {
|
|
f(id, pr)
|
|
}
|
|
|
|
for id, pr := range r.learnerPrs {
|
|
f(id, pr)
|
|
}
|
|
}
|
|
|
|
// bcastAppend sends RPC, with entries to all peers that are not up-to-date
|
|
// according to the progress recorded in r.prs.
|
|
func (r *raft) bcastAppend() {
|
|
r.forEachProgress(func(id uint64, _ *Progress) {
|
|
if id == r.id {
|
|
return
|
|
}
|
|
|
|
r.sendAppend(id)
|
|
})
|
|
}
|
|
|
|
// bcastHeartbeat sends RPC, without entries to all the peers.
|
|
func (r *raft) bcastHeartbeat() {
|
|
lastCtx := r.readOnly.lastPendingRequestCtx()
|
|
if len(lastCtx) == 0 {
|
|
r.bcastHeartbeatWithCtx(nil)
|
|
} else {
|
|
r.bcastHeartbeatWithCtx([]byte(lastCtx))
|
|
}
|
|
}
|
|
|
|
func (r *raft) bcastHeartbeatWithCtx(ctx []byte) {
|
|
r.forEachProgress(func(id uint64, _ *Progress) {
|
|
if id == r.id {
|
|
return
|
|
}
|
|
r.sendHeartbeat(id, ctx)
|
|
})
|
|
}
|
|
|
|
// maybeCommit attempts to advance the commit index. Returns true if
|
|
// the commit index changed (in which case the caller should call
|
|
// r.bcastAppend).
|
|
func (r *raft) maybeCommit() bool {
|
|
// TODO(bmizerany): optimize.. Currently naive
|
|
mis := make(uint64Slice, 0, len(r.prs))
|
|
for _, p := range r.prs {
|
|
mis = append(mis, p.Match)
|
|
}
|
|
sort.Sort(sort.Reverse(mis))
|
|
mci := mis[r.quorum()-1]
|
|
return r.raftLog.maybeCommit(mci, r.Term)
|
|
}
|
|
|
|
func (r *raft) reset(term uint64) {
|
|
if r.Term != term {
|
|
r.Term = term
|
|
r.Vote = None
|
|
}
|
|
r.lead = None
|
|
|
|
r.electionElapsed = 0
|
|
r.heartbeatElapsed = 0
|
|
r.resetRandomizedElectionTimeout()
|
|
|
|
r.abortLeaderTransfer()
|
|
|
|
r.votes = make(map[uint64]bool)
|
|
r.forEachProgress(func(id uint64, pr *Progress) {
|
|
*pr = Progress{Next: r.raftLog.lastIndex() + 1, ins: newInflights(r.maxInflight), IsLearner: pr.IsLearner}
|
|
if id == r.id {
|
|
pr.Match = r.raftLog.lastIndex()
|
|
}
|
|
})
|
|
|
|
r.pendingConfIndex = 0
|
|
r.readOnly = newReadOnly(r.readOnly.option)
|
|
}
|
|
|
|
func (r *raft) appendEntry(es ...pb.Entry) {
|
|
li := r.raftLog.lastIndex()
|
|
for i := range es {
|
|
es[i].Term = r.Term
|
|
es[i].Index = li + 1 + uint64(i)
|
|
}
|
|
// use latest "last" index after truncate/append
|
|
li = r.raftLog.append(es...)
|
|
r.getProgress(r.id).maybeUpdate(li)
|
|
// Regardless of maybeCommit's return, our caller will call bcastAppend.
|
|
r.maybeCommit()
|
|
}
|
|
|
|
// tickElection is run by followers and candidates after r.electionTimeout.
|
|
func (r *raft) tickElection() {
|
|
r.electionElapsed++
|
|
|
|
if r.promotable() && r.pastElectionTimeout() {
|
|
r.electionElapsed = 0
|
|
r.Step(pb.Message{From: r.id, Type: pb.MsgHup})
|
|
}
|
|
}
|
|
|
|
// tickHeartbeat is run by leaders to send a MsgBeat after r.heartbeatTimeout.
|
|
func (r *raft) tickHeartbeat() {
|
|
r.heartbeatElapsed++
|
|
r.electionElapsed++
|
|
|
|
if r.electionElapsed >= r.electionTimeout {
|
|
r.electionElapsed = 0
|
|
if r.checkQuorum {
|
|
r.Step(pb.Message{From: r.id, Type: pb.MsgCheckQuorum})
|
|
}
|
|
// If current leader cannot transfer leadership in electionTimeout, it becomes leader again.
