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Merge pull request #18085 from holiman/downloader_span 

downloader: different sync strategy
This commit is contained in:
Péter Szilágyi 2018-11-16 16:34:30 +02:00 committed by GitHub
parent 68be45e5f8 accc0fab4f
commit 91c66d47ef
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 225 additions and 54 deletions
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13
core/blockchain.go
View File

@ -561,6 +561,17 @@ func (bc *BlockChain) HasBlock(hash common.Hash, number uint64) bool {
return rawdb.HasBody(bc.db, hash, number)
}
// HasFastBlock checks if a fast block is fully present in the database or not.
func (bc *BlockChain) HasFastBlock(hash common.Hash, number uint64) bool {
if !bc.HasBlock(hash, number) {
return false
}
if bc.receiptsCache.Contains(hash) {
return true
}
return rawdb.HasReceipts(bc.db, hash, number)
}
// HasState checks if state trie is fully present in the database or not.
func (bc *BlockChain) HasState(hash common.Hash) bool {
_, err := bc.stateCache.OpenTrie(hash)
@ -618,12 +629,10 @@ func (bc *BlockChain) GetReceiptsByHash(hash common.Hash) types.Receipts {
if receipts, ok := bc.receiptsCache.Get(hash); ok {
return receipts.(types.Receipts)
}
number := rawdb.ReadHeaderNumber(bc.db, hash)
if number == nil {
return nil
}
receipts := rawdb.ReadReceipts(bc.db, hash, *number)
bc.receiptsCache.Add(hash, receipts)
return receipts

9
core/rawdb/accessors_chain.go
View File

@ -271,6 +271,15 @@ func DeleteTd(db DatabaseDeleter, hash common.Hash, number uint64) {
}
}
// HasReceipts verifies the existence of all the transaction receipts belonging
// to a block.
func HasReceipts(db DatabaseReader, hash common.Hash, number uint64) bool {
if has, err := db.Has(blockReceiptsKey(number, hash)); !has || err != nil {
return false
}
return true
}
// ReadReceipts retrieves all the transaction receipts belonging to a block.
func ReadReceipts(db DatabaseReader, hash common.Hash, number uint64) types.Receipts {
// Retrieve the flattened receipt slice

