package chain import ( "context" "os" "sort" "strconv" "strings" "sync" "time" "github.com/libp2p/go-libp2p/core/peer" "github.com/filecoin-project/go-address" "github.com/filecoin-project/lotus/build" "github.com/filecoin-project/lotus/chain/types" ) var ( BootstrapPeerThreshold = build.BootstrapPeerThreshold RecentSyncBufferSize = 10 MaxSyncWorkers = 5 SyncWorkerHistory = 3 InitialSyncTimeThreshold = 15 * time.Minute coalesceTipsets = false ) func init() { coalesceTipsets = os.Getenv("LOTUS_SYNC_FORMTS_PEND") == "yes" if bootstrapPeerThreshold := os.Getenv("LOTUS_SYNC_BOOTSTRAP_PEERS"); bootstrapPeerThreshold != "" { threshold, err := strconv.Atoi(bootstrapPeerThreshold) if err != nil { log.Errorf("failed to parse 'LOTUS_SYNC_BOOTSTRAP_PEERS' env var: %s", err) } else { BootstrapPeerThreshold = threshold } } } type SyncFunc func(context.Context, *types.TipSet) error // SyncManager manages the chain synchronization process, both at bootstrap time // and during ongoing operation. // // It receives candidate chain heads in the form of tipsets from peers, // and schedules them onto sync workers, deduplicating processing for // already-active syncs. type SyncManager interface { // Start starts the SyncManager. Start() // Stop stops the SyncManager. Stop() // SetPeerHead informs the SyncManager that the supplied peer reported the // supplied tipset. SetPeerHead(ctx context.Context, p peer.ID, ts *types.TipSet) // State retrieves the state of the sync workers. State() []SyncerStateSnapshot } type syncManager struct { ctx context.Context cancel func() workq chan peerHead statusq chan workerStatus nextWorker uint64 pend syncBucketSet deferred syncBucketSet heads map[peer.ID]*types.TipSet recent *syncBuffer initialSyncDone bool mx sync.Mutex state map[uint64]*workerState history []*workerState historyI int doSync func(context.Context, *types.TipSet) error } var _ SyncManager = (*syncManager)(nil) type peerHead struct { // Note: this doesn't _necessarily_ mean that p's head is ts, just that ts is a tipset that p sent to us p peer.ID ts *types.TipSet } type workerState struct { id uint64 ts *types.TipSet ss *SyncerState dt time.Duration } type workerStatus struct { id uint64 err error } // sync manager interface func NewSyncManager(sync SyncFunc) SyncManager { ctx, cancel := context.WithCancel(context.Background()) return &syncManager{ ctx: ctx, cancel: cancel, workq: make(chan peerHead), statusq: make(chan workerStatus), heads: make(map[peer.ID]*types.TipSet), state: make(map[uint64]*workerState), recent: newSyncBuffer(RecentSyncBufferSize), history: make([]*workerState, SyncWorkerHistory), doSync: sync, } } func (sm *syncManager) Start() { go sm.scheduler() } func (sm *syncManager) Stop() { select { case <-sm.ctx.Done(): default: sm.cancel() } } func (sm *syncManager) SetPeerHead(ctx context.Context, p peer.ID, ts *types.TipSet) { select { case sm.workq <- peerHead{p: p, ts: ts}: case <-sm.ctx.Done(): case <-ctx.Done(): } } func (sm *syncManager) State() []SyncerStateSnapshot { sm.mx.Lock() workerStates := make([]*workerState, 0, len(sm.state)+len(sm.history)) for _, ws := range sm.state { workerStates = append(workerStates, ws) } for _, ws := range sm.history { if ws != nil { workerStates = append(workerStates, ws) } } sm.mx.Unlock() sort.Slice(workerStates, func(i, j int) bool { return workerStates[i].id < workerStates[j].id }) result := make([]SyncerStateSnapshot, 0, len(workerStates)) for _, ws := range workerStates { result = append(result, ws.ss.Snapshot()) } return result } // sync manager internals func (sm *syncManager) scheduler() { ticker := time.NewTicker(time.Minute) tickerC := ticker.C for { select { case head := <-sm.workq: sm.handlePeerHead(head) case status := <-sm.statusq: sm.handleWorkerStatus(status) case <-tickerC: if sm.initialSyncDone { ticker.Stop() tickerC = nil sm.handleInitialSyncDone() } case <-sm.ctx.Done(): return } } } func (sm *syncManager) handlePeerHead(head peerHead) { log.Debugf("new peer head: %s %s", head.p, head.ts) // have we started syncing yet? if sm.nextWorker == 0 { // track the peer head until we