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downloader: implemented new downloader

This commit is contained in:
obscuren 2015-04-12 12:38:25 +02:00
parent 61db7a71dd
commit acf8452c33
4 changed files with 602 additions and 0 deletions
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98
eth/downloader/chunk.go Normal file
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package downloader
import (
"math"
"sync"
"time"
"github.com/ethereum/go-ethereum/core/types"
"gopkg.in/fatih/set.v0"
)
// queue represents hashes that are either need fetching or are being fetched
type queue struct {
hashPool *set.Set
mu sync.Mutex
fetching map[string]*chunk
blocks []*types.Block
}
func newqueue() *queue {
return &queue{
hashPool: set.New(),
fetching: make(map[string]*chunk),
}
}
// reserve a `max` set of hashes for `p` peer.
func (c *queue) get(p *peer, max int) *chunk {
c.mu.Lock()
defer c.mu.Unlock()
// return nothing if the pool has been depleted
if c.hashPool.Size() == 0 {
return nil
}
limit := int(math.Min(float64(max), float64(c.hashPool.Size())))
// Create a new set of hashes
hashes, i := set.New(), 0
c.hashPool.Each(func(v interface{}) bool {
if i == limit {
return false
}
hashes.Add(v)
i++
return true
})
// remove the fetchable hashes from hash pool
c.hashPool.Separate(hashes)
// Create a new chunk for the seperated hashes. The time is being used
// to reset the chunk (timeout)
chunk := &chunk{hashes, time.Now()}
// register as 'fetching' state
c.fetching[p.id] = chunk
// create new chunk for peer
return chunk
}
func (c *queue) deliver(id string, blocks []*types.Block) {
c.mu.Lock()
defer c.mu.Unlock()
chunk := c.fetching[id]
// If the chunk was never requested simply ignore it
if chunk != nil {
delete(c.fetching, id)
// seperate the blocks and the hashes
chunk.seperate(blocks)
// Add the blocks
c.blocks = append(c.blocks, blocks...)
// Add back whatever couldn't be delivered
c.hashPool.Merge(chunk.hashes)
}
}
func (c *queue) put(hashes *set.Set) {
c.mu.Lock()
defer c.mu.Unlock()
c.hashPool.Merge(hashes)
}
type chunk struct {
hashes *set.Set
itime time.Time
}
func (ch *chunk) seperate(blocks []*types.Block) {
for _, block := range blocks {
ch.hashes.Remove(block.Hash())
}
}

328
eth/downloader/downloader.go Normal file
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package downloader
import (
"math"
"math/big"
"sync"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"gopkg.in/fatih/set.v0"
)
const maxBlockFetch = 256
type hashFetcherFn func(common.Hash) error
type blockFetcherFn func([]common.Hash) error
type hashCheckFn func(common.Hash) bool
type chainInsertFn func(types.Blocks) error
type hashIterFn func() (common.Hash, error)
// XXX make threadsafe!!!!
