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core, eth: improve delivery speed on header requests (#23105) 

This PR reduces the amount of work we do when answering header queries, e.g. when a peer
is syncing from us.

For some items, e.g block bodies, when we read the rlp-data from database, we plug it
directly into the response package. We didn't do that for headers, but instead read
headers-rlp, decode to types.Header, and re-encode to rlp. This PR changes that to keep it
in RLP-form as much as possible. When a node is syncing from us, it typically requests 192
contiguous headers. On master it has the following effect:

- For headers not in ancient: 2 db lookups. One for translating hash->number (even though
  the request is by number), and another for reading by hash (this latter one is sometimes
  cached).
  
- For headers in ancient: 1 file lookup/syscall for translating hash->number (even though
  the request is by number), and another for reading the header itself. After this, it
  also performes a hashing of the header, to ensure that the hash is what it expected. In
  this PR, I instead move the logic for "give me a sequence of blocks" into the lower
  layers, where the database can determine how and what to read from leveldb and/or
  ancients.

There are basically four types of requests; three of them are improved this way. The
fourth, by hash going backwards, is more tricky to optimize. However, since we know that
the gap is 0, we can look up by the parentHash, and stlil shave off all the number->hash
lookups.

The gapped collection can be optimized similarly, as a follow-up, at least in three out of
four cases.

Co-authored-by: Felix Lange <fjl@twurst.com>
This commit is contained in:
Martin Holst Swende 2021-12-07 17:50:58 +01:00 committed by GitHub
parent 7f7877a023
commit db03faa10d
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
13 changed files with 368 additions and 24 deletions
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6
core/blockchain_reader.go
View File

@ -73,6 +73,12 @@ func (bc *BlockChain) GetHeaderByNumber(number uint64) *types.Header {
return bc.hc.GetHeaderByNumber(number)
}
// GetHeadersFrom returns a contiguous segment of headers, in rlp-form, going
// backwards from the given number.
func (bc *BlockChain) GetHeadersFrom(number, count uint64) []rlp.RawValue {
return bc.hc.GetHeadersFrom(number, count)
}
// GetBody retrieves a block body (transactions and uncles) from the database by
// hash, caching it if found.
func (bc *BlockChain) GetBody(hash common.Hash) *types.Body {

41
core/headerchain.go
View File

@ -33,6 +33,7 @@ import (
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/rlp"
lru "github.com/hashicorp/golang-lru"
)
@ -498,6 +499,46 @@ func (hc *HeaderChain) GetHeaderByNumber(number uint64) *types.Header {
return hc.GetHeader(hash, number)
}
// GetHeadersFrom returns a contiguous segment of headers, in rlp-form, going
// backwards from the given number.
// If the 'number' is higher than the highest local header, this method will
// return a best-effort response, containing the headers that we do have.
func (hc *HeaderChain) GetHeadersFrom(number, count uint64) []rlp.RawValue {
// If the request is for future headers, we still return the portion of
// headers that we are able to serve
if current := hc.CurrentHeader().Number.Uint64(); current < number {
if count > number-current {
count -= number - current
number = current
} else {
return nil
}
}
var headers []rlp.RawValue
// If we have some of the headers in cache already, use that before going to db.
hash := rawdb.ReadCanonicalHash(hc.chainDb, number)
if hash == (common.Hash{}) {
return nil
}
for count > 0 {
header, ok := hc.headerCache.Get(hash)
if !ok {
break
}
h := header.(*types.Header)
rlpData, _ := rlp.EncodeToBytes(h)
headers = append(headers, rlpData)
hash = h.ParentHash
count--
number--
}
// Read remaining from db
if count > 0 {
headers = append(headers, rawdb.ReadHeaderRange(hc.chainDb, number, count)...)
}
return headers
}
func (hc *HeaderChain) GetCanonicalHash(number uint64) common.Hash {
return rawdb.ReadCanonicalHash(hc.chainDb, number)
}

