mirror of
https://gitlab.com/pulsechaincom/go-pulse.git
synced 2024-12-25 12:57:17 +00:00
417 lines
13 KiB
Go
417 lines
13 KiB
Go
package downloader
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import (
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"errors"
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"fmt"
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"sync"
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"sync/atomic"
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"time"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core/types"
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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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maxBlockFetch = 128 // Amount of max blocks to be fetched per chunk
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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 = 20 * time.Second // The amount of time it takes for a hash request to time out
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)
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var (
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minDesiredPeerCount = 5 // Amount of peers desired to start syncing
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blockTtl = 20 * time.Second // The amount of time it takes for a block request to time out
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errLowTd = errors.New("peer's TD is too low")
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ErrBusy = errors.New("busy")
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errUnknownPeer = errors.New("peer's unknown or unhealthy")
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errBadPeer = errors.New("action from bad peer ignored")
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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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errBlockNumberOverflow = errors.New("received block which overflows")
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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 syncPack struct {
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peer *peer
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hash common.Hash
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ignoreInitial bool
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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 Downloader struct {
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mu sync.RWMutex
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queue *queue
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peers peers
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activePeer string
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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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// 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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}
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func New(hasBlock hashCheckFn, getBlock getBlockFn) *Downloader {
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downloader := &Downloader{
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queue: newQueue(),
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peers: make(peers),
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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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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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func (d *Downloader) RegisterPeer(id string, hash common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) error {
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d.mu.Lock()
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defer d.mu.Unlock()
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glog.V(logger.Detail).Infoln("Register peer", id)
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// Create a new peer and add it to the list of known peers
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peer := newPeer(id, hash, getHashes, getBlocks)
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// add peer to our peer set
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d.peers[id] = peer
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// broadcast new peer
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return nil
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}
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// UnregisterPeer unregisters a peer. This will prevent any action from the specified peer.
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func (d *Downloader) UnregisterPeer(id string) {
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d.mu.Lock()
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defer d.mu.Unlock()
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glog.V(logger.Detail).Infoln("Unregister peer", id)
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delete(d.peers, id)
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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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// 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 to clean any internal leftover state
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d.queue.Reset()
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// Retrieve the origin peer and initiate the downloading process
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p := d.peers[id]
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if p == nil {
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return errUnknownPeer
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}
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return d.getFromPeer(p, hash, false)
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}
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// TakeBlocks takes blocks from the queue and yields them to the blockTaker handler
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// it's possible it yields no blocks
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func (d *Downloader) TakeBlocks() types.Blocks {
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// Check that there are blocks available and its parents are known
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head := d.queue.GetHeadBlock()
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if head == nil || !d.hasBlock(head.ParentHash()) {
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return nil
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}
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// Retrieve a full batch of blocks
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return d.queue.TakeBlocks(head)
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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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func (d *Downloader) getFromPeer(p *peer, hash common.Hash, ignoreInitial bool) (err error) {
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d.activePeer = p.id
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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.queue.Reset()
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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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// Start the fetcher. This will block the update entirely
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// interupts need to be send to the appropriate channels
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// respectively.
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if err = d.startFetchingHashes(p, hash, ignoreInitial); err != nil {
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return err
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}
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// Start fetching blocks in paralel. The strategy is simple
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// take any available peers, seserve a chunk for each peer available,
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// let the peer deliver the chunkn and periodically check if a peer
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// has timedout.
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if err = d.startFetchingBlocks(p); 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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// XXX Make synchronous
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func (d *Downloader) startFetchingHashes(p *peer, h common.Hash, ignoreInitial bool) 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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// We ignore the initial hash in some cases (e.g. we received a block without it's parent)
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// In such circumstances we don't need to download the block so don't add it to the queue.
