以太坊区块设计

// filedir: go-ethereum-1.10.2coretypesblock.go  L149// Block represents an entire block in the Ethereum blockchain.type Block struct {  header       *Header  uncles       []*Header  transactions Transactions
  // caches  hash atomic.Value  size atomic.Value
  // Td is used by package core to store the total difficulty  // of the chain up to and including the block.  td *big.Int
  // These fields are used by package eth to track  // inter-peer block relay.  ReceivedAt   time.Time  ReceivedFrom interface{}}

// filedir:go-ethereum-1.10.2coretypesblock.go  L66//go:generate gencodec -type Header -field-override headerMarshaling -out gen_header_json.go
// Header represents a block header in the Ethereum blockchain.type Header struct {  ParentHash  common.Hash    `json:"parentHash"       gencodec:"required"`  UncleHash   common.Hash    `json:"sha3Uncles"       gencodec:"required"`  Coinbase    common.Address `json:"miner"            gencodec:"required"`  Root        common.Hash    `json:"stateRoot"        gencodec:"required"`  TxHash      common.Hash    `json:"transactionsRoot" gencodec:"required"`  ReceiptHash common.Hash    `json:"receiptsRoot"     gencodec:"required"`  Bloom       Bloom          `json:"logsBloom"        gencodec:"required"`  Difficulty  *big.Int       `json:"difficulty"       gencodec:"required"`  Number      *big.Int       `json:"number"           gencodec:"required"`  GasLimit    uint64         `json:"gasLimit"         gencodec:"required"`  GasUsed     uint64         `json:"gasUsed"          gencodec:"required"`  Time        uint64         `json:"timestamp"        gencodec:"required"`  Extra       []byte         `json:"extraData"        gencodec:"required"`  MixDigest   common.Hash    `json:"mixHash"`  Nonce       BlockNonce     `json:"nonce"`}

// filedir: go-ethereum-1.10.2paramsconfig.go  L28// Genesis hashes to enforce below configs on.var (  MainnetGenesisHash = common.HexToHash("0xd4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3")  RopstenGenesisHash = common.HexToHash("0x41941023680923e0fe4d74a34bdac8141f2540e3ae90623718e47d66d1ca4a2d")  RinkebyGenesisHash = common.HexToHash("0x6341fd3daf94b748c72ced5a5b26028f2474f5f00d824504e4fa37a75767e177")  GoerliGenesisHash  = common.HexToHash("0xbf7e331f7f7c1dd2e05159666b3bf8bc7a8a3a9eb1d518969eab529dd9b88c1a")  YoloV3GenesisHash  = common.HexToHash("0x374f07cc7fa7c251fc5f36849f574b43db43600526410349efdca2bcea14101a"))
// TrustedCheckpoints associates each known checkpoint with the genesis hash of// the chain it belongs to.var TrustedCheckpoints = map[common.Hash]*TrustedCheckpoint{  MainnetGenesisHash: MainnetTrustedCheckpoint,  RopstenGenesisHash: RopstenTrustedCheckpoint,  RinkebyGenesisHash: RinkebyTrustedCheckpoint,  GoerliGenesisHash:  GoerliTrustedCheckpoint,}
// CheckpointOracles associates each known checkpoint oracles with the genesis hash of// the chain it belongs to.var CheckpointOracles = map[common.Hash]*CheckpointOracleConfig{  MainnetGenesisHash: MainnetCheckpointOracle,  RopstenGenesisHash: RopstenCheckpointOracle,  RinkebyGenesisHash: RinkebyCheckpointOracle,  GoerliGenesisHash:  GoerliCheckpointOracle,}
var (  // MainnetChainConfig is the chain parameters to run a node on the main network.  MainnetChainConfig = &ChainConfig{    ChainID:             big.NewInt(1),    HomesteadBlock:      big.NewInt(1_150_000),    DAOForkBlock:        big.NewInt(1_920_000),    DAOForkSupport:      true,    EIP150Block:         big.NewInt(2_463_000),    EIP150Hash:          common.HexToHash("0x2086799aeebeae135c246c65021c82b4e15a2c451340993aacfd2751886514f0"),    EIP155Block:         big.NewInt(2_675_000),    EIP158Block:         big.NewInt(2_675_000),    ByzantiumBlock:      big.NewInt(4_370_000),    ConstantinopleBlock: big.NewInt(7_280_000),    PetersburgBlock:     big.NewInt(7_280_000),    IstanbulBlock:       big.NewInt(9_069_000),    MuirGlacierBlock:    big.NewInt(9_200_000),    BerlinBlock:         big.NewInt(12_244_000),    Ethash:              new(EthashConfig),  }
  // MainnetTrustedCheckpoint contains the light client trusted checkpoint for the main network.  MainnetTrustedCheckpoint = &TrustedCheckpoint{    SectionIndex: 371,    SectionHead:  common.HexToHash("0x50fd3cec5376ede90ef9129772022690cd1467f22c18abb7faa11e793c51e9c9"),    CHTRoot:      common.HexToHash("0xb57b4b22a77b5930847b1ca9f62daa11eae6578948cb7b18997f2c0fe5757025"),    BloomRoot:    common.HexToHash("0xa338f8a868a194fa90327d0f5877f656a9f3640c618d2a01a01f2e76ef9ef954"),  }
  // MainnetCheckpointOracle contains a set of configs for the main network oracle.  MainnetCheckpointOracle = &CheckpointOracleConfig{    Address: common.HexToAddress("0x9a9070028361F7AAbeB3f2F2Dc07F82C4a98A02a"),    Signers: []common.Address{      common.HexToAddress("0x1b2C260efc720BE89101890E4Db589b44E950527"), // Peter      common.HexToAddress("0x78d1aD571A1A09D60D9BBf25894b44e4C8859595"), // Martin      common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt      common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary      common.HexToAddress("0x0DF8fa387C602AE62559cC4aFa4972A7045d6707"), // Guillaume    },    Threshold: 2,  }
  // RopstenChainConfig contains the chain parameters to run a node on the Ropsten test network.  RopstenChainConfig = &ChainConfig{    ChainID:             big.NewInt(3),    HomesteadBlock:      big.NewInt(0),    DAOForkBlock:        nil,    DAOForkSupport:      true,    EIP150Block:         big.NewInt(0),    EIP150Hash:          common.HexToHash("0x41941023680923e0fe4d74a34bdac8141f2540e3ae90623718e47d66d1ca4a2d"),    EIP155Block:         big.NewInt(10),    EIP158Block:         big.NewInt(10),    ByzantiumBlock:      big.NewInt(1_700_000),    ConstantinopleBlock: big.NewInt(4_230_000),    PetersburgBlock:     big.NewInt(4_939_394),    IstanbulBlock:       big.NewInt(6_485_846),    MuirGlacierBlock:    big.NewInt(7_117_117),    BerlinBlock:         big.NewInt(9_812_189),    Ethash:              new(EthashConfig),  }
  // RopstenTrustedCheckpoint contains the light client trusted checkpoint for the Ropsten test network.  RopstenTrustedCheckpoint = &TrustedCheckpoint{    SectionIndex: 279,    SectionHead:  common.HexToHash("0x4a4912848d4c06090097073357c10015d11c6f4544a0f93cbdd584701c3b7d58"),    CHTRoot:      common.HexToHash("0x9053b7867ae921e80a4e2f5a4b15212e4af3d691ca712fb33dc150e9c6ea221c"),    BloomRoot:    common.HexToHash("0x3dc04cb1be7ddc271f3f83469b47b76184a79d7209ef51d85b1539ea6d25a645"),  }
  // RopstenCheckpointOracle contains a set of configs for the Ropsten test network oracle.  RopstenCheckpointOracle = &CheckpointOracleConfig{    Address: common.HexToAddress("0xEF79475013f154E6A65b54cB2742867791bf0B84"),    Signers: []common.Address{      common.HexToAddress("0x32162F3581E88a5f62e8A61892B42C46E2c18f7b"), // Peter      common.HexToAddress("0x78d1aD571A1A09D60D9BBf25894b44e4C8859595"), // Martin      common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt      common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary      common.HexToAddress("0x0DF8fa387C602AE62559cC4aFa4972A7045d6707"), // Guillaume    },    Threshold: 2,  }
  // RinkebyChainConfig contains the chain parameters to run a node on the Rinkeby test network.  RinkebyChainConfig = &ChainConfig{    ChainID:             big.NewInt(4),    HomesteadBlock:      big.NewInt(1),    DAOForkBlock:        nil,    DAOForkSupport:      true,    EIP150Block:         big.NewInt(2),    EIP150Hash:          common.HexToHash("0x9b095b36c15eaf13044373aef8ee0bd3a382a5abb92e402afa44b8249c3a90e9"),    EIP155Block:         big.NewInt(3),    EIP158Block:         big.NewInt(3),    ByzantiumBlock:      big.NewInt(1_035_301),    ConstantinopleBlock: big.NewInt(3_660_663),    PetersburgBlock:     big.NewInt(4_321_234),    IstanbulBlock:       big.NewInt(5_435_345),    MuirGlacierBlock:    nil,    BerlinBlock:         big.NewInt(8_290_928),    Clique: &CliqueConfig{      Period: 15,      Epoch:  30000,    },  }
  // RinkebyTrustedCheckpoint contains the light client trusted checkpoint for the Rinkeby test network.  RinkebyTrustedCheckpoint = &TrustedCheckpoint{    SectionIndex: 254,    SectionHead:  common.HexToHash("0x0cba01dd71baa22ac8fa0b105bc908e94f9ecfbc79b4eb97427fe07b5851dd10"),    CHTRoot:      common.HexToHash("0x5673d8fc49c9c7d8729068640e4b392d46952a5a38798973bac1cf1d0d27ad7d"),    BloomRoot:    common.HexToHash("0x70e01232b66df9a7778ae3291c9217afb9a2d9f799f32d7b912bd37e7bce83a8"),  }
  // RinkebyCheckpointOracle contains a set of configs for the Rinkeby test network oracle.  RinkebyCheckpointOracle = &CheckpointOracleConfig{    Address: common.HexToAddress("0xebe8eFA441B9302A0d7eaECc277c09d20D684540"),    Signers: []common.Address{      common.HexToAddress("0xd9c9cd5f6779558b6e0ed4e6acf6b1947e7fa1f3"), // Peter      common.HexToAddress("0x78d1aD571A1A09D60D9BBf25894b44e4C8859595"), // Martin      common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt      common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary    },    Threshold: 2,  }
  // GoerliChainConfig contains the chain parameters to run a node on the Görli test network.  GoerliChainConfig = &ChainConfig{    ChainID:             big.NewInt(5),    HomesteadBlock:      big.NewInt(0),    DAOForkBlock:        nil,    DAOForkSupport:      true,    EIP150Block:         big.NewInt(0),    EIP155Block:         big.NewInt(0),    EIP158Block:         big.NewInt(0),    ByzantiumBlock:      big.NewInt(0),    ConstantinopleBlock: big.NewInt(0),    PetersburgBlock:     big.NewInt(0),    IstanbulBlock:       big.NewInt(1_561_651),    MuirGlacierBlock:    nil,    BerlinBlock:         big.NewInt(4_460_644),    Clique: &CliqueConfig{      Period: 15,      Epoch:  30000,    },  }
  // GoerliTrustedCheckpoint contains the light client trusted checkpoint for the Görli test network.  GoerliTrustedCheckpoint = &TrustedCheckpoint{    SectionIndex: 138,    SectionHead:  common.HexToHash("0xb7ea0566abd7d0def5b3c9afa3431debb7bb30b65af35f106ca93a59e6c859a7"),    CHTRoot:      common.HexToHash("0x378c7ea9081242beb982e2e39567ba12f2ed3e59e5aba3f9db1d595646d7c9f4"),    BloomRoot:    common.HexToHash("0x523c169286cfca52e8a6579d8c35dc8bf093412d8a7478163bfa81ae91c2492d"),  }
  // GoerliCheckpointOracle contains a set of configs for the Goerli test network oracle.  GoerliCheckpointOracle = &CheckpointOracleConfig{    Address: common.HexToAddress("0x18CA0E045F0D772a851BC7e48357Bcaab0a0795D"),    Signers: []common.Address{      common.HexToAddress("0x4769bcaD07e3b938B7f43EB7D278Bc7Cb9efFb38"), // Peter      common.HexToAddress("0x78d1aD571A1A09D60D9BBf25894b44e4C8859595"), // Martin      common.HexToAddress("0x286834935f4A8Cfb4FF4C77D5770C2775aE2b0E7"), // Zsolt      common.HexToAddress("0xb86e2B0Ab5A4B1373e40c51A7C712c70Ba2f9f8E"), // Gary      common.HexToAddress("0x0DF8fa387C602AE62559cC4aFa4972A7045d6707"), // Guillaume    },    Threshold: 2,  }
  // YoloV3ChainConfig contains the chain parameters to run a node on the YOLOv3 test network.  YoloV3ChainConfig = &ChainConfig{    ChainID:             new(big.Int).SetBytes([]byte("yolov3x")),    HomesteadBlock:      big.NewInt(0),    DAOForkBlock:        nil,    DAOForkSupport:      true,    EIP150Block:         big.NewInt(0),    EIP155Block:         big.NewInt(0),    EIP158Block:         big.NewInt(0),    ByzantiumBlock:      big.NewInt(0),    ConstantinopleBlock: big.NewInt(0),    PetersburgBlock:     big.NewInt(0),    IstanbulBlock:       big.NewInt(0),    MuirGlacierBlock:    nil,    BerlinBlock:         nil, // Don't enable Berlin directly, we're YOLOing it    YoloV3Block:         big.NewInt(0),    Clique: &CliqueConfig{      Period: 15,      Epoch:  30000,    },  }
  // AllEthashProtocolChanges contains every protocol change (EIPs) introduced  // and accepted by the Ethereum core developers into the Ethash consensus.  //  // This configuration is intentionally not using keyed fields to force anyone  // adding flags to the config to also have to set these fields.  AllEthashProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, new(EthashConfig), nil}
  // AllCliqueProtocolChanges contains every protocol change (EIPs) introduced  // and accepted by the Ethereum core developers into the Clique consensus.  //  // This configuration is intentionally not using keyed fields to force anyone  // adding flags to the config to also have to set these fields.  AllCliqueProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, nil, &CliqueConfig{Period: 0, Epoch: 30000}}
  TestChainConfig = &ChainConfig{big.NewInt(1), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, new(EthashConfig), nil}  TestRules       = TestChainConfig.Rules(new(big.Int)))

