mirror of https://github.com/poanetwork/quorum.git
551 lines
17 KiB
Go
551 lines
17 KiB
Go
package downloader
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import (
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"errors"
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"math/rand"
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"sync"
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"sync/atomic"
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"time"
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"gopkg.in/fatih/set.v0"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/event"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/logger/glog"
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)
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const (
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MinHashFetch = 512 // Minimum amount of hashes to not consider a peer stalling
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MaxHashFetch = 2048 // Amount of hashes to be fetched per retrieval request
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MaxBlockFetch = 128 // Amount of blocks to be fetched per retrieval request
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peerCountTimeout = 12 * time.Second // Amount of time it takes for the peer handler to ignore minDesiredPeerCount
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hashTTL = 5 * time.Second // Time it takes for a hash request to time out
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)
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var (
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blockTTL = 5 * time.Second // Time it takes for a block request to time out
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crossCheckCycle = time.Second // Period after which to check for expired cross checks
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minDesiredPeerCount = 5 // Amount of peers desired to start syncing
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)
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var (
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errLowTd = errors.New("peers TD is too low")
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ErrBusy = errors.New("busy")
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errUnknownPeer = errors.New("peer is unknown or unhealthy")
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ErrBadPeer = errors.New("action from bad peer ignored")
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ErrStallingPeer = errors.New("peer is stalling")
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errNoPeers = errors.New("no peers to keep download active")
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ErrPendingQueue = errors.New("pending items in queue")
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ErrTimeout = errors.New("timeout")
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errEmptyHashSet = errors.New("empty hash set by peer")
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errPeersUnavailable = errors.New("no peers available or all peers tried for block download process")
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errAlreadyInPool = errors.New("hash already in pool")
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ErrInvalidChain = errors.New("retrieved hash chain is invalid")
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ErrCrossCheckFailed = errors.New("block cross-check failed")
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errCancelHashFetch = errors.New("hash fetching cancelled (requested)")
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errCancelBlockFetch = errors.New("block downloading cancelled (requested)")
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errNoSyncActive = errors.New("no sync active")
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)
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type hashCheckFn func(common.Hash) bool
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type getBlockFn func(common.Hash) *types.Block
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type chainInsertFn func(types.Blocks) (int, error)
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type hashIterFn func() (common.Hash, error)
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type blockPack struct {
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peerId string
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blocks []*types.Block
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}
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type hashPack struct {
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peerId string
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hashes []common.Hash
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}
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type crossCheck struct {
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expire time.Time
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parent common.Hash
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}
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type Downloader struct {
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mux *event.TypeMux
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mu sync.RWMutex
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queue *queue // Scheduler for selecting the hashes to download
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peers *peerSet // Set of active peers from which download can proceed
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checks map[common.Hash]*crossCheck // Pending cross checks to verify a hash chain
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banned *set.SetNonTS // Set of hashes we've received and banned
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// Callbacks
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hasBlock hashCheckFn
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getBlock getBlockFn
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// Status
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synchronising int32
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notified int32
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// Channels
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newPeerCh chan *peer
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hashCh chan hashPack
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blockCh chan blockPack
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cancelCh chan struct{} // Channel to cancel mid-flight syncs
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cancelLock sync.RWMutex // Lock to protect the cancel channel in delivers
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}
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// Block is an origin-tagged blockchain block.
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type Block struct {
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RawBlock *types.Block
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OriginPeer string
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}
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func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock getBlockFn) *Downloader {
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// Create the base downloader
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downloader := &Downloader{
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mux: mux,
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queue: newQueue(),
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peers: newPeerSet(),
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hasBlock: hasBlock,
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getBlock: getBlock,
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newPeerCh: make(chan *peer, 1),
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hashCh: make(chan hashPack, 1),
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blockCh: make(chan blockPack, 1),
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}
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// Inject all the known bad hashes
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downloader.banned = set.NewNonTS()
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for hash, _ := range core.BadHashes {
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downloader.banned.Add(hash)
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}
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return downloader
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}
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func (d *Downloader) Stats() (current int, max int) {
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return d.queue.Size()
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}
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// Synchronising returns the state of the downloader
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func (d *Downloader) Synchronising() bool {
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return atomic.LoadInt32(&d.synchronising) > 0
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}
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// RegisterPeer injects a new download peer into the set of block source to be
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// used for fetching hashes and blocks from.
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func (d *Downloader) RegisterPeer(id string, head common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) error {
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glog.V(logger.Detail).Infoln("Registering peer", id)
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if err := d.peers.Register(newPeer(id, head, getHashes, getBlocks)); err != nil {
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glog.V(logger.Error).Infoln("Register failed:", err)
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return err
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}
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return nil
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}
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// UnregisterPeer remove a peer from the known list, preventing any action from
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// the specified peer.