149
eth/downloader/downloader.go
View File

@ -181,6 +181,9 @@ type BlockChain interface {
// HasBlock verifies a block's presence in the local chain.
HasBlock(common.Hash, uint64) bool
// HasFastBlock verifies a fast block's presence in the local chain.
HasFastBlock(common.Hash, uint64) bool
// GetBlockByHash retrieves a block from the local chain.
GetBlockByHash(common.Hash) *types.Block
@ -430,7 +433,7 @@ func (d *Downloader) syncWithPeer(p *peerConnection, hash common.Hash, td *big.I
}
height := latest.Number.Uint64()
origin, err := d.findAncestor(p, height)
origin, err := d.findAncestor(p, latest)
if err != nil {
return err
}
@ -587,41 +590,86 @@ func (d *Downloader) fetchHeight(p *peerConnection) (*types.Header, error) {
}
}
// calculateRequestSpan calculates what headers to request from a peer when trying to determine the
// common ancestor.
// It returns parameters to be used for peer.RequestHeadersByNumber:
// from - starting block number
// count - number of headers to request
// skip - number of headers to skip
// and also returns 'max', the last block which is expected to be returned by the remote peers,
// given the (from,count,skip)
func calculateRequestSpan(remoteHeight, localHeight uint64) (int64, int, int, uint64) {
var (
from int
count int
MaxCount = MaxHeaderFetch / 16
)
// requestHead is the highest block that we will ask for. If requestHead is not offset,
// the highest block that we will get is 16 blocks back from head, which means we
// will fetch 14 or 15 blocks unnecessarily in the case the height difference
// between us and the peer is 1-2 blocks, which is most common
requestHead := int(remoteHeight) - 1
if requestHead < 0 {
requestHead = 0
}
// requestBottom is the lowest block we want included in the query
// Ideally, we want to include just below own head
requestBottom := int(localHeight - 1)
if requestBottom < 0 {
requestBottom = 0
}
totalSpan := requestHead - requestBottom
span := 1 + totalSpan/MaxCount
if span < 2 {
span = 2
}
if span > 16 {
span = 16
}
count = 1 + totalSpan/span
if count > MaxCount {
count = MaxCount
}
if count < 2 {
count = 2
}
from = requestHead - (count-1)*span
if from < 0 {
from = 0
}
max := from + (count-1)*span
return int64(from), count, span - 1, uint64(max)
}
// findAncestor tries to locate the common ancestor link 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 links should already get us a match.
// In the rare scenario when we ended up on a long reorganisation (i.e. none of
// the head links match), we do a binary search to find the common ancestor.
func (d *Downloader) findAncestor(p *peerConnection, height uint64) (uint64, error) {
func (d *Downloader) findAncestor(p *peerConnection, remoteHeader *types.Header) (uint64, error) {
// Figure out the valid ancestor range to prevent rewrite attacks
floor, ceil := int64(-1), d.lightchain.CurrentHeader().Number.Uint64()
var (
floor = int64(-1)
localHeight uint64
remoteHeight = remoteHeader.Number.Uint64()
)
switch d.mode {
case FullSync:
localHeight = d.blockchain.CurrentBlock().NumberU64()
case FastSync:
localHeight = d.blockchain.CurrentFastBlock().NumberU64()
default:
localHeight = d.lightchain.CurrentHeader().Number.Uint64()
}
p.log.Debug("Looking for common ancestor", "local", localHeight, "remote", remoteHeight)
if localHeight >= MaxForkAncestry {
floor = int64(localHeight - MaxForkAncestry)
}
from, count, skip, max := calculateRequestSpan(remoteHeight, localHeight)
if d.mode == FullSync {
ceil = d.blockchain.CurrentBlock().NumberU64()
} else if d.mode == FastSync {
ceil = d.blockchain.CurrentFastBlock().NumberU64()
