Official Go implementation of the Ethereum protocol
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go-ethereum/light/lightchain.go

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// Copyright 2016 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 light implements on-demand retrieval capable state and chain objects
// for the Ethereum Light Client.
package light
import (
"context"
"errors"
"math/big"
"sync"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/lru"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/core"
"github.com/ethereum/go-ethereum/core/rawdb"
"github.com/ethereum/go-ethereum/core/state"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/ethdb"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/rlp"
)
var (
bodyCacheLimit = 256
blockCacheLimit = 256
)
// LightChain represents a canonical chain that by default only handles block
// headers, downloading block bodies and receipts on demand through an ODR
// interface. It only does header validation during chain insertion.
type LightChain struct {
hc *core.HeaderChain
indexerConfig *IndexerConfig
chainDb ethdb.Database
engine consensus.Engine
odr OdrBackend
chainFeed event.Feed
chainSideFeed event.Feed
chainHeadFeed event.Feed
scope event.SubscriptionScope
genesisBlock *types.Block
forker *core.ForkChoice
bodyCache *lru.Cache[common.Hash, *types.Body]
bodyRLPCache *lru.Cache[common.Hash, rlp.RawValue]
blockCache *lru.Cache[common.Hash, *types.Block]
chainmu sync.RWMutex // protects header inserts
quit chan struct{}
wg sync.WaitGroup
// Atomic boolean switches:
stopped atomic.Bool // whether LightChain is stopped or running
procInterrupt atomic.Bool // interrupts chain insert
disableCheckFreq atomic.Bool // disables header verification
}
// NewLightChain returns a fully initialised light chain using information
// available in the database. It initialises the default Ethereum header
// validator.
func NewLightChain(odr OdrBackend, config *params.ChainConfig, engine consensus.Engine) (*LightChain, error) {
bc := &LightChain{
chainDb: odr.Database(),
indexerConfig: odr.IndexerConfig(),
odr: odr,
quit: make(chan struct{}),
bodyCache: lru.NewCache[common.Hash, *types.Body](bodyCacheLimit),
bodyRLPCache: lru.NewCache[common.Hash, rlp.RawValue](bodyCacheLimit),
blockCache: lru.NewCache[common.Hash, *types.Block](blockCacheLimit),
engine: engine,
}
bc.forker = core.NewForkChoice(bc, nil)
var err error
bc.hc, err = core.NewHeaderChain(odr.Database(), config, bc.engine, bc.getProcInterrupt)
if err != nil {
return nil, err
}
bc.genesisBlock, _ = bc.GetBlockByNumber(NoOdr, 0)
if bc.genesisBlock == nil {
return nil, core.ErrNoGenesis
}
if err := bc.loadLastState(); err != nil {
return nil, err
}
// Check the current state of the block hashes and make sure that we do not have any of the bad blocks in our chain
for hash := range core.BadHashes {
if header := bc.GetHeaderByHash(hash); header != nil {
log.Error("Found bad hash, rewinding chain", "number", header.Number, "hash", header.ParentHash)
bc.SetHead(header.Number.Uint64() - 1)
log.Info("Chain rewind was successful, resuming normal operation")
}
}
return bc, nil
}
func (lc *LightChain) getProcInterrupt() bool {
return lc.procInterrupt.Load()
}
// Odr returns the ODR backend of the chain
func (lc *LightChain) Odr() OdrBackend {
return lc.odr
}
// HeaderChain returns the underlying header chain.
func (lc *LightChain) HeaderChain() *core.HeaderChain {
return lc.hc
}
// loadLastState loads the last known chain state from the database. This method
// assumes that the chain manager mutex is held.
func (lc *LightChain) loadLastState() error {
if head := rawdb.ReadHeadHeaderHash(lc.chainDb); head == (common.Hash{}) {
// Corrupt or empty database, init from scratch
lc.Reset()
} else {
header := lc.GetHeaderByHash(head)
if header == nil {
// Corrupt or empty database, init from scratch
lc.Reset()
} else {
lc.hc.SetCurrentHeader(header)
}
}
// Issue a status log and return
header := lc.hc.CurrentHeader()
headerTd := lc.GetTd(header.Hash(), header.Number.Uint64())
log.Info("Loaded most recent local header", "number", header.Number, "hash", header.Hash(), "td", headerTd, "age", common.PrettyAge(time.Unix(int64(header.Time), 0)))
return nil
}
// SetHead rewinds the local chain to a new head. Everything above the new
// head will be deleted and the new one set.
func (lc *LightChain) SetHead(head uint64) error {
lc.chainmu.Lock()
defer lc.chainmu.Unlock()
lc.hc.SetHead(head, nil, nil)
return lc.loadLastState()
}
// SetHeadWithTimestamp rewinds the local chain to a new head that has at max
// the given timestamp. Everything above the new head will be deleted and the
// new one set.
