Naveen Sampath | 04696f7 | 2022-06-13 15:19:14 +0530 | [diff] [blame] | 1 | // Copyright 2015 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package raft |
| 16 | |
| 17 | import ( |
| 18 | "errors" |
| 19 | |
| 20 | pb "github.com/coreos/etcd/raft/raftpb" |
| 21 | ) |
| 22 | |
| 23 | // ErrStepLocalMsg is returned when try to step a local raft message |
| 24 | var ErrStepLocalMsg = errors.New("raft: cannot step raft local message") |
| 25 | |
| 26 | // ErrStepPeerNotFound is returned when try to step a response message |
| 27 | // but there is no peer found in raft.prs for that node. |
| 28 | var ErrStepPeerNotFound = errors.New("raft: cannot step as peer not found") |
| 29 | |
| 30 | // RawNode is a thread-unsafe Node. |
| 31 | // The methods of this struct correspond to the methods of Node and are described |
| 32 | // more fully there. |
| 33 | type RawNode struct { |
| 34 | raft *raft |
| 35 | prevSoftSt *SoftState |
| 36 | prevHardSt pb.HardState |
| 37 | } |
| 38 | |
| 39 | func (rn *RawNode) newReady() Ready { |
| 40 | return newReady(rn.raft, rn.prevSoftSt, rn.prevHardSt) |
| 41 | } |
| 42 | |
| 43 | func (rn *RawNode) commitReady(rd Ready) { |
| 44 | if rd.SoftState != nil { |
| 45 | rn.prevSoftSt = rd.SoftState |
| 46 | } |
| 47 | if !IsEmptyHardState(rd.HardState) { |
| 48 | rn.prevHardSt = rd.HardState |
| 49 | } |
| 50 | if rn.prevHardSt.Commit != 0 { |
| 51 | // In most cases, prevHardSt and rd.HardState will be the same |
| 52 | // because when there are new entries to apply we just sent a |
| 53 | // HardState with an updated Commit value. However, on initial |
| 54 | // startup the two are different because we don't send a HardState |
| 55 | // until something changes, but we do send any un-applied but |
| 56 | // committed entries (and previously-committed entries may be |
| 57 | // incorporated into the snapshot, even if rd.CommittedEntries is |
| 58 | // empty). Therefore we mark all committed entries as applied |
| 59 | // whether they were included in rd.HardState or not. |
| 60 | rn.raft.raftLog.appliedTo(rn.prevHardSt.Commit) |
| 61 | } |
| 62 | if len(rd.Entries) > 0 { |
| 63 | e := rd.Entries[len(rd.Entries)-1] |
| 64 | rn.raft.raftLog.stableTo(e.Index, e.Term) |
| 65 | } |
| 66 | if !IsEmptySnap(rd.Snapshot) { |
| 67 | rn.raft.raftLog.stableSnapTo(rd.Snapshot.Metadata.Index) |
| 68 | } |
| 69 | if len(rd.ReadStates) != 0 { |
| 70 | rn.raft.readStates = nil |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | // NewRawNode returns a new RawNode given configuration and a list of raft peers. |
| 75 | func NewRawNode(config *Config, peers []Peer) (*RawNode, error) { |
| 76 | if config.ID == 0 { |
| 77 | panic("config.ID must not be zero") |
| 78 | } |
| 79 | r := newRaft(config) |
| 80 | rn := &RawNode{ |
| 81 | raft: r, |
| 82 | } |
| 83 | lastIndex, err := config.Storage.LastIndex() |
| 84 | if err != nil { |
| 85 | panic(err) // TODO(bdarnell) |
| 86 | } |
| 87 | // If the log is empty, this is a new RawNode (like StartNode); otherwise it's |
| 88 | // restoring an existing RawNode (like RestartNode). |
| 89 | // TODO(bdarnell): rethink RawNode initialization and whether the application needs |
| 90 | // to be able to tell us when it expects the RawNode to exist. |
| 91 | if lastIndex == 0 { |
| 92 | r.becomeFollower(1, None) |
| 93 | ents := make([]pb.Entry, len(peers)) |
| 94 | for i, peer := range peers { |