50
core/rawdb/accessors_chain.go
View File

@ -279,6 +279,56 @@ func WriteFastTxLookupLimit(db ethdb.KeyValueWriter, number uint64) {
}
}
// ReadHeaderRange returns the rlp-encoded headers, starting at 'number', and going
// backwards towards genesis. This method assumes that the caller already has
// placed a cap on count, to prevent DoS issues.
// Since this method operates in head-towards-genesis mode, it will return an empty
// slice in case the head ('number') is missing. Hence, the caller must ensure that
// the head ('number') argument is actually an existing header.
//
// N.B: Since the input is a number, as opposed to a hash, it's implicit that
// this method only operates on canon headers.
func ReadHeaderRange(db ethdb.Reader, number uint64, count uint64) []rlp.RawValue {
var rlpHeaders []rlp.RawValue
if count == 0 {
return rlpHeaders
}
i := number
if count-1 > number {
// It's ok to request block 0, 1 item
count = number + 1
}
limit, _ := db.Ancients()
// First read live blocks
if i >= limit {
// If we need to read live blocks, we need to figure out the hash first
hash := ReadCanonicalHash(db, number)
for ; i >= limit && count > 0; i-- {
if data, _ := db.Get(headerKey(i, hash)); len(data) > 0 {
rlpHeaders = append(rlpHeaders, data)
// Get the parent hash for next query
hash = types.HeaderParentHashFromRLP(data)
} else {
break // Maybe got moved to ancients
}
count--
}
}
if count == 0 {
return rlpHeaders
}
// read remaining from ancients
max := count * 700
data, err := db.AncientRange(freezerHeaderTable, i+1-count, count, max)
if err == nil && uint64(len(data)) == count {
// the data is on the order [h, h+1, .., n] -- reordering needed
for i := range data {
rlpHeaders = append(rlpHeaders, data[len(data)-1-i])
}
}
return rlpHeaders
}
// ReadHeaderRLP retrieves a block header in its raw RLP database encoding.
func ReadHeaderRLP(db ethdb.Reader, hash common.Hash, number uint64) rlp.RawValue {
var data []byte

64
core/rawdb/accessors_chain_test.go
View File

@ -883,3 +883,67 @@ func BenchmarkDecodeRLPLogs(b *testing.B) {
}
})
}
func TestHeadersRLPStorage(t *testing.T) {
// Have N headers in the freezer
frdir, err := ioutil.TempDir("", "")
if err != nil {
t.Fatalf("failed to create temp freezer dir: %v", err)
}
defer os.Remove(frdir)
db, err := NewDatabaseWithFreezer(NewMemoryDatabase(), frdir, "", false)
if err != nil {
t.Fatalf("failed to create database with ancient backend")
}
defer db.Close()
// Create blocks
var chain []*types.Block
var pHash common.Hash
for i := 0; i < 100; i++ {
block := types.NewBlockWithHeader(&types.Header{
Number: big.NewInt(int64(i)),
Extra: []byte("test block"),
UncleHash: types.EmptyUncleHash,
TxHash: types.EmptyRootHash,
ReceiptHash: types.EmptyRootHash,
ParentHash: pHash,
})
chain = append(chain, block)
pHash = block.Hash()
}
var receipts []types.Receipts = make([]types.Receipts, 100)
// Write first half to ancients
WriteAncientBlocks(db, chain[:50], receipts[:50], big.NewInt(100))
// Write second half to db
for i := 50; i < 100; i++ {
WriteCanonicalHash(db, chain[i].Hash(), chain[i].NumberU64())
WriteBlock(db, chain[i])
}
checkSequence := func(from, amount int) {
headersRlp := ReadHeaderRange(db, uint64(from), uint64(amount))
if have, want := len(headersRlp), amount; have != want {
t.Fatalf("have %d headers, want %d", have, want)
}
for i, headerRlp := range headersRlp {
var header types.Header
if err := rlp.DecodeBytes(headerRlp, &header); err != nil {
t.Fatal(err)
}
if have, want := header.Number.Uint64(), uint64(from-i); have != want {
t.Fatalf("wrong number, have %d want %d", have, want)
}
}
}
checkSequence(99, 20) // Latest block and 19 parents
checkSequence(99, 50) // Latest block -> all db blocks
checkSequence(99, 51) // Latest block -> one from ancients
checkSequence(99, 52) // Latest blocks -> two from ancients
checkSequence(50, 2) // One from db, one from ancients
checkSequence(49, 1) // One from ancients
checkSequence(49, 50) // All ancient ones
checkSequence(99, 100) // All blocks
checkSequence(0, 1) // Only genesis
checkSequence(1, 1) // Only block 1
checkSequence(1, 2) // Genesis + block 1
}

