gaspersic/go-ethereum
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

eth, eth/downloader: transition to eth 61

Browse Source
This commit is contained in:
Péter Szilágyi
2015-06-30 19:05:06 +03:00
parent af51dc4d63
commit f43c07cb3c
8 changed files with 695 additions and 146 deletions
Download Patch File Download Diff File Expand all files Collapse all files

397
eth/downloader/downloader.go
View File

@ -19,6 +19,11 @@ import (
"gopkg.in/fatih/set.v0"
)
const (
eth60 = 60 // Constant to check for old protocol support
eth61 = 61 // Constant to check for new protocol support
)
var (
MinHashFetch = 512 // Minimum amount of hashes to not consider a peer stalling
MaxHashFetch = 2048 // Amount of hashes to be fetched per retrieval request
@ -58,6 +63,9 @@ type hashCheckFn func(common.Hash) bool
// blockRetrievalFn is a callback type for retrieving a block from the local chain.
type blockRetrievalFn func(common.Hash) *types.Block
// headRetrievalFn is a callback type for retrieving the head block from the local chain.
type headRetrievalFn func() *types.Block
// chainInsertFn is a callback type to insert a batch of blocks into the local chain.
type chainInsertFn func(types.Blocks) (int, error)
@ -98,6 +106,7 @@ type Downloader struct {
// Callbacks
hasBlock hashCheckFn // Checks if a block is present in the chain
getBlock blockRetrievalFn // Retrieves a block from the chain
headBlock headRetrievalFn // Retrieves the head block from the chain
insertChain chainInsertFn // Injects a batch of blocks into the chain
dropPeer peerDropFn // Drops a peer for misbehaving
@ -109,8 +118,9 @@ type Downloader struct {
// Channels
newPeerCh chan *peer
hashCh chan hashPack
blockCh chan blockPack
hashCh chan hashPack // Channel receiving inbound hashes
blockCh chan blockPack // Channel receiving inbound blocks
processCh chan bool // Channel to signal the block fetcher of new or finished work
cancelCh chan struct{} // Channel to cancel mid-flight syncs
cancelLock sync.RWMutex // Lock to protect the cancel channel in delivers
@ -123,7 +133,7 @@ type Block struct {
}
// New creates a new downloader to fetch hashes and blocks from remote peers.
func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock blockRetrievalFn, insertChain chainInsertFn, dropPeer peerDropFn) *Downloader {
func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock blockRetrievalFn, headBlock headRetrievalFn, insertChain chainInsertFn, dropPeer peerDropFn) *Downloader {
// Create the base downloader
downloader := &Downloader{
mux: mux,
@ -131,11 +141,13 @@ func New(mux *event.TypeMux, hasBlock hashCheckFn, getBlock blockRetrievalFn, in
peers: newPeerSet(),
hasBlock: hasBlock,
getBlock: getBlock,
headBlock: headBlock,
insertChain: insertChain,
dropPeer: dropPeer,
newPeerCh: make(chan *peer, 1),
hashCh: make(chan hashPack, 1),
blockCh: make(chan blockPack, 1),
processCh: make(chan bool, 1),
}
// Inject all the known bad hashes
downloader.banned = set.New()
@ -175,7 +187,7 @@ func (d *Downloader) Synchronising() bool {
// RegisterPeer injects a new download peer into the set of block source to be
// used for fetching hashes and blocks from.