| 95 | cc := pb.ConfChange{Type: pb.ConfChangeAddNode, NodeID: peer.ID, Context: peer.Context} |
| 96 | data, err := cc.Marshal() |
| 97 | if err != nil { |
| 98 | panic("unexpected marshal error") |
| 99 | } |
| 100 | |
| 101 | ents[i] = pb.Entry{Type: pb.EntryConfChange, Term: 1, Index: uint64(i + 1), Data: data} |
| 102 | } |
| 103 | r.raftLog.append(ents...) |
| 104 | r.raftLog.committed = uint64(len(ents)) |
| 105 | for _, peer := range peers { |
| 106 | r.addNode(peer.ID) |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | // Set the initial hard and soft states after performing all initialization. |
| 111 | rn.prevSoftSt = r.softState() |
| 112 | if lastIndex == 0 { |
| 113 | rn.prevHardSt = emptyState |
| 114 | } else { |
| 115 | rn.prevHardSt = r.hardState() |
| 116 | } |
| 117 | |
| 118 | return rn, nil |
| 119 | } |
| 120 | |
| 121 | // Tick advances the internal logical clock by a single tick. |
| 122 | func (rn *RawNode) Tick() { |
| 123 | rn.raft.tick() |
| 124 | } |
| 125 | |
| 126 | // TickQuiesced advances the internal logical clock by a single tick without |
| 127 | // performing any other state machine processing. It allows the caller to avoid |
| 128 | // periodic heartbeats and elections when all of the peers in a Raft group are |
| 129 | // known to be at the same state. Expected usage is to periodically invoke Tick |
| 130 | // or TickQuiesced depending on whether the group is "active" or "quiesced". |
| 131 | // |
| 132 | // WARNING: Be very careful about using this method as it subverts the Raft |
| 133 | // state machine. You should probably be using Tick instead. |
| 134 | func (rn *RawNode) TickQuiesced() { |
| 135 | rn.raft.electionElapsed++ |
| 136 | } |
| 137 | |
| 138 | // Campaign causes this RawNode to transition to candidate state. |
| 139 | func (rn *RawNode) Campaign() error { |
| 140 | return rn.raft.Step(pb.Message{ |
| 141 | Type: pb.MsgHup, |
| 142 | }) |
| 143 | } |
| 144 | |
| 145 | // Propose proposes data be appended to the raft log. |
| 146 | func (rn *RawNode) Propose(data []byte) error { |
| 147 | return rn.raft.Step(pb.Message{ |
| 148 | Type: pb.MsgProp, |
| 149 | From: rn.raft.id, |
| 150 | Entries: []pb.Entry{ |
| 151 | {Data: data}, |
| 152 | }}) |
| 153 | } |
| 154 | |
| 155 | // ProposeConfChange proposes a config change. |
| 156 | func (rn *RawNode) ProposeConfChange(cc pb.ConfChange) error { |
| 157 | data, err := cc.Marshal() |
| 158 | if err != nil { |
| 159 | return err |
| 160 | } |
| 161 | return rn.raft.Step(pb.Message{ |
| 162 | Type: pb.MsgProp, |
| 163 | Entries: []pb.Entry{ |
| 164 | {Type: pb.EntryConfChange, Data: data}, |
| 165 | }, |
| 166 | }) |
| 167 | } |
| 168 | |
| 169 | // ApplyConfChange applies a config change to the local node. |
| 170 | func (rn *RawNode) ApplyConfChange(cc pb.ConfChange) *pb.ConfState { |
| 171 | if cc.NodeID == None { |
| 172 | rn.raft.resetPendingConf() |
| 173 | return &pb.ConfState{Nodes: rn.raft.nodes()} |
| 174 | } |
| 175 | switch cc.Type { |
| 176 | case pb.ConfChangeAddNode: |
| 177 | rn.raft.addNode(cc.NodeID) |
| 178 | case pb.ConfChangeAddLearnerNode: |
| 179 | rn.raft.addLearner(cc.NodeID) |
| 180 | case pb.ConfChangeRemoveNode: |
| 181 | rn.raft.removeNode(cc.NodeID) |
| 182 | case pb.ConfChangeUpdateNode: |
| 183 | rn.raft.resetPendingConf() |
| 184 | default: |
| 185 | panic("unexpected conf type") |
