plugeth/core/headerchain.go

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// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
2016-04-14 16:18:24 +00:00
package core
import (
crand "crypto/rand"
"errors"
"fmt"
"math"
"math/big"
mrand "math/rand"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/core/rawdb"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/params"
lru "github.com/hashicorp/golang-lru"
)
const (
headerCacheLimit = 512
tdCacheLimit = 1024
numberCacheLimit = 2048
)
// HeaderChain implements the basic block header chain logic that is shared by
// core.BlockChain and light.LightChain. It is not usable in itself, only as
// a part of either structure.
//
// HeaderChain is responsible for maintaining the header chain including the
// header query and updating.
//
// The components maintained by headerchain includes: (1) total difficult
// (2) header (3) block hash -> number mapping (4) canonical number -> hash mapping
// and (5) head header flag.
//
// It is not thread safe either, the encapsulating chain structures should do
// the necessary mutex locking/unlocking.
type HeaderChain struct {
config *params.ChainConfig
chainDb ethdb.Database
genesisHeader *types.Header
currentHeader atomic.Value // Current head of the header chain (may be above the block chain!)
currentHeaderHash common.Hash // Hash of the current head of the header chain (prevent recomputing all the time)
headerCache *lru.Cache // Cache for the most recent block headers
tdCache *lru.Cache // Cache for the most recent block total difficulties
numberCache *lru.Cache // Cache for the most recent block numbers
procInterrupt func() bool
rand *mrand.Rand
engine consensus.Engine
}
// NewHeaderChain creates a new HeaderChain structure. ProcInterrupt points
// to the parent's interrupt semaphore.
func NewHeaderChain(chainDb ethdb.Database, config *params.ChainConfig, engine consensus.Engine, procInterrupt func() bool) (*HeaderChain, error) {
headerCache, _ := lru.New(headerCacheLimit)
tdCache, _ := lru.New(tdCacheLimit)
numberCache, _ := lru.New(numberCacheLimit)
// Seed a fast but crypto originating random generator
seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
if err != nil {
return nil, err
}
hc := &HeaderChain{
config: config,
chainDb: chainDb,
headerCache: headerCache,
tdCache: tdCache,
numberCache: numberCache,
procInterrupt: procInterrupt,
rand: mrand.New(mrand.NewSource(seed.Int64())),
engine: engine,
}
hc.genesisHeader = hc.GetHeaderByNumber(0)
if hc.genesisHeader == nil {
return nil, ErrNoGenesis
}
hc.currentHeader.Store(hc.genesisHeader)
if head := rawdb.ReadHeadBlockHash(chainDb); head != (common.Hash{}) {
if chead := hc.GetHeaderByHash(head); chead != nil {
hc.currentHeader.Store(chead)
}
}
hc.currentHeaderHash = hc.CurrentHeader().Hash()
headHeaderGauge.Update(hc.CurrentHeader().Number.Int64())
return hc, nil
}
// GetBlockNumber retrieves the block number belonging to the given hash
// from the cache or database
func (hc *HeaderChain) GetBlockNumber(hash common.Hash) *uint64 {
if cached, ok := hc.numberCache.Get(hash); ok {
number := cached.(uint64)
return &number
}
number := rawdb.ReadHeaderNumber(hc.chainDb, hash)
if number != nil {
hc.numberCache.Add(hash, *number)
}
return number
}
type headerWriteResult struct {
status WriteStatus
ignored int
imported int
lastHash common.Hash
lastHeader *types.Header
}
// WriteHeaders writes a chain of headers into the local chain, given that the parents
// are already known. If the total difficulty of the newly inserted chain becomes
// greater than the current known TD, the canonical chain is reorged.
//
// Note: This method is not concurrent-safe with inserting blocks simultaneously
// into the chain, as side effects caused by reorganisations cannot be emulated
// without the real blocks. Hence, writing headers directly should only be done
// in two scenarios: pure-header mode of operation (light clients), or properly
// separated header/block phases (non-archive clients).