./geth init <genesispath>

// filedir: go-ethereum-1.10.2cmdgethchaincmd.go  L38var (  initCommand = cli.Command{    Action:    utils.MigrateFlags(initGenesis),    Name:      "init",    Usage:     "Bootstrap and initialize a new genesis block",    ArgsUsage: "<genesisPath>",    Flags: []cli.Flag{      utils.DataDirFlag,    },    Category: "BLOCKCHAIN COMMANDS",    Description: `The init command initializes a new genesis block and definition for the network.This is a destructive action and changes the network in which you will beparticipating.
It expects the genesis file as argument.`,  }

// filedir:go-ethereum-1.10.2cmdgethchaincmd.go  L172// initGenesis will initialise the given JSON format genesis file and writes it as// the zero'd block (i.e. genesis) or will fail hard if it can't succeed.func initGenesis(ctx *cli.Context) error {  // Make sure we have a valid genesis JSON  genesisPath := ctx.Args().First()  if len(genesisPath) == 0 {    utils.Fatalf("Must supply path to genesis JSON file")  }  file, err := os.Open(genesisPath)  if err != nil {    utils.Fatalf("Failed to read genesis file: %v", err)  }  defer file.Close()
  genesis := new(core.Genesis)  if err := json.NewDecoder(file).Decode(genesis); err != nil {    utils.Fatalf("invalid genesis file: %v", err)  }  // Open and initialise both full and light databases  stack, _ := makeConfigNode(ctx)  defer stack.Close()
  for _, name := range []string{"chaindata", "lightchaindata"} {    chaindb, err := stack.OpenDatabase(name, 0, 0, "", false)    if err != nil {      utils.Fatalf("Failed to open database: %v", err)    }    _, hash, err := core.SetupGenesisBlock(chaindb, genesis)    if err != nil {      utils.Fatalf("Failed to write genesis block: %v", err)    }    chaindb.Close()    log.Info("Successfully wrote genesis state", "database", name, "hash", hash)  }  return nil}

// filedir: go-ethereum-1.10.2coregenesis.go  L142// SetupGenesisBlock writes or updates the genesis block in db.// The block that will be used is:////                          genesis == nil       genesis != nil//                       +------------------------------------------//     db has no genesis |  main-net default  |  genesis//     db has genesis    |  from DB           |  genesis (if compatible)//// The stored chain configuration will be updated if it is compatible (i.e. does not// specify a fork block below the local head block). In case of a conflict, the// error is a *params.ConfigCompatError and the new, unwritten config is returned.//// The returned chain configuration is never nil.func SetupGenesisBlock(db ethdb.Database, genesis *Genesis) (*params.ChainConfig, common.Hash, error) {  return SetupGenesisBlockWithOverride(db, genesis, nil)}
func SetupGenesisBlockWithOverride(db ethdb.Database, genesis *Genesis, overrideBerlin *big.Int) (*params.ChainConfig, common.Hash, error) {  if genesis != nil && genesis.Config == nil {    return params.AllEthashProtocolChanges, common.Hash{}, errGenesisNoConfig  }  // Just commit the new block if there is no stored genesis block.  stored := rawdb.ReadCanonicalHash(db, 0)  if (stored == common.Hash{}) {    if genesis == nil {      log.Info("Writing default main-net genesis block")      genesis = DefaultGenesisBlock()    } else {      log.Info("Writing custom genesis block")    }    block, err := genesis.Commit(db)    if err != nil {      return genesis.Config, common.Hash{}, err    }    return genesis.Config, block.Hash(), nil  }  // We have the genesis block in database(perhaps in ancient database)  // but the corresponding state is missing.  header := rawdb.ReadHeader(db, stored, 0)  if _, err := state.New(header.Root, state.NewDatabaseWithConfig(db, nil), nil); err != nil {    if genesis == nil {      genesis = DefaultGenesisBlock()    }    // Ensure the stored genesis matches with the given one.    hash := genesis.ToBlock(nil).Hash()    if hash != stored {      return genesis.Config, hash, &GenesisMismatchError{stored, hash}    }    block, err := genesis.Commit(db)    if err != nil {      return genesis.Config, hash, err    }    return genesis.Config, block.Hash(), nil  }  // Check whether the genesis block is already written.  if genesis != nil {    hash := genesis.ToBlock(nil).Hash()    if hash != stored {      return genesis.Config, hash, &GenesisMismatchError{stored, hash}    }  }  // Get the existing chain configuration.  newcfg := genesis.configOrDefault(stored)  if overrideBerlin != nil {    newcfg.BerlinBlock = overrideBerlin  }  if err := newcfg.CheckConfigForkOrder(); err != nil {    return newcfg, common.Hash{}, err  }  storedcfg := rawdb.ReadChainConfig(db, stored)  if storedcfg == nil {    log.Warn("Found genesis block without chain config")    rawdb.WriteChainConfig(db, stored, newcfg)    return newcfg, stored, nil  }  // Special case: don't change the existing config of a non-mainnet chain if no new  // config is supplied. These chains would get AllProtocolChanges (and a compat error)  // if we just continued here.  if genesis == nil && stored != params.MainnetGenesisHash {    return storedcfg, stored, nil  }  // Check config compatibility and write the config. Compatibility errors  // are returned to the caller unless we're already at block zero.  height := rawdb.ReadHeaderNumber(db, rawdb.ReadHeadHeaderHash(db))  if height == nil {    return newcfg, stored, fmt.Errorf("missing block number for head header hash")  }  compatErr := storedcfg.CheckCompatible(newcfg, *height)  if compatErr != nil && *height != 0 && compatErr.RewindTo != 0 {    return newcfg, stored, compatErr  }  rawdb.WriteChainConfig(db, stored, newcfg)  return newcfg, stored, nil}

// filedir:go-ethereum-1.10.2coregenesis.go  L338// DefaultGenesisBlock returns the Ethereum main net genesis block.func DefaultGenesisBlock() *Genesis {  return &Genesis{    Config:     params.MainnetChainConfig,    Nonce:      66,    ExtraData:  hexutil.MustDecode("0x11bbe8db4e347b4e8c937c1c8370e4b5ed33adb3db69cbdb7a38e1e50b1b82fa"),    GasLimit:   5000,    Difficulty: big.NewInt(17179869184),    Alloc:      decodePrealloc(mainnetAllocData),  }}

// The block is committed as the canonical head block.func (g *Genesis) Commit(db ethdb.Database) (*types.Block, error) {  block := g.ToBlock(db)  if block.Number().Sign() != 0 {    return nil, fmt.Errorf("can't commit genesis block with number > 0")  }  config := g.Config  if config == nil {    config = params.AllEthashProtocolChanges  }  if err := config.CheckConfigForkOrder(); err != nil {    return nil, err  }  rawdb.WriteTd(db, block.Hash(), block.NumberU64(), g.Difficulty)  rawdb.WriteBlock(db, block)  rawdb.WriteReceipts(db, block.Hash(), block.NumberU64(), nil)  rawdb.WriteCanonicalHash(db, block.Hash(), block.NumberU64())  rawdb.WriteHeadBlockHash(db, block.Hash())  rawdb.WriteHeadFastBlockHash(db, block.Hash())  rawdb.WriteHeadHeaderHash(db, block.Hash())  rawdb.WriteChainConfig(db, block.Hash(), config)  return block, nil}

// filedir:go-ethereum-1.10.2minerworker.go  L432// mainLoop is a standalone goroutine to regenerate the sealing task based on the received event.func (w *worker) mainLoop() {  defer w.txsSub.Unsubscribe()  defer w.chainHeadSub.Unsubscribe()  defer w.chainSideSub.Unsubscribe()
  for {    select {    case req := <-w.newWorkCh:      w.commitNewWork(req.interrupt, req.noempty, req.timestamp)
    case ev := <-w.chainSideCh:      ......
    case ev := <-w.txsCh:      // Apply transactions to the pending state if we're not mining.      //      // Note all transactions received may not be continuous with transactions      // already included in the current mining block. These transactions will      // be automatically eliminated.      if !w.isRunning() && w.current != nil {        // If block is already full, abort        if gp := w.current.gasPool; gp != nil && gp.Gas() < params.TxGas {          continue        }        ......        if tcount != w.current.tcount {          w.updateSnapshot()        }        ......    // System stopped    case <-w.exitCh:      return    case <-w.txsSub.Err():      return    case <-w.chainHeadSub.Err():      return    case <-w.chainSideSub.Err():      return    }  }}