type peers map[string]*peer
func (p peers) get(state int) []*peer {
var peers []*peer
for _, peer := range p {
peer.mu.RLock()
if peer.state == state {
peers = append(peers, peer)
}
peer.mu.RUnlock()
}
return peers
}
func (p peers) setState(id string, state int) {
if peer, exist := p[id]; exist {
peer.mu.Lock()
defer peer.mu.Unlock()
peer.state = state
}
}
type Downloader struct {
queue *queue
hasBlock hashCheckFn
insertChain chainInsertFn
mu sync.RWMutex
peers peers
currentPeer *peer
fetchingHashes int32
downloadingBlocks int32
newPeerCh chan *peer
selectPeerCh chan *peer
HashCh chan []common.Hash
blockCh chan blockPack
quit chan struct{}
}
type blockPack struct {
peerId string
blocks []*types.Block
}
func New(hasBlock hashCheckFn, insertChain chainInsertFn) *Downloader {
downloader := &Downloader{
queue: newqueue(),
peers: make(peers),
hasBlock: hasBlock,
insertChain: insertChain,
newPeerCh: make(chan *peer, 1),
selectPeerCh: make(chan *peer, 1),
HashCh: make(chan []common.Hash, 1),
blockCh: make(chan blockPack, 1),
quit: make(chan struct{}),
}
go downloader.peerHandler()
go downloader.update()
return downloader
}
func (d *Downloader) RegisterPeer(id string, td *big.Int, hash common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) error {
d.mu.Lock()
defer d.mu.Unlock()
glog.V(logger.Detail).Infoln("Register peer", id)
// Create a new peer and add it to the list of known peers
peer := newPeer(id, td, hash, getHashes, getBlocks)
// add peer to our peer set
d.peers[id] = peer
// broadcast new peer
d.newPeerCh <- peer
return nil
}
func (d *Downloader) UnregisterPeer(id string) {
d.mu.Lock()
defer d.mu.Unlock()
glog.V(logger.Detail).Infoln("Unregister peer", id)
delete(d.peers, id)
}
func (d *Downloader) peerHandler() {
// Fields defined here so we can reduce the amount of locking
// that needs to be done
var highestTd = new(big.Int)
out:
for {
select {
case newPeer := <-d.newPeerCh:
// Check if TD of peer is higher than our current
if newPeer.td.Cmp(highestTd) > 0 {
glog.V(logger.Detail).Infoln("New peer with highest TD =", newPeer.td)
highestTd.Set(newPeer.td)
// select the peer for downloading
d.selectPeerCh <- newPeer
}
case <-d.quit:
break out
}
}
}
func (d *Downloader) update() {
out:
for {
select {
case selectedPeer := <-d.selectPeerCh:
// Make sure it's doing neither. Once done we can restart the
// downloading process if the TD is higher. For now just get on
// with whatever is going on. This prevents unecessary switching.
if !(d.isFetchingHashes() || d.isDownloadingBlocks()) {
glog.V(logger.Detail).Infoln("Selected new peer", selectedPeer.id)
// Start the fetcher. This will block the update entirely
// interupts need to be send to the appropriate channels
// respectively.
if err := d.startFetchingHashes(selectedPeer); err != nil {
// handle error
glog.V(logger.Debug).Infoln("Error fetching hashes:", err)
// Reset
break
}
// Start fetching blocks in paralel. The strategy is simple
// take any available peers, seserve a chunk for each peer available,
// let the peer deliver the chunkn and periodically check if a peer
// has timedout. When done downloading, process blocks.
if err := d.startFetchingBlocks(selectedPeer); err != nil {
glog.V(logger.Debug).Infoln("Error downloading blocks:", err)
// reset
break
}
// XXX this will move when optimised
// Sort the blocks by number. This bit needs much improvement. Right now
// it assumes full honesty form peers (i.e. it's not checked when the blocks
// link). We should at least check whihc queue match. This code could move
// to a seperate goroutine where it periodically checks for linked pieces.
types.BlockBy(types.Number).Sort(d.queue.blocks)
blocks := d.queue.blocks
glog.V(logger.Debug).Infoln("Inserting chain with", len(blocks), "blocks")
// Loop untill we're out of queue
for len(blocks) != 0 {
max := int(math.Min(float64(len(blocks)), 256))
// TODO check for parent error. When there's a parent error we should stop
// processing and start requesting the `block.hash` so that it's parent and
// grandparents can be requested and queued.