|
|
if r.state == StateLeader && r.leadTransferee != None {
|
|
r.abortLeaderTransfer()
|
|
}
|
|
}
|
|
|
|
if r.state != StateLeader {
|
|
return
|
|
}
|
|
|
|
if r.heartbeatElapsed >= r.heartbeatTimeout {
|
|
r.heartbeatElapsed = 0
|
|
r.Step(pb.Message{From: r.id, Type: pb.MsgBeat})
|
|
}
|
|
}
|
|
|
|
func (r *raft) becomeFollower(term uint64, lead uint64) {
|
|
r.step = stepFollower
|
|
r.reset(term)
|
|
r.tick = r.tickElection
|
|
r.lead = lead
|
|
r.state = StateFollower
|
|
r.logger.Infof("%x became follower at term %d", r.id, r.Term)
|
|
}
|
|
|
|
func (r *raft) becomeCandidate() {
|
|
// TODO(xiangli) remove the panic when the raft implementation is stable
|
|
if r.state == StateLeader {
|
|
panic("invalid transition [leader -> candidate]")
|
|
}
|
|
r.step = stepCandidate
|
|
r.reset(r.Term + 1)
|
|
r.tick = r.tickElection
|
|
r.Vote = r.id
|
|
r.state = StateCandidate
|
|
r.logger.Infof("%x became candidate at term %d", r.id, r.Term)
|
|
}
|
|
|
|
func (r *raft) becomePreCandidate() {
|
|
// TODO(xiangli) remove the panic when the raft implementation is stable
|
|
if r.state == StateLeader {
|
|
panic("invalid transition [leader -> pre-candidate]")
|
|
}
|
|
// Becoming a pre-candidate changes our step functions and state,
|
|
// but doesn't change anything else. In particular it does not increase
|
|
// r.Term or change r.Vote.
|
|
r.step = stepCandidate
|
|
r.votes = make(map[uint64]bool)
|
|
r.tick = r.tickElection
|
|
r.state = StatePreCandidate
|
|
r.logger.Infof("%x became pre-candidate at term %d", r.id, r.Term)
|
|
}
|
|
|
|
func (r *raft) becomeLeader() {
|
|
// TODO(xiangli) remove the panic when the raft implementation is stable
|
|
if r.state == StateFollower {
|
|
panic("invalid transition [follower -> leader]")
|
|
}
|
|
r.step = stepLeader
|
|
r.reset(r.Term)
|
|
r.tick = r.tickHeartbeat
|
|
r.lead = r.id
|
|
r.state = StateLeader
|
|
ents, err := r.raftLog.entries(r.raftLog.committed+1, noLimit)
|
|
if err != nil {
|
|
r.logger.Panicf("unexpected error getting uncommitted entries (%v)", err)
|
|
}
|
|
|
|
// Conservatively set the pendingConfIndex to the last index in the
|
|
// log. There may or may not be a pending config change, but it's
|
|
// safe to delay any future proposals until we commit all our
|
|
// pending log entries, and scanning the entire tail of the log
|
|
// could be expensive.
|
|
if len(ents) > 0 {
|
|
r.pendingConfIndex = ents[len(ents)-1].Index
|
|
}
|
|
|
|
r.appendEntry(pb.Entry{Data: nil})
|
|
r.logger.Infof("%x became leader at term %d", r.id, r.Term)
|
|
}
|
|
|
|
func (r *raft) campaign(t CampaignType) {
|
|
var term uint64
|
|
var voteMsg pb.MessageType
|
|
if t == campaignPreElection {
|
|
r.becomePreCandidate()
|
|
voteMsg = pb.MsgPreVote
|
|
// PreVote RPCs are sent for the next term before we've incremented r.Term.
|
|
term = r.Term + 1
|
|
} else {
|
|
r.becomeCandidate()
|
|
voteMsg = pb.MsgVote
|
|
term = r.Term
|
|
}
|
|
if r.quorum() == r.poll(r.id, voteRespMsgType(voteMsg), true) {
|
|
// We won the election after voting for ourselves (which must mean that
|
|
// this is a single-node cluster). Advance to the next state.
|
|
if t == campaignPreElection {
|
|
r.campaign(campaignElection)
|
|
} else {
|
|
r.becomeLeader()
|
|
}
|
|
return
|
|
}
|
|
for id := range r.prs {
|
|
if id == r.id {
|
|
continue
|
|
}
|
|
r.logger.Infof("%x [logterm: %d, index: %d] sent %s request to %x at term %d",
|
|
r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), voteMsg, id, r.Term)
|
|
|
|
var ctx []byte
|
|
if t == campaignTransfer {
|
|
ctx = []byte(t)
|
|
}
|
|
r.send(pb.Message{Term: term, To: id, Type: voteMsg, Index: r.raftLog.lastIndex(), LogTerm: r.raftLog.lastTerm(), Context: ctx})
|
|
}
|
|
}
|
|
|
|
func (r *raft) poll(id uint64, t pb.MessageType, v bool) (granted int) {
|
|
if v {
|
|
r.logger.Infof("%x received %s from %x at term %d", r.id, t, id, r.Term)
|
|
} else {
|
|
r.logger.Infof("%x received %s rejection from %x at term %d", r.id, t, id, r.Term)
|
|
}
|
|
if _, ok := r.votes[id]; !ok {
|
|
r.votes[id] = v
|
|
}
|
|
for _, vv := range r.votes {
|
|
if vv {
|
|
granted++
|
|
}
|
|
}
|
|
return granted
|
|
}
|
|
|
|
func (r *raft) Step(m pb.Message) error {
|
|
// Handle the message term, which may result in our stepping down to a follower.