// filedir:go-ethereum-1.10.2minerworker.go  L705// updateSnapshot updates pending snapshot block and state.// Note this function assumes the current variable is thread safe.func (w *worker) updateSnapshot() {  w.snapshotMu.Lock()  defer w.snapshotMu.Unlock()
  var uncles []*types.Header  w.current.uncles.Each(func(item interface{}) bool {    hash, ok := item.(common.Hash)    if !ok {      return false    }    uncle, exist := w.localUncles[hash]    if !exist {      uncle, exist = w.remoteUncles[hash]    }    if !exist {      return false    }    uncles = append(uncles, uncle.Header())    return false  })
  w.snapshotBlock = types.NewBlock(    w.current.header,    w.current.txs,    uncles,    w.current.receipts,    trie.NewStackTrie(nil),  )  w.snapshotState = w.current.state.Copy()}

// filedir:go-ethereum-1.10.2coretypesblock.go  L198// NewBlock creates a new block. The input data is copied,// changes to header and to the field values will not affect the// block.//// The values of TxHash, UncleHash, ReceiptHash and Bloom in header// are ignored and set to values derived from the given txs, uncles// and receipts.func NewBlock(header *Header, txs []*Transaction, uncles []*Header, receipts []*Receipt, hasher TrieHasher) *Block {  b := &Block{header: CopyHeader(header), td: new(big.Int)}
  // TODO: panic if len(txs) != len(receipts)  if len(txs) == 0 {    b.header.TxHash = EmptyRootHash  } else {    b.header.TxHash = DeriveSha(Transactions(txs), hasher)    b.transactions = make(Transactions, len(txs))    copy(b.transactions, txs)  }
  if len(receipts) == 0 {    b.header.ReceiptHash = EmptyRootHash  } else {    b.header.ReceiptHash = DeriveSha(Receipts(receipts), hasher)    b.header.Bloom = CreateBloom(receipts)  }
  if len(uncles) == 0 {    b.header.UncleHash = EmptyUncleHash  } else {    b.header.UncleHash = CalcUncleHash(uncles)    b.uncles = make([]*Header, len(uncles))    for i := range uncles {      b.uncles[i] = CopyHeader(uncles[i])    }  }
  return b}

// filedir:go-ethereum-1.10.2coreblock_validator.go   L48// ValidateBody validates the given block's uncles and verifies the block// header's transaction and uncle roots. The headers are assumed to be already// validated at this point.func (v *BlockValidator) ValidateBody(block *types.Block) error {    // Check whether the block's known, and if not, that it's linkable    if v.bc.HasBlockAndState(block.Hash(), block.NumberU64()) {        return ErrKnownBlock    }    // Header validity is known at this point, check the uncles and transactions    header := block.Header()    if err := v.engine.VerifyUncles(v.bc, block); err != nil {        return err    }    if hash := types.CalcUncleHash(block.Uncles()); hash != header.UncleHash {        return fmt.Errorf("uncle root hash mismatch: have %x, want %x", hash, header.UncleHash)    }    if hash := types.DeriveSha(block.Transactions(), trie.NewStackTrie(nil)); hash != header.TxHash {        return fmt.Errorf("transaction root hash mismatch: have %x, want %x", hash, header.TxHash)    }    if !v.bc.HasBlockAndState(block.ParentHash(), block.NumberU64()-1) {        if !v.bc.HasBlock(block.ParentHash(), block.NumberU64()-1) {            return consensus.ErrUnknownAncestor        }        return consensus.ErrPrunedAncestor    }    return nil}

// VerifyUncles verifies that the given block's uncles conform to the consensus// rules of the stock Ethereum ethash engine.func (ethash *Ethash) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {    // If we're running a full engine faking, accept any input as valid    if ethash.config.PowMode == ModeFullFake {        return nil    }    // Verify that there are at most 2 uncles included in this block    if len(block.Uncles()) > maxUncles {        return errTooManyUncles    }    if len(block.Uncles()) == 0 {        return nil    }    // Gather the set of past uncles and ancestors    uncles, ancestors := mapset.NewSet(), make(map[common.Hash]*types.Header)
    number, parent := block.NumberU64()-1, block.ParentHash()    for i := 0; i < 7; i++ {        ancestor := chain.GetBlock(parent, number)        if ancestor == nil {            break        }        ancestors[ancestor.Hash()] = ancestor.Header()        for _, uncle := range ancestor.Uncles() {            uncles.Add(uncle.Hash())        }        parent, number = ancestor.ParentHash(), number-1    }    ancestors[block.Hash()] = block.Header()    uncles.Add(block.Hash())
    // Verify each of the uncles that it's recent, but not an ancestor    for _, uncle := range block.Uncles() {        // Make sure every uncle is rewarded only once        hash := uncle.Hash()        if uncles.Contains(hash) {            return errDuplicateUncle        }        uncles.Add(hash)
        // Make sure the uncle has a valid ancestry        if ancestors[hash] != nil {            return errUncleIsAncestor        }        if ancestors[uncle.ParentHash] == nil || uncle.ParentHash == block.ParentHash() {            return errDanglingUncle        }        if err := ethash.verifyHeader(chain, uncle, ancestors[uncle.ParentHash], true, true, time.Now().Unix()); err != nil {            return err        }    }    return nil}

// filedir:go-ethereum-1.10.2consensusethashconsensus.go  L88// VerifyHeader checks whether a header conforms to the consensus rules of the// stock Ethereum ethash engine.func (ethash *Ethash) VerifyHeader(chain consensus.ChainHeaderReader, header *types.Header, seal bool) error {  // If we're running a full engine faking, accept any input as valid  if ethash.config.PowMode == ModeFullFake {    return nil  }  // Short circuit if the header is known, or its parent not  number := header.Number.Uint64()  if chain.GetHeader(header.Hash(), number) != nil {    return nil  }  parent := chain.GetHeader(header.ParentHash, number-1)  if parent == nil {    return consensus.ErrUnknownAncestor  }  // Sanity checks passed, do a proper verification  return ethash.verifyHeader(chain, header, parent, false, seal, time.Now().Unix())}

// filedir:go-ethereum-1.10.2consensusethashconsensus.go  L242// verifyHeader checks whether a header conforms to the consensus rules of the// stock Ethereum ethash engine.// See YP section 4.3.4. "Block Header Validity"func (ethash *Ethash) verifyHeader(chain consensus.ChainHeaderReader, header, parent *types.Header, uncle bool, seal bool, unixNow int64) error {  // Ensure that the header's extra-data section is of a reasonable size  if uint64(len(header.Extra)) > params.MaximumExtraDataSize {    return fmt.Errorf("extra-data too long: %d > %d", len(header.Extra), params.MaximumExtraDataSize)  }  // Verify the header's timestamp  if !uncle {    if header.Time > uint64(unixNow+allowedFutureBlockTimeSeconds) {      return consensus.ErrFutureBlock    }  }  if header.Time <= parent.Time {    return errOlderBlockTime  }  // Verify the block's difficulty based on its timestamp and parent's difficulty  expected := ethash.CalcDifficulty(chain, header.Time, parent)
  if expected.Cmp(header.Difficulty) != 0 {    return fmt.Errorf("invalid difficulty: have %v, want %v", header.Difficulty, expected)  }  // Verify that the gas limit is <= 2^63-1  cap := uint64(0x7fffffffffffffff)  if header.GasLimit > cap {    return fmt.Errorf("invalid gasLimit: have %v, max %v", header.GasLimit, cap)  }  // Verify that the gasUsed is <= gasLimit  if header.GasUsed > header.GasLimit {    return fmt.Errorf("invalid gasUsed: have %d, gasLimit %d", header.GasUsed, header.GasLimit)  }
  // Verify that the gas limit remains within allowed bounds  diff := int64(parent.GasLimit) - int64(header.GasLimit)  if diff < 0 {    diff *= -1  }  limit := parent.GasLimit / params.GasLimitBoundDivisor
  if uint64(diff) >= limit || header.GasLimit < params.MinGasLimit {    return fmt.Errorf("invalid gas limit: have %d, want %d += %d", header.GasLimit, parent.GasLimit, limit)  }  // Verify that the block number is parent's +1  if diff := new(big.Int).Sub(header.Number, parent.Number); diff.Cmp(big.NewInt(1)) != 0 {    return consensus.ErrInvalidNumber  }  // Verify the engine specific seal securing the block  if seal {    if err := ethash.verifySeal(chain, header, false); err != nil {      return err    }  }  // If all checks passed, validate any special fields for hard forks  if err := misc.VerifyDAOHeaderExtraData(chain.Config(), header); err != nil {    return err  }  if err := misc.VerifyForkHashes(chain.Config(), header, uncle); err != nil {    return err  }  return nil}

// filedir:go-ethereum-1.10.2consensusethashconsensus.go  L490// verifySeal checks whether a block satisfies the PoW difficulty requirements,// either using the usual ethash cache for it, or alternatively using a full DAG// to make remote mining fast.func (ethash *Ethash) verifySeal(chain consensus.ChainHeaderReader, header *types.Header, fulldag bool) error {  // If we're running a fake PoW, accept any seal as valid  if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {    time.Sleep(ethash.fakeDelay)    if ethash.fakeFail == header.Number.Uint64() {      return errInvalidPoW    }    return nil  }  // If we're running a shared PoW, delegate verification to it  if ethash.shared != nil {    return ethash.shared.verifySeal(chain, header, fulldag)  }  // Ensure that we have a valid difficulty for the block  if header.Difficulty.Sign() <= 0 {    return errInvalidDifficulty  }  // Recompute the digest and PoW values  number := header.Number.Uint64()
  var (    digest []byte    result []byte  )  // If fast-but-heavy PoW verification was requested, use an ethash dataset  if fulldag {    dataset := ethash.dataset(number, true)    if dataset.generated() {      digest, result = hashimotoFull(dataset.dataset, ethash.SealHash(header).Bytes(), header.Nonce.Uint64())
      // Datasets are unmapped in a finalizer. Ensure that the dataset stays alive      // until after the call to hashimotoFull so it's not unmapped while being used.      runtime.KeepAlive(dataset)    } else {      // Dataset not yet generated, don't hang, use a cache instead      fulldag = false    }  }  // If slow-but-light PoW verification was requested (or DAG not yet ready), use an ethash cache  if !fulldag {    cache := ethash.cache(number)
    size := datasetSize(number)    if ethash.config.PowMode == ModeTest {      size = 32 * 1024    }    digest, result = hashimotoLight(size, cache.cache, ethash.SealHash(header).Bytes(), header.Nonce.Uint64())
    // Caches are unmapped in a finalizer. Ensure that the cache stays alive    // until after the call to hashimotoLight so it's not unmapped while being used.    runtime.KeepAlive(cache)  }  // Verify the calculated values against the ones provided in the header  if !bytes.Equal(header.MixDigest[:], digest) {    return errInvalidMixDigest  }  target := new(big.Int).Div(two256, header.Difficulty)  if new(big.Int).SetBytes(result).Cmp(target) > 0 {    return errInvalidPoW  }  return nil}

