/
blocks_fetcher.go
622 lines (576 loc) · 21 KB
/
blocks_fetcher.go
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package initialsync
import (
"context"
"fmt"
"sort"
"strings"
"sync"
"time"
"github.com/libp2p/go-libp2p/core/peer"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"github.com/theQRL/qrysm/v4/beacon-chain/db"
"github.com/theQRL/qrysm/v4/beacon-chain/p2p"
p2pTypes "github.com/theQRL/qrysm/v4/beacon-chain/p2p/types"
"github.com/theQRL/qrysm/v4/beacon-chain/startup"
prysmsync "github.com/theQRL/qrysm/v4/beacon-chain/sync"
"github.com/theQRL/qrysm/v4/cmd/beacon-chain/flags"
"github.com/theQRL/qrysm/v4/config/params"
consensus_types "github.com/theQRL/qrysm/v4/consensus-types"
blocks2 "github.com/theQRL/qrysm/v4/consensus-types/blocks"
"github.com/theQRL/qrysm/v4/consensus-types/interfaces"
"github.com/theQRL/qrysm/v4/consensus-types/primitives"
leakybucket "github.com/theQRL/qrysm/v4/container/leaky-bucket"
"github.com/theQRL/qrysm/v4/crypto/rand"
"github.com/theQRL/qrysm/v4/encoding/bytesutil"
"github.com/theQRL/qrysm/v4/math"
p2ppb "github.com/theQRL/qrysm/v4/proto/prysm/v1alpha1"
"github.com/theQRL/qrysm/v4/time/slots"
"go.opencensus.io/trace"
)
const (
// maxPendingRequests limits how many concurrent fetch request one can initiate.
maxPendingRequests = 64
// peersPercentagePerRequest caps percentage of peers to be used in a request.
peersPercentagePerRequest = 0.75
// handshakePollingInterval is a polling interval for checking the number of received handshakes.
handshakePollingInterval = 5 * time.Second
// peerLocksPollingInterval is a polling interval for checking if there are stale peer locks.
peerLocksPollingInterval = 5 * time.Minute
// peerLockMaxAge is maximum time before stale lock is purged.
peerLockMaxAge = 60 * time.Minute
// nonSkippedSlotsFullSearchEpochs how many epochs to check in full, before resorting to random
// sampling of slots once per epoch
nonSkippedSlotsFullSearchEpochs = 10
// peerFilterCapacityWeight defines how peer's capacity affects peer's score. Provided as
// percentage, i.e. 0.3 means capacity will determine 30% of peer's score.
peerFilterCapacityWeight = 0.2
// backtrackingMaxHops how many hops (during search for common ancestor in backtracking) to do
// before giving up.
backtrackingMaxHops = 128
)
var (
errNoPeersAvailable = errors.New("no peers available, waiting for reconnect")
errFetcherCtxIsDone = errors.New("fetcher's context is done, reinitialize")
errSlotIsTooHigh = errors.New("slot is higher than the finalized slot")
errBlockAlreadyProcessed = errors.New("block is already processed")
errParentDoesNotExist = errors.New("beacon node doesn't have a parent in db with root")
errNoPeersWithAltBlocks = errors.New("no peers with alternative blocks found")
)
// Period to calculate expected limit for a single peer.
var blockLimiterPeriod = 30 * time.Second
// blocksFetcherConfig is a config to setup the block fetcher.
type blocksFetcherConfig struct {
clock *startup.Clock
ctxMap prysmsync.ContextByteVersions
chain blockchainService
p2p p2p.P2P
db db.ReadOnlyDatabase
peerFilterCapacityWeight float64
mode syncMode
}
// blocksFetcher is a service to fetch chain data from peers.