d.insertChain(blocks[:max])
blocks = blocks[max:]
}
}
case <-d.quit:
break out
}
}
}
func (d *Downloader) startFetchingHashes(p *peer) error {
glog.V(logger.Debug).Infoln("Downloading hashes")
start := time.Now()
// Get the first batch of hashes
p.getHashes(p.recentHash)
atomic.StoreInt32(&d.fetchingHashes, 1)
out:
for {
select {
case hashes := <-d.HashCh:
var done bool // determines whether we're done fetching hashes (i.e. common hash found)
hashSet := set.New()
for _, hash := range hashes {
if d.hasBlock(hash) {
glog.V(logger.Debug).Infof("Found common hash %x\n", hash)
done = true
break
}
hashSet.Add(hash)
}
d.queue.put(hashSet)
// Add hashes to the chunk set
// Check if we're done fetching
if !done {
//fmt.Println("re-fetch. current =", d.queue.hashPool.Size())
// Get the next set of hashes
p.getHashes(hashes[len(hashes)-1])
atomic.StoreInt32(&d.fetchingHashes, 1)
} else {
atomic.StoreInt32(&d.fetchingHashes, 0)
break out
}
}
}
glog.V(logger.Detail).Infoln("Download hashes: done. Took", time.Since(start))
return nil
}
func (d *Downloader) DeliverBlocks(id string, block []*types.Block) {
d.blockCh <- blockPack{id, block}
}
func (d *Downloader) startFetchingBlocks(p *peer) error {
glog.V(logger.Detail).Infoln("Downloading", d.queue.hashPool.Size(), "blocks")
atomic.StoreInt32(&d.downloadingBlocks, 1)
start := time.Now()
// default ticker for re-fetching blocks everynow and then
ticker := time.NewTicker(20 * time.Millisecond)
out:
for {
select {
case blockPack := <-d.blockCh:
//fmt.Println("get for", blockPack.peerId)
d.queue.deliver(blockPack.peerId, blockPack.blocks)
d.peers.setState(blockPack.peerId, idleState)
case <-ticker.C:
// If there are unrequested hashes left start fetching
// from the available peers.
if d.queue.hashPool.Size() > 0 {
availablePeers := d.peers.get(idleState)
for _, peer := range availablePeers {
// Get a possible chunk. If nil is returned no chunk
// could be returned due to no hashes available.
chunk := d.queue.get(peer, maxBlockFetch)
if chunk != nil {
//fmt.Println("fetching for", peer.id)
// Fetch the chunk.
peer.fetch(chunk)
}
}
atomic.StoreInt32(&d.downloadingBlocks, 1)
} else if len(d.queue.fetching) == 0 {
// Whene there are no more queue and no more `fetching`. We can
// safely assume we're done. Another part of the process will check
// for parent errors and will re-request anything that's missing
atomic.StoreInt32(&d.downloadingBlocks, 0)
// Break out so that we can process with processing blocks
break out
} else {
// Check for bad peers. Bad peers may indicate a peer not responding
// to a `getBlocks` message. A timeout of 5 seconds is set. Peers
// that badly or poorly behave are removed from the peer set (not banned).
// Bad peers are excluded from the available peer set and therefor won't be
// reused. XXX We could re-introduce peers after X time.
d.queue.mu.Lock()
var badPeers []string
for pid, chunk := range d.queue.fetching {
if time.Since(chunk.itime) > 5*time.Second {
badPeers = append(badPeers, pid)
// remove peer as good peer from peer list
d.UnregisterPeer(pid)
}
}
d.queue.mu.Unlock()
for _, pid := range badPeers {
// A nil chunk is delivered so that the chunk's hashes are given
// back to the queue objects. When hashes are put back in the queue
// other (decent) peers can pick them up.
// XXX We could make use of a reputation system here ranking peers
// in their performance
// 1) Time for them to respond;
// 2) Measure their speed;
// 3) Amount and availability.