// filedir:go-ethereum-1.10.2consensusmiscforks.go  L26// VerifyForkHashes verifies that blocks conforming to network hard-forks do have// the correct hashes, to avoid clients going off on different chains. This is an// optional feature.func VerifyForkHashes(config *params.ChainConfig, header *types.Header, uncle bool) error {  // We don't care about uncles  if uncle {    return nil  }  // If the homestead reprice hash is set, validate it  if config.EIP150Block != nil && config.EIP150Block.Cmp(header.Number) == 0 {    if config.EIP150Hash != (common.Hash{}) && config.EIP150Hash != header.Hash() {      return fmt.Errorf("homestead gas reprice fork: have 0x%x, want 0x%x", header.Hash(), config.EIP150Hash)    }  }  // All ok, return  return nil}

// filedir:go-ethereum-1.10.2consensusethashconsensus.go  L304// CalcDifficulty is the difficulty adjustment algorithm. It returns// the difficulty that a new block should have when created at time// given the parent block's time and difficulty.func (ethash *Ethash) CalcDifficulty(chain consensus.ChainHeaderReader, time uint64, parent *types.Header) *big.Int {  return CalcDifficulty(chain.Config(), time, parent)}
// CalcDifficulty is the difficulty adjustment algorithm. It returns// the difficulty that a new block should have when created at time// given the parent block's time and difficulty.func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Header) *big.Int {  next := new(big.Int).Add(parent.Number, big1)  switch {  case config.IsMuirGlacier(next):    return calcDifficultyEip2384(time, parent)  case config.IsConstantinople(next):    return calcDifficultyConstantinople(time, parent)  case config.IsByzantium(next):    return calcDifficultyByzantium(time, parent)  case config.IsHomestead(next):    return calcDifficultyHomestead(time, parent)  default:    return calcDifficultyFrontier(time, parent)  }}

// filedir:go-ethereum-1.10.2consensusethashconsensus.go  L404// calcDifficultyHomestead is the difficulty adjustment algorithm. It returns// the difficulty that a new block should have when created at time given the// parent block's time and difficulty. The calculation uses the Homestead rules.func calcDifficultyHomestead(time uint64, parent *types.Header) *big.Int {  // https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.md  // algorithm:  // diff = (parent_diff +  //         (parent_diff / 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))  //        ) + 2^(periodCount - 2)
  bigTime := new(big.Int).SetUint64(time)  bigParentTime := new(big.Int).SetUint64(parent.Time)
  // holds intermediate values to make the algo easier to read & audit  x := new(big.Int)  y := new(big.Int)
  // 1 - (block_timestamp - parent_timestamp) // 10  x.Sub(bigTime, bigParentTime)  x.Div(x, big10)  x.Sub(big1, x)
  // max(1 - (block_timestamp - parent_timestamp) // 10, -99)  if x.Cmp(bigMinus99) < 0 {    x.Set(bigMinus99)  }  // (parent_diff + parent_diff // 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99))  y.Div(parent.Difficulty, params.DifficultyBoundDivisor)  x.Mul(y, x)  x.Add(parent.Difficulty, x)
  // minimum difficulty can ever be (before exponential factor)  if x.Cmp(params.MinimumDifficulty) < 0 {    x.Set(params.MinimumDifficulty)  }  // for the exponential factor  periodCount := new(big.Int).Add(parent.Number, big1)  periodCount.Div(periodCount, expDiffPeriod)
  // the exponential factor, commonly referred to as "the bomb"  // diff = diff + 2^(periodCount - 2)  if periodCount.Cmp(big1) > 0 {    y.Sub(periodCount, big2)    y.Exp(big2, y, nil)    x.Add(x, y)  }  return x}

diff = (parent_diff + (parent_diff / 2048 * max(1 - (block_timestamp - parent_timestamp)))) + 2^(periodCount - 2)

geth ——> makeFullNode ——> RegisterEthService ——> eth.New ——> core.NewBlockChain

// filedir:go-ethereum-1.10.2ethbackend.go  L98// New creates a new Ethereum object (including the// initialisation of the common Ethereum object)func New(stack *node.Node, config *ethconfig.Config) (*Ethereum, error) {  // Ensure configuration values are compatible and sane  if config.SyncMode == downloader.LightSync {    return nil, errors.New("can't run eth.Ethereum in light sync mode, use les.LightEthereum")  }  if !config.SyncMode.IsValid() {    return nil, fmt.Errorf("invalid sync mode %d", config.SyncMode)  }  if config.Miner.GasPrice == nil || config.Miner.GasPrice.Cmp(common.Big0) <= 0 {    log.Warn("Sanitizing invalid miner gas price", "provided", config.Miner.GasPrice, "updated", ethconfig.Defaults.Miner.GasPrice)    config.Miner.GasPrice = new(big.Int).Set(ethconfig.Defaults.Miner.GasPrice)  }  if config.NoPruning && config.TrieDirtyCache > 0 {    if config.SnapshotCache > 0 {      config.TrieCleanCache += config.TrieDirtyCache * 3 / 5      config.SnapshotCache += config.TrieDirtyCache * 2 / 5    } else {      config.TrieCleanCache += config.TrieDirtyCache    }    config.TrieDirtyCache = 0  }  log.Info("Allocated trie memory caches", "clean", common.StorageSize(config.TrieCleanCache)*1024*1024, "dirty", common.StorageSize(config.TrieDirtyCache)*1024*1024)
  // Transfer mining-related config to the ethash config.  ethashConfig := config.Ethash  ethashConfig.NotifyFull = config.Miner.NotifyFull
  // Assemble the Ethereum object  chainDb, err := stack.OpenDatabaseWithFreezer("chaindata", config.DatabaseCache, config.DatabaseHandles, config.DatabaseFreezer, "eth/db/chaindata/", false)  if err != nil {    return nil, err  }  chainConfig, genesisHash, genesisErr := core.SetupGenesisBlockWithOverride(chainDb, config.Genesis, config.OverrideBerlin)  if _, ok := genesisErr.(*params.ConfigCompatError); genesisErr != nil && !ok {    return nil, genesisErr  }  log.Info("Initialised chain configuration", "config", chainConfig)
  if err := pruner.RecoverPruning(stack.ResolvePath(""), chainDb, stack.ResolvePath(config.TrieCleanCacheJournal)); err != nil {    log.Error("Failed to recover state", "error", err)  }  eth := &Ethereum{    config:            config,    chainDb:           chainDb,    eventMux:          stack.EventMux(),    accountManager:    stack.AccountManager(),    engine:            ethconfig.CreateConsensusEngine(stack, chainConfig, &ethashConfig, config.Miner.Notify, config.Miner.Noverify, chainDb),    closeBloomHandler: make(chan struct{}),    networkID:         config.NetworkId,    gasPrice:          config.Miner.GasPrice,    etherbase:         config.Miner.Etherbase,    bloomRequests:     make(chan chan *bloombits.Retrieval),    bloomIndexer:      core.NewBloomIndexer(chainDb, params.BloomBitsBlocks, params.BloomConfirms),    p2pServer:         stack.Server(),  }
  bcVersion := rawdb.ReadDatabaseVersion(chainDb)  var dbVer = "<nil>"  if bcVersion != nil {    dbVer = fmt.Sprintf("%d", *bcVersion)  }  log.Info("Initialising Ethereum protocol", "network", config.NetworkId, "dbversion", dbVer)
  if !config.SkipBcVersionCheck {    if bcVersion != nil && *bcVersion > core.BlockChainVersion {      return nil, fmt.Errorf("database version is v%d, Geth %s only supports v%d", *bcVersion, params.VersionWithMeta, core.BlockChainVersion)    } else if bcVersion == nil || *bcVersion < core.BlockChainVersion {      log.Warn("Upgrade blockchain database version", "from", dbVer, "to", core.BlockChainVersion)      rawdb.WriteDatabaseVersion(chainDb, core.BlockChainVersion)    }  }  var (    vmConfig = vm.Config{      EnablePreimageRecording: config.EnablePreimageRecording,      EWASMInterpreter:        config.EWASMInterpreter,      EVMInterpreter:          config.EVMInterpreter,    }    cacheConfig = &core.CacheConfig{      TrieCleanLimit:      config.TrieCleanCache,      TrieCleanJournal:    stack.ResolvePath(config.TrieCleanCacheJournal),      TrieCleanRejournal:  config.TrieCleanCacheRejournal,      TrieCleanNoPrefetch: config.NoPrefetch,      TrieDirtyLimit:      config.TrieDirtyCache,      TrieDirtyDisabled:   config.NoPruning,      TrieTimeLimit:       config.TrieTimeout,      SnapshotLimit:       config.SnapshotCache,      Preimages:           config.Preimages,    }  )  eth.blockchain, err = core.NewBlockChain(chainDb, cacheConfig, chainConfig, eth.engine, vmConfig, eth.shouldPreserve, &config.TxLookupLimit)  if err != nil {    return nil, err  }  // Rewind the chain in case of an incompatible config upgrade.  if compat, ok := genesisErr.(*params.ConfigCompatError); ok {    log.Warn("Rewinding chain to upgrade configuration", "err", compat)    eth.blockchain.SetHead(compat.RewindTo)    rawdb.WriteChainConfig(chainDb, genesisHash, chainConfig)  }  eth.bloomIndexer.Start(eth.blockchain)
  if config.TxPool.Journal != "" {    config.TxPool.Journal = stack.ResolvePath(config.TxPool.Journal)  }  eth.txPool = core.NewTxPool(config.TxPool, chainConfig, eth.blockchain)
  // Permit the downloader to use the trie cache allowance during fast sync  cacheLimit := cacheConfig.TrieCleanLimit + cacheConfig.TrieDirtyLimit + cacheConfig.SnapshotLimit  checkpoint := config.Checkpoint  if checkpoint == nil {    checkpoint = params.TrustedCheckpoints[genesisHash]  }  if eth.handler, err = newHandler(&handlerConfig{    Database:   chainDb,    Chain:      eth.blockchain,    TxPool:     eth.txPool,    Network:    config.NetworkId,    Sync:       config.SyncMode,    BloomCache: uint64(cacheLimit),    EventMux:   eth.eventMux,    Checkpoint: checkpoint,    Whitelist:  config.Whitelist,  }); err != nil {    return nil, err  }  eth.miner = miner.New(eth, &config.Miner, chainConfig, eth.EventMux(), eth.engine, eth.isLocalBlock)  eth.miner.SetExtra(makeExtraData(config.Miner.ExtraData))
  eth.APIBackend = &EthAPIBackend{stack.Config().ExtRPCEnabled(), stack.Config().AllowUnprotectedTxs, eth, nil}  if eth.APIBackend.allowUnprotectedTxs {    log.Info("Unprotected transactions allowed")  }  gpoParams := config.GPO  if gpoParams.Default == nil {    gpoParams.Default = config.Miner.GasPrice  }  eth.APIBackend.gpo = gasprice.NewOracle(eth.APIBackend, gpoParams)
  eth.ethDialCandidates, err = setupDiscovery(eth.config.EthDiscoveryURLs)  if err != nil {    return nil, err  }  eth.snapDialCandidates, err = setupDiscovery(eth.config.SnapDiscoveryURLs)  if err != nil {    return nil, err  }  // Start the RPC service  eth.netRPCService = ethapi.NewPublicNetAPI(eth.p2pServer, config.NetworkId)
  // Register the backend on the node  stack.RegisterAPIs(eth.APIs())  stack.RegisterProtocols(eth.Protocols())  stack.RegisterLifecycle(eth)  // Check for unclean shutdown  if uncleanShutdowns, discards, err := rawdb.PushUncleanShutdownMarker(chainDb); err != nil {    log.Error("Could not update unclean-shutdown-marker list", "error", err)  } else {    if discards > 0 {      log.Warn("Old unclean shutdowns found", "count", discards)    }    for _, tstamp := range uncleanShutdowns {      t := time.Unix(int64(tstamp), 0)      log.Warn("Unclean shutdown detected", "booted", t,        "age", common.PrettyAge(t))    }  }  return eth, nil}