// On an incoming requests, requested block range is evenly divided
// among available peers (for fair network load distribution).
type blocksFetcher struct {
sync.Mutex
ctx context.Context
cancel context.CancelFunc
rand *rand.Rand
chain blockchainService
clock *startup.Clock
ctxMap prysmsync.ContextByteVersions
p2p p2p.P2P
db db.ReadOnlyDatabase
blocksPerPeriod uint64
rateLimiter *leakybucket.Collector
peerLocks map[peer.ID]*peerLock
fetchRequests chan *fetchRequestParams
fetchResponses chan *fetchRequestResponse
capacityWeight float64 // how remaining capacity affects peer selection
mode syncMode // allows to use fetcher in different sync scenarios
quit chan struct{} // termination notifier
}
// peerLock restricts fetcher actions on per peer basis. Currently, used for rate limiting.
type peerLock struct {
sync.Mutex
accessed time.Time
}
// fetchRequestParams holds parameters necessary to schedule a fetch request.
type fetchRequestParams struct {
ctx context.Context // if provided, it is used instead of global fetcher's context
start primitives.Slot // starting slot
count uint64 // how many slots to receive (fetcher may return fewer slots)
}
// fetchRequestResponse is a combined type to hold results of both successful executions and errors.
// Valid usage pattern will be to check whether result's `err` is nil, before using `blocks`.
type fetchRequestResponse struct {
pid peer.ID
start primitives.Slot
count uint64
bwb []blocks2.BlockWithVerifiedBlobs
err error
}
// newBlocksFetcher creates ready to use fetcher.
func newBlocksFetcher(ctx context.Context, cfg *blocksFetcherConfig) *blocksFetcher {
blocksPerPeriod := flags.Get().BlockBatchLimit
allowedBlocksBurst := flags.Get().BlockBatchLimitBurstFactor * flags.Get().BlockBatchLimit
// Allow fetcher to go almost to the full burst capacity (less a single batch).
rateLimiter := leakybucket.NewCollector(
float64(blocksPerPeriod), int64(allowedBlocksBurst-blocksPerPeriod),
blockLimiterPeriod, false /* deleteEmptyBuckets */)
capacityWeight := cfg.peerFilterCapacityWeight
if capacityWeight >= 1 {
capacityWeight = peerFilterCapacityWeight
}
ctx, cancel := context.WithCancel(ctx)
return &blocksFetcher{
ctx: ctx,
cancel: cancel,
rand: rand.NewGenerator(),
chain: cfg.chain,
clock: cfg.clock,
ctxMap: cfg.ctxMap,
p2p: cfg.p2p,
db: cfg.db,
blocksPerPeriod: uint64(blocksPerPeriod),
rateLimiter: rateLimiter,
peerLocks: make(map[peer.ID]*peerLock),
fetchRequests: make(chan *fetchRequestParams, maxPendingRequests),
fetchResponses: make(chan *fetchRequestResponse, maxPendingRequests),
capacityWeight: capacityWeight,
mode: cfg.mode,
quit: make(chan struct{}),
}
}
// start boots up the fetcher, which starts listening for incoming fetch requests.
func (f *blocksFetcher) start() error {
select {
case <-f.ctx.Done():
return errFetcherCtxIsDone
default:
go f.loop()
return nil
}
}
// stop terminates all fetcher operations.
func (f *blocksFetcher) stop() {
defer func() {
if f.rateLimiter != nil {
f.rateLimiter.Free()
f.rateLimiter = nil
}
}()
f.cancel()
<-f.quit // make sure that loop() is done
}
// requestResponses exposes a channel into which fetcher pushes generated request responses.
func (f *blocksFetcher) requestResponses() <-chan *fetchRequestResponse {
return f.fetchResponses
}
// loop is a main fetcher loop, listens for incoming requests/cancellations, forwards outgoing responses.
func (f *blocksFetcher) loop() {
defer close(f.quit)
// Wait for all loop's goroutines to finish, and safely release resources.
wg := &sync.WaitGroup{}
defer func() {
wg.Wait()
close(f.fetchResponses)
}()
// Periodically remove stale peer locks.
go func() {
ticker := time.NewTicker(peerLocksPollingInterval)
defer ticker.Stop()
for {
select {
case <-ticker.C:
f.removeStalePeerLocks(peerLockMaxAge)
case <-f.ctx.Done():
return
}
}
}()
// Main loop.