func (hc *HeaderChain) writeHeaders(headers []*types.Header) (result *headerWriteResult, err error) {
if len(headers) == 0 {
return &headerWriteResult{}, nil
}
ptd := hc.GetTd(headers[0].ParentHash, headers[0].Number.Uint64()-1)
if ptd == nil {
return &headerWriteResult{}, consensus.ErrUnknownAncestor
}
var (
lastNumber = headers[0].Number.Uint64() - 1 // Last successfully imported number
lastHash = headers[0].ParentHash // Last imported header hash
newTD = new(big.Int).Set(ptd) // Total difficulty of inserted chain
lastHeader *types.Header
inserted []numberHash // Ephemeral lookup of number/hash for the chain
firstInserted = -1 // Index of the first non-ignored header
)
batch := hc.chainDb.NewBatch()
for i, header := range headers {
var hash common.Hash
// The headers have already been validated at this point, so we already
// know that it's a contiguous chain, where
// headers[i].Hash() == headers[i+1].ParentHash
if i < len(headers)-1 {
hash = headers[i+1].ParentHash
} else {
hash = header.Hash()
}
number := header.Number.Uint64()
newTD.Add(newTD, header.Difficulty)
// If the header is already known, skip it, otherwise store
if !hc.HasHeader(hash, number) {
// Irrelevant of the canonical status, write the TD and header to the database.
rawdb.WriteTd(batch, hash, number, newTD)
hc.tdCache.Add(hash, new(big.Int).Set(newTD))
rawdb.WriteHeader(batch, header)
inserted = append(inserted, numberHash{number, hash})
hc.headerCache.Add(hash, header)
hc.numberCache.Add(hash, number)
if firstInserted < 0 {
firstInserted = i
}
}
lastHeader, lastHash, lastNumber = header, hash, number
}
// Skip the slow disk write of all headers if interrupted.
if hc.procInterrupt() {
log.Debug("Premature abort during headers import")
return &headerWriteResult{}, errors.New("aborted")
}
// Commit to disk!
if err := batch.Write(); err != nil {
log.Crit("Failed to write headers", "error", err)
}
batch.Reset()
var (
head = hc.CurrentHeader().Number.Uint64()
localTD = hc.GetTd(hc.currentHeaderHash, head)
status = SideStatTy
)
// If the total difficulty is higher than our known, add it to the canonical chain
// Second clause in the if statement reduces the vulnerability to selfish mining.
// Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
reorg := newTD.Cmp(localTD) > 0
if !reorg && newTD.Cmp(localTD) == 0 {
if lastNumber < head {
reorg = true
} else if lastNumber == head {
reorg = mrand.Float64() < 0.5
}
}
// If the parent of the (first) block is already the canon header,
// we don't have to go backwards to delete canon blocks, but
// simply pile them onto the existing chain
chainAlreadyCanon := headers[0].ParentHash == hc.currentHeaderHash
if reorg {
// If the header can be added into canonical chain, adjust the
// header chain markers(canonical indexes and head header flag).
//
// Note all markers should be written atomically.
markerBatch := batch // we can reuse the batch to keep allocs down
if !chainAlreadyCanon {
// Delete any canonical number assignments above the new head
for i := lastNumber + 1; ; i++ {
hash := rawdb.ReadCanonicalHash(hc.chainDb, i)
if hash == (common.Hash{}) {
break
}
rawdb.DeleteCanonicalHash(markerBatch, i)
}
// Overwrite any stale canonical number assignments, going
// backwards from the first header in this import
var (
headHash = headers[0].ParentHash // inserted[0].parent?
headNumber = headers[0].Number.Uint64() - 1 // inserted[0].num-1 ?
headHeader = hc.GetHeader(headHash, headNumber)
)
for rawdb.ReadCanonicalHash(hc.chainDb, headNumber) != headHash {
rawdb.WriteCanonicalHash(markerBatch, headHash, headNumber)
headHash = headHeader.ParentHash
headNumber = headHeader.Number.Uint64() - 1
headHeader = hc.GetHeader(headHash, headNumber)
}
// If some of the older headers were already known, but obtained canon-status
// during this import batch, then we need to write that now
// Further down, we continue writing the staus for the ones that
// were not already known
for i := 0; i < firstInserted; i++ {
hash := headers[i].Hash()
num := headers[i].Number.Uint64()
rawdb.WriteCanonicalHash(markerBatch, hash, num)
rawdb.WriteHeadHeaderHash(markerBatch, hash)
}
}
// Extend the canonical chain with the new headers
for _, hn := range inserted {
rawdb.WriteCanonicalHash(markerBatch, hn.hash, hn.number)
rawdb.WriteHeadHeaderHash(markerBatch, hn.hash)
}
if err := markerBatch.Write(); err != nil {
log.Crit("Failed to write header markers into disk", "err", err)
}
markerBatch.Reset()
// Last step update all in-memory head header markers
hc.currentHeaderHash = lastHash
hc.currentHeader.Store(types.CopyHeader(lastHeader))
headHeaderGauge.Update(lastHeader.Number.Int64())
// Chain status is canonical since this insert was a reorg.