// filedir:go-ethereum-1.10.2coreblockchain.go L214// NewBlockChain returns a fully initialised block chain using information// available in the database. It initialises the default Ethereum Validator and// Processor.func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *params.ChainConfig, engine consensus.Engine, vmConfig vm.Config, shouldPreserve func(block *types.Block) bool, txLookupLimit *uint64) (*BlockChain, error) {  if cacheConfig == nil {    cacheConfig = defaultCacheConfig  }  bodyCache, _ := lru.New(bodyCacheLimit)  bodyRLPCache, _ := lru.New(bodyCacheLimit)  receiptsCache, _ := lru.New(receiptsCacheLimit)  blockCache, _ := lru.New(blockCacheLimit)  txLookupCache, _ := lru.New(txLookupCacheLimit)  futureBlocks, _ := lru.New(maxFutureBlocks)
  bc := &BlockChain{    chainConfig: chainConfig,    cacheConfig: cacheConfig,    db:          db,    triegc:      prque.New(nil),    stateCache: state.NewDatabaseWithConfig(db, &trie.Config{      Cache:     cacheConfig.TrieCleanLimit,      Journal:   cacheConfig.TrieCleanJournal,      Preimages: cacheConfig.Preimages,    }),    quit:           make(chan struct{}),    shouldPreserve: shouldPreserve,    bodyCache:      bodyCache,    bodyRLPCache:   bodyRLPCache,    receiptsCache:  receiptsCache,    blockCache:     blockCache,    txLookupCache:  txLookupCache,    futureBlocks:   futureBlocks,    engine:         engine,    vmConfig:       vmConfig,  }  bc.validator = NewBlockValidator(chainConfig, bc, engine)  bc.prefetcher = newStatePrefetcher(chainConfig, bc, engine)  bc.processor = NewStateProcessor(chainConfig, bc, engine)
  var err error  bc.hc, err = NewHeaderChain(db, chainConfig, engine, bc.insertStopped)  if err != nil {    return nil, err  }  bc.genesisBlock = bc.GetBlockByNumber(0)    if bc.genesisBlock == nil {    return nil, ErrNoGenesis  }
  var nilBlock *types.Block  bc.currentBlock.Store(nilBlock)  bc.currentFastBlock.Store(nilBlock)
  // Initialize the chain with ancient data if it isn't empty.  var txIndexBlock uint64
  if bc.empty() {    rawdb.InitDatabaseFromFreezer(bc.db)    // If ancient database is not empty, reconstruct all missing    // indices in the background.    frozen, _ := bc.db.Ancients()    if frozen > 0 {      txIndexBlock = frozen    }  }  if err := bc.loadLastState(); err != nil {    //加载最新的状态    return nil, err  }  // Make sure the state associated with the block is available  head := bc.CurrentBlock()  if _, err := state.New(head.Root(), bc.stateCache, bc.snaps); err != nil {    // Head state is missing, before the state recovery, find out the    // disk layer point of snapshot(if it's enabled). Make sure the    // rewound point is lower than disk layer.    var diskRoot common.Hash    if bc.cacheConfig.SnapshotLimit > 0 {      diskRoot = rawdb.ReadSnapshotRoot(bc.db)    }    if diskRoot != (common.Hash{}) {      log.Warn("Head state missing, repairing", "number", head.Number(), "hash", head.Hash(), "snaproot", diskRoot)
      snapDisk, err := bc.SetHeadBeyondRoot(head.NumberU64(), diskRoot)      if err != nil {        return nil, err      }      // Chain rewound, persist old snapshot number to indicate recovery procedure      if snapDisk != 0 {        rawdb.WriteSnapshotRecoveryNumber(bc.db, snapDisk)      }    } else {      log.Warn("Head state missing, repairing", "number", head.Number(), "hash", head.Hash())      if err := bc.SetHead(head.NumberU64()); err != nil {        return nil, err      }    }  }  // Ensure that a previous crash in SetHead doesn't leave extra ancients  if frozen, err := bc.db.Ancients(); err == nil && frozen > 0 {    var (      needRewind bool      low        uint64    )    // The head full block may be rolled back to a very low height due to    // blockchain repair. If the head full block is even lower than the ancient    // chain, truncate the ancient store.    fullBlock := bc.CurrentBlock()    if fullBlock != nil && fullBlock.Hash() != bc.genesisBlock.Hash() && fullBlock.NumberU64() < frozen-1 {      needRewind = true      low = fullBlock.NumberU64()    }    // In fast sync, it may happen that ancient data has been written to the    // ancient store, but the LastFastBlock has not been updated, truncate the    // extra data here.    fastBlock := bc.CurrentFastBlock()    if fastBlock != nil && fastBlock.NumberU64() < frozen-1 {      needRewind = true      if fastBlock.NumberU64() < low || low == 0 {        low = fastBlock.NumberU64()      }    }    if needRewind {      log.Error("Truncating ancient chain", "from", bc.CurrentHeader().Number.Uint64(), "to", low)      if err := bc.SetHead(low); err != nil {        return nil, err      }    }  }  // The first thing the node will do is reconstruct the verification data for  // the head block (ethash cache or clique voting snapshot). Might as well do  // it in advance.  bc.engine.VerifyHeader(bc, bc.CurrentHeader(), true)
  // 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 BadHashes {    if header := bc.GetHeaderByHash(hash); header != nil {      // get the canonical block corresponding to the offending header's number      headerByNumber := bc.GetHeaderByNumber(header.Number.Uint64())      // make sure the headerByNumber (if present) is in our current canonical chain      if headerByNumber != nil && headerByNumber.Hash() == header.Hash() {        log.Error("Found bad hash, rewinding chain", "number", header.Number, "hash", header.ParentHash)        if err := bc.SetHead(header.Number.Uint64() - 1); err != nil {          return nil, err        }        log.Error("Chain rewind was successful, resuming normal operation")      }    }  }  // Load any existing snapshot, regenerating it if loading failed  if bc.cacheConfig.SnapshotLimit > 0 {    // If the chain was rewound past the snapshot persistent layer (causing    // a recovery block number to be persisted to disk), check if we're still    // in recovery mode and in that case, don't invalidate the snapshot on a    // head mismatch.    var recover bool
    head := bc.CurrentBlock()    if layer := rawdb.ReadSnapshotRecoveryNumber(bc.db); layer != nil && *layer > head.NumberU64() {      log.Warn("Enabling snapshot recovery", "chainhead", head.NumberU64(), "diskbase", *layer)      recover = true    }    bc.snaps, _ = snapshot.New(bc.db, bc.stateCache.TrieDB(), bc.cacheConfig.SnapshotLimit, head.Root(), !bc.cacheConfig.SnapshotWait, true, recover)  }  // Take ownership of this particular state  go bc.update()  if txLookupLimit != nil {    bc.txLookupLimit = *txLookupLimit
    bc.wg.Add(1)    go bc.maintainTxIndex(txIndexBlock)  }  // If periodic cache journal is required, spin it up.  if bc.cacheConfig.TrieCleanRejournal > 0 {    if bc.cacheConfig.TrieCleanRejournal < time.Minute {      log.Warn("Sanitizing invalid trie cache journal time", "provided", bc.cacheConfig.TrieCleanRejournal, "updated", time.Minute)      bc.cacheConfig.TrieCleanRejournal = time.Minute    }    triedb := bc.stateCache.TrieDB()    bc.wg.Add(1)    go func() {      defer bc.wg.Done()      triedb.SaveCachePeriodically(bc.cacheConfig.TrieCleanJournal, bc.cacheConfig.TrieCleanRejournal, bc.quit)    }()  }  return bc, nil}

  bc.genesisBlock = bc.GetBlockByNumber(0)  if bc.genesisBlock == nil {    return nil, ErrNoGenesis  }

  if bc.empty() {    rawdb.InitDatabaseFromFreezer(bc.db)    // If ancient database is not empty, reconstruct all missing    // indices in the background.    frozen, _ := bc.db.Ancients()    if frozen > 0 {      txIndexBlock = frozen    }  }

// loadLastState loads the last known chain state from the database. This method// assumes that the chain manager mutex is held.func (bc *BlockChain) loadLastState() error {  // Restore the last known head block  head := rawdb.ReadHeadBlockHash(bc.db)  if head == (common.Hash{}) {    // Corrupt or empty database, init from scratch    log.Warn("Empty database, resetting chain")    return bc.Reset()  }  // Make sure the entire head block is available  currentBlock := bc.GetBlockByHash(head)  if currentBlock == nil {    // Corrupt or empty database, init from scratch    log.Warn("Head block missing, resetting chain", "hash", head)    return bc.Reset()  }  // Everything seems to be fine, set as the head block  bc.currentBlock.Store(currentBlock)  headBlockGauge.Update(int64(currentBlock.NumberU64()))
  // Restore the last known head header  currentHeader := currentBlock.Header()  if head := rawdb.ReadHeadHeaderHash(bc.db); head != (common.Hash{}) {    if header := bc.GetHeaderByHash(head); header != nil {      currentHeader = header    }  }  bc.hc.SetCurrentHeader(currentHeader)
  // Restore the last known head fast block  bc.currentFastBlock.Store(currentBlock)  headFastBlockGauge.Update(int64(currentBlock.NumberU64()))
  if head := rawdb.ReadHeadFastBlockHash(bc.db); head != (common.Hash{}) {    if block := bc.GetBlockByHash(head); block != nil {      bc.currentFastBlock.Store(block)      headFastBlockGauge.Update(int64(block.NumberU64()))    }  }  // Issue a status log for the user  currentFastBlock := bc.CurrentFastBlock()
  headerTd := bc.GetTd(currentHeader.Hash(), currentHeader.Number.Uint64())  blockTd := bc.GetTd(currentBlock.Hash(), currentBlock.NumberU64())  fastTd := bc.GetTd(currentFastBlock.Hash(), currentFastBlock.NumberU64())
  log.Info("Loaded most recent local header", "number", currentHeader.Number, "hash", currentHeader.Hash(), "td", headerTd, "age", common.PrettyAge(time.Unix(int64(currentHeader.Time), 0)))  log.Info("Loaded most recent local full block", "number", currentBlock.Number(), "hash", currentBlock.Hash(), "td", blockTd, "age", common.PrettyAge(time.Unix(int64(currentBlock.Time()), 0)))  log.Info("Loaded most recent local fast block", "number", currentFastBlock.Number(), "hash", currentFastBlock.Hash(), "td", fastTd, "age", common.PrettyAge(time.Unix(int64(currentFastBlock.Time()), 0)))  if pivot := rawdb.ReadLastPivotNumber(bc.db); pivot != nil {    log.Info("Loaded last fast-sync pivot marker", "number", *pivot)  }  return nil}