for {
// Make sure there is are available peers before processing requests.
if _, err := f.waitForMinimumPeers(f.ctx); err != nil {
log.Error(err)
}
select {
case <-f.ctx.Done():
log.Debug("Context closed, exiting goroutine (blocks fetcher)")
return
case req := <-f.fetchRequests:
wg.Add(1)
go func() {
defer wg.Done()
select {
case <-f.ctx.Done():
case f.fetchResponses <- f.handleRequest(req.ctx, req.start, req.count):
}
}()
}
}
}
// scheduleRequest adds request to incoming queue.
func (f *blocksFetcher) scheduleRequest(ctx context.Context, start primitives.Slot, count uint64) error {
if ctx.Err() != nil {
return ctx.Err()
}
request := &fetchRequestParams{
ctx: ctx,
start: start,
count: count,
}
select {
case <-f.ctx.Done():
return errFetcherCtxIsDone
case f.fetchRequests <- request:
}
return nil
}
// handleRequest parses fetch request and forwards it to response builder.
func (f *blocksFetcher) handleRequest(ctx context.Context, start primitives.Slot, count uint64) *fetchRequestResponse {
ctx, span := trace.StartSpan(ctx, "initialsync.handleRequest")
defer span.End()
response := &fetchRequestResponse{
start: start,
count: count,
bwb: []blocks2.BlockWithVerifiedBlobs{},
err: nil,
}
if ctx.Err() != nil {
response.err = ctx.Err()
return response
}
_, targetEpoch, peers := f.calculateHeadAndTargetEpochs()
if len(peers) == 0 {
response.err = errNoPeersAvailable
return response
}
// Short circuit start far exceeding the highest finalized epoch in some infinite loop.
if f.mode == modeStopOnFinalizedEpoch {
highestFinalizedSlot := params.BeaconConfig().SlotsPerEpoch.Mul(uint64(targetEpoch + 1))
if start > highestFinalizedSlot {
response.err = fmt.Errorf("%w, slot: %d, highest finalized slot: %d",
errSlotIsTooHigh, start, highestFinalizedSlot)
return response
}
}
response.bwb, response.pid, response.err = f.fetchBlocksFromPeer(ctx, start, count, peers)
if response.err == nil {
bwb, err := f.fetchBlobsFromPeer(ctx, response.bwb, response.pid)
if err != nil {
response.err = err
}
response.bwb = bwb
}
return response
}
// fetchBlocksFromPeer fetches blocks from a single randomly selected peer.
func (f *blocksFetcher) fetchBlocksFromPeer(
ctx context.Context,
start primitives.Slot, count uint64,
peers []peer.ID,
) ([]blocks2.BlockWithVerifiedBlobs, peer.ID, error) {
ctx, span := trace.StartSpan(ctx, "initialsync.fetchBlocksFromPeer")
defer span.End()
peers = f.filterPeers(ctx, peers, peersPercentagePerRequest)
req := &p2ppb.BeaconBlocksByRangeRequest{
StartSlot: start,
Count: count,
Step: 1,
}
for i := 0; i < len(peers); i++ {
p := peers[i]
blocks, err := f.requestBlocks(ctx, req, p)
if err != nil {
log.WithField("peer", p).WithError(err).Debug("Could not request blocks by range from peer")
continue
}
f.p2p.Peers().Scorers().BlockProviderScorer().Touch(p)
robs, err := sortedBlockWithVerifiedBlobSlice(blocks)
if err != nil {
log.WithField("peer", p).WithError(err).Debug("invalid BeaconBlocksByRange response")
continue
}
return robs, p, err
}
return nil, "", errNoPeersAvailable
}
func sortedBlockWithVerifiedBlobSlice(blocks []interfaces.ReadOnlySignedBeaconBlock) ([]blocks2.BlockWithVerifiedBlobs, error) {
rb := make([]blocks2.BlockWithVerifiedBlobs, len(blocks))
for i, b := range blocks {
ro, err := blocks2.NewROBlock(b)
if err != nil {
return nil, err
}
rb[i] = blocks2.BlockWithVerifiedBlobs{Block: ro}
}
sort.Sort(blocks2.BlockWithVerifiedBlobsSlice(rb))
return rb, nil
}
func blobRequest(bwb []blocks2.BlockWithVerifiedBlobs, blobWindowStart primitives.Slot) *p2ppb.BlobSidecarsByRangeRequest {
if len(bwb) == 0 {
return nil
}
lowest := lowestSlotNeedsBlob(blobWindowStart, bwb)
if lowest == nil {
return nil
}
highest := bwb[len(bwb)-1].Block.Block().Slot()
return &p2ppb.BlobSidecarsByRangeRequest{
StartSlot: *lowest,
Count: uint64(highest.SubSlot(*lowest)) + 1,
}
}
func lowestSlotNeedsBlob(retentionStart primitives.Slot, bwb []blocks2.BlockWithVerifiedBlobs) *primitives.Slot {
if len(bwb) == 0 {
return nil
}
// Short-circuit if the highest block is before the deneb start epoch or retention period start.
