09777952ee
This commit adds pluggable consensus engines to go-ethereum. In short, it introduces a generic consensus interface, and refactors the entire codebase to use this interface.
450 lines
16 KiB
Go
450 lines
16 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package core
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import (
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crand "crypto/rand"
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"errors"
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"fmt"
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"math"
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"math/big"
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mrand "math/rand"
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"time"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/consensus"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/ethdb"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/params"
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"github.com/hashicorp/golang-lru"
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)
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const (
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headerCacheLimit = 512
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tdCacheLimit = 1024
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numberCacheLimit = 2048
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)
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// HeaderChain implements the basic block header chain logic that is shared by
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// core.BlockChain and light.LightChain. It is not usable in itself, only as
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// a part of either structure.
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// It is not thread safe either, the encapsulating chain structures should do
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// the necessary mutex locking/unlocking.
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type HeaderChain struct {
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config *params.ChainConfig
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chainDb ethdb.Database
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genesisHeader *types.Header
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currentHeader *types.Header // Current head of the header chain (may be above the block chain!)
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currentHeaderHash common.Hash // Hash of the current head of the header chain (prevent recomputing all the time)
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headerCache *lru.Cache // Cache for the most recent block headers
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tdCache *lru.Cache // Cache for the most recent block total difficulties
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numberCache *lru.Cache // Cache for the most recent block numbers
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procInterrupt func() bool
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rand *mrand.Rand
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engine consensus.Engine
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}
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// NewHeaderChain creates a new HeaderChain structure.
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// getValidator should return the parent's validator
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// procInterrupt points to the parent's interrupt semaphore
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// wg points to the parent's shutdown wait group
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func NewHeaderChain(chainDb ethdb.Database, config *params.ChainConfig, engine consensus.Engine, procInterrupt func() bool) (*HeaderChain, error) {
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headerCache, _ := lru.New(headerCacheLimit)
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tdCache, _ := lru.New(tdCacheLimit)
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numberCache, _ := lru.New(numberCacheLimit)
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// Seed a fast but crypto originating random generator
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seed, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
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if err != nil {
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return nil, err
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}
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hc := &HeaderChain{
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config: config,
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chainDb: chainDb,
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headerCache: headerCache,
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tdCache: tdCache,
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numberCache: numberCache,
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procInterrupt: procInterrupt,
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rand: mrand.New(mrand.NewSource(seed.Int64())),
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engine: engine,
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}
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hc.genesisHeader = hc.GetHeaderByNumber(0)
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if hc.genesisHeader == nil {
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return nil, ErrNoGenesis
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}
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hc.currentHeader = hc.genesisHeader
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if head := GetHeadBlockHash(chainDb); head != (common.Hash{}) {
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if chead := hc.GetHeaderByHash(head); chead != nil {
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hc.currentHeader = chead
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}
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}
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hc.currentHeaderHash = hc.currentHeader.Hash()
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return hc, nil
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}
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// GetBlockNumber retrieves the block number belonging to the given hash
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// from the cache or database
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func (hc *HeaderChain) GetBlockNumber(hash common.Hash) uint64 {
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if cached, ok := hc.numberCache.Get(hash); ok {
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return cached.(uint64)
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}
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number := GetBlockNumber(hc.chainDb, hash)
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if number != missingNumber {
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hc.numberCache.Add(hash, number)
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}
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return number
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}
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// WriteHeader writes a header into the local chain, given that its parent is
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// already known. If the total difficulty of the newly inserted header becomes
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// greater than the current known TD, the canonical chain is re-routed.
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//
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// Note: This method is not concurrent-safe with inserting blocks simultaneously
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// into the chain, as side effects caused by reorganisations cannot be emulated
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// without the real blocks. Hence, writing headers directly should only be done
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// in two scenarios: pure-header mode of operation (light clients), or properly
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// separated header/block phases (non-archive clients).