func (lc *LightChain) SetHeadWithTimestamp(timestamp uint64) error {
lc.chainmu.Lock()
defer lc.chainmu.Unlock()
lc.hc.SetHeadWithTimestamp(timestamp, nil, nil)
return lc.loadLastState()
}
// GasLimit returns the gas limit of the current HEAD block.
func (lc *LightChain) GasLimit() uint64 {
return lc.hc.CurrentHeader().GasLimit
}
// Reset purges the entire blockchain, restoring it to its genesis state.
func (lc *LightChain) Reset() {
lc.ResetWithGenesisBlock(lc.genesisBlock)
}
// ResetWithGenesisBlock purges the entire blockchain, restoring it to the
// specified genesis state.
func (lc *LightChain) ResetWithGenesisBlock(genesis *types.Block) {
// Dump the entire block chain and purge the caches
lc.SetHead(0)
lc.chainmu.Lock()
defer lc.chainmu.Unlock()
// Prepare the genesis block and reinitialise the chain
batch := lc.chainDb.NewBatch()
rawdb.WriteTd(batch, genesis.Hash(), genesis.NumberU64(), genesis.Difficulty())
rawdb.WriteBlock(batch, genesis)
rawdb.WriteHeadHeaderHash(batch, genesis.Hash())
if err := batch.Write(); err != nil {
log.Crit("Failed to reset genesis block", "err", err)
}
lc.genesisBlock = genesis
lc.hc.SetGenesis(lc.genesisBlock.Header())
lc.hc.SetCurrentHeader(lc.genesisBlock.Header())
}
// Accessors
// Engine retrieves the light chain's consensus engine.
func (lc *LightChain) Engine() consensus.Engine { return lc.engine }
// Genesis returns the genesis block
func (lc *LightChain) Genesis() *types.Block {
return lc.genesisBlock
}
func (lc *LightChain) StateCache() state.Database {
panic("not implemented")
}
// GetBody retrieves a block body (transactions and uncles) from the database
// or ODR service by hash, caching it if found.
func (lc *LightChain) GetBody(ctx context.Context, hash common.Hash) (*types.Body, error) {
// Short circuit if the body's already in the cache, retrieve otherwise
if cached, ok := lc.bodyCache.Get(hash); ok {
return cached, nil
}
number := lc.hc.GetBlockNumber(hash)
if number == nil {
return nil, errors.New("unknown block")
}
body, err := GetBody(ctx, lc.odr, hash, *number)
if err != nil {
return nil, err
}
// Cache the found body for next time and return
lc.bodyCache.Add(hash, body)
return body, nil
}
// GetBodyRLP retrieves a block body in RLP encoding from the database or
// ODR service by hash, caching it if found.
func (lc *LightChain) GetBodyRLP(ctx context.Context, hash common.Hash) (rlp.RawValue, error) {
// Short circuit if the body's already in the cache, retrieve otherwise
if cached, ok := lc.bodyRLPCache.Get(hash); ok {
return cached, nil
}
number := lc.hc.GetBlockNumber(hash)
if number == nil {
return nil, errors.New("unknown block")
}
body, err := GetBodyRLP(ctx, lc.odr, hash, *number)
if err != nil {
return nil, err
}
// Cache the found body for next time and return
lc.bodyRLPCache.Add(hash, body)
return body, nil
}
// HasBlock checks if a block is fully present in the database or not, caching
// it if present.
func (lc *LightChain) HasBlock(hash common.Hash, number uint64) bool {
blk, _ := lc.GetBlock(NoOdr, hash, number)
return blk != nil
}
// GetBlock retrieves a block from the database or ODR service by hash and number,
// caching it if found.
func (lc *LightChain) GetBlock(ctx context.Context, hash common.Hash, number uint64) (*types.Block, error) {
// Short circuit if the block's already in the cache, retrieve otherwise
if block, ok := lc.blockCache.Get(hash); ok {
return block, nil
}
block, err := GetBlock(ctx, lc.odr, hash, number)
if err != nil {
return nil, err
}
// Cache the found block for next time and return
lc.blockCache.Add(block.Hash(), block)
return block, nil
}
// GetBlockByHash retrieves a block from the database or ODR service by hash,
// caching it if found.
func (lc *LightChain) GetBlockByHash(ctx context.Context, hash common.Hash) (*types.Block, error) {
number := lc.hc.GetBlockNumber(hash)
if number == nil {
return nil, errors.New("unknown block")
}
return lc.GetBlock(ctx, hash, *number)
}
// GetBlockByNumber retrieves a block from the database or ODR service by
// number, caching it (associated with its hash) if found.