// filedir:go-ethereum-1.10.2coreblockchain.go  L476// SetHead rewinds the local chain to a new head. Depending on whether the node// was fast synced or full synced and in which state, the method will try to// delete minimal data from disk whilst retaining chain consistency.func (bc *BlockChain) SetHead(head uint64) error {  _, err := bc.SetHeadBeyondRoot(head, common.Hash{})  return err}
// SetHeadBeyondRoot rewinds the local chain to a new head with the extra condition// that the rewind must pass the specified state root. This method is meant to be// used when rewiding with snapshots enabled to ensure that we go back further than// persistent disk layer. Depending on whether the node was fast synced or full, and// in which state, the method will try to delete minimal data from disk whilst// retaining chain consistency.//// The method returns the block number where the requested root cap was found.func (bc *BlockChain) SetHeadBeyondRoot(head uint64, root common.Hash) (uint64, error) {  bc.chainmu.Lock()  defer bc.chainmu.Unlock()
  // Track the block number of the requested root hash  var rootNumber uint64 // (no root == always 0)
  // Retrieve the last pivot block to short circuit rollbacks beyond it and the  // current freezer limit to start nuking id underflown  pivot := rawdb.ReadLastPivotNumber(bc.db)  frozen, _ := bc.db.Ancients()
  updateFn := func(db ethdb.KeyValueWriter, header *types.Header) (uint64, bool) {    // Rewind the block chain, ensuring we don't end up with a stateless head    // block. Note, depth equality is permitted to allow using SetHead as a    // chain reparation mechanism without deleting any data!    if currentBlock := bc.CurrentBlock(); currentBlock != nil && header.Number.Uint64() <= currentBlock.NumberU64() {      newHeadBlock := bc.GetBlock(header.Hash(), header.Number.Uint64())      if newHeadBlock == nil {        log.Error("Gap in the chain, rewinding to genesis", "number", header.Number, "hash", header.Hash())        newHeadBlock = bc.genesisBlock      } else {        // Block exists, keep rewinding until we find one with state,        // keeping rewinding until we exceed the optional threshold        // root hash        beyondRoot := (root == common.Hash{}) // Flag whether we're beyond the requested root (no root, always true)
        for {          // If a root threshold was requested but not yet crossed, check          if root != (common.Hash{}) && !beyondRoot && newHeadBlock.Root() == root {            beyondRoot, rootNumber = true, newHeadBlock.NumberU64()          }          if _, err := state.New(newHeadBlock.Root(), bc.stateCache, bc.snaps); err != nil {            log.Trace("Block state missing, rewinding further", "number", newHeadBlock.NumberU64(), "hash", newHeadBlock.Hash())            if pivot == nil || newHeadBlock.NumberU64() > *pivot {              parent := bc.GetBlock(newHeadBlock.ParentHash(), newHeadBlock.NumberU64()-1)              if parent != nil {                newHeadBlock = parent                continue              }              log.Error("Missing block in the middle, aiming genesis", "number", newHeadBlock.NumberU64()-1, "hash", newHeadBlock.ParentHash())              newHeadBlock = bc.genesisBlock            } else {              log.Trace("Rewind passed pivot, aiming genesis", "number", newHeadBlock.NumberU64(), "hash", newHeadBlock.Hash(), "pivot", *pivot)              newHeadBlock = bc.genesisBlock            }          }          if beyondRoot || newHeadBlock.NumberU64() == 0 {            log.Debug("Rewound to block with state", "number", newHeadBlock.NumberU64(), "hash", newHeadBlock.Hash())            break          }          log.Debug("Skipping block with threshold state", "number", newHeadBlock.NumberU64(), "hash", newHeadBlock.Hash(), "root", newHeadBlock.Root())          newHeadBlock = bc.GetBlock(newHeadBlock.ParentHash(), newHeadBlock.NumberU64()-1) // Keep rewinding        }      }      rawdb.WriteHeadBlockHash(db, newHeadBlock.Hash())
      // 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 SetHead is from high      // to low, so it's safe the update in-memory markers directly.      bc.currentBlock.Store(newHeadBlock)      headBlockGauge.Update(int64(newHeadBlock.NumberU64()))    }    // Rewind the fast block in a simpleton way to the target head    if currentFastBlock := bc.CurrentFastBlock(); currentFastBlock != nil && header.Number.Uint64() < currentFastBlock.NumberU64() {      newHeadFastBlock := bc.GetBlock(header.Hash(), header.Number.Uint64())      // If either blocks reached nil, reset to the genesis state      if newHeadFastBlock == nil {        newHeadFastBlock = bc.genesisBlock      }      rawdb.WriteHeadFastBlockHash(db, newHeadFastBlock.Hash())
      // 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 SetHead is from high      // to low, so it's safe the update in-memory markers directly.      bc.currentFastBlock.Store(newHeadFastBlock)      headFastBlockGauge.Update(int64(newHeadFastBlock.NumberU64()))    }    head := bc.CurrentBlock().NumberU64()
    // If setHead underflown the freezer threshold and the block processing    // intent afterwards is full block importing, delete the chain segment    // between the stateful-block and the sethead target.    var wipe bool    if head+1 < frozen {      wipe = pivot == nil || head >= *pivot    }    return head, wipe // Only force wipe if full synced  }  // Rewind the header chain, deleting all block bodies until then  delFn := func(db ethdb.KeyValueWriter, hash common.Hash, num uint64) {    // Ignore the error here since light client won't hit this path    frozen, _ := bc.db.Ancients()    if num+1 <= frozen {      // Truncate all relative data(header, total difficulty, body, receipt      // and canonical hash) from ancient store.      if err := bc.db.TruncateAncients(num); err != nil {        log.Crit("Failed to truncate ancient data", "number", num, "err", err)      }      // Remove the hash <-> number mapping from the active store.      rawdb.DeleteHeaderNumber(db, hash)    } else {      // Remove relative body and receipts from the active store.      // The header, total difficulty and canonical hash will be      // removed in the hc.SetHead function.      rawdb.DeleteBody(db, hash, num)      rawdb.DeleteReceipts(db, hash, num)    }    // Todo(rjl493456442) txlookup, bloombits, etc  }  // If SetHead was only called as a chain reparation method, try to skip  // touching the header chain altogether, unless the freezer is broken  if block := bc.CurrentBlock(); block.NumberU64() == head {    if target, force := updateFn(bc.db, block.Header()); force {      bc.hc.SetHead(target, updateFn, delFn)    }  } else {    // Rewind the chain to the requested head and keep going backwards until a    // block with a state is found or fast sync pivot is passed    log.Warn("Rewinding blockchain", "target", head)    bc.hc.SetHead(head, updateFn, delFn)  }  // Clear out any stale content from the caches  bc.bodyCache.Purge()  bc.bodyRLPCache.Purge()  bc.receiptsCache.Purge()  bc.blockCache.Purge()  bc.txLookupCache.Purge()  bc.futureBlocks.Purge()
  return rootNumber, bc.loadLastState()}

// loadLastState loads the last known chain state from the database. This method// assumes that the chain manager mutex is held.func (bc *BlockChain) loadLastState() error {  // Restore the last known head block  head := rawdb.ReadHeadBlockHash(bc.db)  if head == (common.Hash{}) {    // Corrupt or empty database, init from scratch    log.Warn("Empty database, resetting chain")    return bc.Reset()  }  // Make sure the entire head block is available  currentBlock := bc.GetBlockByHash(head)  if currentBlock == nil {    // Corrupt or empty database, init from scratch    log.Warn("Head block missing, resetting chain", "hash", head)    return bc.Reset()  }  // Everything seems to be fine, set as the head block  bc.currentBlock.Store(currentBlock)  headBlockGauge.Update(int64(currentBlock.NumberU64()))
  // Restore the last known head header  currentHeader := currentBlock.Header()  if head := rawdb.ReadHeadHeaderHash(bc.db); head != (common.Hash{}) {    if header := bc.GetHeaderByHash(head); header != nil {      currentHeader = header    }  }  bc.hc.SetCurrentHeader(currentHeader)
  // Restore the last known head fast block  bc.currentFastBlock.Store(currentBlock)  headFastBlockGauge.Update(int64(currentBlock.NumberU64()))
  if head := rawdb.ReadHeadFastBlockHash(bc.db); head != (common.Hash{}) {    if block := bc.GetBlockByHash(head); block != nil {      bc.currentFastBlock.Store(block)      headFastBlockGauge.Update(int64(block.NumberU64()))    }  }  // Issue a status log for the user  currentFastBlock := bc.CurrentFastBlock()
  headerTd := bc.GetTd(currentHeader.Hash(), currentHeader.Number.Uint64())  blockTd := bc.GetTd(currentBlock.Hash(), currentBlock.NumberU64())  fastTd := bc.GetTd(currentFastBlock.Hash(), currentFastBlock.NumberU64())
  log.Info("Loaded most recent local header", "number", currentHeader.Number, "hash", currentHeader.Hash(), "td", headerTd, "age", common.PrettyAge(time.Unix(int64(currentHeader.Time), 0)))  log.Info("Loaded most recent local full block", "number", currentBlock.Number(), "hash", currentBlock.Hash(), "td", blockTd, "age", common.PrettyAge(time.Unix(int64(currentBlock.Time()), 0)))  log.Info("Loaded most recent local fast block", "number", currentFastBlock.Number(), "hash", currentFastBlock.Hash(), "td", fastTd, "age", common.PrettyAge(time.Unix(int64(currentFastBlock.Time()), 0)))  if pivot := rawdb.ReadLastPivotNumber(bc.db); pivot != nil {    log.Info("Loaded last fast-sync pivot marker", "number", *pivot)  }  return nil}

func NewBlockChain(db ethdb.Database, cacheConfig *CacheConfig, chainConfig *params.ChainConfig, engine consensus.Engine, vmConfig vm.Config, shouldPreserve func(block *types.Block) bool, txLookupLimit *uint64) (*BlockChain, error) {  if cacheConfig == nil {     ......  // Load any existing snapshot, regenerating it if loading failed  if bc.cacheConfig.SnapshotLimit > 0 {    // If the chain was rewound past the snapshot persistent layer (causing    // a recovery block number to be persisted to disk), check if we're still    // in recovery mode and in that case, don't invalidate the snapshot on a    // head mismatch.    var recover bool
    head := bc.CurrentBlock()    if layer := rawdb.ReadSnapshotRecoveryNumber(bc.db); layer != nil && *layer > head.NumberU64() {      log.Warn("Enabling snapshot recovery", "chainhead", head.NumberU64(), "diskbase", *layer)      recover = true    }    bc.snaps, _ = snapshot.New(bc.db, bc.stateCache.TrieDB(), bc.cacheConfig.SnapshotLimit, head.Root(), !bc.cacheConfig.SnapshotWait, true, recover)  }  // Take ownership of this particular state  go bc.update()  if txLookupLimit != nil {    bc.txLookupLimit = *txLookupLimit
    bc.wg.Add(1)    go bc.maintainTxIndex(txIndexBlock)  }  // If periodic cache journal is required, spin it up.  if bc.cacheConfig.TrieCleanRejournal > 0 {    if bc.cacheConfig.TrieCleanRejournal < time.Minute {      log.Warn("Sanitizing invalid trie cache journal time", "provided", bc.cacheConfig.TrieCleanRejournal, "updated", time.Minute)      bc.cacheConfig.TrieCleanRejournal = time.Minute    }    triedb := bc.stateCache.TrieDB()    bc.wg.Add(1)    go func() {      defer bc.wg.Done()      triedb.SaveCachePeriodically(bc.cacheConfig.TrieCleanJournal, bc.cacheConfig.TrieCleanRejournal, bc.quit)    }()  }  return bc, nil}