}
if ceil >= MaxForkAncestry {
floor = int64(ceil - MaxForkAncestry)
}
p.log.Debug("Looking for common ancestor", "local", ceil, "remote", height)
// Request the topmost blocks to short circuit binary ancestor lookup
head := ceil
if head > height {
head = height
}
from := int64(head) - int64(MaxHeaderFetch)
if from < 0 {
from = 0
}
// Span out with 15 block gaps into the future to catch bad head reports
limit := 2 * MaxHeaderFetch / 16
count := 1 + int((int64(ceil)-from)/16)
if count > limit {
count = limit
}
go p.peer.RequestHeadersByNumber(uint64(from), count, 15, false)
p.log.Trace("Span searching for common ancestor", "count", count, "from", from, "skip", skip)
go p.peer.RequestHeadersByNumber(uint64(from), count, skip, false)
// Wait for the remote response to the head fetch
number, hash := uint64(0), common.Hash{}
@ -647,9 +695,10 @@ func (d *Downloader) findAncestor(p *peerConnection, height uint64) (uint64, err
return 0, errEmptyHeaderSet
}
// Make sure the peer's reply conforms to the request
for i := 0; i < len(headers); i++ {
if number := headers[i].Number.Int64(); number != from+int64(i)*16 {
p.log.Warn("Head headers broke chain ordering", "index", i, "requested", from+int64(i)*16, "received", number)
for i, header := range headers {
expectNumber := from + int64(i)*int64((skip+1))
if number := header.Number.Int64(); number != expectNumber {
p.log.Warn("Head headers broke chain ordering", "index", i, "requested", expectNumber, "received", number)
return 0, errInvalidChain
}
}
@ -657,20 +706,24 @@ func (d *Downloader) findAncestor(p *peerConnection, height uint64) (uint64, err
finished = true
for i := len(headers) - 1; i >= 0; i-- {
// Skip any headers that underflow/overflow our requested set
if headers[i].Number.Int64() < from || headers[i].Number.Uint64() > ceil {
if headers[i].Number.Int64() < from || headers[i].Number.Uint64() > max {
continue
}
// Otherwise check if we already know the header or not
h := headers[i].Hash()
n := headers[i].Number.Uint64()
if (d.mode == FullSync && d.blockchain.HasBlock(h, n)) || (d.mode != FullSync && d.lightchain.HasHeader(h, n)) {
number, hash = n, h
// If every header is known, even future ones, the peer straight out lied about its head
if number > height && i == limit-1 {
p.log.Warn("Lied about chain head", "reported", height, "found", number)
return 0, errStallingPeer
}
var known bool
switch d.mode {
case FullSync:
known = d.blockchain.HasBlock(h, n)
case FastSync:
known = d.blockchain.HasFastBlock(h, n)
default:
known = d.lightchain.HasHeader(h, n)
}
if known {
number, hash = n, h
break
}
}
@ -694,10 +747,12 @@ func (d *Downloader) findAncestor(p *peerConnection, height uint64) (uint64, err
return number, nil
}
// Ancestor not found, we need to binary search over our chain
start, end := uint64(0), head
start, end := uint64(0), remoteHeight
if floor > 0 {
start = uint64(floor)
}
p.log.Trace("Binary searching for common ancestor", "start", start, "end", end)
for start+1 < end {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
@ -730,7 +785,17 @@ func (d *Downloader) findAncestor(p *peerConnection, height uint64) (uint64, err
// Modify the search interval based on the response
h := headers[0].Hash()
n := headers[0].Number.Uint64()
if (d.mode == FullSync && !d.blockchain.HasBlock(h, n)) || (d.mode != FullSync && !d.lightchain.HasHeader(h, n)) {
var known bool
switch d.mode {
case FullSync:
known = d.blockchain.HasBlock(h, n)
case FastSync:
known = d.blockchain.HasFastBlock(h, n)
default:
known = d.lightchain.HasHeader(h, n)
}
if !known {
end = check
break
}