func (lc *LightChain) GetBlockByNumber(ctx context.Context, number uint64) (*types.Block, error) {
hash, err := GetCanonicalHash(ctx, lc.odr, number)
if hash == (common.Hash{}) || err != nil {
return nil, err
}
return lc.GetBlock(ctx, hash, number)
}
// Stop stops the blockchain service. If any imports are currently in progress
// it will abort them using the procInterrupt.
func (lc *LightChain) Stop() {
if !lc.stopped.CompareAndSwap(false, true) {
return
}
close(lc.quit)
lc.StopInsert()
lc.wg.Wait()
log.Info("Blockchain stopped")
}
// StopInsert interrupts all insertion methods, causing them to return
// errInsertionInterrupted as soon as possible. Insertion is permanently disabled after
// calling this method.
func (lc *LightChain) StopInsert() {
lc.procInterrupt.Store(true)
}
// Rollback is designed to remove a chain of links from the database that aren't
// certain enough to be valid.
func (lc *LightChain) Rollback(chain []common.Hash) {
lc.chainmu.Lock()
defer lc.chainmu.Unlock()
batch := lc.chainDb.NewBatch()
for i := len(chain) - 1; i >= 0; i-- {
hash := chain[i]
// Degrade the chain markers if they are explicitly reverted.
// In theory we should update all in-memory markers in the
// last step, however the direction of rollback is from high
// to low, so it's safe the update in-memory markers directly.
if head := lc.hc.CurrentHeader(); head.Hash() == hash {
rawdb.WriteHeadHeaderHash(batch, head.ParentHash)
lc.hc.SetCurrentHeader(lc.GetHeader(head.ParentHash, head.Number.Uint64()-1))
}
}
if err := batch.Write(); err != nil {
log.Crit("Failed to rollback light chain", "error", err)
}
}
func (lc *LightChain) InsertHeader(header *types.Header) error {
// Verify the header first before obtaining the lock
headers := []*types.Header{header}
if _, err := lc.hc.ValidateHeaderChain(headers, 100); err != nil {
return err
}
// Make sure only one thread manipulates the chain at once
lc.chainmu.Lock()
defer lc.chainmu.Unlock()
lc.wg.Add(1)
defer lc.wg.Done()
_, err := lc.hc.WriteHeaders(headers)
log.Info("Inserted header", "number", header.Number, "hash", header.Hash())
return err
}
func (lc *LightChain) SetCanonical(header *types.Header) error {
lc.chainmu.Lock()
defer lc.chainmu.Unlock()
lc.wg.Add(1)
defer lc.wg.Done()
if err := lc.hc.Reorg([]*types.Header{header}); err != nil {
return err
}
// Emit events
block := types.NewBlockWithHeader(header)
lc.chainFeed.Send(core.ChainEvent{Block: block, Hash: block.Hash()})
lc.chainHeadFeed.Send(core.ChainHeadEvent{Block: block})
log.Info("Set the chain head", "number", block.Number(), "hash", block.Hash())
return nil
}
// InsertHeaderChain attempts to insert the given header chain in to the local
// chain, possibly creating a reorg. If an error is returned, it will return the
// index number of the failing header as well an error describing what went wrong.
//
// The verify parameter can be used to fine tune whether nonce verification
// should be done or not. The reason behind the optional check is because some
// of the header retrieval mechanisms already need to verify nonces, as well as
// because nonces can be verified sparsely, not needing to check each.
//
// In the case of a light chain, InsertHeaderChain also creates and posts light
// chain events when necessary.
func (lc *LightChain) InsertHeaderChain(chain []*types.Header, checkFreq int) (int, error) {
if len(chain) == 0 {
return 0, nil
}
if lc.disableCheckFreq.Load() {
checkFreq = 0
}
start := time.Now()
if i, err := lc.hc.ValidateHeaderChain(chain, checkFreq); err != nil {
return i, err
}
// Make sure only one thread manipulates the chain at once
lc.chainmu.Lock()
defer lc.chainmu.Unlock()
lc.wg.Add(1)
defer lc.wg.Done()
status, err := lc.hc.InsertHeaderChain(chain, start, lc.forker)
if err != nil || len(chain) == 0 {
return 0, err
}
// Create chain event for the new head block of this insertion.
var (
lastHeader = chain[len(chain)-1]
block = types.NewBlockWithHeader(lastHeader)
)
switch status {
case core.CanonStatTy:
lc.chainFeed.Send(core.ChainEvent{Block: block, Hash: block.Hash()})
lc.chainHeadFeed.Send(core.ChainHeadEvent{Block: block})
case core.SideStatTy:
lc.chainSideFeed.Send(core.ChainSideEvent{Block: block})
}
return 0, err
}
// CurrentHeader retrieves the current head header of the canonical chain. The
// header is retrieved from the HeaderChain's internal cache.