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func (d *Downloader) UnregisterPeer(id string) error {
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glog.V(logger.Detail).Infoln("Unregistering peer", id)
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if err := d.peers.Unregister(id); err != nil {
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glog.V(logger.Error).Infoln("Unregister failed:", err)
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return err
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}
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return nil
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}
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// Synchronise will select the peer and use it for synchronising. If an empty string is given
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// it will use the best peer possible and synchronize if it's TD is higher than our own. If any of the
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// checks fail an error will be returned. This method is synchronous
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func (d *Downloader) Synchronise(id string, hash common.Hash) error {
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// Make sure only one goroutine is ever allowed past this point at once
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if !atomic.CompareAndSwapInt32(&d.synchronising, 0, 1) {
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return ErrBusy
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}
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defer atomic.StoreInt32(&d.synchronising, 0)
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// Post a user notification of the sync (only once per session)
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if atomic.CompareAndSwapInt32(&d.notified, 0, 1) {
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glog.V(logger.Info).Infoln("Block synchronisation started")
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}
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// Create cancel channel for aborting mid-flight
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d.cancelLock.Lock()
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d.cancelCh = make(chan struct{})
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d.cancelLock.Unlock()
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// Abort if the queue still contains some leftover data
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if _, cached := d.queue.Size(); cached > 0 && d.queue.GetHeadBlock() != nil {
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return ErrPendingQueue
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}
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// Reset the queue and peer set to clean any internal leftover state
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d.queue.Reset()
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d.peers.Reset()
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d.checks = make(map[common.Hash]*crossCheck)
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// Retrieve the origin peer and initiate the downloading process
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p := d.peers.Peer(id)
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if p == nil {
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return errUnknownPeer
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}
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return d.syncWithPeer(p, hash)
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}
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// TakeBlocks takes blocks from the queue and yields them to the caller.
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func (d *Downloader) TakeBlocks() []*Block {
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return d.queue.TakeBlocks()
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}
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func (d *Downloader) Has(hash common.Hash) bool {
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return d.queue.Has(hash)
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}
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// syncWithPeer starts a block synchronization based on the hash chain from the
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// specified peer and head hash.
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func (d *Downloader) syncWithPeer(p *peer, hash common.Hash) (err error) {
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d.mux.Post(StartEvent{})
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defer func() {
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// reset on error
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if err != nil {
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d.Cancel()
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d.mux.Post(FailedEvent{err})
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} else {
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d.mux.Post(DoneEvent{})
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}
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}()
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glog.V(logger.Debug).Infoln("Synchronizing with the network using:", p.id)
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if err = d.fetchHashes(p, hash); err != nil {
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return err
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}
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if err = d.fetchBlocks(); err != nil {
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return err
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}
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glog.V(logger.Debug).Infoln("Synchronization completed")
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return nil
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}
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// Cancel cancels all of the operations and resets the queue. It returns true
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// if the cancel operation was completed.
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func (d *Downloader) Cancel() bool {
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// If we're not syncing just return.
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hs, bs := d.queue.Size()
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if atomic.LoadInt32(&d.synchronising) == 0 && hs == 0 && bs == 0 {
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return false
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}
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// Close the current cancel channel
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d.cancelLock.Lock()
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select {
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case <-d.cancelCh:
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// Channel was already closed
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default:
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close(d.cancelCh)
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}
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d.cancelLock.Unlock()
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// reset the queue
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d.queue.Reset()
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return true
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}
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// XXX Make synchronous
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func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
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glog.V(logger.Debug).Infof("Downloading hashes (%x) from %s", h[:4], p.id)
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start := time.Now()
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// Add the hash to the queue first, and start hash retrieval
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d.queue.Insert([]common.Hash{h})
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p.getHashes(h)
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var (
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active = p // active peer will help determine the current active peer
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head = common.Hash{} // common and last hash
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timeout = time.NewTimer(hashTTL) // timer to dump a non-responsive active peer
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attempted = make(map[string]bool) // attempted peers will help with retries
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crossTicker = time.NewTicker(crossCheckCycle) // ticker to periodically check expired cross checks
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)
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defer crossTicker.Stop()
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attempted[p.id] = true
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for finished := false; !finished; {
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select {
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case <-d.cancelCh:
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return errCancelHashFetch
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case hashPack := <-d.hashCh:
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// Make sure the active peer is giving us the hashes
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if hashPack.peerId != active.id {
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glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)\n", hashPack.peerId)
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break
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}
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timeout.Reset(hashTTL)
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// Make sure the peer actually gave something valid
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if len(hashPack.hashes) == 0 {
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glog.V(logger.Debug).Infof("Peer (%s) responded with empty hash set\n", active.id)
