506 lines
15 KiB
Go
506 lines
15 KiB
Go
package downloader
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import (
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"errors"
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"fmt"
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"math"
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"math/big"
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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"
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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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"gopkg.in/fatih/set.v0"
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)
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const (
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maxBlockFetch = 256 // 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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blockTtl = 20 * time.Second // The amount of time it takes for a block request to time out
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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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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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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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)
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type hashCheckFn func(common.Hash) bool
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type chainInsertFn func(types.Blocks) error
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type hashIterFn func() (common.Hash, error)
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type currentTdFn func() *big.Int
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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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insertChain chainInsertFn
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currentTd currentTdFn
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// Status
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fetchingHashes int32
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downloadingBlocks int32
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processingBlocks int32
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// Channels
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newPeerCh chan *peer
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syncCh chan syncPack
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hashCh chan []common.Hash
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blockCh chan blockPack
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quit chan struct{}
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}
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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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func New(hasBlock hashCheckFn, insertChain chainInsertFn, currentTd currentTdFn) *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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insertChain: insertChain,
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currentTd: currentTd,
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newPeerCh: make(chan *peer, 1),
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syncCh: make(chan syncPack, 1),
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hashCh: make(chan []common.Hash, 1),
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blockCh: make(chan blockPack, 1),
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quit: make(chan struct{}),
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}
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go downloader.peerHandler()
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go downloader.update()
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return downloader
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}
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func (d *Downloader) RegisterPeer(id string, td *big.Int, 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, "TD =", td)
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// Create a new peer and add it to the list of known peers
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peer := newPeer(id, td, 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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d.newPeerCh <- peer
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return nil
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}
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// UnregisterPeer unregister's 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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func (d *Downloader) peerHandler() {
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// itimer is used to determine when to start ignoring `minDesiredPeerCount`
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itimer := time.NewTimer(peerCountTimeout)
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out:
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for {
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select {
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case <-d.newPeerCh:
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// Meet the `minDesiredPeerCount` before we select our best peer
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if len(d.peers) < minDesiredPeerCount {
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break
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}
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itimer.Stop()
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d.selectPeer(d.peers.bestPeer())
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case <-itimer.C:
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// The timer will make sure that the downloader keeps an active state
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// in which it attempts to always check the network for highest td peers
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// Either select the peer or restart the timer if no peers could
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// be selected.
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if peer := d.peers.bestPeer(); peer != nil {
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d.selectPeer(d.peers.bestPeer())
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} else {
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itimer.Reset(5 * time.Second)
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}
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case <-d.quit:
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break out
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}
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}
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}
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func (d *Downloader) selectPeer(p *peer) {
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// Make sure it's doing neither. Once done we can restart the
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// downloading process if the TD is higher. For now just get on
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// with whatever is going on. This prevents unecessary switching.
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if d.isBusy() {
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return
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}
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// selected peer must be better than our own
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// XXX we also check the peer's recent hash to make sure we
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// don't have it. Some peers report (i think) incorrect TD.
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if p.td.Cmp(d.currentTd()) <= 0 || d.hasBlock(p.recentHash) {
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return
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}
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glog.V(logger.Detail).Infoln("New peer with highest TD =", p.td)
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d.syncCh <- syncPack{p, p.recentHash, false}
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}
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func (d *Downloader) update() {
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out:
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for {
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select {
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case sync := <-d.syncCh:
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var peer *peer = sync.peer
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err := d.getFromPeer(peer, sync.hash, sync.ignoreInitial)
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if err != nil {
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glog.V(logger.Detail).Infoln(err)
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break
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}
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d.process()
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case <-d.quit:
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break out
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}
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}
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}
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// XXX Make synchronous
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func (d *Downloader) startFetchingHashes(p *peer, hash common.Hash, ignoreInitial bool) error {
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atomic.StoreInt32(&d.fetchingHashes, 1)
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defer atomic.StoreInt32(&d.fetchingHashes, 0)
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glog.V(logger.Debug).Infof("Downloading hashes (%x) from %s", hash.Bytes()[: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.hashPool.Add(hash)
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}
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// Get the first batch of hashes
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p.getHashes(hash)
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failureResponseTimer := time.NewTimer(hashTtl)
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out:
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for {
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select {
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case hashes := <-d.hashCh:
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failureResponseTimer.Reset(hashTtl)
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var done bool // determines whether we're done fetching hashes (i.e. common hash found)
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hashSet := set.New()
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for _, hash := range hashes {
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if d.hasBlock(hash) {
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glog.V(logger.Debug).Infof("Found common hash %x\n", hash[:4])
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done = true
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break
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}
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hashSet.Add(hash)
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}
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d.queue.put(hashSet)
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// Add hashes to the chunk set
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if len(hashes) == 0 { // Make sure the peer actually gave you something valid
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glog.V(logger.Debug).Infof("Peer (%s) responded with empty hash set\n", p.id)
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d.queue.reset()
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return errEmptyHashSet
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} else if !done { // Check if we're done fetching
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// Get the next set of hashes
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p.getHashes(hashes[len(hashes)-1])
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} else { // we're done
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break out
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}
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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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// TODO instead of reseting the queue select a new peer from which we can start downloading hashes.
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// 1. check for peer's best hash to be included in the current hash set;
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// 2. resume from last point (hashes[len(hashes)-1]) using the newly selected peer.