func (lc *LightChain) CurrentHeader() *types.Header {
return lc.hc.CurrentHeader()
}
// GetTd retrieves a block's total difficulty in the canonical chain from the
// database by hash and number, caching it if found.
func (lc *LightChain) GetTd(hash common.Hash, number uint64) *big.Int {
return lc.hc.GetTd(hash, number)
}
// GetTdOdr retrieves the total difficult from the database or
// network by hash and number, caching it (associated with its hash) if found.
func (lc *LightChain) GetTdOdr(ctx context.Context, hash common.Hash, number uint64) *big.Int {
td := lc.GetTd(hash, number)
if td != nil {
return td
}
td, _ = GetTd(ctx, lc.odr, hash, number)
return td
}
// GetHeader retrieves a block header from the database by hash and number,
// caching it if found.
func (lc *LightChain) GetHeader(hash common.Hash, number uint64) *types.Header {
return lc.hc.GetHeader(hash, number)
}
// GetHeaderByHash retrieves a block header from the database by hash, caching it if
// found.
func (lc *LightChain) GetHeaderByHash(hash common.Hash) *types.Header {
return lc.hc.GetHeaderByHash(hash)
}
// HasHeader checks if a block header is present in the database or not, caching
// it if present.
func (lc *LightChain) HasHeader(hash common.Hash, number uint64) bool {
return lc.hc.HasHeader(hash, number)
}
// GetCanonicalHash returns the canonical hash for a given block number
func (bc *LightChain) GetCanonicalHash(number uint64) common.Hash {
return bc.hc.GetCanonicalHash(number)
}
// 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 (lc *LightChain) GetAncestor(hash common.Hash, number, ancestor uint64, maxNonCanonical *uint64) (common.Hash, uint64) {
return lc.hc.GetAncestor(hash, number, ancestor, maxNonCanonical)
}
// GetHeaderByNumber retrieves a block header from the database by number,
// caching it (associated with its hash) if found.
func (lc *LightChain) GetHeaderByNumber(number uint64) *types.Header {
return lc.hc.GetHeaderByNumber(number)
}
// GetHeaderByNumberOdr retrieves a block header from the database or network
// by number, caching it (associated with its hash) if found.
func (lc *LightChain) GetHeaderByNumberOdr(ctx context.Context, number uint64) (*types.Header, error) {
if header := lc.hc.GetHeaderByNumber(number); header != nil {
return header, nil
}
return GetHeaderByNumber(ctx, lc.odr, number)
}
// Config retrieves the header chain's chain configuration.
func (lc *LightChain) Config() *params.ChainConfig { return lc.hc.Config() }
// LockChain locks the chain mutex for reading so that multiple canonical hashes can be
// retrieved while it is guaranteed that they belong to the same version of the chain
func (lc *LightChain) LockChain() {
lc.chainmu.RLock()
}
// UnlockChain unlocks the chain mutex
func (lc *LightChain) UnlockChain() {
lc.chainmu.RUnlock()
}
// SubscribeChainEvent registers a subscription of ChainEvent.
func (lc *LightChain) SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription {
return lc.scope.Track(lc.chainFeed.Subscribe(ch))
}
// SubscribeChainHeadEvent registers a subscription of ChainHeadEvent.
func (lc *LightChain) SubscribeChainHeadEvent(ch chan<- core.ChainHeadEvent) event.Subscription {
return lc.scope.Track(lc.chainHeadFeed.Subscribe(ch))
}
// SubscribeChainSideEvent registers a subscription of ChainSideEvent.
func (lc *LightChain) SubscribeChainSideEvent(ch chan<- core.ChainSideEvent) event.Subscription {
return lc.scope.Track(lc.chainSideFeed.Subscribe(ch))
}
// SubscribeLogsEvent implements the interface of filters.Backend
// LightChain does not send logs events, so return an empty subscription.
func (lc *LightChain) SubscribeLogsEvent(ch chan<- []*types.Log) event.Subscription {
return lc.scope.Track(new(event.Feed).Subscribe(ch))
}
// SubscribeRemovedLogsEvent implements the interface of filters.Backend
// LightChain does not send core.RemovedLogsEvent, so return an empty subscription.
func (lc *LightChain) SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent) event.Subscription {
return lc.scope.Track(new(event.Feed).Subscribe(ch))
}
// DisableCheckFreq disables header validation. This is used for ultralight mode.
func (lc *LightChain) DisableCheckFreq() {
lc.disableCheckFreq.Store(true)
}
// EnableCheckFreq enables header validation.
func (lc *LightChain) EnableCheckFreq() {
lc.disableCheckFreq.Store(false)
}