// 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/>.
package core
import (
crand "crypto/rand"
"errors"
"fmt"
"math"
"math/big"
mrand "math/rand"
"sync/atomic"
"time"
"github.com/ava-labs/coreth/consensus"
"github.com/ava-labs/coreth/core/rawdb"
"github.com/ava-labs/coreth/core/types"
"github.com/ava-labs/coreth/params"
"github.com/ava-labs/go-ethereum/common"
"github.com/ava-labs/go-ethereum/ethdb"
"github.com/ava-labs/go-ethereum/log"
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.
// 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.
// getValidator should return the parent's validator
// procInterrupt points to the parent's interrupt semaphore
// wg points to the parent's shutdown wait group
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
}
// WriteHeader writes a header into the local chain, given that its parent is
// already known. If the total difficulty of the newly inserted header becomes
// greater than the current known TD, the canonical chain is re-routed.
//
// 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) WriteHeader(header *types.Header) (status WriteStatus, err error) {
// Cache some values to prevent constant recalculation
var (
hash = header.Hash()
number = header.Number.Uint64()
)
// Calculate the total difficulty of the header
ptd := hc.GetTd(header.ParentHash, number-1)
if ptd == nil {
return NonStatTy, consensus.ErrUnknownAncestor
}
localTd := hc.GetTd(hc.currentHeaderHash, hc.CurrentHeader().Number.Uint64())
externTd := new(big.Int).Add(header.Difficulty, ptd)
// Irrelevant of the canonical status, write the td and header to the database
if err := hc.WriteTd(hash, number, externTd); err != nil {
log.Crit("Failed to write header total difficulty", "err", err)
}
rawdb.WriteHeader(hc.chainDb, header)
// 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
if externTd.Cmp(localTd) > 0 || (externTd.Cmp(localTd) == 0 && mrand.Float64() < 0.5) {
// Delete any canonical number assignments above the new head
batch := hc.chainDb.NewBatch()
for i := number + 1; ; i++ {
hash := rawdb.ReadCanonicalHash(hc.chainDb, i)
if hash == (common.Hash{}) {
break
}
rawdb.DeleteCanonicalHash(batch, i)
}
batch.Write()
// Overwrite any stale canonical number assignments
var (
headHash = header.ParentHash
headNumber = header.Number.Uint64() - 1
headHeader = hc.GetHeader(headHash, headNumber)
)
for rawdb.ReadCanonicalHash(hc.chainDb, headNumber) != headHash {
rawdb.WriteCanonicalHash(hc.chainDb, headHash, headNumber)
headHash = headHeader.ParentHash
headNumber = headHeader.Number.Uint64() - 1
headHeader = hc.GetHeader(headHash, headNumber)
}
// Extend the canonical chain with the new header
rawdb.WriteCanonicalHash(hc.chainDb, hash, number)
rawdb.WriteHeadHeaderHash(hc.chainDb, hash)
hc.currentHeaderHash = hash
hc.currentHeader.Store(types.CopyHeader(header))
headHeaderGauge.Update(header.Number.Int64())
status = CanonStatTy
} else {
status = SideStatTy
}
hc.headerCache.Add(hash, header)
hc.numberCache.Add(hash, number)
return
}
// WhCallback is a callback function for inserting individual headers.
// A callback is used for two reasons: first, in a LightChain, status should be
// processed and light chain events sent, while in a BlockChain this is not
// necessary since chain events are sent after inserting blocks. Second, the
// header writes should be protected by the parent chain mutex individually.
type WhCallback func(*types.Header) error
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++ {
if chain[i].Number.Uint64() != chain[i-1].Number.Uint64()+1 || chain[i].