func (d *Downloader) RegisterPeer(id string, version int, head common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) error {
func (d *Downloader) RegisterPeer(id string, version int, head common.Hash, getRelHashes relativeHashFetcherFn, getAbsHashes absoluteHashFetcherFn, getBlocks blockFetcherFn) error {
// If the peer wants to send a banned hash, reject
if d.banned.Has(head) {
glog.V(logger.Debug).Infoln("Register rejected, head hash banned:", id)
@ -183,7 +195,7 @@ func (d *Downloader) RegisterPeer(id string, version int, head common.Hash, getH
}
// Otherwise try to construct and register the peer
glog.V(logger.Detail).Infoln("Registering peer", id)
if err := d.peers.Register(newPeer(id, version, head, getHashes, getBlocks)); err != nil {
if err := d.peers.Register(newPeer(id, version, head, getRelHashes, getAbsHashes, getBlocks)); err != nil {
glog.V(logger.Error).Infoln("Register failed:", err)
return err
}
@ -289,12 +301,38 @@ func (d *Downloader) syncWithPeer(p *peer, hash common.Hash) (err error) {
}
}()
glog.V(logger.Debug).Infoln("Synchronizing with the network using:", p.id)
if err = d.fetchHashes(p, hash); err != nil {
return err
}
if err = d.fetchBlocks(); err != nil {
return err
glog.V(logger.Debug).Infof("Synchronizing with the network using: %s, eth/%d", p.id, p.version)
switch p.version {
case eth60:
// Old eth/60 version, use reverse hash retrieval algorithm
if err = d.fetchHashes60(p, hash); err != nil {
return err
}
if err = d.fetchBlocks60(); err != nil {
return err
}
case eth61:
// New eth/61, use forward, concurrent hash and block retrieval algorithm
number, err := d.findAncestor(p)
if err != nil {
return err
}
errc := make(chan error, 2)
go func() { errc <- d.fetchHashes(p, number+1) }()
go func() { errc <- d.fetchBlocks(number + 1) }()
// If any fetcher fails, cancel the other
if err := <-errc; err != nil {
d.cancel()
<-errc
return err
}
return <-errc
default:
// Something very wrong, stop right here
glog.V(logger.Error).Infof("Unsupported eth protocol: %d", p.version)
return errBadPeer
}
glog.V(logger.Debug).Infoln("Synchronization completed")
@ -326,10 +364,10 @@ func (d *Downloader) Terminate() {
d.cancel()
}
// fetchHahes starts retrieving hashes backwards from a specific peer and hash,
// fetchHashes60 starts retrieving hashes backwards from a specific peer and hash,
// up until it finds a common ancestor. If the source peer times out, alternative
// ones are tried for continuation.
func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
func (d *Downloader) fetchHashes60(p *peer, h common.Hash) error {
var (
start = time.Now()
active = p // active peer will help determine the current active peer
@ -346,12 +384,12 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
<-timeout.C // timeout channel should be initially empty.
getHashes := func(from common.Hash) {
go active.getHashes(from)
go active.getRelHashes(from)
timeout.Reset(hashTTL)
}
// Add the hash to the queue, and start hash retrieval.
d.queue.Insert([]common.Hash{h})
d.queue.Insert([]common.Hash{h}, false)
getHashes(h)
attempted[p.id] = true
@ -377,7 +415,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
if d.banned.Has(hash) {
glog.V(logger.Debug).Infof("Peer (%s) sent a known invalid chain", active.id)
d.queue.Insert(hashPack.hashes[:index+1])
d.queue.Insert(hashPack.hashes[:index+1], false)
if err := d.banBlocks(active.id, hash); err != nil {
glog.V(logger.Debug).Infof("Failed to ban batch of blocks: %v", err)
}
@ -395,7 +433,7 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
}
}
// Insert all the new hashes, but only continue if got something useful
inserts := d.queue.Insert(hashPack.hashes)
inserts := d.queue.Insert(hashPack.hashes, false)
if len(inserts) == 0 && !done {
glog.V(logger.Debug).Infof("Peer (%s) responded with stale hashes", active.id)
return errBadPeer
@ -422,9 +460,9 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
continue
}
// We're done, prepare the download cache and proceed pulling the blocks
offset := 0
offset := uint64(0)
if block := d.getBlock(head); block != nil {
offset = int(block.NumberU64() + 1)
offset = block.NumberU64() + 1
}
d.queue.Prepare(offset)
finished = true
@ -481,10 +519,10 @@ func (d *Downloader) fetchHashes(p *peer, h common.Hash) error {
return nil
}
// fetchBlocks iteratively downloads the entire schedules block-chain, taking
// fetchBlocks60 iteratively downloads the entire schedules block-chain, taking
// any available peers, reserving a chunk of blocks for each, wait for delivery
// and periodically checking for timeouts.
func (d *Downloader) fetchBlocks() error {
func (d *Downloader) fetchBlocks60() error {
glog.V(logger.Debug).Infoln("Downloading", d.queue.Pending(), "block(s)")
start := time.Now()
@ -619,6 +657,323 @@ out:
return nil
}
// findAncestor tries to locate the common ancestor block of the local chain and
// a remote peers blockchain. In the general case when our node was in sync and
// on the correct chain, checking the top N blocks should already get us a match.