// This assumes blocks are sorted by sortedBlockWithVerifiedBlobSlice.
// bwb is sorted by slot, so if the last element is outside the retention window, no blobs are needed.
if bwb[len(bwb)-1].Block.Block().Slot() < retentionStart {
return nil
}
for _, b := range bwb {
slot := b.Block.Block().Slot()
if slot < retentionStart {
continue
}
commits, err := b.Block.Block().Body().BlobKzgCommitments()
if err != nil || len(commits) == 0 {
continue
}
return &slot
}
return nil
}
func sortBlobs(blobs []*p2ppb.BlobSidecar) []*p2ppb.BlobSidecar {
sort.Slice(blobs, func(i, j int) bool {
if blobs[i].Slot == blobs[j].Slot {
return blobs[i].Index < blobs[j].Index
}
return blobs[i].Slot < blobs[j].Slot
})
return blobs
}
var errBlobVerification = errors.New("peer unable to serve aligned BlobSidecarsByRange and BeaconBlockSidecarsByRange responses")
var errMissingBlobsForBlockCommitments = errors.Wrap(errBlobVerification, "blobs unavailable for processing block with kzg commitments")
var errMismatchedBlobBlockRoot = errors.Wrap(errBlobVerification, "BlockRoot in BlobSidecar does not match the expected root")
var errMissingBlobIndex = errors.Wrap(errBlobVerification, "missing expected blob index")
var errMismatchedBlobCommitments = errors.Wrap(errBlobVerification, "commitments at given slot, root and index do not match")
func verifyAndPopulateBlobs(bwb []blocks2.BlockWithVerifiedBlobs, blobs []*p2ppb.BlobSidecar, blobWindowStart primitives.Slot) ([]blocks2.BlockWithVerifiedBlobs, error) {
// Assumes bwb has already been sorted by sortedBlockWithVerifiedBlobSlice.
blobs = sortBlobs(blobs)
blobi := 0
// Loop over all blocks, and each time a commitment is observed, advance the index into the blob slice.
// The assumption is that the blob slice contains a value for every commitment in the blocks it is based on,
// correctly ordered by slot and blob index.
for i, bb := range bwb {
block := bb.Block.Block()
if block.Slot() < blobWindowStart {
continue
}
commits, err := block.Body().BlobKzgCommitments()
if err != nil {
if errors.Is(err, consensus_types.ErrUnsupportedField) {
log.
WithField("block_slot", block.Slot()).
WithField("retention_start", blobWindowStart).