// Reset purges the entire blockchain, restoring it to its genesis state.func (bc *BlockChain) Reset() error {  return bc.ResetWithGenesisBlock(bc.genesisBlock)}
// ResetWithGenesisBlock purges the entire blockchain, restoring it to the// specified genesis state.func (bc *BlockChain) ResetWithGenesisBlock(genesis *types.Block) error {  // Dump the entire block chain and purge the caches  if err := bc.SetHead(0); err != nil {    return err  }  bc.chainmu.Lock()  defer bc.chainmu.Unlock()
  // Prepare the genesis block and reinitialise the chain  batch := bc.db.NewBatch()  rawdb.WriteTd(batch, genesis.Hash(), genesis.NumberU64(), genesis.Difficulty())  rawdb.WriteBlock(batch, genesis)  if err := batch.Write(); err != nil {    log.Crit("Failed to write genesis block", "err", err)  }  bc.writeHeadBlock(genesis)
  // Last update all in-memory chain markers  bc.genesisBlock = genesis  bc.currentBlock.Store(bc.genesisBlock)  headBlockGauge.Update(int64(bc.genesisBlock.NumberU64()))  bc.hc.SetGenesis(bc.genesisBlock.Header())  bc.hc.SetCurrentHeader(bc.genesisBlock.Header())  bc.currentFastBlock.Store(bc.genesisBlock)  headFastBlockGauge.Update(int64(bc.genesisBlock.NumberU64()))  return nil}

// filedir:go-ethereum-1.10.2coreblockchain.go  L1654// InsertChain attempts to insert the given batch of blocks in to the canonical// chain or, otherwise, create a fork. If an error is returned it will return// the index number of the failing block as well an error describing what went// wrong.//// After insertion is done, all accumulated events will be fired.func (bc *BlockChain) InsertChain(chain types.Blocks) (int, error) {  // Sanity check that we have something meaningful to import  if len(chain) == 0 {    return 0, nil  }
  bc.blockProcFeed.Send(true)  defer bc.blockProcFeed.Send(false)
  // Remove already known canon-blocks  var (    block, prev *types.Block  )  // Do a sanity check that the provided chain is actually ordered and linked  for i := 1; i < len(chain); i++ {    block = chain[i]    prev = chain[i-1]    if block.NumberU64() != prev.NumberU64()+1 || block.ParentHash() != prev.Hash() {      // Chain broke ancestry, log a message (programming error) and skip insertion      log.Error("Non contiguous block insert", "number", block.Number(), "hash", block.Hash(),        "parent", block.ParentHash(), "prevnumber", prev.Number(), "prevhash", prev.Hash())
      return 0, fmt.Errorf("non contiguous insert: item %d is #%d [%x…], item %d is #%d [%x…] (parent [%x…])", i-1, prev.NumberU64(),        prev.Hash().Bytes()[:4], i, block.NumberU64(), block.Hash().Bytes()[:4], block.ParentHash().Bytes()[:4])    }  }  // Pre-checks passed, start the full block imports  bc.wg.Add(1)  bc.chainmu.Lock()  n, err := bc.insertChain(chain, true)  bc.chainmu.Unlock()  bc.wg.Done()
  return n, err}

// filedir:go-ethereum-1.10.2coreblockchain.go L1696// insertChain is the internal implementation of InsertChain, which assumes that// 1) chains are contiguous, and 2) The chain mutex is held.//// This method is split out so that import batches that require re-injecting// historical blocks can do so without releasing the lock, which could lead to// racey behaviour. If a sidechain import is in progress, and the historic state// is imported, but then new canon-head is added before the actual sidechain// completes, then the historic state could be pruned againfunc (bc *BlockChain) insertChain(chain types.Blocks, verifySeals bool) (int, error) {  // If the chain is terminating, don't even bother starting up  if atomic.LoadInt32(&bc.procInterrupt) == 1 {    return 0, nil  }  // Start a parallel signature recovery (signer will fluke on fork transition, minimal perf loss)  senderCacher.recoverFromBlocks(types.MakeSigner(bc.chainConfig, chain[0].Number()), chain)
  var (    stats     = insertStats{startTime: mclock.Now()}    lastCanon *types.Block  )  // Fire a single chain head event if we've progressed the chain  defer func() {    if lastCanon != nil && bc.CurrentBlock().Hash() == lastCanon.Hash() {      bc.chainHeadFeed.Send(ChainHeadEvent{lastCanon})    }  }()  // Start the parallel header verifier  headers := make([]*types.Header, len(chain))  seals := make([]bool, len(chain))
  for i, block := range chain {    headers[i] = block.Header()    seals[i] = verifySeals  }  abort, results := bc.engine.VerifyHeaders(bc, headers, seals)  defer close(abort)
  // Peek the error for the first block to decide the directing import logic  it := newInsertIterator(chain, results, bc.validator)
  block, err := it.next()
  // Left-trim all the known blocks  if err == ErrKnownBlock {    // First block (and state) is known    //   1. We did a roll-back, and should now do a re-import    //   2. The block is stored as a sidechain, and is lying about it's stateroot, and passes a stateroot    //       from the canonical chain, which has not been verified.    // Skip all known blocks that are behind us    var (      current  = bc.CurrentBlock()      localTd  = bc.GetTd(current.Hash(), current.NumberU64())      externTd = bc.GetTd(block.ParentHash(), block.NumberU64()-1) // The first block can't be nil    )    for block != nil && err == ErrKnownBlock {      externTd = new(big.Int).Add(externTd, block.Difficulty())      if localTd.Cmp(externTd) < 0 {        break      }      log.Debug("Ignoring already known block", "number", block.Number(), "hash", block.Hash())      stats.ignored++
      block, err = it.next()    }    // The remaining blocks are still known blocks, the only scenario here is:    // During the fast sync, the pivot point is already submitted but rollback    // happens. Then node resets the head full block to a lower height via `rollback`    // and leaves a few known blocks in the database.    //    // When node runs a fast sync again, it can re-import a batch of known blocks via    // `insertChain` while a part of them have higher total difficulty than current    // head full block(new pivot point).    for block != nil && err == ErrKnownBlock {      log.Debug("Writing previously known block", "number", block.Number(), "hash", block.Hash())      if err := bc.writeKnownBlock(block); err != nil {        return it.index, err      }      lastCanon = block
      block, err = it.next()    }    // Falls through to the block import  }  switch {  // First block is pruned, insert as sidechain and reorg only if TD grows enough  case errors.Is(err, consensus.ErrPrunedAncestor):    log.Debug("Pruned ancestor, inserting as sidechain", "number", block.Number(), "hash", block.Hash())    return bc.insertSideChain(block, it)
  // First block is future, shove it (and all children) to the future queue (unknown ancestor)  case errors.Is(err, consensus.ErrFutureBlock) || (errors.Is(err, consensus.ErrUnknownAncestor) && bc.futureBlocks.Contains(it.first().ParentHash())):    for block != nil && (it.index == 0 || errors.Is(err, consensus.ErrUnknownAncestor)) {      log.Debug("Future block, postponing import", "number", block.Number(), "hash", block.Hash())      if err := bc.addFutureBlock(block); err != nil {        return it.index, err      }      block, err = it.next()    }    stats.queued += it.processed()    stats.ignored += it.remaining()
    // If there are any still remaining, mark as ignored    return it.index, err
  // Some other error occurred, abort  case err != nil:    bc.futureBlocks.Remove(block.Hash())    stats.ignored += len(it.chain)    bc.reportBlock(block, nil, err)    return it.index, err  }  // No validation errors for the first block (or chain prefix skipped)  var activeState *state.StateDB  defer func() {    // The chain importer is starting and stopping trie prefetchers. If a bad    // block or other error is hit however, an early return may not properly    // terminate the background threads. This defer ensures that we clean up    // and dangling prefetcher, without defering each and holding on live refs.    if activeState != nil {      activeState.StopPrefetcher()    }  }()
  for ; block != nil && err == nil || err == ErrKnownBlock; block, err = it.next() {    // If the chain is terminating, stop processing blocks    if bc.insertStopped() {      log.Debug("Abort during block processing")      break    }    // If the header is a banned one, straight out abort    if BadHashes[block.Hash()] {      bc.reportBlock(block, nil, ErrBlacklistedHash)      return it.index, ErrBlacklistedHash    }    // If the block is known (in the middle of the chain), it's a special case for    // Clique blocks where they can share state among each other, so importing an    // older block might complete the state of the subsequent one. In this case,    // just skip the block (we already validated it once fully (and crashed), since    // its header and body was already in the database).    if err == ErrKnownBlock {      logger := log.Debug      if bc.chainConfig.Clique == nil {        logger = log.Warn      }      logger("Inserted known block", "number", block.Number(), "hash", block.Hash(),        "uncles", len(block.Uncles()), "txs", len(block.Transactions()), "gas", block.GasUsed(),        "root", block.Root())
      // Special case. Commit the empty receipt slice if we meet the known      // block in the middle. It can only happen in the clique chain. Whenever      // we insert blocks via `insertSideChain`, we only commit `td`, `header`      // and `body` if it's non-existent. Since we don't have receipts without      // reexecution, so nothing to commit. But if the sidechain will be adpoted      // as the canonical chain eventually, it needs to be reexecuted for missing      // state, but if it's this special case here(skip reexecution) we will lose      // the empty receipt entry.      if len(block.Transactions()) == 0 {        rawdb.WriteReceipts(bc.db, block.Hash(), block.NumberU64(), nil)      } else {        log.Error("Please file an issue, skip known block execution without receipt",          "hash", block.Hash(), "number", block.NumberU64())      }      if err := bc.writeKnownBlock(block); err != nil {        return it.index, err      }      stats.processed++
      // We can assume that logs are empty here, since the only way for consecutive      // Clique blocks to have the same state is if there are no transactions.      lastCanon = block      continue    }    // Retrieve the parent block and it's state to execute on top    start := time.Now()
    parent := it.previous()    if parent == nil {      parent = bc.GetHeader(block.ParentHash(), block.NumberU64()-1)    }    statedb, err := state.New(parent.Root, bc.stateCache, bc.snaps)    if err != nil {      return it.index, err    }    // Enable prefetching to pull in trie node paths while processing transactions    statedb.StartPrefetcher("chain")    activeState = statedb
    // If we have a followup block, run that against the current state to pre-cache    // transactions and probabilistically some of the account/storage trie nodes.    var followupInterrupt uint32    if !bc.cacheConfig.TrieCleanNoPrefetch {      if followup, err := it.peek(); followup != nil && err == nil {        throwaway, _ := state.New(parent.Root, bc.stateCache, bc.snaps)
        go func(start time.Time, followup *types.Block, throwaway *state.StateDB, interrupt *uint32) {          bc.prefetcher.Prefetch(followup, throwaway, bc.vmConfig, &followupInterrupt)
          blockPrefetchExecuteTimer.Update(time.Since(start))          if atomic.LoadUint32(interrupt) == 1 {            blockPrefetchInterruptMeter.Mark(1)          }        }(time.Now(), followup, throwaway, &followupInterrupt)      }    }    // Process block using the parent state as reference point    substart := time.Now()    receipts, logs, usedGas, err := bc.processor.Process(block, statedb, bc.vmConfig)    if err != nil {      bc.reportBlock(block, receipts, err)      atomic.StoreUint32(&followupInterrupt, 1)      return it.index, err    }    // Update the metrics touched during block processing    accountReadTimer.Update(statedb.AccountReads)                 // Account reads are complete, we can mark them    storageReadTimer.Update(statedb.StorageReads)                 // Storage reads are complete, we can mark them    accountUpdateTimer.Update(statedb.AccountUpdates)             // Account updates are complete, we can mark them    storageUpdateTimer.Update(statedb.StorageUpdates)             // Storage updates are complete, we can mark them    snapshotAccountReadTimer.Update(statedb.SnapshotAccountReads) // Account reads are complete, we can mark them    snapshotStorageReadTimer.Update(statedb.SnapshotStorageReads) // Storage reads are complete, we can mark them    triehash := statedb.AccountHashes + statedb.StorageHashes     // Save to not double count in validation    trieproc := statedb.SnapshotAccountReads + statedb.AccountReads + statedb.AccountUpdates    trieproc += statedb.SnapshotStorageReads + statedb.StorageReads + statedb.StorageUpdates
    blockExecutionTimer.Update(time.Since(substart) - trieproc - triehash)
    // Validate the state using the default validator    substart = time.Now()    if err := bc.validator.ValidateState(block, statedb, receipts, usedGas); err != nil {      bc.reportBlock(block, receipts, err)      atomic.StoreUint32(&followupInterrupt, 1)      return it.index, err    }    proctime := time.Since(start)
    // Update the metrics touched during block validation    accountHashTimer.Update(statedb.AccountHashes) // Account hashes are complete, we can mark them    storageHashTimer.Update(statedb.StorageHashes) // Storage hashes are complete, we can mark them
    blockValidationTimer.Update(time.Since(substart) - (statedb.AccountHashes + statedb.StorageHashes - triehash))
    // Write the block to the chain and get the status.    substart = time.Now()    status, err := bc.writeBlockWithState(block, receipts, logs, statedb, false)    atomic.StoreUint32(&followupInterrupt, 1)    if err != nil {      return it.index, err    }    // Update the metrics touched during block commit    accountCommitTimer.Update(statedb.AccountCommits)   // Account commits are complete, we can mark them    storageCommitTimer.Update(statedb.StorageCommits)   // Storage commits are complete, we can mark them    snapshotCommitTimer.Update(statedb.SnapshotCommits) // Snapshot commits are complete, we can mark them
    blockWriteTimer.Update(time.Since(substart) - statedb.AccountCommits - statedb.StorageCommits - statedb.SnapshotCommits)    blockInsertTimer.UpdateSince(start)
    switch status {    case CanonStatTy:      log.Debug("Inserted new block", "number", block.Number(), "hash", block.Hash(),        "uncles", len(block.Uncles()), "txs", len(block.Transactions()), "gas", block.GasUsed(),        "elapsed", common.PrettyDuration(time.Since(start)),        "root", block.Root())
      lastCanon = block
      // Only count canonical blocks for GC processing time      bc.gcproc += proctime
    case SideStatTy:      log.Debug("Inserted forked block", "number", block.Number(), "hash", block.Hash(),        "diff", block.Difficulty(), "elapsed", common.PrettyDuration(time.Since(start)),        "txs", len(block.Transactions()), "gas", block.GasUsed(), "uncles", len(block.Uncles()),        "root", block.Root())
    default:      // This in theory is impossible, but lets be nice to our future selves and leave      // a log, instead of trying to track down blocks imports that don't emit logs.      log.Warn("Inserted block with unknown status", "number", block.Number(), "hash", block.Hash(),        "diff", block.Difficulty(), "elapsed", common.PrettyDuration(time.Since(start)),        "txs", len(block.Transactions()), "gas", block.GasUsed(), "uncles", len(block.Uncles()),        "root", block.Root())    }    stats.processed++    stats.usedGas += usedGas
    dirty, _ := bc.stateCache.TrieDB().Size()    stats.report(chain, it.index, dirty)  }  // Any blocks remaining here? The only ones we care about are the future ones  if block != nil && errors.Is(err, consensus.ErrFutureBlock) {    if err := bc.addFutureBlock(block); err != nil {      return it.index, err    }    block, err = it.next()
    for ; block != nil && errors.Is(err, consensus.ErrUnknownAncestor); block, err = it.next() {      if err := bc.addFutureBlock(block); err != nil {        return it.index, err      }      stats.queued++    }  }  stats.ignored += it.remaining()
  return it.index, err}

