/
snapshot.go
334 lines (266 loc) · 8.84 KB
/
snapshot.go
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package raft
import (
"fmt"
"github.com/coreos/etcd/raft/raftpb"
"github.com/coreos/etcd/snap"
"github.com/coreos/etcd/wal/walpb"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/rlp"
"gopkg.in/fatih/set.v0"
"io"
"log"
"math/big"
"sort"
"time"
)
// Snapshot
type Snapshot struct {
addresses []Address
removedRaftIds []uint16 // Raft IDs for permanently removed peers
headBlockHash common.Hash
}
type ByRaftId []Address
func (a ByRaftId) Len() int { return len(a) }
func (a ByRaftId) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a ByRaftId) Less(i, j int) bool { return a[i].raftId < a[j].raftId }
func (pm *ProtocolManager) buildSnapshot() *Snapshot {
pm.mu.RLock()
defer pm.mu.RUnlock()
numNodes := len(pm.confState.Nodes)
numRemovedNodes := pm.removedPeers.Size()
snapshot := &Snapshot{
addresses: make([]Address, numNodes),
removedRaftIds: make([]uint16, numRemovedNodes),
headBlockHash: pm.blockchain.CurrentBlock().Hash(),
}
// Populate addresses
for i, rawRaftId := range pm.confState.Nodes {
raftId := uint16(rawRaftId)
if raftId == pm.raftId {
snapshot.addresses[i] = *pm.address
} else {
snapshot.addresses[i] = *pm.peers[raftId].address
}
}
sort.Sort(ByRaftId(snapshot.addresses))
// Populate removed IDs
for i, removedIface := range pm.removedPeers.List() {
snapshot.removedRaftIds[i] = removedIface.(uint16)
}
return snapshot
}
// Note that we do *not* read `pm.appliedIndex` here. We only use the `index`
// parameter instead. This is because we need to support a scenario when we
// snapshot for a future index that we have not yet recorded in LevelDB. See
// comments around the use of `forceSnapshot`.
func (pm *ProtocolManager) triggerSnapshot(index uint64) {
pm.mu.RLock()
snapshotIndex := pm.snapshotIndex
pm.mu.RUnlock()
glog.V(logger.Info).Infof("start snapshot [applied index: %d | last snapshot index: %d]", index, snapshotIndex)
snapData := pm.buildSnapshot().toBytes()
snap, err := pm.raftStorage.CreateSnapshot(index, &pm.confState, snapData)
if err != nil {
panic(err)
}
if err := pm.saveRaftSnapshot(snap); err != nil {
panic(err)
}
// Discard all log entries prior to index.
if err := pm.raftStorage.Compact(index); err != nil {
panic(err)
}
glog.V(logger.Info).Infof("compacted log at index %d", index)
pm.mu.Lock()
pm.snapshotIndex = index
pm.mu.Unlock()
}
func confStateIdSet(confState raftpb.ConfState) *set.Set {
set := set.New()
for _, rawRaftId := range confState.Nodes {
set.Add(uint16(rawRaftId))
}
return set
}
func (pm *ProtocolManager) updateClusterMembership(newConfState raftpb.ConfState, addresses []Address, removedRaftIds []uint16) {
glog.V(logger.Info).Infof("updating cluster membership per raft snapshot")
prevConfState := pm.confState
// Update tombstones for permanently removed peers. For simplicity we do not
// allow the re-use of peer IDs once a peer is removed.
removedPeers := set.New()
for _, removedRaftId := range removedRaftIds {
removedPeers.Add(removedRaftId)
}
pm.mu.Lock()
pm.removedPeers = removedPeers
pm.mu.Unlock()
// Remove old peers that we're still connected to
prevIds := confStateIdSet(prevConfState)
newIds := confStateIdSet(newConfState)
idsToRemove := set.Difference(prevIds, newIds)
for _, idIfaceToRemove := range idsToRemove.List() {
raftId := idIfaceToRemove.(uint16)
glog.V(logger.Info).Infof("removing old raft peer %v", raftId)
pm.removePeer(raftId)
}
// Update local and remote addresses
for _, tempAddress := range addresses {
address := tempAddress // Allocate separately on the heap for each iteration.
if address.raftId == pm.raftId {
// If we're a newcomer to an existing cluster, this is where we learn
// our own Address.