18
core/types/block.go
View File

@ -389,3 +389,21 @@ func (b *Block) Hash() common.Hash {
}
type Blocks []*Block
// HeaderParentHashFromRLP returns the parentHash of an RLP-encoded
// header. If 'header' is invalid, the zero hash is returned.
func HeaderParentHashFromRLP(header []byte) common.Hash {
// parentHash is the first list element.
listContent, _, err := rlp.SplitList(header)
if err != nil {
return common.Hash{}
}
parentHash, _, err := rlp.SplitString(listContent)
if err != nil {
return common.Hash{}
}
if len(parentHash) != 32 {
return common.Hash{}
}
return common.BytesToHash(parentHash)
}

61
core/types/block_test.go
View File

@ -281,3 +281,64 @@ func makeBenchBlock() *Block {
}
return NewBlock(header, txs, uncles, receipts, newHasher())
}
func TestRlpDecodeParentHash(t *testing.T) {
// A minimum one
want := common.HexToHash("0x112233445566778899001122334455667788990011223344556677889900aabb")
if rlpData, err := rlp.EncodeToBytes(Header{ParentHash: want}); err != nil {
t.Fatal(err)
} else {
if have := HeaderParentHashFromRLP(rlpData); have != want {
t.Fatalf("have %x, want %x", have, want)
}
}
// And a maximum one
// | Difficulty | dynamic| *big.Int | 0x5ad3c2c71bbff854908 (current mainnet TD: 76 bits) |
// | Number | dynamic| *big.Int | 64 bits |
// | Extra | dynamic| []byte | 65+32 byte (clique) |
// | BaseFee | dynamic| *big.Int | 64 bits |
mainnetTd := new(big.Int)
mainnetTd.SetString("5ad3c2c71bbff854908", 16)
if rlpData, err := rlp.EncodeToBytes(Header{
ParentHash: want,
Difficulty: mainnetTd,
Number: new(big.Int).SetUint64(math.MaxUint64),
Extra: make([]byte, 65+32),
BaseFee: new(big.Int).SetUint64(math.MaxUint64),
}); err != nil {
t.Fatal(err)
} else {
if have := HeaderParentHashFromRLP(rlpData); have != want {
t.Fatalf("have %x, want %x", have, want)
}
}
// Also test a very very large header.
{
// The rlp-encoding of the heder belowCauses _total_ length of 65540,
// which is the first to blow the fast-path.
h := Header{
ParentHash: want,
Extra: make([]byte, 65041),
}
if rlpData, err := rlp.EncodeToBytes(h); err != nil {
t.Fatal(err)
} else {
if have := HeaderParentHashFromRLP(rlpData); have != want {
t.Fatalf("have %x, want %x", have, want)
}
}
}
{
// Test some invalid erroneous stuff
for i, rlpData := range [][]byte{
nil,
common.FromHex("0x"),
common.FromHex("0x01"),
common.FromHex("0x3031323334"),
} {
if have, want := HeaderParentHashFromRLP(rlpData), (common.Hash{}); have != want {
t.Fatalf("invalid %d: have %x, want %x", i, have, want)
}
}
}
}