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d.queue.reset()
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return errTimeout
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}
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}
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glog.V(logger.Detail).Infof("Downloaded hashes (%d) in %v\n", d.queue.hashPool.Size(), 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.Detail).Infoln("Downloading", d.queue.hashPool.Size(), "block(s)")
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atomic.StoreInt32(&d.downloadingBlocks, 1)
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defer atomic.StoreInt32(&d.downloadingBlocks, 0)
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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 everynow 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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d.peers[blockPack.peerId].promote()
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d.queue.deliver(blockPack.peerId, blockPack.blocks)
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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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// If there are unrequested hashes left start fetching
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// from the available peers.
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if d.queue.hashPool.Size() > 0 {
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was := d.queue.hashPool.Size()
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fmt.Println("it was =", was)
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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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chunk := d.queue.get(peer, maxBlockFetch)
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if chunk == 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(chunk); 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.put(chunk.hashes)
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}
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}
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fmt.Println("it is =", d.queue.hashPool.Size())
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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 len(d.queue.fetching) == 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.hashPool.Size())
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}
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} else if len(d.queue.fetching) == 0 {
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// When there are no more queue and no more `fetching`. 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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} else {
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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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d.queue.mu.Lock()
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var badPeers []string
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for pid, chunk := range d.queue.fetching {
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if time.Since(chunk.itime) > blockTtl {
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badPeers = append(badPeers, pid)
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// remove peer as good peer from peer list
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//d.UnregisterPeer(pid)
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}
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}
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d.queue.mu.Unlock()
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for _, pid := range badPeers {
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// A nil chunk is delivered so that the chunk's hashes are given
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// back to the queue objects. When hashes are put back in the queue
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// other (decent) peers can pick them up.
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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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d.queue.deliver(pid, nil)
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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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}
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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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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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d.hashCh <- hashes
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return nil
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}
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// Add an (unrequested) block to the downloader. This is usually done through the
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// NewBlockMsg by the protocol handler.
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// Adding blocks is done synchronously. if there are missing blocks, blocks will be
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// fetched first. If the downloader is busy or if some other processed failed an error
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// will be returned.
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func (d *Downloader) AddBlock(id string, block *types.Block, td *big.Int) error {
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hash := block.Hash()
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if d.hasBlock(hash) {
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return fmt.Errorf("known block %x", hash.Bytes()[:4])
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}
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peer := d.peers.getPeer(id)
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// if the peer is in our healthy list of peers; update the td
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// and add the block. Otherwise just ignore it
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if peer == nil {
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glog.V(logger.Detail).Infof("Ignored block from bad peer %s\n", id)
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return errBadPeer
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}
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peer.mu.Lock()
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peer.td = td
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peer.recentHash = block.Hash()
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peer.mu.Unlock()
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peer.promote()
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glog.V(logger.Detail).Infoln("Inserting new block from:", id)
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d.queue.addBlock(id, block, td)
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// if neither go ahead to process
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if d.isBusy() {
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return errBusy
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}
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// Check if the parent of the received block is known.
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// If the block is not know, request it otherwise, request.
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phash := block.ParentHash()
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if !d.hasBlock(phash) {
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glog.V(logger.Detail).Infof("Missing parent %x, requires fetching\n", phash.Bytes()[:4])
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// Get the missing hashes from the peer (synchronously)
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err := d.getFromPeer(peer, peer.recentHash, true)
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if err != nil {
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return err
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}
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}
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return d.process()
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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) process() error {
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atomic.StoreInt32(&d.processingBlocks, 1)
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defer atomic.StoreInt32(&d.processingBlocks, 0)
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// XXX this will move when optimised
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// Sort the blocks by number. This bit needs much improvement. Right now
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// it assumes full honesty form peers (i.e. it's not checked when the blocks
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// link). We should at least check whihc queue match. This code could move
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// to a seperate goroutine where it periodically checks for linked pieces.
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types.BlockBy(types.Number).Sort(d.queue.blocks)
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blocks := d.queue.blocks
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if len(blocks) == 0 {
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return nil
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}
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glog.V(logger.Debug).Infof("Inserting chain with %d blocks (#%v - #%v)\n", len(blocks), blocks[0].Number(), blocks[len(blocks)-1].Number())
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var err error
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// Loop untill we're out of blocks
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for len(blocks) != 0 {
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max := int(math.Min(float64(len(blocks)), 256))
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// TODO check for parent error. When there's a parent error we should stop
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// processing and start requesting the `block.hash` so that it's parent and
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// grandparents can be requested and queued.
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err = d.insertChain(blocks[:max])
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if err != nil && core.IsParentErr(err) {
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glog.V(logger.Debug).Infoln("Aborting process due to missing parent. Fetching hashes")
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// TODO change this. This shite
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for i, block := range blocks[:max] {
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if !d.hasBlock(block.ParentHash()) {
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d.syncCh <- syncPack{d.peers.bestPeer(), block.Hash(), true}
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// remove processed blocks
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blocks = blocks[i:]
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break
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}
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}
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break
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} else if err != nil {
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// Reset chain completely. This needs much, much improvement.
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// instead: check all blocks leading down to this block false block and remove it
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blocks = nil
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break
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}
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blocks = blocks[max:]
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}
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// This will allow the GC to remove the in memory blocks
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if len(blocks) == 0 {
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d.queue.blocks = nil
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} else {
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d.queue.blocks = blocks
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}
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return err
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}
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func (d *Downloader) isFetchingHashes() bool {
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return atomic.LoadInt32(&d.fetchingHashes) == 1
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}
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func (d *Downloader) isDownloadingBlocks() bool {
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return atomic.LoadInt32(&d.downloadingBlocks) == 1
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}
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func (d *Downloader) isProcessing() bool {
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return atomic.LoadInt32(&d.processingBlocks) == 1
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}
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func (d *Downloader) isBusy() bool {
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return d.isFetchingHashes() || d.isDownloadingBlocks() || d.isProcessing()
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}
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