pm.setLocalAddress(&address)
} else {
pm.mu.RLock()
existingPeer := pm.peers[address.raftId]
pm.mu.RUnlock()
if existingPeer == nil {
glog.V(logger.Info).Infof("adding new raft peer %v", address.raftId)
pm.addPeer(&address)
}
}
}
pm.mu.Lock()
pm.confState = newConfState
pm.mu.Unlock()
glog.V(logger.Info).Infof("updated cluster membership")
}
func (pm *ProtocolManager) maybeTriggerSnapshot() {
pm.mu.RLock()
appliedIndex := pm.appliedIndex
entriesSinceLastSnap := appliedIndex - pm.snapshotIndex
pm.mu.RUnlock()
if entriesSinceLastSnap < snapshotPeriod {
return
}
pm.triggerSnapshot(appliedIndex)
}
func (pm *ProtocolManager) loadSnapshot() *raftpb.Snapshot {
if raftSnapshot := pm.readRaftSnapshot(); raftSnapshot != nil {
glog.V(logger.Info).Infof("loading snapshot")
pm.applyRaftSnapshot(*raftSnapshot)
return raftSnapshot
} else {
glog.V(logger.Info).Infof("no snapshot to load")
return nil
}
}
func (snapshot *Snapshot) toBytes() []byte {
size, r, err := rlp.EncodeToReader(snapshot)
if err != nil {
panic(fmt.Sprintf("error: failed to RLP-encode Snapshot: %s", err.Error()))
}
var buffer = make([]byte, uint32(size))
r.Read(buffer)
return buffer
}
func bytesToSnapshot(bytes []byte) *Snapshot {
var snapshot Snapshot
if err := rlp.DecodeBytes(bytes, &snapshot); err != nil {
log.Fatalf("failed to RLP-decode Snapshot: %v", err)
}
return &snapshot
}
func (snapshot *Snapshot) EncodeRLP(w io.Writer) error {
return rlp.Encode(w, []interface{}{snapshot.addresses, snapshot.removedRaftIds, snapshot.headBlockHash})
}
func (snapshot *Snapshot) DecodeRLP(s *rlp.Stream) error {
// These fields need to be public:
var temp struct {
Addresses []Address
RemovedRaftIds []uint16
HeadBlockHash common.Hash
}
if err := s.Decode(&temp); err != nil {
return err
} else {
snapshot.addresses, snapshot.removedRaftIds, snapshot.headBlockHash = temp.Addresses, temp.RemovedRaftIds, temp.HeadBlockHash
return nil
}
}
// Raft snapshot
func (pm *ProtocolManager) saveRaftSnapshot(snap raftpb.Snapshot) error {
if err := pm.snapshotter.SaveSnap(snap); err != nil {
return err
}
walSnap := walpb.Snapshot{
Index: snap.Metadata.Index,
Term: snap.Metadata.Term,
}
if err := pm.wal.SaveSnapshot(walSnap); err != nil {
return err
}
return pm.wal.ReleaseLockTo(snap.Metadata.Index)
}
func (pm *ProtocolManager) readRaftSnapshot() *raftpb.Snapshot {
snapshot, err := pm.snapshotter.Load()
if err != nil && err != snap.ErrNoSnapshot {
glog.Fatalf("error loading snapshot: %v", err)
}
return snapshot
}
func (pm *ProtocolManager) applyRaftSnapshot(raftSnapshot raftpb.Snapshot) {
glog.V(logger.Info).Infof("applying snapshot to raft storage")
if err := pm.raftStorage.ApplySnapshot(raftSnapshot); err != nil {
glog.Fatalln("failed to apply snapshot: ", err)
}
snapshot := bytesToSnapshot(raftSnapshot.Data)
latestBlockHash := snapshot.headBlockHash
pm.updateClusterMembership(raftSnapshot.Metadata.ConfState, snapshot.addresses, snapshot.removedRaftIds)
preSyncHead := pm.blockchain.CurrentBlock()
glog.V(logger.Info).Infof("before sync, chain head is at block %x", preSyncHead.Hash())
if latestBlock := pm.blockchain.GetBlockByHash(latestBlockHash); latestBlock == nil {
pm.syncBlockchainUntil(latestBlockHash)
pm.logNewlyAcceptedTransactions(preSyncHead)
glog.V(logger.Info).Infof("%s: %x\n", chainExtensionMessage, pm.blockchain.CurrentBlock().Hash())
} else {
glog.V(logger.Info).Infof("blockchain is caught up; no need to synchronize")
}
snapMeta := raftSnapshot.Metadata
pm.confState = snapMeta.ConfState
pm.mu.Lock()
pm.snapshotIndex = snapMeta.Index
pm.mu.Unlock()
}
func (pm *ProtocolManager) syncBlockchainUntil(hash common.Hash) {
pm.mu.RLock()
peerMap := make(map[uint16]*Peer, len(pm.peers))
for raftId, peer := range pm.peers {
peerMap[raftId] = peer
}
pm.mu.RUnlock()
for {
for peerId, peer := range peerMap {
glog.V(logger.Info).Infof("synchronizing with peer %v up to block %x", peerId, hash)
peerId := peer.p2pNode.ID.String()
peerIdPrefix := fmt.Sprintf("%x", peer.p2pNode.ID[:8])
if err := pm.downloader.Synchronise(peerIdPrefix, hash, big.NewInt(0), downloader.BoundedFullSync); err != nil {
glog.V(logger.Warn).Infof("failed to synchronize with peer %v", peerId)
time.Sleep(500 * time.Millisecond)
} else {
return
}
}
}
}
func (pm *ProtocolManager) logNewlyAcceptedTransactions(preSyncHead *types.Block) {
newHead := pm.blockchain.CurrentBlock()
numBlocks := newHead.NumberU64() - preSyncHead.NumberU64()
blocks := make([]*types.Block, numBlocks)
currBlock := newHead
blocksSeen := 0
for currBlock.Hash() != preSyncHead.Hash() {
blocks[int(numBlocks)-(1+blocksSeen)] = currBlock
blocksSeen += 1
currBlock = pm.blockchain.GetBlockByHash(currBlock.ParentHash())
}
for _, block := range blocks {
for _, tx := range block.Transactions() {
logger.LogRaftCheckpoint(logger.TxAccepted, tx.Hash().Hex())
}
}
}