20
eth/downloader/downloader_test.go
View File

@ -154,12 +154,24 @@ func (dlp *downloadTesterPeer) Head() (common.Hash, *big.Int) {
return head.Hash(), dlp.chain.GetTd(head.Hash(), head.NumberU64())
}
func unmarshalRlpHeaders(rlpdata []rlp.RawValue) []*types.Header {
var headers = make([]*types.Header, len(rlpdata))
for i, data := range rlpdata {
var h types.Header
if err := rlp.DecodeBytes(data, &h); err != nil {
panic(err)
}
headers[i] = &h
}
return headers
}
// RequestHeadersByHash constructs a GetBlockHeaders function based on a hashed
// origin; associated with a particular peer in the download tester. The returned
// function can be used to retrieve batches of headers from the particular peer.
func (dlp *downloadTesterPeer) RequestHeadersByHash(origin common.Hash, amount int, skip int, reverse bool, sink chan *eth.Response) (*eth.Request, error) {
// Service the header query via the live handler code
headers := eth.ServiceGetBlockHeadersQuery(dlp.chain, &eth.GetBlockHeadersPacket{
rlpHeaders := eth.ServiceGetBlockHeadersQuery(dlp.chain, &eth.GetBlockHeadersPacket{
Origin: eth.HashOrNumber{
Hash: origin,
},
@ -167,7 +179,7 @@ func (dlp *downloadTesterPeer) RequestHeadersByHash(origin common.Hash, amount i
Skip: uint64(skip),
Reverse: reverse,
}, nil)
headers := unmarshalRlpHeaders(rlpHeaders)
// If a malicious peer is simulated withholding headers, delete them
for hash := range dlp.withholdHeaders {
for i, header := range headers {
@ -203,7 +215,7 @@ func (dlp *downloadTesterPeer) RequestHeadersByHash(origin common.Hash, amount i
// function can be used to retrieve batches of headers from the particular peer.
func (dlp *downloadTesterPeer) RequestHeadersByNumber(origin uint64, amount int, skip int, reverse bool, sink chan *eth.Response) (*eth.Request, error) {
// Service the header query via the live handler code
headers := eth.ServiceGetBlockHeadersQuery(dlp.chain, &eth.GetBlockHeadersPacket{
rlpHeaders := eth.ServiceGetBlockHeadersQuery(dlp.chain, &eth.GetBlockHeadersPacket{
Origin: eth.HashOrNumber{
Number: origin,
},
@ -211,7 +223,7 @@ func (dlp *downloadTesterPeer) RequestHeadersByNumber(origin uint64, amount int,
Skip: uint64(skip),
Reverse: reverse,
}, nil)
headers := unmarshalRlpHeaders(rlpHeaders)
// If a malicious peer is simulated withholding headers, delete them
for hash := range dlp.withholdHeaders {
for i, header := range headers {

9
eth/handler_eth_test.go
View File

@ -38,6 +38,7 @@ import (
"github.com/ethereum/go-ethereum/p2p"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/rlp"
)
// testEthHandler is a mock event handler to listen for inbound network requests
@ -560,15 +561,17 @@ func testCheckpointChallenge(t *testing.T, syncmode downloader.SyncMode, checkpo
// Create a block to reply to the challenge if no timeout is simulated.
if !timeout {
if empty {
if err := remote.ReplyBlockHeaders(request.RequestId, []*types.Header{}); err != nil {
if err := remote.ReplyBlockHeadersRLP(request.RequestId, []rlp.RawValue{}); err != nil {
t.Fatalf("failed to answer challenge: %v", err)
}
} else if match {
if err := remote.ReplyBlockHeaders(request.RequestId, []*types.Header{response}); err != nil {
responseRlp, _ := rlp.EncodeToBytes(response)
if err := remote.ReplyBlockHeadersRLP(request.RequestId, []rlp.RawValue{responseRlp}); err != nil {
t.Fatalf("failed to answer challenge: %v", err)
}
} else {
if err := remote.ReplyBlockHeaders(request.RequestId, []*types.Header{{Number: response.Number}}); err != nil {
responseRlp, _ := rlp.EncodeToBytes(types.Header{Number: response.Number})
if err := remote.ReplyBlockHeadersRLP(request.RequestId, []rlp.RawValue{responseRlp}); err != nil {
t.Fatalf("failed to answer challenge: %v", err)
}
}

3
eth/protocols/eth/handler.go
View File

@ -35,9 +35,6 @@ const (
// softResponseLimit is the target maximum size of replies to data retrievals.
softResponseLimit = 2 * 1024 * 1024
// estHeaderSize is the approximate size of an RLP encoded block header.
estHeaderSize = 500
// maxHeadersServe is the maximum number of block headers to serve. This number
// is there to limit the number of disk lookups.
maxHeadersServe = 1024