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return errEmptyHashSet
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}
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for _, hash := range hashPack.hashes {
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if d.banned.Has(hash) {
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glog.V(logger.Debug).Infof("Peer (%s) sent a known invalid chain\n", active.id)
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return ErrInvalidChain
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}
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}
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// Determine if we're done fetching hashes (queue up all pending), and continue if not done
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done, index := false, 0
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for index, head = range hashPack.hashes {
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if d.hasBlock(head) || d.queue.GetBlock(head) != nil {
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glog.V(logger.Debug).Infof("Found common hash %x\n", head[:4])
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hashPack.hashes = hashPack.hashes[:index]
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done = true
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break
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}
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}
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// Insert all the new hashes, but only continue if got something useful
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inserts := d.queue.Insert(hashPack.hashes)
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if len(inserts) == 0 && !done {
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glog.V(logger.Debug).Infof("Peer (%s) responded with stale hashes\n", active.id)
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return ErrBadPeer
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}
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if !done {
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// Check that the peer is not stalling the sync
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if len(inserts) < MinHashFetch {
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return ErrStallingPeer
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}
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// Try and fetch a random block to verify the hash batch
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// Skip the last hash as the cross check races with the next hash fetch
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cross := rand.Intn(len(inserts) - 1)
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origin, parent := inserts[cross], inserts[cross+1]
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glog.V(logger.Detail).Infof("Cross checking (%s) with %x/%x", active.id, origin, parent)
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d.checks[origin] = &crossCheck{
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expire: time.Now().Add(blockTTL),
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parent: parent,
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}
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active.getBlocks([]common.Hash{origin})
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// Also fetch a fresh
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active.getHashes(head)
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continue
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}
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// We're done, allocate the download cache and proceed pulling the blocks
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offset := 0
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if block := d.getBlock(head); block != nil {
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offset = int(block.NumberU64() + 1)
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}
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d.queue.Alloc(offset)
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finished = true
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case blockPack := <-d.blockCh:
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// Cross check the block with the random verifications
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if blockPack.peerId != active.id || len(blockPack.blocks) != 1 {
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continue
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}
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block := blockPack.blocks[0]
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if check, ok := d.checks[block.Hash()]; ok {
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if block.ParentHash() != check.parent {
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return ErrCrossCheckFailed
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}
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delete(d.checks, block.Hash())
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}
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case <-crossTicker.C:
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// Iterate over all the cross checks and fail the hash chain if they're not verified
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for hash, check := range d.checks {
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if time.Now().After(check.expire) {
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glog.V(logger.Debug).Infof("Cross check timeout for %x", hash)
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return ErrCrossCheckFailed
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}
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}
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case <-timeout.C:
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glog.V(logger.Debug).Infof("Peer (%s) didn't respond in time for hash request\n", p.id)
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var p *peer // p will be set if a peer can be found
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// Attempt to find a new peer by checking inclusion of peers best hash in our
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// already fetched hash list. This can't guarantee 100% correctness but does
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// a fair job. This is always either correct or false incorrect.
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for _, peer := range d.peers.AllPeers() {
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if d.queue.Has(peer.head) && !attempted[peer.id] {
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p = peer
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break
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}
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}
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// if all peers have been tried, abort the process entirely or if the hash is
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// the zero hash.
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if p == nil || (head == common.Hash{}) {
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return ErrTimeout
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}
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// set p to the active peer. this will invalidate any hashes that may be returned
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// by our previous (delayed) peer.
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active = p
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p.getHashes(head)
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glog.V(logger.Debug).Infof("Hash fetching switched to new peer(%s)\n", p.id)
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}
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}
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glog.V(logger.Debug).Infof("Downloaded hashes (%d) in %v\n", d.queue.Pending(), time.Since(start))
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return nil
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}
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// fetchBlocks iteratively downloads the entire schedules block-chain, taking
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// any available peers, reserving a chunk of blocks for each, wait for delivery
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// and periodically checking for timeouts.
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func (d *Downloader) fetchBlocks() error {
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glog.V(logger.Debug).Infoln("Downloading", d.queue.Pending(), "block(s)")
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start := time.Now()
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// default ticker for re-fetching blocks every now and then
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ticker := time.NewTicker(20 * time.Millisecond)
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out:
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for {
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select {
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case <-d.cancelCh:
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return errCancelBlockFetch
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case blockPack := <-d.blockCh:
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// Short circuit if it's a stale cross check
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if len(blockPack.blocks) == 1 {
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block := blockPack.blocks[0]
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if _, ok := d.checks[block.Hash()]; ok {
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delete(d.checks, block.Hash())
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continue
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}
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}
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// If the peer was previously banned and failed to deliver it's pack
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// in a reasonable time frame, ignore it's message.