| 186 | } |
| 187 | return &pb.ConfState{Nodes: rn.raft.nodes()} |
| 188 | } |
| 189 | |
| 190 | // Step advances the state machine using the given message. |
| 191 | func (rn *RawNode) Step(m pb.Message) error { |
| 192 | // ignore unexpected local messages receiving over network |
| 193 | if IsLocalMsg(m.Type) { |
| 194 | return ErrStepLocalMsg |
| 195 | } |
| 196 | if pr := rn.raft.getProgress(m.From); pr != nil || !IsResponseMsg(m.Type) { |
| 197 | return rn.raft.Step(m) |
| 198 | } |
| 199 | return ErrStepPeerNotFound |
| 200 | } |
| 201 | |
| 202 | // Ready returns the current point-in-time state of this RawNode. |
| 203 | func (rn *RawNode) Ready() Ready { |
| 204 | rd := rn.newReady() |
| 205 | rn.raft.msgs = nil |
| 206 | return rd |
| 207 | } |
| 208 | |
| 209 | // HasReady called when RawNode user need to check if any Ready pending. |
| 210 | // Checking logic in this method should be consistent with Ready.containsUpdates(). |
| 211 | func (rn *RawNode) HasReady() bool { |
| 212 | r := rn.raft |
| 213 | if !r.softState().equal(rn.prevSoftSt) { |
| 214 | return true |
| 215 | } |
| 216 | if hardSt := r.hardState(); !IsEmptyHardState(hardSt) && !isHardStateEqual(hardSt, rn.prevHardSt) { |
| 217 | return true |
| 218 | } |
| 219 | if r.raftLog.unstable.snapshot != nil && !IsEmptySnap(*r.raftLog.unstable.snapshot) { |
| 220 | return true |
| 221 | } |
| 222 | if len(r.msgs) > 0 || len(r.raftLog.unstableEntries()) > 0 || r.raftLog.hasNextEnts() { |
| 223 | return true |
| 224 | } |
| 225 | if len(r.readStates) != 0 { |
| 226 | return true |
| 227 | } |
| 228 | return false |
| 229 | } |
| 230 | |
| 231 | // Advance notifies the RawNode that the application has applied and saved progress in the |
| 232 | // last Ready results. |
| 233 | func (rn *RawNode) Advance(rd Ready) { |
| 234 | rn.commitReady(rd) |
| 235 | } |
| 236 | |
| 237 | // Status returns the current status of the given group. |
| 238 | func (rn *RawNode) Status() *Status { |
| 239 | status := getStatus(rn.raft) |
| 240 | return &status |
| 241 | } |
| 242 | |
| 243 | // ReportUnreachable reports the given node is not reachable for the last send. |
| 244 | func (rn *RawNode) ReportUnreachable(id uint64) { |
| 245 | _ = rn.raft.Step(pb.Message{Type: pb.MsgUnreachable, From: id}) |
| 246 | } |
| 247 | |
| 248 | // ReportSnapshot reports the status of the sent snapshot. |
| 249 | func (rn *RawNode) ReportSnapshot(id uint64, status SnapshotStatus) { |
| 250 | rej := status == SnapshotFailure |
| 251 | |
| 252 | _ = rn.raft.Step(pb.Message{Type: pb.MsgSnapStatus, From: id, Reject: rej}) |
| 253 | } |
| 254 | |
| 255 | // TransferLeader tries to transfer leadership to the given transferee. |
| 256 | func (rn *RawNode) TransferLeader(transferee uint64) { |
| 257 | _ = rn.raft.Step(pb.Message{Type: pb.MsgTransferLeader, From: transferee}) |
| 258 | } |
| 259 | |
| 260 | // ReadIndex requests a read state. The read state will be set in ready. |
| 261 | // Read State has a read index. Once the application advances further than the read |
| 262 | // index, any linearizable read requests issued before the read request can be |
| 263 | // processed safely. The read state will have the same rctx attached. |
| 264 | func (rn *RawNode) ReadIndex(rctx []byte) { |
| 265 | _ = rn.raft.Step(pb.Message{Type: pb.MsgReadIndex, Entries: []pb.Entry{{Data: rctx}}}) |
| 266 | } |