|
|
switch {
|
|
case m.Term == 0:
|
|
// local message
|
|
case m.Term > r.Term:
|
|
if m.Type == pb.MsgVote || m.Type == pb.MsgPreVote {
|
|
force := bytes.Equal(m.Context, []byte(campaignTransfer))
|
|
inLease := r.checkQuorum && r.lead != None && r.electionElapsed < r.electionTimeout
|
|
if !force && inLease {
|
|
// If a server receives a RequestVote request within the minimum election timeout
|
|
// of hearing from a current leader, it does not update its term or grant its vote
|
|
r.logger.Infof("%x [logterm: %d, index: %d, vote: %x] ignored %s from %x [logterm: %d, index: %d] at term %d: lease is not expired (remaining ticks: %d)",
|
|
r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.Vote, m.Type, m.From, m.LogTerm, m.Index, r.Term, r.electionTimeout-r.electionElapsed)
|
|
return nil
|
|
}
|
|
}
|
|
switch {
|
|
case m.Type == pb.MsgPreVote:
|
|
// Never change our term in response to a PreVote
|
|
case m.Type == pb.MsgPreVoteResp && !m.Reject:
|
|
// We send pre-vote requests with a term in our future. If the
|
|
// pre-vote is granted, we will increment our term when we get a
|
|
// quorum. If it is not, the term comes from the node that
|
|
// rejected our vote so we should become a follower at the new
|
|
// term.
|
|
default:
|
|
r.logger.Infof("%x [term: %d] received a %s message with higher term from %x [term: %d]",
|
|
r.id, r.Term, m.Type, m.From, m.Term)
|
|
if m.Type == pb.MsgApp || m.Type == pb.MsgHeartbeat || m.Type == pb.MsgSnap {
|
|
r.becomeFollower(m.Term, m.From)
|
|
} else {
|
|
r.becomeFollower(m.Term, None)
|
|
}
|
|
}
|
|
|
|
case m.Term < r.Term:
|
|
if (r.checkQuorum || r.preVote) && (m.Type == pb.MsgHeartbeat || m.Type == pb.MsgApp) {
|
|
// We have received messages from a leader at a lower term. It is possible
|
|
// that these messages were simply delayed in the network, but this could
|
|
// also mean that this node has advanced its term number during a network
|
|
// partition, and it is now unable to either win an election or to rejoin
|
|
// the majority on the old term. If checkQuorum is false, this will be
|
|
// handled by incrementing term numbers in response to MsgVote with a
|
|
// higher term, but if checkQuorum is true we may not advance the term on
|
|
// MsgVote and must generate other messages to advance the term. The net
|
|
// result of these two features is to minimize the disruption caused by
|
|
// nodes that have been removed from the cluster's configuration: a
|
|
// removed node will send MsgVotes (or MsgPreVotes) which will be ignored,
|
|
// but it will not receive MsgApp or MsgHeartbeat, so it will not create
|
|
// disruptive term increases, by notifying leader of this node's activeness.
|
|
// The above comments also true for Pre-Vote
|
|
//
|
|
// When follower gets isolated, it soon starts an election ending
|
|
// up with a higher term than leader, although it won't receive enough
|
|
// votes to win the election. When it regains connectivity, this response
|
|
// with "pb.MsgAppResp" of higher term would force leader to step down.
|
|
// However, this disruption is inevitable to free this stuck node with
|
|
// fresh election. This can be prevented with Pre-Vote phase.
|
|
r.send(pb.Message{To: m.From, Type: pb.MsgAppResp})
|
|
} else if m.Type == pb.MsgPreVote {
|
|
// Before Pre-Vote enable, there may have candidate with higher term,
|
|
// but less log. After update to Pre-Vote, the cluster may deadlock if
|
|
// we drop messages with a lower term.
|
|
r.logger.Infof("%x [logterm: %d, index: %d, vote: %x] rejected %s from %x [logterm: %d, index: %d] at term %d",
|
|
r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.Vote, m.Type, m.From, m.LogTerm, m.Index, r.Term)
|
|
r.send(pb.Message{To: m.From, Term: r.Term, Type: pb.MsgPreVoteResp, Reject: true})
|
|
} else {
|
|
// ignore other cases
|
|
r.logger.Infof("%x [term: %d] ignored a %s message with lower term from %x [term: %d]",
|
|
r.id, r.Term, m.Type, m.From, m.Term)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
switch m.Type {
|
|
case pb.MsgHup:
|
|
if r.state != StateLeader {
|
|
ents, err := r.raftLog.slice(r.raftLog.applied+1, r.raftLog.committed+1, noLimit)
|
|
if err != nil {
|
|
r.logger.Panicf("unexpected error getting unapplied entries (%v)", err)
|
|
}
|
|
if n := numOfPendingConf(ents); n != 0 && r.raftLog.committed > r.raftLog.applied {
|
|
r.logger.Warningf("%x cannot campaign at term %d since there are still %d pending configuration changes to apply", r.id, r.Term, n)
|
|
return nil
|
|
}
|
|
|
|
r.logger.Infof("%x is starting a new election at term %d", r.id, r.Term)
|
|
if r.preVote {
|
|
r.campaign(campaignPreElection)
|
|
} else {
|
|
r.campaign(campaignElection)
|
|
}
|
|
} else {
|
|
r.logger.Debugf("%x ignoring MsgHup because already leader", r.id)
|
|
}
|
|
|
|
case pb.MsgVote, pb.MsgPreVote:
|
|
if r.isLearner {
|
|
// TODO: learner may need to vote, in case of node down when confchange.
|
|
r.logger.Infof("%x [logterm: %d, index: %d, vote: %x] ignored %s from %x [logterm: %d, index: %d] at term %d: learner can not vote",
|
|
r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.Vote, m.Type, m.From, m.LogTerm, m.Index, r.Term)
|
|
return nil
|
|
}
|
|
// We can vote if this is a repeat of a vote we've already cast...