// In the rare scenario when we ended up on a long soft fork (i.e. none of the
// head blocks match), we do a binary search to find the common ancestor.
func (d *Downloader) findAncestor(p *peer) (uint64, error) {
glog.V(logger.Debug).Infof("%v: looking for common ancestor", p)
// Request out head blocks to short circuit ancestor location
head := d.headBlock().NumberU64()
from := int64(head) - int64(MaxHashFetch)
if from < 0 {
from = 0
}
go p.getAbsHashes(uint64(from), MaxHashFetch)
// Wait for the remote response to the head fetch
number, hash := uint64(0), common.Hash{}
timeout := time.After(hashTTL)
for finished := false; !finished; {
select {
case <-d.cancelCh:
return 0, errCancelHashFetch
case hashPack := <-d.hashCh:
// Discard anything not from the origin peer
if hashPack.peerId != p.id {
glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", hashPack.peerId)
break
}
// Make sure the peer actually gave something valid
hashes := hashPack.hashes
if len(hashes) == 0 {
glog.V(logger.Debug).Infof("%v: empty head hash set", p)
return 0, errEmptyHashSet
}
// Check if a common ancestor was found
finished = true
for i := len(hashes) - 1; i >= 0; i-- {
if d.hasBlock(hashes[i]) {
number, hash = uint64(from)+uint64(i), hashes[i]
break
}
}
case <-d.blockCh:
// Out of bounds blocks received, ignore them
case <-timeout:
glog.V(logger.Debug).Infof("%v: head hash timeout", p)
return 0, errTimeout
}
}
// If the head fetch already found an ancestor, return
if !common.EmptyHash(hash) {
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x]", p, number, hash[:4])
return number, nil
}
// Ancestor not found, we need to binary search over our chain
start, end := uint64(0), head
for start+1 < end {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
timeout := time.After(hashTTL)
go p.getAbsHashes(uint64(check), 1)
// Wait until a reply arrives to this request
for arrived := false; !arrived; {
select {
case <-d.cancelCh:
return 0, errCancelHashFetch
case hashPack := <-d.hashCh:
// Discard anything not from the origin peer
if hashPack.peerId != p.id {
glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", hashPack.peerId)
break
}
// Make sure the peer actually gave something valid
hashes := hashPack.hashes
if len(hashes) != 1 {
glog.V(logger.Debug).Infof("%v: invalid search hash set (%d)", p, len(hashes))
return 0, errBadPeer
}
arrived = true
// Modify the search interval based on the response
block := d.getBlock(hashes[0])
if block == nil {
end = check
break
}
if block.NumberU64() != check {
glog.V(logger.Debug).Infof("%v: non requested hash #%d [%x], instead of #%d", p, block.NumberU64(), block.Hash().Bytes()[:4], check)
return 0, errBadPeer
}
start = check
case <-d.blockCh:
// Out of bounds blocks received, ignore them
case <-timeout:
glog.V(logger.Debug).Infof("%v: search hash timeout", p)
return 0, errTimeout
}
}
}
return start, nil
}
// fetchHashes keeps retrieving hashes from the requested number, until no more
// are returned, potentially throttling on the way.
func (d *Downloader) fetchHashes(p *peer, from uint64) error {
glog.V(logger.Debug).Infof("%v: downloading hashes from #%d", p, from)
// Create a timeout timer, and the associated hash fetcher
timeout := time.NewTimer(0) // timer to dump a non-responsive active peer
<-timeout.C // timeout channel should be initially empty
defer timeout.Stop()
getHashes := func(from uint64) {
go p.getAbsHashes(from, MaxHashFetch)
timeout.Reset(hashTTL)
}
// Start pulling hashes, until all are exhausted
getHashes(from)
for {
select {
case <-d.cancelCh:
return errCancelHashFetch
case hashPack := <-d.hashCh:
// Make sure the active peer is giving us the hashes
if hashPack.peerId != p.id {
glog.V(logger.Debug).Infof("Received hashes from incorrect peer(%s)", hashPack.peerId)
break
}
timeout.Stop()
// If no more hashes are inbound, notify the block fetcher and return
if len(hashPack.hashes) == 0 {
glog.V(logger.Debug).Infof("%v: no available hashes", p)
select {
case d.processCh <- false:
case <-d.cancelCh:
}
return nil
}
// Otherwise insert all the new hashes, aborting in case of junk
inserts := d.queue.Insert(hashPack.hashes, true)
if len(inserts) != len(hashPack.hashes) {
glog.V(logger.Debug).Infof("%v: stale hashes", p)
return errBadPeer
}
// Notify the block fetcher of new hashes, and continue fetching
select {
case d.processCh <- true:
default:
}
from += uint64(len(hashPack.hashes))
getHashes(from)
case <-timeout.C:
glog.V(logger.Debug).Infof("%v: hash request timed out", p)
return errTimeout
}
}
}
// fetchBlocks iteratively downloads the scheduled hashes, taking any available
// peers, reserving a chunk of blocks for each, waiting for delivery and also
// periodically checking for timeouts.