15
eth/protocols/eth/handler_test.go
View File

@ -136,11 +136,13 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
query *GetBlockHeadersPacket // The query to execute for header retrieval
expect []common.Hash // The hashes of the block whose headers are expected
}{
// A single random block should be retrievable by hash and number too
// A single random block should be retrievable by hash
{
&GetBlockHeadersPacket{Origin: HashOrNumber{Hash: backend.chain.GetBlockByNumber(limit / 2).Hash()}, Amount: 1},
[]common.Hash{backend.chain.GetBlockByNumber(limit / 2).Hash()},
}, {
},
// A single random block should be retrievable by number
{
&GetBlockHeadersPacket{Origin: HashOrNumber{Number: limit / 2}, Amount: 1},
[]common.Hash{backend.chain.GetBlockByNumber(limit / 2).Hash()},
},
@ -180,10 +182,15 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
{
&GetBlockHeadersPacket{Origin: HashOrNumber{Number: 0}, Amount: 1},
[]common.Hash{backend.chain.GetBlockByNumber(0).Hash()},
}, {
},
{
&GetBlockHeadersPacket{Origin: HashOrNumber{Number: backend.chain.CurrentBlock().NumberU64()}, Amount: 1},
[]common.Hash{backend.chain.CurrentBlock().Hash()},
},
{ // If the peer requests a bit into the future, we deliver what we have
&GetBlockHeadersPacket{Origin: HashOrNumber{Number: backend.chain.CurrentBlock().NumberU64()}, Amount: 10},
[]common.Hash{backend.chain.CurrentBlock().Hash()},
},
// Ensure protocol limits are honored
{
&GetBlockHeadersPacket{Origin: HashOrNumber{Number: backend.chain.CurrentBlock().NumberU64() - 1}, Amount: limit + 10, Reverse: true},
@ -280,7 +287,7 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
RequestId: 456,
BlockHeadersPacket: headers,
}); err != nil {
t.Errorf("test %d: headers mismatch: %v", i, err)
t.Errorf("test %d by hash: headers mismatch: %v", i, err)
}
}
}