start syncing sm.heads[head.p] = head.ts // not yet; do we have enough peers? if len(sm.heads) < BootstrapPeerThreshold { log.Debugw("not tracking enough peers to start sync worker", "have", len(sm.heads), "need", BootstrapPeerThreshold) // not enough peers; track it and wait return } // we are ready to start syncing; select the sync target and spawn a worker target, err := sm.selectInitialSyncTarget() if err != nil { log.Errorf("failed to select initial sync target: %s", err) return } log.Infof("selected initial sync target: %s", target) sm.spawnWorker(target) return } // we have started syncing, add peer head to the queue if applicable and maybe spawn a worker // if there is work to do (possibly in a fork) target, work, err := sm.addSyncTarget(head.ts) if err != nil { log.Warnf("failed to add sync target: %s", err) return } if work { log.Infof("selected sync target: %s", target) sm.spawnWorker(target) } } func (sm *syncManager) handleWorkerStatus(status workerStatus) { log.Debugf("worker %d done; status error: %s", status.id, status.err) sm.mx.Lock() ws := sm.state[status.id] delete(sm.state, status.id) // we track the last few workers for debug purposes sm.history[sm.historyI] = ws sm.historyI++ sm.historyI %= len(sm.history) sm.mx.Unlock() if status.err != nil { // we failed to sync this target -- log it and try to work on an extended chain // if there is nothing related to be worked on, we stop working on this chain. log.Errorf("error during sync in %s: %s", ws.ts, status.err) } else { // add to the recently synced buffer sm.recent.Push(ws.ts) // if we are still in initial sync and this was fast enough, mark the end of the initial sync if !sm.initialSyncDone && ws.dt < InitialSyncTimeThreshold { sm.initialSyncDone = true } } // we are done with this target, select the next sync target and spawn a worker if there is work // to do, because of an extension of this chain. target, work, err := sm.selectSyncTarget(ws.ts) if err != nil { log.Warnf("failed to select sync target: %s", err) return } if work { log.Infof("selected sync target: %s", target) sm.spawnWorker(target) } } func (sm *syncManager) handleInitialSyncDone() { // we have just finished the initial sync; spawn some additional workers in deferred syncs // as needed (and up to MaxSyncWorkers) to ramp up chain sync for len(sm.state) < MaxSyncWorkers { target, work, err := sm.selectDeferredSyncTarget() if err != nil { log.Errorf("error selecting deferred sync target: %s", err) return } if !work { return } log.Infof("selected deferred sync target: %s", target) sm.spawnWorker(target) } } func (sm *syncManager) spawnWorker(target *types.TipSet) { id := sm.nextWorker sm.nextWorker++ ws := &workerState{ id: id, ts: target, ss: new(SyncerState), } ws.ss.data.WorkerID = id sm.mx.Lock() sm.state[id] = ws sm.mx.Unlock() go sm.worker(ws) } func (sm *syncManager) worker(ws *workerState) { log.Infof("worker %d syncing in %s", ws.id, ws.ts) start := build.Clock.Now() ctx := context.WithValue(sm.ctx, syncStateKey{}, ws.ss) err := sm.doSync(ctx, ws.ts) ws.dt = build.Clock.Since(start) log.Infof("worker %d done; took %s", ws.id, ws.dt) select { case sm.statusq <- workerStatus{id: ws.id, err: err}: case <-sm.ctx.Done(): } } // selects the initial sync target by examining known peer heads; only called once for the initial // sync. func (sm *syncManager) selectInitialSyncTarget() (*types.TipSet, error) { var buckets syncBucketSet var peerHeads []*types.TipSet for _, ts := range sm.heads { peerHeads = append(peerHeads, ts) } // clear the map, we don't use it any longer sm.heads = nil sort.Slice(peerHeads, func(i, j int) bool { return peerHeads[i].Height() < peerHeads[j].Height() }) for _, ts := range peerHeads { buckets.Insert(ts) } if len(buckets.buckets) > 1 { log.Warn("caution, multiple distinct chains seen during head selections") // TODO: we *could* refuse to sync here without user intervention. // For now, just select the best cluster } return buckets.Heaviest(), nil } // adds a tipset to the potential sync targets; returns true if there is a a tipset to work on. // this could be either