108
eth/downloader/downloader_test.go
View File

@ -20,6 +20,7 @@ import (
"errors"
"fmt"
"math/big"
"strings"
"sync"
"sync/atomic"
"testing"
@ -114,6 +115,15 @@ func (dl *downloadTester) HasBlock(hash common.Hash, number uint64) bool {
return dl.GetBlockByHash(hash) != nil
}
// HasFastBlock checks if a block is present in the testers canonical chain.
func (dl *downloadTester) HasFastBlock(hash common.Hash, number uint64) bool {
dl.lock.RLock()
defer dl.lock.RUnlock()
_, ok := dl.ownReceipts[hash]
return ok
}
// GetHeader retrieves a header from the testers canonical chain.
func (dl *downloadTester) GetHeaderByHash(hash common.Hash) *types.Header {
dl.lock.RLock()
@ -234,6 +244,7 @@ func (dl *downloadTester) InsertChain(blocks types.Blocks) (i int, err error) {
dl.ownHeaders[block.Hash()] = block.Header()
}
dl.ownBlocks[block.Hash()] = block
dl.ownReceipts[block.Hash()] = make(types.Receipts, 0)
dl.stateDb.Put(block.Root().Bytes(), []byte{0x00})
dl.ownChainTd[block.Hash()] = new(big.Int).Add(dl.ownChainTd[block.ParentHash()], block.Difficulty())
}
@ -374,28 +385,28 @@ func (dlp *downloadTesterPeer) RequestNodeData(hashes []common.Hash) error {
// assertOwnChain checks if the local chain contains the correct number of items
// of the various chain components.
func assertOwnChain(t *testing.T, tester *downloadTester, length int) {
// Mark this method as a helper to report errors at callsite, not in here
t.Helper()
assertOwnForkedChain(t, tester, 1, []int{length})
}
// assertOwnForkedChain checks if the local forked chain contains the correct
// number of items of the various chain components.
func assertOwnForkedChain(t *testing.T, tester *downloadTester, common int, lengths []int) {
// Initialize the counters for the first fork
headers, blocks, receipts := lengths[0], lengths[0], lengths[0]-fsMinFullBlocks
// Mark this method as a helper to report errors at callsite, not in here
t.Helper()
// Initialize the counters for the first fork
headers, blocks, receipts := lengths[0], lengths[0], lengths[0]
if receipts < 0 {
receipts = 1
}
// Update the counters for each subsequent fork
for _, length := range lengths[1:] {
headers += length - common
blocks += length - common
receipts += length - common - fsMinFullBlocks
receipts += length - common
}
switch tester.downloader.mode {
case FullSync:
receipts = 1
case LightSync:
if tester.downloader.mode == LightSync {
blocks, receipts = 1, 1
}
if hs := len(tester.ownHeaders); hs != headers {
@ -1149,7 +1160,9 @@ func testSyncProgress(t *testing.T, protocol int, mode SyncMode) {
}
func checkProgress(t *testing.T, d *Downloader, stage string, want ethereum.SyncProgress) {
// Mark this method as a helper to report errors at callsite, not in here
t.Helper()
p := d.Progress()
p.KnownStates, p.PulledStates = 0, 0
want.KnownStates, want.PulledStates = 0, 0
@ -1479,3 +1492,78 @@ func (ftp *floodingTestPeer) RequestHeadersByNumber(from uint64, count, skip int
}
return nil
}
func TestRemoteHeaderRequestSpan(t *testing.T) {
testCases := []struct {
remoteHeight uint64
localHeight uint64
expected []int
}{
// Remote is way higher. We should ask for the remote head and go backwards
{1500, 1000,
[]int{1323, 1339, 1355, 1371, 1387, 1403, 1419, 1435, 1451, 1467, 1483, 1499},
},
{15000, 13006,
[]int{14823, 14839, 14855, 14871, 14887, 14903, 14919, 14935, 14951, 14967, 14983, 14999},
},
//Remote is pretty close to us. We don't have to fetch as many
{1200, 1150,
[]int{1149, 1154, 1159, 1164, 1169, 1174, 1179, 1184, 1189, 1194, 1199},
},
// Remote is equal to us (so on a fork with higher td)
// We should get the closest couple of ancestors
{1500, 1500,
[]int{1497, 1499},
},
// We're higher than the remote! Odd
{1000, 1500,
[]int{997, 999},
},
// Check some weird edgecases that it behaves somewhat rationally
{0, 1500,
[]int{0, 2},
},
{6000000, 0,
[]int{5999823, 5999839, 5999855, 5999871, 5999887, 5999903, 5999919, 5999935, 5999951, 5999967, 5999983, 5999999},
},
{0, 0,
[]int{0, 2},
},
}
reqs := func(from, count, span int) []int {
var r []int
num := from
for len(r) < count {
r = append(r, num)
num += span + 1
}
return r
}
for i, tt := range testCases {
from, count, span, max := calculateRequestSpan(tt.remoteHeight, tt.localHeight)
data := reqs(int(from), count, span)
if max != uint64(data[len(data)-1]) {
t.Errorf("test %d: wrong last value %d != %d", i, data[len(data)-1], max)
}
failed := false
if len(data) != len(tt.expected) {
failed = true
t.Errorf("test %d: length wrong, expected %d got %d", i, len(tt.expected), len(data))
} else {
for j, n := range data {
if n != tt.expected[j] {
failed = true
break
}
}
}
if failed {
res := strings.Replace(fmt.Sprint(data), " ", ",", -1)
exp := strings.Replace(fmt.Sprint(tt.expected), " ", ",", -1)
fmt.Printf("got: %v\n", res)
fmt.Printf("exp: %v\n", exp)
t.Errorf("test %d: wrong values", i)
}
}
}