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if peer := d.peers.Peer(blockPack.peerId); peer != nil {
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// Deliver the received chunk of blocks
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if err := d.queue.Deliver(blockPack.peerId, blockPack.blocks); err != nil {
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if err == ErrInvalidChain {
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// The hash chain is invalid (blocks are not ordered properly), abort
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return err
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}
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// Peer did deliver, but some blocks were off, penalize
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glog.V(logger.Debug).Infof("Failed delivery for peer %s: %v\n", blockPack.peerId, err)
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peer.Demote()
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break
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}
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if glog.V(logger.Debug) && len(blockPack.blocks) > 0 {
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glog.Infof("Added %d blocks from: %s\n", len(blockPack.blocks), blockPack.peerId)
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}
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// Promote the peer and update it's idle state
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peer.Promote()
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peer.SetIdle()
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}
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case <-ticker.C:
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// Check for bad peers. Bad peers may indicate a peer not responding
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// to a `getBlocks` message. A timeout of 5 seconds is set. Peers
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// that badly or poorly behave are removed from the peer set (not banned).
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// Bad peers are excluded from the available peer set and therefor won't be
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// reused. XXX We could re-introduce peers after X time.
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badPeers := d.queue.Expire(blockTTL)
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for _, pid := range badPeers {
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// XXX We could make use of a reputation system here ranking peers
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// in their performance
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// 1) Time for them to respond;
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// 2) Measure their speed;
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// 3) Amount and availability.
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if peer := d.peers.Peer(pid); peer != nil {
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peer.Demote()
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}
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}
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// After removing bad peers make sure we actually have sufficient peer left to keep downloading
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if d.peers.Len() == 0 {
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return errNoPeers
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}
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// If there are unrequested hashes left start fetching
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// from the available peers.
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if d.queue.Pending() > 0 {
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// Throttle the download if block cache is full and waiting processing
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if d.queue.Throttle() {
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continue
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}
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// Send a download request to all idle peers, until throttled
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idlePeers := d.peers.IdlePeers()
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for _, peer := range idlePeers {
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// Short circuit if throttling activated since above
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if d.queue.Throttle() {
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break
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}
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// Get a possible chunk. If nil is returned no chunk
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// could be returned due to no hashes available.
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request := d.queue.Reserve(peer, MaxBlockFetch)
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if request == nil {
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continue
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}
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// Fetch the chunk and check for error. If the peer was somehow
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// already fetching a chunk due to a bug, it will be returned to
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// the queue
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if err := peer.Fetch(request); err != nil {
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glog.V(logger.Error).Infof("Peer %s received double work\n", peer.id)
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d.queue.Cancel(request)
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}
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}
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// Make sure that we have peers available for fetching. If all peers have been tried
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// and all failed throw an error
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if d.queue.InFlight() == 0 {
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return errPeersUnavailable
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}
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} else if d.queue.InFlight() == 0 {
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// When there are no more queue and no more in flight, We can
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// safely assume we're done. Another part of the process will check
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|
// for parent errors and will re-request anything that's missing
|
|
break out
|
|
}
|
|
}
|
|
}
|
|
glog.V(logger.Detail).Infoln("Downloaded block(s) in", time.Since(start))
|
|
|
|
return nil
|
|
}
|
|
|
|
// DeliverBlocks injects a new batch of blocks received from a remote node.
|
|
// This is usually invoked through the BlocksMsg by the protocol handler.
|
|
func (d *Downloader) DeliverBlocks(id string, blocks []*types.Block) error {
|
|
// Make sure the downloader is active
|
|
if atomic.LoadInt32(&d.synchronising) == 0 {
|
|
return errNoSyncActive
|
|
}
|
|
// Deliver or abort if the sync is canceled while queuing
|
|
d.cancelLock.RLock()
|
|
cancel := d.cancelCh
|
|
d.cancelLock.RUnlock()
|
|
|
|
select {
|
|
case d.blockCh <- blockPack{id, blocks}:
|
|
return nil
|
|
|
|
case <-cancel:
|
|
return errNoSyncActive
|
|
}
|
|
}
|
|
|
|
// DeliverHashes injects a new batch of hashes received from a remote node into
|
|
// the download schedule. This is usually invoked through the BlockHashesMsg by
|
|
// the protocol handler.
|
|
func (d *Downloader) DeliverHashes(id string, hashes []common.Hash) error {
|
|
// Make sure the downloader is active
|
|
if atomic.LoadInt32(&d.synchronising) == 0 {
|
|
return errNoSyncActive
|
|
}
|
|
// Deliver or abort if the sync is canceled while queuing
|
|
d.cancelLock.RLock()
|
|
cancel := d.cancelCh
|
|
d.cancelLock.RUnlock()
|
|
|
|
select {
|
|
case d.hashCh <- hashPack{id, hashes}:
|
|
return nil
|
|
|
|
case <-cancel:
|
|
return errNoSyncActive
|
|
}
|
|
}
|