// Note that all inserts which have higher TD than existing are 'reorg'.
status = CanonStatTy
}
if len(inserted) == 0 {
status = NonStatTy
}
return &headerWriteResult{
status: status,
ignored: len(headers) - len(inserted),
imported: len(inserted),
lastHash: lastHash,
lastHeader: lastHeader,
}, nil
}
func (hc *HeaderChain) ValidateHeaderChain(chain []*types.Header, checkFreq int) (int, error) {
// Do a sanity check that the provided chain is actually ordered and linked
for i := 1; i < len(chain); i++ {
parentHash := chain[i-1].Hash()
if chain[i].Number.Uint64() != chain[i-1].Number.Uint64()+1 || chain[i].ParentHash != parentHash {
// Chain broke ancestry, log a message (programming error) and skip insertion
log.Error("Non contiguous header insert", "number", chain[i].Number, "hash", chain[i].Hash(),
"parent", chain[i].ParentHash, "prevnumber", chain[i-1].Number, "prevhash", parentHash)
return 0, fmt.Errorf("non contiguous insert: item %d is #%d [%x…], item %d is #%d [%x…] (parent [%x…])", i-1, chain[i-1].Number,
parentHash.Bytes()[:4], i, chain[i].Number, chain[i].Hash().Bytes()[:4], chain[i].ParentHash[:4])
}
// If the header is a banned one, straight out abort
if BadHashes[parentHash] {
return i - 1, ErrBlacklistedHash
}
// If it's the last header in the cunk, we need to check it too
if i == len(chain)-1 && BadHashes[chain[i].Hash()] {
return i, ErrBlacklistedHash
}
}
// Generate the list of seal verification requests, and start the parallel verifier
seals := make([]bool, len(chain))
if checkFreq != 0 {
// In case of checkFreq == 0 all seals are left false.
for i := 0; i < len(seals)/checkFreq; i++ {
index := i*checkFreq + hc.rand.Intn(checkFreq)
if index >= len(seals) {
index = len(seals) - 1
}
seals[index] = true
}
// Last should always be verified to avoid junk.
seals[len(seals)-1] = true
}
abort, results := hc.engine.VerifyHeaders(hc, chain, seals)
defer close(abort)
// Iterate over the headers and ensure they all check out
for i := range chain {
// If the chain is terminating, stop processing blocks
if hc.procInterrupt() {
log.Debug("Premature abort during headers verification")
return 0, errors.New("aborted")
}
// Otherwise wait for headers checks and ensure they pass
if err := <-results; err != nil {
return i, err
}
}
return 0, nil
}
// InsertHeaderChain inserts the given headers.
//
// The validity of the headers is NOT CHECKED by this method, i.e. they need to be
// validated by ValidateHeaderChain before calling InsertHeaderChain.
//
// This insert is all-or-nothing. If this returns an error, no headers were written,
// otherwise they were all processed successfully.
//
// The returned 'write status' says if the inserted headers are part of the canonical chain
// or a side chain.
func (hc *HeaderChain) InsertHeaderChain(chain []*types.Header, start time.Time) (WriteStatus, error) {
if hc.procInterrupt() {
return 0, errors.New("aborted")
}
res, err := hc.writeHeaders(chain)
// Report some public statistics so the user has a clue what's going on
context := []interface{}{
"count", res.imported,
"elapsed", common.PrettyDuration(time.Since(start)),
}
if err != nil {
context = append(context, "err", err)
}
if last := res.lastHeader; last != nil {
context = append(context, "number", last.Number, "hash", res.lastHash)
if timestamp := time.Unix(int64(last.Time), 0); time.Since(timestamp) > time.Minute {
context = append(context, []interface{}{"age", common.PrettyAge(timestamp)}...)
}
}
if res.ignored > 0 {
context = append(context, []interface{}{"ignored", res.ignored}...)