|
|
canVote := r.Vote == m.From ||
|
|
// ...we haven't voted and we don't think there's a leader yet in this term...
|
|
(r.Vote == None && r.lead == None) ||
|
|
// ...or this is a PreVote for a future term...
|
|
(m.Type == pb.MsgPreVote && m.Term > r.Term)
|
|
// ...and we believe the candidate is up to date.
|
|
if canVote && r.raftLog.isUpToDate(m.Index, m.LogTerm) {
|
|
r.logger.Infof("%x [logterm: %d, index: %d, vote: %x] cast %s for %x [logterm: %d, index: %d] at term %d",
|
|
r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.Vote, m.Type, m.From, m.LogTerm, m.Index, r.Term)
|
|
// When responding to Msg{Pre,}Vote messages we include the term
|
|
// from the message, not the local term. To see why consider the
|
|
// case where a single node was previously partitioned away and
|
|
// it's local term is now of date. If we include the local term
|
|
// (recall that for pre-votes we don't update the local term), the
|
|
// (pre-)campaigning node on the other end will proceed to ignore
|
|
// the message (it ignores all out of date messages).
|
|
// The term in the original message and current local term are the
|
|
// same in the case of regular votes, but different for pre-votes.
|
|
r.send(pb.Message{To: m.From, Term: m.Term, Type: voteRespMsgType(m.Type)})
|
|
if m.Type == pb.MsgVote {
|
|
// Only record real votes.
|
|
r.electionElapsed = 0
|
|
r.Vote = m.From
|
|
}
|
|
} else {
|
|
r.logger.Infof("%x [logterm: %d, index: %d, vote: %x] rejected %s from %x [logterm: %d, index: %d] at term %d",
|
|
r.id, r.raftLog.lastTerm(), r.raftLog.lastIndex(), r.Vote, m.Type, m.From, m.LogTerm, m.Index, r.Term)
|
|
r.send(pb.Message{To: m.From, Term: r.Term, Type: voteRespMsgType(m.Type), Reject: true})
|
|
}
|
|
|
|
default:
|
|
err := r.step(r, m)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
type stepFunc func(r *raft, m pb.Message) error
|
|
|
|
func stepLeader(r *raft, m pb.Message) error {
|
|
// These message types do not require any progress for m.From.
|
|
switch m.Type {
|
|
case pb.MsgBeat:
|
|
r.bcastHeartbeat()
|
|
return nil
|
|
case pb.MsgCheckQuorum:
|
|
if !r.checkQuorumActive() {
|
|
r.logger.Warningf("%x stepped down to follower since quorum is not active", r.id)
|
|
r.becomeFollower(r.Term, None)
|
|
}
|
|
return nil
|
|
case pb.MsgProp:
|
|
if len(m.Entries) == 0 {
|
|
r.logger.Panicf("%x stepped empty MsgProp", r.id)
|
|
}
|
|
if _, ok := r.prs[r.id]; !ok {
|
|
// If we are not currently a member of the range (i.e. this node
|
|
// was removed from the configuration while serving as leader),
|
|
// drop any new proposals.
|
|
return ErrProposalDropped
|
|
}
|
|
if r.leadTransferee != None {
|
|
r.logger.Debugf("%x [term %d] transfer leadership to %x is in progress; dropping proposal", r.id, r.Term, r.leadTransferee)
|
|
return ErrProposalDropped
|
|
}
|
|
|
|
for i, e := range m.Entries {
|
|
if e.Type == pb.EntryConfChange {
|
|
if r.pendingConfIndex > r.raftLog.applied {
|
|
r.logger.Infof("propose conf %s ignored since pending unapplied configuration [index %d, applied %d]",
|
|
e.String(), r.pendingConfIndex, r.raftLog.applied)
|
|
m.Entries[i] = pb.Entry{Type: pb.EntryNormal}
|
|
} else {
|
|
r.pendingConfIndex = r.raftLog.lastIndex() + uint64(i) + 1
|
|
}
|
|
}
|
|
}
|
|
r.appendEntry(m.Entries...)
|
|
r.bcastAppend()
|
|
return nil
|
|
case pb.MsgReadIndex:
|
|
if r.quorum() > 1 {
|
|
if r.raftLog.zeroTermOnErrCompacted(r.raftLog.term(r.raftLog.committed)) != r.Term {
|
|
// Reject read only request when this leader has not committed any log entry at its term.
|
|
return nil
|
|
}
|
|
|
|
// thinking: use an interally defined context instead of the user given context.
|
|
// We can express this in terms of the term and index instead of a user-supplied value.
|
|
// This would allow multiple reads to piggyback on the same message.
|
|
switch r.readOnly.option {
|
|
case ReadOnlySafe:
|
|
r.readOnly.addRequest(r.raftLog.committed, m)
|
|
r.bcastHeartbeatWithCtx(m.Entries[0].Data)
|
|
case ReadOnlyLeaseBased:
|
|
ri := r.raftLog.committed
|
|
if m.From == None || m.From == r.id { // from local member
|
|
r.readStates = append(r.readStates, ReadState{Index: r.raftLog.committed, RequestCtx: m.Entries[0].Data})
|
|
} else {
|
|
r.send(pb.Message{To: m.From, Type: pb.MsgReadIndexResp, Index: ri, Entries: m.Entries})
|
|
}
|
|
}
|
|
} else {
|
|
r.readStates = append(r.readStates, ReadState{Index: r.raftLog.committed, RequestCtx: m.Entries[0].Data})
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// All other message types require a progress for m.From (pr).