a restart, eg because there is no currently scheduled sync work or a worker // failed or a potential fork. func (sm *syncManager) addSyncTarget(ts *types.TipSet) (*types.TipSet, bool, error) { // Note: we don't need the state lock here to access the active worker states, as the only // competing threads that may access it do so through State() which is read only. // if we have recently synced this or any heavier tipset we just ignore it; this can happen // with an empty worker set after we just finished syncing to a target if sm.recent.Synced(ts) { return nil, false, nil } // if the worker set is empty, we have finished syncing and were waiting for the next tipset // in this case, we just return the tipset as work to be done if len(sm.state) == 0 { return ts, true, nil } // check if it is related to any active sync; if so insert into the pending sync queue for _, ws := range sm.state { if ts.Equals(ws.ts) { // ignore it, we are already syncing it return nil, false, nil } if ts.Parents() == ws.ts.Key() { // schedule for syncing next; it's an extension of an active sync sm.pend.Insert(ts) return nil, false, nil } } // check to see if it is related to any pending sync; if so insert it into the pending sync queue if sm.pend.RelatedToAny(ts) { sm.pend.Insert(ts) return nil, false, nil } // it's not related to any active or pending sync; this could be a fork in which case we // start a new worker to sync it, if it is *heavier* than any active or pending set; // if it is not, we ignore it. for _, ws := range sm.state { if isHeavier(ws.ts, ts) { return nil, false, nil } } pendHeaviest := sm.pend.Heaviest() if pendHeaviest != nil && isHeavier(pendHeaviest, ts) { return nil, false, nil } // if we have not finished the initial sync or have too many workers, add it to the deferred queue; // it will be processed once a worker is freed from syncing a chain (or the initial sync finishes) if !sm.initialSyncDone || len(sm.state) >= MaxSyncWorkers { log.Debugf("deferring sync on %s", ts) sm.deferred.Insert(ts) return nil, false, nil } // start a new worker, seems heavy enough and unrelated to active or pending syncs return ts, true, nil } // selects the next sync target after a worker sync has finished; returns true and a target // TipSet if this chain should continue to sync because there is a heavier related tipset. func (sm *syncManager) selectSyncTarget(done *types.TipSet) (*types.TipSet, bool, error) { // we pop the related bucket and if there is any related tipset, we work on the heaviest one next // if we are not already working on a heavier tipset related := sm.pend.PopRelated(done) if related == nil { return sm.selectDeferredSyncTarget() } heaviest := related.heaviestTipSet() if isHeavier(done, heaviest) { return sm.selectDeferredSyncTarget() } for _, ws := range sm.state { if isHeavier(ws.ts, heaviest) { return sm.selectDeferredSyncTarget() } } if sm.recent.Synced(heaviest) { return sm.selectDeferredSyncTarget() } return heaviest, true, nil } // selects a deferred sync target if there is any; these are sync targets that were not related to // active syncs and were deferred because there were too many workers running func (sm *syncManager) selectDeferredSyncTarget() (*types.TipSet, bool, error) { deferredLoop: for !sm.deferred.Empty() { bucket := sm.deferred.Pop() heaviest := bucket.heaviestTipSet() if sm.recent.Synced(heaviest) { // we have synced it or something heavier recently, skip it continue deferredLoop } if sm.pend.RelatedToAny(heaviest) { // this has converged to a pending sync, insert it to the pending queue sm.pend.Insert(heaviest) continue deferredLoop } for _, ws := range sm.state { if ws.ts.Equals(heaviest) || isHeavier(ws.ts, heaviest) { // we have converged and are already syncing it or we are syncing on something heavier // ignore it and pop the next deferred bucket continue deferredLoop } if heaviest.Parents() == ws.ts.Key() { // we have converged and we are syncing its parent; insert it to the pending queue sm.pend.Insert(heaviest) continue deferredLoop } // it's not related to any active or pending sync and this worker is