}
log.Info("Imported new block headers", context...)
return res.status, err
}
// GetBlockHashesFromHash retrieves a number of block hashes starting at a given
// hash, fetching towards the genesis block.
func (hc *HeaderChain) GetBlockHashesFromHash(hash common.Hash, max uint64) []common.Hash {
// Get the origin header from which to fetch
header := hc.GetHeaderByHash(hash)
if header == nil {
return nil
}
// Iterate the headers until enough is collected or the genesis reached
chain := make([]common.Hash, 0, max)
for i := uint64(0); i < max; i++ {
next := header.ParentHash
if header = hc.GetHeader(next, header.Number.Uint64()-1); header == nil {
break
}
chain = append(chain, next)
if header.Number.Sign() == 0 {
break
}
}
return chain
}
// GetAncestor retrieves the Nth ancestor of a given block. It assumes that either the given block or
// a close ancestor of it is canonical. maxNonCanonical points to a downwards counter limiting the
// number of blocks to be individually checked before we reach the canonical chain.
//
// Note: ancestor == 0 returns the same block, 1 returns its parent and so on.
func (hc *HeaderChain) GetAncestor(hash common.Hash, number, ancestor uint64, maxNonCanonical *uint64) (common.Hash, uint64) {
if ancestor > number {
return common.Hash{}, 0
}
if ancestor == 1 {
// in this case it is cheaper to just read the header
if header := hc.GetHeader(hash, number); header != nil {
return header.ParentHash, number - 1
}
return common.Hash{}, 0
}
for ancestor != 0 {
if rawdb.ReadCanonicalHash(hc.chainDb, number) == hash {
ancestorHash := rawdb.ReadCanonicalHash(hc.chainDb, number-ancestor)
if rawdb.ReadCanonicalHash(hc.chainDb, number) == hash {
number -= ancestor
return ancestorHash, number
}
}
if *maxNonCanonical == 0 {
return common.Hash{}, 0
}
*maxNonCanonical--
ancestor--
header := hc.GetHeader(hash, number)
if header == nil {
return common.Hash{}, 0
}
hash = header.ParentHash
number--
}
return hash, number
}
// GetTd retrieves a block's total difficulty in the canonical chain from the
// database by hash and number, caching it if found.
func (hc *HeaderChain) GetTd(hash common.Hash, number uint64) *big.Int {
// Short circuit if the td's already in the cache, retrieve otherwise
if cached, ok := hc.tdCache.Get(hash); ok {
return cached.(*big.Int)
}
td := rawdb.ReadTd(hc.chainDb, hash, number)
if td == nil {
return nil
}
// Cache the found body for next time and return
hc.tdCache.Add(hash, td)
return td
}
// GetTdByHash retrieves a block's total difficulty in the canonical chain from the
// database by hash, caching it if found.
func (hc *HeaderChain) GetTdByHash(hash common.Hash) *big.Int {
number := hc.GetBlockNumber(hash)
if number == nil {
return nil
}
return hc.GetTd(hash, *number)
}
// GetHeader retrieves a block header from the database by hash and number,
// caching it if found.
func (hc *HeaderChain) GetHeader(hash common.Hash, number uint64) *types.Header {
// Short circuit if the header's already in the cache, retrieve otherwise
if header, ok := hc.headerCache.Get(hash); ok {
return header.(*types.Header)
}
header := rawdb.ReadHeader(hc.chainDb, hash, number)
if header == nil {
return nil
}
// Cache the found header for next time and return
hc.headerCache.Add(hash, header)
return header
}
// GetHeaderByHash retrieves a block header from the database by hash, caching it if
// found.
func (hc *HeaderChain) GetHeaderByHash(hash common.Hash) *types.Header {
number := hc.GetBlockNumber(hash)
if number == nil {
return nil
}
return hc.GetHeader(hash, *number)
}
// HasHeader checks if a block header is present in the database or not.
// In theory, if header is present in the database, all relative components
// like td and hash->number should be present too.
func (hc *HeaderChain) HasHeader(hash common.Hash, number uint64) bool {
if hc.numberCache.Contains(hash) || hc.headerCache.Contains(hash) {
return true
}
return rawdb.HasHeader(hc.chainDb, hash, number)
}
// GetHeaderByNumber retrieves a block header from the database by number,
// caching it (associated with its hash) if found.
func (hc *HeaderChain) GetHeaderByNumber(number uint64) *types.Header {
hash := rawdb.ReadCanonicalHash(hc.chainDb, number)
if hash == (common.Hash{}) {
return nil
}
return hc.GetHeader(hash, number)
}
func (hc *HeaderChain) GetCanonicalHash(number uint64) common.Hash {
return rawdb.ReadCanonicalHash(hc.chainDb, number)
}
// CurrentHeader retrieves the current head header of the canonical chain. The
// header is retrieved from the HeaderChain's internal cache.