|
|
pr := r.getProgress(m.From)
|
|
if pr == nil {
|
|
r.logger.Debugf("%x no progress available for %x", r.id, m.From)
|
|
return nil
|
|
}
|
|
switch m.Type {
|
|
case pb.MsgAppResp:
|
|
pr.RecentActive = true
|
|
|
|
if m.Reject {
|
|
r.logger.Debugf("%x received msgApp rejection(lastindex: %d) from %x for index %d",
|
|
r.id, m.RejectHint, m.From, m.Index)
|
|
if pr.maybeDecrTo(m.Index, m.RejectHint) {
|
|
r.logger.Debugf("%x decreased progress of %x to [%s]", r.id, m.From, pr)
|
|
if pr.State == ProgressStateReplicate {
|
|
pr.becomeProbe()
|
|
}
|
|
r.sendAppend(m.From)
|
|
}
|
|
} else {
|
|
oldPaused := pr.IsPaused()
|
|
if pr.maybeUpdate(m.Index) {
|
|
switch {
|
|
case pr.State == ProgressStateProbe:
|
|
pr.becomeReplicate()
|
|
case pr.State == ProgressStateSnapshot && pr.needSnapshotAbort():
|
|
r.logger.Debugf("%x snapshot aborted, resumed sending replication messages to %x [%s]", r.id, m.From, pr)
|
|
pr.becomeProbe()
|
|
case pr.State == ProgressStateReplicate:
|
|
pr.ins.freeTo(m.Index)
|
|
}
|
|
|
|
if r.maybeCommit() {
|
|
r.bcastAppend()
|
|
} else if oldPaused {
|
|
// update() reset the wait state on this node. If we had delayed sending
|
|
// an update before, send it now.
|
|
r.sendAppend(m.From)
|
|
}
|
|
// Transfer leadership is in progress.
|
|
if m.From == r.leadTransferee && pr.Match == r.raftLog.lastIndex() {
|
|
r.logger.Infof("%x sent MsgTimeoutNow to %x after received MsgAppResp", r.id, m.From)
|
|
r.sendTimeoutNow(m.From)
|
|
}
|
|
}
|
|
}
|
|
case pb.MsgHeartbeatResp:
|
|
pr.RecentActive = true
|
|
pr.resume()
|
|
|
|
// free one slot for the full inflights window to allow progress.
|
|
if pr.State == ProgressStateReplicate && pr.ins.full() {
|
|
pr.ins.freeFirstOne()
|
|
}
|
|
if pr.Match < r.raftLog.lastIndex() {
|
|
r.sendAppend(m.From)
|
|
}
|
|
|
|
if r.readOnly.option != ReadOnlySafe || len(m.Context) == 0 {
|
|
return nil
|
|
}
|
|
|
|
ackCount := r.readOnly.recvAck(m)
|
|
if ackCount < r.quorum() {
|
|
return nil
|
|
}
|
|
|
|
rss := r.readOnly.advance(m)
|
|
for _, rs := range rss {
|
|
req := rs.req
|
|
if req.From == None || req.From == r.id { // from local member
|
|
r.readStates = append(r.readStates, ReadState{Index: rs.index, RequestCtx: req.Entries[0].Data})
|
|
} else {
|
|
r.send(pb.Message{To: req.From, Type: pb.MsgReadIndexResp, Index: rs.index, Entries: req.Entries})
|
|
}
|
|
}
|
|
case pb.MsgSnapStatus:
|
|
if pr.State != ProgressStateSnapshot {
|
|
return nil
|
|
}
|
|
if !m.Reject {
|
|
pr.becomeProbe()
|
|
r.logger.Debugf("%x snapshot succeeded, resumed sending replication messages to %x [%s]", r.id, m.From, pr)
|
|
} else {
|
|
pr.snapshotFailure()
|
|
pr.becomeProbe()
|
|
r.logger.Debugf("%x snapshot failed, resumed sending replication messages to %x [%s]", r.id, m.From, pr)
|
|
}
|
|
// If snapshot finish, wait for the msgAppResp from the remote node before sending
|
|
// out the next msgApp.
|
|
// If snapshot failure, wait for a heartbeat interval before next try
|
|
pr.pause()
|
|
case pb.MsgUnreachable:
|
|
// During optimistic replication, if the remote becomes unreachable,
|
|
// there is huge probability that a MsgApp is lost.
|
|
if pr.State == ProgressStateReplicate {
|
|
pr.becomeProbe()
|
|
}
|
|
r.logger.Debugf("%x failed to send message to %x because it is unreachable [%s]", r.id, m.From, pr)
|
|
case pb.MsgTransferLeader:
|
|
if pr.IsLearner {
|
|
r.logger.Debugf("%x is learner. Ignored transferring leadership", r.id)
|
|
return nil
|
|
}
|
|
leadTransferee := m.From
|
|
lastLeadTransferee := r.leadTransferee
|
|
if lastLeadTransferee != None {
|
|
if lastLeadTransferee == leadTransferee {
|
|
r.logger.Infof("%x [term %d] transfer leadership to %x is in progress, ignores request to same node %x",
|
|
r.id, r.Term, leadTransferee, leadTransferee)
|
|
return nil
|
|
}
|
|
r.abortLeaderTransfer()
|
|
r.logger.Infof("%x [term %d] abort previous transferring leadership to %x", r.id, r.Term, lastLeadTransferee)
|
|
}
|
|
if leadTransferee == r.id {
|
|
r.logger.Debugf("%x is already leader. Ignored transferring leadership to self", r.id)
|
|
return nil
|
|
}
|
|
// Transfer leadership to third party.