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func (hc *HeaderChain) WriteHeader(header *types.Header) (status WriteStatus, err error) {
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// Cache some values to prevent constant recalculation
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var (
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hash = header.Hash()
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number = header.Number.Uint64()
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)
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// Calculate the total difficulty of the header
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ptd := hc.GetTd(header.ParentHash, number-1)
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if ptd == nil {
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return NonStatTy, ParentError(header.ParentHash)
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}
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localTd := hc.GetTd(hc.currentHeaderHash, hc.currentHeader.Number.Uint64())
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externTd := new(big.Int).Add(header.Difficulty, ptd)
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// Irrelevant of the canonical status, write the td and header to the database
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if err := hc.WriteTd(hash, number, externTd); err != nil {
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log.Crit("Failed to write header total difficulty", "err", err)
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}
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if err := WriteHeader(hc.chainDb, header); err != nil {
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log.Crit("Failed to write header content", "err", err)
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}
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// If the total difficulty is higher than our known, add it to the canonical chain
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// Second clause in the if statement reduces the vulnerability to selfish mining.
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// Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
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if externTd.Cmp(localTd) > 0 || (externTd.Cmp(localTd) == 0 && mrand.Float64() < 0.5) {
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// Delete any canonical number assignments above the new head
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for i := number + 1; ; i++ {
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hash := GetCanonicalHash(hc.chainDb, i)
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if hash == (common.Hash{}) {
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break
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}
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DeleteCanonicalHash(hc.chainDb, i)
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}
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// Overwrite any stale canonical number assignments
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var (
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headHash = header.ParentHash
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headNumber = header.Number.Uint64() - 1
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headHeader = hc.GetHeader(headHash, headNumber)
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)
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for GetCanonicalHash(hc.chainDb, headNumber) != headHash {
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WriteCanonicalHash(hc.chainDb, headHash, headNumber)
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headHash = headHeader.ParentHash
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headNumber = headHeader.Number.Uint64() - 1
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headHeader = hc.GetHeader(headHash, headNumber)
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}
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// Extend the canonical chain with the new header
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if err := WriteCanonicalHash(hc.chainDb, hash, number); err != nil {
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log.Crit("Failed to insert header number", "err", err)
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}
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if err := WriteHeadHeaderHash(hc.chainDb, hash); err != nil {
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log.Crit("Failed to insert head header hash", "err", err)
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}
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hc.currentHeaderHash, hc.currentHeader = hash, types.CopyHeader(header)
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status = CanonStatTy
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} else {
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status = SideStatTy
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}
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hc.headerCache.Add(hash, header)
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hc.numberCache.Add(hash, number)
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return
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}
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// WhCallback is a callback function for inserting individual headers.
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// A callback is used for two reasons: first, in a LightChain, status should be
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// processed and light chain events sent, while in a BlockChain this is not
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// necessary since chain events are sent after inserting blocks. Second, the
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// header writes should be protected by the parent chain mutex individually.
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type WhCallback func(*types.Header) error
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// InsertHeaderChain attempts to insert the given header chain in to the local
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// chain, possibly creating a reorg. If an error is returned, it will return the
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// index number of the failing header as well an error describing what went wrong.
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//
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// The verify parameter can be used to fine tune whether nonce verification
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// should be done or not. The reason behind the optional check is because some
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// of the header retrieval mechanisms already need to verfy nonces, as well as
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// because nonces can be verified sparsely, not needing to check each.