func (hc *HeaderChain) CurrentHeader() *types.Header {
return hc.currentHeader.Load().(*types.Header)
}
// SetCurrentHeader sets the in-memory head header marker of the canonical chan
// as the given header.
func (hc *HeaderChain) SetCurrentHeader(head *types.Header) {
hc.currentHeader.Store(head)
hc.currentHeaderHash = head.Hash()
headHeaderGauge.Update(head.Number.Int64())
}
type (
// UpdateHeadBlocksCallback is a callback function that is called by SetHead
// before head header is updated. The method will return the actual block it
// updated the head to (missing state) and a flag if setHead should continue
// rewinding till that forcefully (exceeded ancient limits)
UpdateHeadBlocksCallback func(ethdb.KeyValueWriter, *types.Header) (uint64, bool)
// DeleteBlockContentCallback is a callback function that is called by SetHead
// before each header is deleted.
DeleteBlockContentCallback func(ethdb.KeyValueWriter, common.Hash, uint64)
)
// SetHead rewinds the local chain to a new head. Everything above the new head
// will be deleted and the new one set.
func (hc *HeaderChain) SetHead(head uint64, updateFn UpdateHeadBlocksCallback, delFn DeleteBlockContentCallback) {
var (
parentHash common.Hash
batch = hc.chainDb.NewBatch()
origin = true
)
for hdr := hc.CurrentHeader(); hdr != nil && hdr.Number.Uint64() > head; hdr = hc.CurrentHeader() {
num := hdr.Number.Uint64()
// Rewind block chain to new head.
parent := hc.GetHeader(hdr.ParentHash, num-1)
if parent == nil {
parent = hc.genesisHeader
}
parentHash = hdr.ParentHash
// Notably, since geth has the possibility for setting the head to a low
// height which is even lower than ancient head.
// In order to ensure that the head is always no higher than the data in
// the database (ancient store or active store), we need to update head
// first then remove the relative data from the database.
//
// Update head first(head fast block, head full block) before deleting the data.
markerBatch := hc.chainDb.NewBatch()
if updateFn != nil {
newHead, force := updateFn(markerBatch, parent)
if force && newHead < head {
log.Warn("Force rewinding till ancient limit", "head", newHead)
head = newHead
}
}
// Update head header then.
rawdb.WriteHeadHeaderHash(markerBatch, parentHash)
if err := markerBatch.Write(); err != nil {
log.Crit("Failed to update chain markers", "error", err)
}
hc.currentHeader.Store(parent)
hc.currentHeaderHash = parentHash
headHeaderGauge.Update(parent.Number.Int64())
// If this is the first iteration, wipe any leftover data upwards too so
// we don't end up with dangling daps in the database
var nums []uint64
if origin {
for n := num + 1; len(rawdb.ReadAllHashes(hc.chainDb, n)) > 0; n++ {
nums = append([]uint64{n}, nums...) // suboptimal, but we don't really expect this path
}
origin = false
}
nums = append(nums, num)
// Remove the related data from the database on all sidechains
for _, num := range nums {
// Gather all the side fork hashes
hashes := rawdb.ReadAllHashes(hc.chainDb, num)
if len(hashes) == 0 {
// No hashes in the database whatsoever, probably frozen already
hashes = append(hashes, hdr.Hash())
}
for _, hash := range hashes {
if delFn != nil {
delFn(batch, hash, num)
}
rawdb.DeleteHeader(batch, hash, num)
rawdb.DeleteTd(batch, hash, num)
}
rawdb.DeleteCanonicalHash(batch, num)
}
}
// Flush all accumulated deletions.
if err := batch.Write(); err != nil {
log.Crit("Failed to rewind block", "error", err)
}
// Clear out any stale content from the caches
hc.headerCache.Purge()
hc.tdCache.Purge()
hc.numberCache.Purge()
}
// SetGenesis sets a new genesis block header for the chain
func (hc *HeaderChain) SetGenesis(head *types.Header) {
hc.genesisHeader = head
}
// Config retrieves the header chain's chain configuration.
func (hc *HeaderChain) Config() *params.ChainConfig { return hc.config }
// Engine retrieves the header chain's consensus engine.
func (hc *HeaderChain) Engine() consensus.Engine { return hc.engine }
// GetBlock implements consensus.ChainReader, and returns nil for every input as
// a header chain does not have blocks available for retrieval.
func (hc *HeaderChain) GetBlock(hash common.Hash, number uint64) *types.Block {
return nil
}