|
|
r.logger.Infof("%x [term %d] starts to transfer leadership to %x", r.id, r.Term, leadTransferee)
|
|
// Transfer leadership should be finished in one electionTimeout, so reset r.electionElapsed.
|
|
r.electionElapsed = 0
|
|
r.leadTransferee = leadTransferee
|
|
if pr.Match == r.raftLog.lastIndex() {
|
|
r.sendTimeoutNow(leadTransferee)
|
|
r.logger.Infof("%x sends MsgTimeoutNow to %x immediately as %x already has up-to-date log", r.id, leadTransferee, leadTransferee)
|
|
} else {
|
|
r.sendAppend(leadTransferee)
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// stepCandidate is shared by StateCandidate and StatePreCandidate; the difference is
|
|
// whether they respond to MsgVoteResp or MsgPreVoteResp.
|
|
func stepCandidate(r *raft, m pb.Message) error {
|
|
// Only handle vote responses corresponding to our candidacy (while in
|
|
// StateCandidate, we may get stale MsgPreVoteResp messages in this term from
|
|
// our pre-candidate state).
|
|
var myVoteRespType pb.MessageType
|
|
if r.state == StatePreCandidate {
|
|
myVoteRespType = pb.MsgPreVoteResp
|
|
} else {
|
|
myVoteRespType = pb.MsgVoteResp
|
|
}
|
|
switch m.Type {
|
|
case pb.MsgProp:
|
|
r.logger.Infof("%x no leader at term %d; dropping proposal", r.id, r.Term)
|
|
return ErrProposalDropped
|
|
case pb.MsgApp:
|
|
r.becomeFollower(m.Term, m.From) // always m.Term == r.Term
|
|
r.handleAppendEntries(m)
|
|
case pb.MsgHeartbeat:
|
|
r.becomeFollower(m.Term, m.From) // always m.Term == r.Term
|
|
r.handleHeartbeat(m)
|
|
case pb.MsgSnap:
|
|
r.becomeFollower(m.Term, m.From) // always m.Term == r.Term
|
|
r.handleSnapshot(m)
|
|
case myVoteRespType:
|
|
gr := r.poll(m.From, m.Type, !m.Reject)
|
|
r.logger.Infof("%x [quorum:%d] has received %d %s votes and %d vote rejections", r.id, r.quorum(), gr, m.Type, len(r.votes)-gr)
|
|
switch r.quorum() {
|
|
case gr:
|
|
if r.state == StatePreCandidate {
|
|
r.campaign(campaignElection)
|
|
} else {
|
|
r.becomeLeader()
|
|
r.bcastAppend()
|
|
}
|
|
case len(r.votes) - gr:
|
|
// pb.MsgPreVoteResp contains future term of pre-candidate
|
|
// m.Term > r.Term; reuse r.Term
|
|
r.becomeFollower(r.Term, None)
|
|
}
|
|
case pb.MsgTimeoutNow:
|
|
r.logger.Debugf("%x [term %d state %v] ignored MsgTimeoutNow from %x", r.id, r.Term, r.state, m.From)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func stepFollower(r *raft, m pb.Message) error {
|
|
switch m.Type {
|
|
case pb.MsgProp:
|
|
if r.lead == None {
|
|
r.logger.Infof("%x no leader at term %d; dropping proposal", r.id, r.Term)
|
|
return ErrProposalDropped
|
|
} else if r.disableProposalForwarding {
|
|
r.logger.Infof("%x not forwarding to leader %x at term %d; dropping proposal", r.id, r.lead, r.Term)
|
|
return ErrProposalDropped
|
|
}
|
|
m.To = r.lead
|
|
r.send(m)
|
|
case pb.MsgApp:
|
|
r.electionElapsed = 0
|
|
r.lead = m.From
|
|
r.handleAppendEntries(m)
|
|
case pb.MsgHeartbeat:
|
|
r.electionElapsed = 0
|
|
r.lead = m.From
|
|
r.handleHeartbeat(m)
|
|
case pb.MsgSnap:
|
|
r.electionElapsed = 0
|
|
r.lead = m.From
|
|
r.handleSnapshot(m)
|
|
case pb.MsgTransferLeader:
|
|
if r.lead == None {
|
|
r.logger.Infof("%x no leader at term %d; dropping leader transfer msg", r.id, r.Term)
|
|
return nil
|
|
}
|
|
m.To = r.lead
|
|
r.send(m)
|
|
case pb.MsgTimeoutNow:
|
|
if r.promotable() {
|
|
r.logger.Infof("%x [term %d] received MsgTimeoutNow from %x and starts an election to get leadership.", r.id, r.Term, m.From)
|
|
// Leadership transfers never use pre-vote even if r.preVote is true; we
|
|
// know we are not recovering from a partition so there is no need for the
|
|
// extra round trip.