Warn("block with slot within blob retention period has version which does not support commitments")
continue
}
return nil, err
}
bb.Blobs = make([]*p2ppb.BlobSidecar, len(commits))
for ci := range commits {
// There are more expected commitments in this block, but we've run out of blobs from the response
// (out-of-bound error guard).
if blobi == len(blobs) {
return nil, missingCommitError(bb.Block.Root(), bb.Block.Block().Slot(), commits[ci:])
}
bl := blobs[blobi]
if bl.Slot != block.Slot() {
return nil, missingCommitError(bb.Block.Root(), bb.Block.Block().Slot(), commits[ci:])
}
if bytesutil.ToBytes32(bl.BlockRoot) != bb.Block.Root() {
return nil, errors.Wrapf(errMismatchedBlobBlockRoot,
"block root %#x != BlobSidecar.BlockRoot %#x at slot %d", bb.Block.Root(), bl.BlockRoot, block.Slot())
}
if ci != int(bl.Index) {
return nil, errors.Wrapf(errMissingBlobIndex,
"did not receive blob index %d for block root %#x at slot %d", ci, bb.Block.Root(), block.Slot())
}
ec := bytesutil.ToBytes48(commits[ci])
ac := bytesutil.ToBytes48(bl.KzgCommitment)
if ec != ac {
return nil, errors.Wrapf(errMismatchedBlobCommitments,
"commitment %#x != block commitment %#x, at index %d for block root %#x at slot %d ",
ac, ec, bl.Index, bb.Block.Root(), block.Slot())
}
bb.Blobs[ci] = bl
blobi += 1
}
bwb[i] = bb
}
return bwb, nil
}
func missingCommitError(root [32]byte, slot primitives.Slot, missing [][]byte) error {
missStr := make([]string, len(missing))
for k := range missing {
missStr = append(missStr, fmt.Sprintf("%#x", k))
}
return errors.Wrapf(errMissingBlobsForBlockCommitments,
"block root %#x at slot %d missing %d commitments %s", root, slot, len(missing), strings.Join(missStr, ","))
}
// fetchBlobsFromPeer fetches blocks from a single randomly selected peer.
func (f *blocksFetcher) fetchBlobsFromPeer(ctx context.Context, bwb []blocks2.BlockWithVerifiedBlobs, pid peer.ID) ([]blocks2.BlockWithVerifiedBlobs, error) {
ctx, span := trace.StartSpan(ctx, "initialsync.fetchBlobsFromPeer")
defer span.End()
if slots.ToEpoch(f.clock.CurrentSlot()) < params.BeaconConfig().DenebForkEpoch {
return bwb, nil
}
blobWindowStart, err := prysmsync.BlobsByRangeMinStartSlot(f.clock.CurrentSlot())
if err != nil {
return nil, err
}
// Construct request message based on observed interval of blocks in need of blobs.
req := blobRequest(bwb, blobWindowStart)
if req == nil {
return bwb, nil
}
// Request blobs from the same peer that gave us the blob batch.
blobs, err := f.requestBlobs(ctx, req, pid)
if err != nil {
return nil, errors.Wrap(err, "could not request blobs by range")
}
f.p2p.Peers().Scorers().BlockProviderScorer().Touch(pid)
return verifyAndPopulateBlobs(bwb, blobs, blobWindowStart)
}
// requestBlocks is a wrapper for handling BeaconBlocksByRangeRequest requests/streams.
func (f *blocksFetcher) requestBlocks(
ctx context.Context,
req *p2ppb.BeaconBlocksByRangeRequest,
pid peer.ID,
) ([]interfaces.ReadOnlySignedBeaconBlock, error) {
if ctx.Err() != nil {
return nil, ctx.Err()
}
l := f.peerLock(pid)
l.Lock()
log.WithFields(logrus.Fields{
"peer": pid,
"start": req.StartSlot,
"count": req.Count,
"step": req.Step,
"capacity": f.rateLimiter.Remaining(pid.String()),
"score": f.p2p.Peers().Scorers().BlockProviderScorer().FormatScorePretty(pid),
}).Debug("Requesting blocks")
if f.rateLimiter.Remaining(pid.String()) < int64(req.Count) {
if err := f.waitForBandwidth(pid, req.Count); err != nil {
l.Unlock()
return nil, err
}
}
f.rateLimiter.Add(pid.String(), int64(req.Count))
l.Unlock()
return prysmsync.SendBeaconBlocksByRangeRequest(ctx, f.chain, f.p2p, pid, req, nil)
}
func (f *blocksFetcher) requestBlobs(ctx context.Context, req *p2ppb.BlobSidecarsByRangeRequest, pid peer.ID) ([]*p2ppb.BlobSidecar, error) {
if ctx.Err() != nil {
return nil, ctx.Err()
}
l := f.peerLock(pid)
l.Lock()
log.WithFields(logrus.Fields{
"peer": pid,
"start": req.StartSlot,
"count": req.Count,
"capacity": f.rateLimiter.Remaining(pid.String()),
"score": f.p2p.Peers().Scorers().BlockProviderScorer().FormatScorePretty(pid),
}).Debug("Requesting blobs")
// We're intentionally abusing the block rate limit here, treating blob requests as if they were blob requests.