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func (hc *HeaderChain) ValidateHeaderChain(chain []*types.Header, checkFreq int) (int, error) {
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// Do a sanity check that the provided chain is actually ordered and linked
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for i := 1; i < len(chain); i++ {
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if chain[i].Number.Uint64() != chain[i-1].Number.Uint64()+1 || chain[i].ParentHash != chain[i-1].Hash() {
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// Chain broke ancestry, log a messge (programming error) and skip insertion
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log.Error("Non contiguous header insert", "number", chain[i].Number, "hash", chain[i].Hash(),
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"parent", chain[i].ParentHash, "prevnumber", chain[i-1].Number, "prevhash", chain[i-1].Hash())
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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,
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chain[i-1].Hash().Bytes()[:4], i, chain[i].Number, chain[i].Hash().Bytes()[:4], chain[i].ParentHash[:4])
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}
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}
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// Generate the list of seal verification requests, and start the parallel verifier
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seals := make([]bool, len(chain))
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for i := 0; i < len(seals)/checkFreq; i++ {
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index := i*checkFreq + hc.rand.Intn(checkFreq)
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if index >= len(seals) {
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index = len(seals) - 1
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}
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seals[index] = true
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}
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seals[len(seals)-1] = true // Last should always be verified to avoid junk
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abort, results := hc.engine.VerifyHeaders(hc, chain, seals)
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defer close(abort)
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// Iterate over the headers and ensure they all check out
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for i, header := range chain {
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// If the chain is terminating, stop processing blocks
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if hc.procInterrupt() {
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log.Debug("Premature abort during headers verification")
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return 0, errors.New("aborted")
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}
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// If the header is a banned one, straight out abort
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if BadHashes[header.Hash()] {
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return i, BadHashError(header.Hash())
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}
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// Otherwise wait for headers checks and ensure they pass
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if err := <-results; err != nil {
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return i, err
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}
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}
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return 0, nil
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}
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func (hc *HeaderChain) InsertHeaderChain(chain []*types.Header, writeHeader WhCallback, start time.Time) (int, error) {
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// Collect some import statistics to report on
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stats := struct{ processed, ignored int }{}
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// All headers passed verification, import them into the database
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for i, header := range chain {
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// Short circuit insertion if shutting down
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if hc.procInterrupt() {
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log.Debug("Premature abort during headers import")
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return i, errors.New("aborted")
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}
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// If the header's already known, skip it, otherwise store
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if hc.GetHeader(header.Hash(), header.Number.Uint64()) != nil {
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stats.ignored++
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continue
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}
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if err := writeHeader(header); err != nil {
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return i, err
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}
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stats.processed++
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}
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// Report some public statistics so the user has a clue what's going on
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last := chain[len(chain)-1]
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log.Info("Imported new block headers", "count", stats.processed, "elapsed", common.PrettyDuration(time.Since(start)),
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"number", last.Number, "hash", last.Hash(), "ignored", stats.ignored)
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return 0, nil
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}
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// GetBlockHashesFromHash retrieves a number of block hashes starting at a given
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// hash, fetching towards the genesis block.
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func (hc *HeaderChain) GetBlockHashesFromHash(hash common.Hash, max uint64) []common.Hash {
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// Get the origin header from which to fetch
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header := hc.GetHeaderByHash(hash)
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if header == nil {
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return nil
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}
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// Iterate the headers until enough is collected or the genesis reached
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chain := make([]common.Hash, 0, max)
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for i := uint64(0); i < max; i++ {
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next := header.ParentHash
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if header = hc.GetHeader(next, header.Number.Uint64()-1); header == nil {
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break
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}
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chain = append(chain, next)
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if header.Number.Sign() == 0 {
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break
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}
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}
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return chain
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}
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// GetTd retrieves a block's total difficulty in the canonical chain from the
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// database by hash and number, caching it if found.
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func (hc *HeaderChain) GetTd(hash common.Hash, number uint64) *big.Int {
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// Short circuit if the td's already in the cache, retrieve otherwise
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if cached, ok := hc.tdCache.Get(hash); ok {
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return cached.(*big.Int)
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}
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td := GetTd(hc.chainDb, hash, number)
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if td == nil {
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return nil
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}
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// Cache the found body for next time and return
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hc.tdCache.Add(hash, td)
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return td
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}
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// GetTdByHash retrieves a block's total difficulty in the canonical chain from the
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// database by hash, caching it if found.
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func (hc *HeaderChain) GetTdByHash(hash common.Hash) *big.Int {
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return hc.GetTd(hash, hc.GetBlockNumber(hash))
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}
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// WriteTd stores a block's total difficulty into the database, also caching it
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// along the way.
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func (hc *HeaderChain) WriteTd(hash common.Hash, number uint64, td *big.Int) error {
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if err := WriteTd(hc.chainDb, hash, number, td); err != nil {
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return err
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}
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hc.tdCache.Add(hash, new(big.Int).Set(td))
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return nil
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}
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// GetHeader retrieves a block header from the database by hash and number,
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// caching it if found.