|
|
r.campaign(campaignTransfer)
|
|
} else {
|
|
r.logger.Infof("%x received MsgTimeoutNow from %x but is not promotable", r.id, m.From)
|
|
}
|
|
case pb.MsgReadIndex:
|
|
if r.lead == None {
|
|
r.logger.Infof("%x no leader at term %d; dropping index reading msg", r.id, r.Term)
|
|
return nil
|
|
}
|
|
m.To = r.lead
|
|
r.send(m)
|
|
case pb.MsgReadIndexResp:
|
|
if len(m.Entries) != 1 {
|
|
r.logger.Errorf("%x invalid format of MsgReadIndexResp from %x, entries count: %d", r.id, m.From, len(m.Entries))
|
|
return nil
|
|
}
|
|
r.readStates = append(r.readStates, ReadState{Index: m.Index, RequestCtx: m.Entries[0].Data})
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (r *raft) handleAppendEntries(m pb.Message) {
|
|
if m.Index < r.raftLog.committed {
|
|
r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: r.raftLog.committed})
|
|
return
|
|
}
|
|
|
|
if mlastIndex, ok := r.raftLog.maybeAppend(m.Index, m.LogTerm, m.Commit, m.Entries...); ok {
|
|
r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: mlastIndex})
|
|
} else {
|
|
r.logger.Debugf("%x [logterm: %d, index: %d] rejected msgApp [logterm: %d, index: %d] from %x",
|
|
r.id, r.raftLog.zeroTermOnErrCompacted(r.raftLog.term(m.Index)), m.Index, m.LogTerm, m.Index, m.From)
|
|
r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: m.Index, Reject: true, RejectHint: r.raftLog.lastIndex()})
|
|
}
|
|
}
|
|
|
|
func (r *raft) handleHeartbeat(m pb.Message) {
|
|
r.raftLog.commitTo(m.Commit)
|
|
r.send(pb.Message{To: m.From, Type: pb.MsgHeartbeatResp, Context: m.Context})
|
|
}
|
|
|
|
func (r *raft) handleSnapshot(m pb.Message) {
|
|
sindex, sterm := m.Snapshot.Metadata.Index, m.Snapshot.Metadata.Term
|
|
if r.restore(m.Snapshot) {
|
|
r.logger.Infof("%x [commit: %d] restored snapshot [index: %d, term: %d]",
|
|
r.id, r.raftLog.committed, sindex, sterm)
|
|
r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: r.raftLog.lastIndex()})
|
|
} else {
|
|
r.logger.Infof("%x [commit: %d] ignored snapshot [index: %d, term: %d]",
|
|
r.id, r.raftLog.committed, sindex, sterm)
|
|
r.send(pb.Message{To: m.From, Type: pb.MsgAppResp, Index: r.raftLog.committed})
|
|
}
|
|
}
|
|
|
|
// restore recovers the state machine from a snapshot. It restores the log and the
|
|
// configuration of state machine.
|
|
func (r *raft) restore(s pb.Snapshot) bool {
|
|
if s.Metadata.Index <= r.raftLog.committed {
|
|
return false
|
|
}
|
|
if r.raftLog.matchTerm(s.Metadata.Index, s.Metadata.Term) {
|
|
r.logger.Infof("%x [commit: %d, lastindex: %d, lastterm: %d] fast-forwarded commit to snapshot [index: %d, term: %d]",
|
|
r.id, r.raftLog.committed, r.raftLog.lastIndex(), r.raftLog.lastTerm(), s.Metadata.Index, s.Metadata.Term)
|
|
r.raftLog.commitTo(s.Metadata.Index)
|
|
return false
|
|
}
|
|
|
|
// The normal peer can't become learner.
|
|
if !r.isLearner {
|
|
for _, id := range s.Metadata.ConfState.Learners {
|
|
if id == r.id {
|
|
r.logger.Errorf("%x can't become learner when restores snapshot [index: %d, term: %d]", r.id, s.Metadata.Index, s.Metadata.Term)
|
|
return false
|
|
}
|
|
}
|
|
}
|
|
|
|
r.logger.Infof("%x [commit: %d, lastindex: %d, lastterm: %d] starts to restore snapshot [index: %d, term: %d]",
|
|
r.id, r.raftLog.committed, r.raftLog.lastIndex(), r.raftLog.lastTerm(), s.Metadata.Index, s.Metadata.Term)
|
|
|
|
r.raftLog.restore(s)
|
|
r.prs = make(map[uint64]*Progress)
|
|
r.learnerPrs = make(map[uint64]*Progress)
|
|
r.restoreNode(s.Metadata.ConfState.Nodes, false)
|
|
r.restoreNode(s.Metadata.ConfState.Learners, true)
|
|
return true
|
|
}
|
|
|
|
func (r *raft) restoreNode(nodes []uint64, isLearner bool) {
|
|
for _, n := range nodes {
|
|
match, next := uint64(0), r.raftLog.lastIndex()+1
|
|
if n == r.id {
|
|
match = next - 1
|
|
r.isLearner = isLearner
|
|
}
|
|
r.setProgress(n, match, next, isLearner)
|
|
r.logger.Infof("%x restored progress of %x [%s]", r.id, n, r.getProgress(n))
|
|
}
|
|
}
|
|
|
|
// promotable indicates whether state machine can be promoted to leader,
|
|
// which is true when its own id is in progress list.