func (d *Downloader) fetchBlocks(from uint64) error {
glog.V(logger.Debug).Infof("Downloading blocks from #%d", from)
defer glog.V(logger.Debug).Infof("Block download terminated")
// Create a timeout timer for scheduling expiration tasks
ticker := time.NewTicker(100 * time.Millisecond)
defer ticker.Stop()
update := make(chan struct{}, 1)
// Prepare the queue and fetch blocks until the hash fetcher's done
d.queue.Prepare(from)
finished := false
for {
select {
case <-d.cancelCh:
return errCancelBlockFetch
case blockPack := <-d.blockCh:
// If the peer was previously banned and failed to deliver it's pack
// in a reasonable time frame, ignore it's message.
if peer := d.peers.Peer(blockPack.peerId); peer != nil {
// Deliver the received chunk of blocks, and demote in case of errors
err := d.queue.Deliver(blockPack.peerId, blockPack.blocks)
switch err {
case nil:
// If no blocks were delivered, demote the peer (need the delivery above)
if len(blockPack.blocks) == 0 {
peer.Demote()
peer.SetIdle()
glog.V(logger.Detail).Infof("%s: no blocks delivered", peer)
break
}
// All was successful, promote the peer and potentially start processing
peer.Promote()
peer.SetIdle()
glog.V(logger.Detail).Infof("%s: delivered %d blocks", peer, len(blockPack.blocks))
go d.process()
case errInvalidChain:
// The hash chain is invalid (blocks are not ordered properly), abort
return err
case errNoFetchesPending:
// Peer probably timed out with its delivery but came through
// in the end, demote, but allow to to pull from this peer.
peer.Demote()
peer.SetIdle()
glog.V(logger.Detail).Infof("%s: out of bound delivery", peer)
case errStaleDelivery:
// Delivered something completely else than requested, usually
// caused by a timeout and delivery during a new sync cycle.
// Don't set it to idle as the original request should still be
// in flight.
peer.Demote()
glog.V(logger.Detail).Infof("%s: stale delivery", peer)
default:
// Peer did something semi-useful, demote but keep it around
peer.Demote()
peer.SetIdle()
glog.V(logger.Detail).Infof("%s: delivery partially failed: %v", peer, err)
go d.process()
}
}
// Blocks arrived, try to update the progress
select {
case update <- struct{}{}:
default:
}
case cont := <-d.processCh:
// The hash fetcher sent a continuation flag, check if it's done
if !cont {
finished = true
}
// Hashes arrive, try to update the progress
select {
case update <- struct{}{}:
default:
}
case <-ticker.C:
// Sanity check update the progress
select {
case update <- struct{}{}:
default:
}
case <-update:
// Short circuit if we lost all our peers
if d.peers.Len() == 0 {
return errNoPeers
}
// Check for block request timeouts and demote the responsible peers
for _, pid := range d.queue.Expire(blockHardTTL) {
if peer := d.peers.Peer(pid); peer != nil {
peer.Demote()
glog.V(logger.Detail).Infof("%s: block delivery timeout", peer)
}
}
// If there's noting more to fetch, wait or terminate
if d.queue.Pending() == 0 {
if d.queue.InFlight() == 0 && finished {
glog.V(logger.Debug).Infof("Block fetching completed")
return nil
}
break
}
// Send a download request to all idle peers, until throttled
for _, peer := range d.peers.IdlePeers() {
// Short circuit if throttling activated
if d.queue.Throttle() {
break
}
// Reserve a chunk of hashes for a peer. A nil can mean either that
// no more hashes are available, or that the peer is known not to
// have them.
request := d.queue.Reserve(peer, peer.Capacity())
if request == nil {
continue
}
if glog.V(logger.Detail) {
glog.Infof("%s: requesting %d blocks", peer, len(request.Hashes))
}
// Fetch the chunk and make sure any errors return the hashes to the queue
if err := peer.Fetch(request); err != nil {
glog.V(logger.Error).Infof("%v: fetch failed, rescheduling", peer)
d.queue.Cancel(request)
}
}
// Make sure that we have peers available for fetching. If all peers have been tried
// and all failed throw an error
if !d.queue.Throttle() && d.queue.InFlight() == 0 {
return errPeersUnavailable
}
}
}
}
// banBlocks retrieves a batch of blocks from a peer feeding us invalid hashes,
// and bans the head of the retrieved batch.
//