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if !ignoreInitial {
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// Add the hash to the queue first
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d.queue.Insert([]common.Hash{h})
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}
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// Get the first batch of hashes
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p.getHashes(h)
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var (
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failureResponseTimer = time.NewTimer(hashTtl)
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attemptedPeers = make(map[string]bool) // attempted peers will help with retries
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activePeer = p // active peer will help determine the current active peer
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hash common.Hash // common and last hash
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)
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attemptedPeers[p.id] = true
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out:
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for {
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select {
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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 != activePeer.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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failureResponseTimer.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", activePeer.id)
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d.queue.Reset()
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return errEmptyHashSet
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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, hash = range hashPack.hashes {
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if d.hasBlock(hash) || d.queue.GetBlock(hash) != nil {
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glog.V(logger.Debug).Infof("Found common hash %x\n", hash[: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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d.queue.Insert(hashPack.hashes)
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if !done {
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activePeer.getHashes(hash)
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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(hash); 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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break out
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case <-failureResponseTimer.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 id, peer := range d.peers {
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if d.queue.Has(peer.recentHash) && !attemptedPeers[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 || (hash == common.Hash{}) {
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d.queue.Reset()
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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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activePeer = p
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p.getHashes(hash)
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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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func (d *Downloader) startFetchingBlocks(p *peer) error {
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glog.V(logger.Debug).Infoln("Downloading", d.queue.Pending(), "block(s)")
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// Defer the peer reset. This will empty the peer requested set
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// and makes sure there are no lingering peers with an incorrect
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// state
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defer d.peers.reset()
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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 blockPack := <-d.blockCh:
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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 d.peers[blockPack.peerId] != nil {
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err := d.queue.Deliver(blockPack.peerId, blockPack.blocks)
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if err != nil {
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glog.V(logger.Debug).Infof("deliver failed for peer %s: %v\n", blockPack.peerId, err)
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// FIXME d.UnregisterPeer(blockPack.peerId)
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break
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}
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if glog.V(logger.Debug) {
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glog.Infof("adding %d blocks from: %s\n", len(blockPack.blocks), blockPack.peerId)
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}
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d.peers[blockPack.peerId].promote()
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d.peers.setState(blockPack.peerId, idleState)
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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[pid]; peer != nil {
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peer.demote()
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peer.reset()
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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 len(d.peers) == 0 {
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d.queue.Reset()
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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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availablePeers := d.peers.get(idleState)
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for _, peer := range availablePeers {
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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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// XXX make fetch blocking.
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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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// log for tracing
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glog.V(logger.Debug).Infof("peer %s received double work (state = %v)\n", peer.id, peer.state)
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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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d.queue.Reset()
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return fmt.Errorf("%v peers avaialable = %d. total peers = %d. hashes needed = %d", errPeersUnavailable, len(availablePeers), len(d.peers), d.queue.Pending())
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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
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break out
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}
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}
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}
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glog.V(logger.Detail).Infoln("Downloaded block(s) in", time.Since(start))
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return nil
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}
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// Deliver a chunk to the downloader. This is usually done through the BlocksMsg by
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// the protocol handler.
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func (d *Downloader) DeliverChunk(id string, blocks []*types.Block) {
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d.blockCh <- blockPack{id, blocks}
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}
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func (d *Downloader) AddHashes(id string, hashes []common.Hash) error {
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// make sure that the hashes that are being added are actually from the peer
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// that's the current active peer. hashes that have been received from other
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// peers are dropped and ignored.
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if d.activePeer != id {
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return fmt.Errorf("received hashes from %s while active peer is %s", id, d.activePeer)
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}
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if glog.V(logger.Debug) && len(hashes) != 0 {
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from, to := hashes[0], hashes[len(hashes)-1]
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glog.V(logger.Debug).Infof("adding %d (T=%d) hashes [ %x / %x ] from: %s\n", len(hashes), d.queue.Pending(), from[:4], to[:4], id)
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}
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d.hashCh <- hashPack{id, hashes}
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return nil
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}
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