// Since blob requests take more bandwidth than blocks, we should improve how we account for the different kinds
// of requests, more in proportion to the cost of serving them.
if f.rateLimiter.Remaining(pid.String()) < int64(req.Count) {
if err := f.waitForBandwidth(pid, req.Count); err != nil {
l.Unlock()
return nil, err
}
}
f.rateLimiter.Add(pid.String(), int64(req.Count))
l.Unlock()
return prysmsync.SendBlobsByRangeRequest(ctx, f.clock, f.p2p, pid, f.ctxMap, req)
}
// requestBlocksByRoot is a wrapper for handling BeaconBlockByRootsReq requests/streams.
func (f *blocksFetcher) requestBlocksByRoot(
ctx context.Context,
req *p2pTypes.BeaconBlockByRootsReq,
pid peer.ID,
) ([]interfaces.ReadOnlySignedBeaconBlock, error) {
if ctx.Err() != nil {
return nil, ctx.Err()
}
l := f.peerLock(pid)
l.Lock()
log.WithFields(logrus.Fields{
"peer": pid,
"numRoots": len(*req),
"capacity": f.rateLimiter.Remaining(pid.String()),
"score": f.p2p.Peers().Scorers().BlockProviderScorer().FormatScorePretty(pid),
}).Debug("Requesting blocks (by roots)")
if f.rateLimiter.Remaining(pid.String()) < int64(len(*req)) {
if err := f.waitForBandwidth(pid, uint64(len(*req))); err != nil {
l.Unlock()
return nil, err
}
}
f.rateLimiter.Add(pid.String(), int64(len(*req)))
l.Unlock()
return prysmsync.SendBeaconBlocksByRootRequest(ctx, f.chain, f.p2p, pid, req, nil)
}
// waitForBandwidth blocks up until peer's bandwidth is restored.
func (f *blocksFetcher) waitForBandwidth(pid peer.ID, count uint64) error {
log.WithField("peer", pid).Debug("Slowing down for rate limit")
rem := f.rateLimiter.Remaining(pid.String())
if uint64(rem) >= count {
// Exit early if we have sufficient capacity
return nil
}
intCount, err := math.Int(count)
if err != nil {
return err
}
toWait := timeToWait(int64(intCount), rem, f.rateLimiter.Capacity(), f.rateLimiter.TillEmpty(pid.String()))
timer := time.NewTimer(toWait)
defer timer.Stop()
select {
case <-f.ctx.Done():
return errFetcherCtxIsDone
case <-timer.C:
// Peer has gathered enough capacity to be polled again.
}
return nil
}
// Determine how long it will take for us to have the required number of blocks allowed by our rate limiter.
// We do this by calculating the duration till the rate limiter can request these blocks without exceeding
// the provided bandwidth limits per peer.
func timeToWait(wanted, rem, capacity int64, timeTillEmpty time.Duration) time.Duration {
// Defensive check if we have more than enough blocks
// to request from the peer.
if rem >= wanted {
return 0
}
// Handle edge case where capacity is equal to the remaining amount
// of blocks. This also handles the impossible case in where remaining blocks
// exceed the limiter's capacity.
if capacity <= rem {
return 0
}
blocksNeeded := wanted - rem
currentNumBlks := capacity - rem
expectedTime := int64(timeTillEmpty) * blocksNeeded / currentNumBlks
return time.Duration(expectedTime)
}