87
eth/protocols/eth/handlers.go
View File

@ -36,12 +36,21 @@ func handleGetBlockHeaders66(backend Backend, msg Decoder, peer *Peer) error {
return fmt.Errorf("%w: message %v: %v", errDecode, msg, err)
}
response := ServiceGetBlockHeadersQuery(backend.Chain(), query.GetBlockHeadersPacket, peer)
return peer.ReplyBlockHeaders(query.RequestId, response)
return peer.ReplyBlockHeadersRLP(query.RequestId, response)
}
// ServiceGetBlockHeadersQuery assembles the response to a header query. It is
// exposed to allow external packages to test protocol behavior.
func ServiceGetBlockHeadersQuery(chain *core.BlockChain, query *GetBlockHeadersPacket, peer *Peer) []*types.Header {
func ServiceGetBlockHeadersQuery(chain *core.BlockChain, query *GetBlockHeadersPacket, peer *Peer) []rlp.RawValue {
if query.Skip == 0 {
// The fast path: when the request is for a contiguous segment of headers.
return serviceContiguousBlockHeaderQuery(chain, query)
} else {
return serviceNonContiguousBlockHeaderQuery(chain, query, peer)
}
}
func serviceNonContiguousBlockHeaderQuery(chain *core.BlockChain, query *GetBlockHeadersPacket, peer *Peer) []rlp.RawValue {
hashMode := query.Origin.Hash != (common.Hash{})
first := true
maxNonCanonical := uint64(100)
@ -49,7 +58,7 @@ func ServiceGetBlockHeadersQuery(chain *core.BlockChain, query *GetBlockHeadersP
// Gather headers until the fetch or network limits is reached
var (
bytes common.StorageSize
headers []*types.Header
headers []rlp.RawValue
unknown bool
lookups int
)
@ -74,9 +83,12 @@ func ServiceGetBlockHeadersQuery(chain *core.BlockChain, query *GetBlockHeadersP
if origin == nil {
break
}
headers = append(headers, origin)
bytes += estHeaderSize
if rlpData, err := rlp.EncodeToBytes(origin); err != nil {
log.Crit("Unable to decode our own headers", "err", err)
} else {
headers = append(headers, rlp.RawValue(rlpData))
bytes += common.StorageSize(len(rlpData))
}
// Advance to the next header of the query
switch {
case hashMode && query.Reverse:
@ -127,6 +139,69 @@ func ServiceGetBlockHeadersQuery(chain *core.BlockChain, query *GetBlockHeadersP
return headers
}
func serviceContiguousBlockHeaderQuery(chain *core.BlockChain, query *GetBlockHeadersPacket) []rlp.RawValue {
count := query.Amount
if count > maxHeadersServe {
count = maxHeadersServe
}
if query.Origin.Hash == (common.Hash{}) {
// Number mode, just return the canon chain segment. The backend
// delivers in [N, N-1, N-2..] descending order, so we need to
// accommodate for that.
from := query.Origin.Number
if !query.Reverse {
from = from + count - 1
}
headers := chain.GetHeadersFrom(from, count)
if !query.Reverse {
for i, j := 0, len(headers)-1; i < j; i, j = i+1, j-1 {
headers[i], headers[j] = headers[j], headers[i]
}
}
return headers
}
// Hash mode.
var (
headers []rlp.RawValue
hash = query.Origin.Hash
header = chain.GetHeaderByHash(hash)
)
if header != nil {
rlpData, _ := rlp.EncodeToBytes(header)
headers = append(headers, rlpData)
} else {
// We don't even have the origin header
return headers
}
num := header.Number.Uint64()
if !query.Reverse {
// Theoretically, we are tasked to deliver header by hash H, and onwards.
// However, if H is not canon, we will be unable to deliver any descendants of
// H.
if canonHash := chain.GetCanonicalHash(num); canonHash != hash {
// Not canon, we can't deliver descendants
return headers
}
descendants := chain.GetHeadersFrom(num+count-1, count-1)
for i, j := 0, len(descendants)-1; i < j; i, j = i+1, j-1 {
descendants[i], descendants[j] = descendants[j], descendants[i]
}
headers = append(headers, descendants...)
return headers
}
{ // Last mode: deliver ancestors of H
for i := uint64(1); header != nil && i < count; i++ {
header = chain.GetHeaderByHash(header.ParentHash)
if header == nil {
break
}
rlpData, _ := rlp.EncodeToBytes(header)
headers = append(headers, rlpData)
}
return headers
}
}
func handleGetBlockBodies66(backend Backend, msg Decoder, peer *Peer) error {
// Decode the block body retrieval message
var query GetBlockBodiesPacket66

8
eth/protocols/eth/peer.go
View File

@ -297,10 +297,10 @@ func (p *Peer) AsyncSendNewBlock(block *types.Block, td *big.Int) {
}
// ReplyBlockHeaders is the eth/66 version of SendBlockHeaders.
func (p *Peer) ReplyBlockHeaders(id uint64, headers []*types.Header) error {
return p2p.Send(p.rw, BlockHeadersMsg, BlockHeadersPacket66{
RequestId: id,
BlockHeadersPacket: headers,
func (p *Peer) ReplyBlockHeadersRLP(id uint64, headers []rlp.RawValue) error {
return p2p.Send(p.rw, BlockHeadersMsg, BlockHeadersRLPPacket66{
RequestId: id,
BlockHeadersRLPPacket: headers,
})
}

10
eth/protocols/eth/protocol.go
View File

@ -175,6 +175,16 @@ type BlockHeadersPacket66 struct {
BlockHeadersPacket
}
// BlockHeadersRLPPacket represents a block header response, to use when we already
// have the headers rlp encoded.
type BlockHeadersRLPPacket []rlp.RawValue
// BlockHeadersPacket represents a block header response over eth/66.
type BlockHeadersRLPPacket66 struct {
RequestId uint64
BlockHeadersRLPPacket
}
// NewBlockPacket is the network packet for the block propagation message.
type NewBlockPacket struct {
Block *types.Block