|
|
func (r *raft) promotable() bool {
|
|
_, ok := r.prs[r.id]
|
|
return ok
|
|
}
|
|
|
|
func (r *raft) addNode(id uint64) {
|
|
r.addNodeOrLearnerNode(id, false)
|
|
}
|
|
|
|
func (r *raft) addLearner(id uint64) {
|
|
r.addNodeOrLearnerNode(id, true)
|
|
}
|
|
|
|
func (r *raft) addNodeOrLearnerNode(id uint64, isLearner bool) {
|
|
pr := r.getProgress(id)
|
|
if pr == nil {
|
|
r.setProgress(id, 0, r.raftLog.lastIndex()+1, isLearner)
|
|
} else {
|
|
if isLearner && !pr.IsLearner {
|
|
// can only change Learner to Voter
|
|
r.logger.Infof("%x ignored addLearner: do not support changing %x from raft peer to learner.", r.id, id)
|
|
return
|
|
}
|
|
|
|
if isLearner == pr.IsLearner {
|
|
// Ignore any redundant addNode calls (which can happen because the
|
|
// initial bootstrapping entries are applied twice).
|
|
return
|
|
}
|
|
|
|
// change Learner to Voter, use origin Learner progress
|
|
delete(r.learnerPrs, id)
|
|
pr.IsLearner = false
|
|
r.prs[id] = pr
|
|
}
|
|
|
|
if r.id == id {
|
|
r.isLearner = isLearner
|
|
}
|
|
|
|
// When a node is first added, we should mark it as recently active.
|
|
// Otherwise, CheckQuorum may cause us to step down if it is invoked
|
|
// before the added node has a chance to communicate with us.
|
|
pr = r.getProgress(id)
|
|
pr.RecentActive = true
|
|
}
|
|
|
|
func (r *raft) removeNode(id uint64) {
|
|
r.delProgress(id)
|
|
|
|
// do not try to commit or abort transferring if there is no nodes in the cluster.
|
|
if len(r.prs) == 0 && len(r.learnerPrs) == 0 {
|
|
return
|
|
}
|
|
|
|
// The quorum size is now smaller, so see if any pending entries can
|
|
// be committed.
|
|
if r.maybeCommit() {
|
|
r.bcastAppend()
|
|
}
|
|
// If the removed node is the leadTransferee, then abort the leadership transferring.
|
|
if r.state == StateLeader && r.leadTransferee == id {
|
|
r.abortLeaderTransfer()
|
|
}
|
|
}
|
|
|
|
func (r *raft) setProgress(id, match, next uint64, isLearner bool) {
|
|
if !isLearner {
|
|
delete(r.learnerPrs, id)
|
|
r.prs[id] = &Progress{Next: next, Match: match, ins: newInflights(r.maxInflight)}
|
|
return
|
|
}
|
|
|
|
if _, ok := r.prs[id]; ok {
|
|
panic(fmt.Sprintf("%x unexpected changing from voter to learner for %x", r.id, id))
|
|
}
|
|
r.learnerPrs[id] = &Progress{Next: next, Match: match, ins: newInflights(r.maxInflight), IsLearner: true}
|
|
}
|
|
|
|
func (r *raft) delProgress(id uint64) {
|
|
delete(r.prs, id)
|
|
delete(r.learnerPrs, id)
|
|
}
|
|
|
|
func (r *raft) loadState(state pb.HardState) {
|
|
if state.Commit < r.raftLog.committed || state.Commit > r.raftLog.lastIndex() {
|
|
r.logger.Panicf("%x state.commit %d is out of range [%d, %d]", r.id, state.Commit, r.raftLog.committed, r.raftLog.lastIndex())
|
|
}
|
|
r.raftLog.committed = state.Commit
|
|
r.Term = state.Term
|
|
r.Vote = state.Vote
|
|
}
|
|
|
|
// pastElectionTimeout returns true iff r.electionElapsed is greater
|
|
// than or equal to the randomized election timeout in
|
|
// [electiontimeout, 2 * electiontimeout - 1].
|
|
func (r *raft) pastElectionTimeout() bool {
|
|
return r.electionElapsed >= r.randomizedElectionTimeout
|
|
}
|
|
|
|
func (r *raft) resetRandomizedElectionTimeout() {
|
|
r.randomizedElectionTimeout = r.electionTimeout + globalRand.Intn(r.electionTimeout)
|
|
}
|
|
|
|
// checkQuorumActive returns true if the quorum is active from
|
|
// the view of the local raft state machine. Otherwise, it returns
|
|
// false.
|
|
// checkQuorumActive also resets all RecentActive to false.
|
|
func (r *raft) checkQuorumActive() bool {
|
|
var act int
|
|
|
|
r.forEachProgress(func(id uint64, pr *Progress) {
|
|
if id == r.id { // self is always active
|
|
act++
|
|
return
|
|
}
|
|
|
|
if pr.RecentActive && !pr.IsLearner {
|
|
act++
|
|
}
|
|
|
|
pr.RecentActive = false
|
|
})
|
|
|
|
return act >= r.quorum()
|
|
}
|
|
|
|
func (r *raft) sendTimeoutNow(to uint64) {
|
|
r.send(pb.Message{To: to, Type: pb.MsgTimeoutNow})
|
|
}
|
|
|
|
func (r *raft) abortLeaderTransfer() {
|
|
r.leadTransferee = None
|
|
}
|
|
|
|
func numOfPendingConf(ents []pb.Entry) int {
|
|
n := 0
|
|
for i := range ents {
|
|
if ents[i].Type == pb.EntryConfChange {
|
|
n++
|
|
}
|
|
}
|
|
return n
|
|
}
|