free, so sync it! return heaviest, true, nil } } return nil, false, nil } func isHeavier(a, b *types.TipSet) bool { return a.ParentWeight().GreaterThan(b.ParentWeight()) } // sync buffer -- this is a circular buffer of recently synced tipsets type syncBuffer struct { buf []*types.TipSet next int } func newSyncBuffer(size int) *syncBuffer { return &syncBuffer{buf: make([]*types.TipSet, size)} } func (sb *syncBuffer) Push(ts *types.TipSet) { sb.buf[sb.next] = ts sb.next++ sb.next %= len(sb.buf) } func (sb *syncBuffer) Synced(ts *types.TipSet) bool { for _, rts := range sb.buf { if rts != nil && (rts.Equals(ts) || isHeavier(rts, ts)) { return true } } return false } // sync buckets and related utilities type syncBucketSet struct { buckets []*syncTargetBucket } type syncTargetBucket struct { tips []*types.TipSet } func newSyncTargetBucket(tipsets ...*types.TipSet) *syncTargetBucket { var stb syncTargetBucket for _, ts := range tipsets { stb.add(ts) } return &stb } func (sbs *syncBucketSet) String() string { var bStrings []string for _, b := range sbs.buckets { var tsStrings []string for _, t := range b.tips { tsStrings = append(tsStrings, t.String()) } bStrings = append(bStrings, "["+strings.Join(tsStrings, ",")+"]") } return "{" + strings.Join(bStrings, ";") + "}" } func (sbs *syncBucketSet) RelatedToAny(ts *types.TipSet) bool { for _, b := range sbs.buckets { if b.sameChainAs(ts) { return true } } return false } func (sbs *syncBucketSet) Insert(ts *types.TipSet) { for _, b := range sbs.buckets { if b.sameChainAs(ts) { b.add(ts) return } } sbs.buckets = append(sbs.buckets, newSyncTargetBucket(ts)) } func (sbs *syncBucketSet) Pop() *syncTargetBucket { var bestBuck *syncTargetBucket var bestTs *types.TipSet for _, b := range sbs.buckets { hts := b.heaviestTipSet() if bestBuck == nil || bestTs.ParentWeight().LessThan(hts.ParentWeight()) { bestBuck = b bestTs = hts } } sbs.removeBucket(bestBuck) return bestBuck } func (sbs *syncBucketSet) removeBucket(toremove *syncTargetBucket) { nbuckets := make([]*syncTargetBucket, 0, len(sbs.buckets)-1) for _, b := range sbs.buckets { if b != toremove { nbuckets = append(nbuckets, b) } } sbs.buckets = nbuckets } func (sbs *syncBucketSet) PopRelated(ts *types.TipSet) *syncTargetBucket { var bOut *syncTargetBucket for _, b := range sbs.buckets { if b.sameChainAs(ts) { sbs.removeBucket(b) if bOut == nil { bOut = &syncTargetBucket{} } bOut.tips = append(bOut.tips, b.tips...) } } return bOut } func (sbs *syncBucketSet) Heaviest() *types.TipSet { // TODO: should also consider factoring in number of peers represented by each bucket here var bestTs *types.TipSet for _, b := range sbs.buckets { bhts := b.heaviestTipSet() if bestTs == nil || bhts.ParentWeight().GreaterThan(bestTs.ParentWeight()) { bestTs = bhts } } return bestTs } func (sbs *syncBucketSet) Empty() bool { return len(sbs.buckets) == 0 } func (stb *syncTargetBucket) sameChainAs(ts *types.TipSet) bool { for _, t := range stb.tips { if ts.Equals(t) { return true } if ts.Key() == t.Parents() { return true } if ts.Parents() == t.Key() { return true } } return false } func (stb *syncTargetBucket) add(ts *types.TipSet) { for i, t := range stb.tips { if t.Equals(ts) { return } if coalesceTipsets && t.Height() == ts.Height() && types.CidArrsEqual(t.Blocks()[0].Parents, ts.Blocks()[0].Parents) { miners := make(map[address.Address]struct{}) newTs := []*types.BlockHeader{} for _, b := range t.Blocks() { _, have := miners[b.Miner] if !have { newTs = append(newTs, b) miners[b.Miner] = struct{}{} } } for _, b := range ts.Blocks() { _, have := miners[b.Miner] if !have { newTs = append(newTs, b) miners[b.Miner] = struct{}{} } } ts2, err := types.NewTipSet(newTs) if err != nil { log.Warnf("error while trying to recombine a tipset in a bucket: %+v", err) continue } stb.tips[i] = ts2 return } } stb.tips = append(stb.tips, ts) } func (stb *syncTargetBucket) heaviestTipSet() *types.TipSet { if stb == nil { return nil } var best *types.TipSet for _, ts := range stb.tips { if best == nil || ts.ParentWeight().GreaterThan(best.ParentWeight()) { best = ts } } return best }