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func (hc *HeaderChain) GetHeader(hash common.Hash, number uint64) *types.Header {
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// Short circuit if the header's already in the cache, retrieve otherwise
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if header, ok := hc.headerCache.Get(hash); ok {
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return header.(*types.Header)
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}
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header := GetHeader(hc.chainDb, hash, number)
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if header == nil {
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return nil
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}
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// Cache the found header for next time and return
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hc.headerCache.Add(hash, header)
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return header
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}
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// GetHeaderByHash retrieves a block header from the database by hash, caching it if
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// found.
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func (hc *HeaderChain) GetHeaderByHash(hash common.Hash) *types.Header {
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return hc.GetHeader(hash, hc.GetBlockNumber(hash))
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}
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// HasHeader checks if a block header is present in the database or not, caching
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// it if present.
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func (hc *HeaderChain) HasHeader(hash common.Hash) bool {
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return hc.GetHeaderByHash(hash) != nil
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}
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// GetHeaderByNumber retrieves a block header from the database by number,
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// caching it (associated with its hash) if found.
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func (hc *HeaderChain) GetHeaderByNumber(number uint64) *types.Header {
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hash := GetCanonicalHash(hc.chainDb, number)
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if hash == (common.Hash{}) {
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return nil
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}
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return hc.GetHeader(hash, number)
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}
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// CurrentHeader retrieves the current head header of the canonical chain. The
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// header is retrieved from the HeaderChain's internal cache.
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func (hc *HeaderChain) CurrentHeader() *types.Header {
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return hc.currentHeader
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}
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// SetCurrentHeader sets the current head header of the canonical chain.
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func (hc *HeaderChain) SetCurrentHeader(head *types.Header) {
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if err := WriteHeadHeaderHash(hc.chainDb, head.Hash()); err != nil {
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log.Crit("Failed to insert head header hash", "err", err)
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}
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hc.currentHeader = head
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hc.currentHeaderHash = head.Hash()
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}
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// DeleteCallback is a callback function that is called by SetHead before
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// each header is deleted.
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type DeleteCallback func(common.Hash, uint64)
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// SetHead rewinds the local chain to a new head. Everything above the new head
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// will be deleted and the new one set.
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func (hc *HeaderChain) SetHead(head uint64, delFn DeleteCallback) {
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height := uint64(0)
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if hc.currentHeader != nil {
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height = hc.currentHeader.Number.Uint64()
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}
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for hc.currentHeader != nil && hc.currentHeader.Number.Uint64() > head {
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hash := hc.currentHeader.Hash()
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num := hc.currentHeader.Number.Uint64()
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if delFn != nil {
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delFn(hash, num)
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}
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DeleteHeader(hc.chainDb, hash, num)
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DeleteTd(hc.chainDb, hash, num)
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hc.currentHeader = hc.GetHeader(hc.currentHeader.ParentHash, hc.currentHeader.Number.Uint64()-1)
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}
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// Roll back the canonical chain numbering
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for i := height; i > head; i-- {
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DeleteCanonicalHash(hc.chainDb, i)
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}
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// Clear out any stale content from the caches
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hc.headerCache.Purge()
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hc.tdCache.Purge()
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hc.numberCache.Purge()
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if hc.currentHeader == nil {
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hc.currentHeader = hc.genesisHeader
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}
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hc.currentHeaderHash = hc.currentHeader.Hash()
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if err := WriteHeadHeaderHash(hc.chainDb, hc.currentHeaderHash); err != nil {
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log.Crit("Failed to reset head header hash", "err", err)
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}
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}
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// SetGenesis sets a new genesis block header for the chain
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func (hc *HeaderChain) SetGenesis(head *types.Header) {
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hc.genesisHeader = head
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}
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// Config retrieves the header chain's chain configuration.
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func (hc *HeaderChain) Config() *params.ChainConfig { return hc.config }
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// GetBlock implements consensus.ChainReader, and returns nil for every input as
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// a header chain does not have blocks available for retrieval.
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func (hc *HeaderChain) GetBlock(hash common.Hash, number uint64) *types.Block {
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return nil
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}
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