d.queue.deliver(pid, nil)
}
}
//fmt.Println(d.queue.hashPool.Size(), len(d.queue.fetching))
}
}
glog.V(logger.Detail).Infoln("Download blocks: done. Took", time.Since(start))
return nil
}
func (d *Downloader) isFetchingHashes() bool {
return atomic.LoadInt32(&d.fetchingHashes) == 1
}
func (d *Downloader) isDownloadingBlocks() bool {
return atomic.LoadInt32(&d.downloadingBlocks) == 1
}

128
eth/downloader/downloader_test.go Normal file
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package downloader
import (
"encoding/binary"
"math/big"
"testing"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
)
var knownHash = common.Hash{1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
func createHashes(amount int) (hashes []common.Hash) {
hashes = make([]common.Hash, amount+1)
hashes[len(hashes)-1] = knownHash
for i := range hashes[:len(hashes)-1] {
binary.BigEndian.PutUint64(hashes[i][:8], uint64(i+2))
}
return
}
func createBlocksFromHashes(hashes []common.Hash) map[common.Hash]*types.Block {
blocks := make(map[common.Hash]*types.Block)
for i, hash := range hashes {
header := &types.Header{Number: big.NewInt(int64(i))}
blocks[hash] = types.NewBlockWithHeader(header)
blocks[hash].HeaderHash = hash
}
return blocks
}
type downloadTester struct {
downloader *Downloader
hashes []common.Hash
blocks map[common.Hash]*types.Block
t *testing.T
pcount int
done chan bool
insertedBlocks int
}
func newTester(t *testing.T, hashes []common.Hash, blocks map[common.Hash]*types.Block) *downloadTester {
tester := &downloadTester{t: t, hashes: hashes, blocks: blocks, done: make(chan bool)}
downloader := New(tester.hasBlock, tester.insertChain)
tester.downloader = downloader
return tester
}
func (dl *downloadTester) hasBlock(hash common.Hash) bool {
if knownHash == hash {
return true
}
return false
}
func (dl *downloadTester) insertChain(blocks types.Blocks) error {
dl.insertedBlocks += len(blocks)
if len(dl.blocks)-1 <= dl.insertedBlocks {
dl.done <- true
}
return nil
}
func (dl *downloadTester) getHashes(hash common.Hash) error {
dl.downloader.HashCh <- dl.hashes
return nil
}
func (dl *downloadTester) getBlocks(id string) func([]common.Hash) error {
return func(hashes []common.Hash) error {
blocks := make([]*types.Block, len(hashes))
for i, hash := range hashes {
blocks[i] = dl.blocks[hash]
}
go dl.downloader.DeliverBlocks(id, blocks)
return nil
}
}
func (dl *downloadTester) newPeer(id string, td *big.Int, hash common.Hash) {
dl.pcount++
dl.downloader.RegisterPeer(id, td, hash, dl.getHashes, dl.getBlocks(id))
}
func (dl *downloadTester) badBlocksPeer(id string, td *big.Int, hash common.Hash) {
dl.pcount++
// This bad peer never returns any blocks
dl.downloader.RegisterPeer(id, td, hash, dl.getHashes, func([]common.Hash) error {
return nil
})
}
func TestDownload(t *testing.T) {
glog.SetV(logger.Detail)
glog.SetToStderr(true)
hashes := createHashes(1000)
blocks := createBlocksFromHashes(hashes)
tester := newTester(t, hashes, blocks)
tester.newPeer("peer1", big.NewInt(10000), hashes[len(hashes)-1])
tester.newPeer("peer2", big.NewInt(0), common.Hash{})
tester.badBlocksPeer("peer3", big.NewInt(0), common.Hash{})
tester.badBlocksPeer("peer4", big.NewInt(0), common.Hash{})
success:
select {
case <-tester.done:
break success
case <-time.After(10 * time.Second): // XXX this could actually fail on a slow computer
t.Error("timout")
}
}

48
eth/downloader/peer.go Normal file
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package downloader
import (
"math/big"
"sync"
"github.com/ethereum/go-ethereum/common"
)
const (
workingState = 2
idleState = 4
)
// peer represents an active peer
type peer struct {
state int
mu sync.RWMutex
id string
td *big.Int
recentHash common.Hash
getHashes hashFetcherFn
getBlocks blockFetcherFn
}
// create a new peer
func newPeer(id string, td *big.Int, hash common.Hash, getHashes hashFetcherFn, getBlocks blockFetcherFn) *peer {
return &peer{id: id, td: td, recentHash: hash, getHashes: getHashes, getBlocks: getBlocks, state: idleState}
}
// fetch a chunk using the peer
func (p *peer) fetch(chunk *chunk) {
p.mu.Lock()
defer p.mu.Unlock()
// set working state
p.state = workingState
// convert the set to a fetchable slice
hashes, i := make([]common.Hash, chunk.hashes.Size()), 0
chunk.hashes.Each(func(v interface{}) bool {
hashes[i] = v.(common.Hash)
i++
return true
})
p.getBlocks(hashes)
}