  // If the chain is terminating, don't even bother starting up  if atomic.LoadInt32(&bc.procInterrupt) == 1 {    return 0, nil  }

  // Start the parallel header verifier  headers := make([]*types.Header, len(chain))  seals := make([]bool, len(chain))
  for i, block := range chain {    headers[i] = block.Header()    seals[i] = verifySeals  }  abort, results := bc.engine.VerifyHeaders(bc, headers, seals)  defer close(abort)

  // Peek the error for the first block to decide the directing import logic  it := newInsertIterator(chain, results, bc.validator)
  block, err := it.next()

  // Left-trim all the known blocks  if err == ErrKnownBlock {    // First block (and state) is known    //   1. We did a roll-back, and should now do a re-import    //   2. The block is stored as a sidechain, and is lying about it's stateroot, and passes a stateroot    //       from the canonical chain, which has not been verified.    // Skip all known blocks that are behind us    var (      current  = bc.CurrentBlock()      localTd  = bc.GetTd(current.Hash(), current.NumberU64())      externTd = bc.GetTd(block.ParentHash(), block.NumberU64()-1) // The first block can't be nil    )    for block != nil && err == ErrKnownBlock {      externTd = new(big.Int).Add(externTd, block.Difficulty())      if localTd.Cmp(externTd) < 0 {        break      }      log.Debug("Ignoring already known block", "number", block.Number(), "hash", block.Hash())      stats.ignored++
      block, err = it.next()    }    // The remaining blocks are still known blocks, the only scenario here is:    // During the fast sync, the pivot point is already submitted but rollback    // happens. Then node resets the head full block to a lower height via `rollback`    // and leaves a few known blocks in the database.    //    // When node runs a fast sync again, it can re-import a batch of known blocks via    // `insertChain` while a part of them have higher total difficulty than current    // head full block(new pivot point).    for block != nil && err == ErrKnownBlock {      log.Debug("Writing previously known block", "number", block.Number(), "hash", block.Hash())      if err := bc.writeKnownBlock(block); err != nil {        return it.index, err      }      lastCanon = block
      block, err = it.next()    }    // Falls through to the block import  }

  switch {  // First block is pruned, insert as sidechain and reorg only if TD grows enough  case errors.Is(err, consensus.ErrPrunedAncestor):    log.Debug("Pruned ancestor, inserting as sidechain", "number", block.Number(), "hash", block.Hash())    return bc.insertSideChain(block, it)
  // First block is future, shove it (and all children) to the future queue (unknown ancestor)  case errors.Is(err, consensus.ErrFutureBlock) || (errors.Is(err, consensus.ErrUnknownAncestor) && bc.futureBlocks.Contains(it.first().ParentHash())):    for block != nil && (it.index == 0 || errors.Is(err, consensus.ErrUnknownAncestor)) {      log.Debug("Future block, postponing import", "number", block.Number(), "hash", block.Hash())      if err := bc.addFutureBlock(block); err != nil {        return it.index, err      }      block, err = it.next()    }    stats.queued += it.processed()    stats.ignored += it.remaining()
    // If there are any still remaining, mark as ignored    return it.index, err
  // Some other error occurred, abort  case err != nil:    bc.futureBlocks.Remove(block.Hash())    stats.ignored += len(it.chain)    bc.reportBlock(block, nil, err)    return it.index, err  }

  for ; block != nil && err == nil || err == ErrKnownBlock; block, err = it.next() {    // If the chain is terminating, stop processing blocks    if bc.insertStopped() {      log.Debug("Abort during block processing")      break    }    // If the header is a banned one, straight out abort    if BadHashes[block.Hash()] {      bc.reportBlock(block, nil, ErrBlacklistedHash)      return it.index, ErrBlacklistedHash    }    // If the block is known (in the middle of the chain), it's a special case for    // Clique blocks where they can share state among each other, so importing an    // older block might complete the state of the subsequent one. In this case,    // just skip the block (we already validated it once fully (and crashed), since    // its header and body was already in the database).    if err == ErrKnownBlock {      logger := log.Debug      if bc.chainConfig.Clique == nil {        logger = log.Warn      }      logger("Inserted known block", "number", block.Number(), "hash", block.Hash(),        "uncles", len(block.Uncles()), "txs", len(block.Transactions()), "gas", block.GasUsed(),        "root", block.Root())
      // Special case. Commit the empty receipt slice if we meet the known      // block in the middle. It can only happen in the clique chain. Whenever      // we insert blocks via `insertSideChain`, we only commit `td`, `header`      // and `body` if it's non-existent. Since we don't have receipts without      // reexecution, so nothing to commit. But if the sidechain will be adpoted      // as the canonical chain eventually, it needs to be reexecuted for missing      // state, but if it's this special case here(skip reexecution) we will lose      // the empty receipt entry.      if len(block.Transactions()) == 0 {        rawdb.WriteReceipts(bc.db, block.Hash(), block.NumberU64(), nil)      } else {        log.Error("Please file an issue, skip known block execution without receipt",          "hash", block.Hash(), "number", block.NumberU64())      }      if err := bc.writeKnownBlock(block); err != nil {        return it.index, err      }      stats.processed++
      // We can assume that logs are empty here, since the only way for consecutive      // Clique blocks to have the same state is if there are no transactions.      lastCanon = block      continue    }    ......  }

    // Retrieve the parent block and it's state to execute on top    start := time.Now()
    parent := it.previous()    if parent == nil {      parent = bc.GetHeader(block.ParentHash(), block.uNmberU64()-1)    }    statedb, err := state.New(parent.Root, bc.stateCache, bc.snaps)    if err != nil {      return it.index, err    }    // Enable prefetching to pull in trie node paths while processing transactions    statedb.StartPrefetcher("chain")    activeState = statedb
    // If we have a followup block, run that against the current state to pre-cache    // transactions and probabilistically some of the account/storage trie nodes.    var followupInterrupt uint32    if !bc.cacheConfig.TrieCleanNoPrefetch {      if followup, err := it.peek(); followup != nil && err == nil {        throwaway, _ := state.New(parent.Root, bc.stateCache, bc.snaps)
        go func(start time.Time, followup *types.Block, throwaway *state.StateDB, interrupt *uint32) {          bc.prefetcher.Prefetch(followup, throwaway, bc.vmConfig, &followupInterrupt)
          blockPrefetchExecuteTimer.Update(time.Since(start))          if atomic.LoadUint32(interrupt) == 1 {            blockPrefetchInterruptMeter.Mark(1)          }        }(time.Now(), followup, throwaway, &followupInterrupt)      }    }    // Process block using the parent state as reference point    substart := time.Now()    receipts, logs, usedGas, err := bc.processor.Process(block, statedb, bc.vmConfig)    if err != nil {      bc.reportBlock(block, receipts, err)      atomic.StoreUint32(&followupInterrupt, 1)      return it.index, err    }    // Update the metrics touched during block processing    accountReadTimer.Update(statedb.AccountReads)                 // Account reads are complete, we can mark them    storageReadTimer.Update(statedb.StorageReads)                 // Storage reads are complete, we can mark them    accountUpdateTimer.Update(statedb.AccountUpdates)             // Account updates are complete, we can mark them    storageUpdateTimer.Update(statedb.StorageUpdates)             // Storage updates are complete, we can mark them    snapshotAccountReadTimer.Update(statedb.SnapshotAccountReads) // Account reads are complete, we can mark them    snapshotStorageReadTimer.Update(statedb.SnapshotStorageReads) // Storage reads are complete, we can mark them    triehash := statedb.AccountHashes + statedb.StorageHashes     // Save to not double count in validation    trieproc := statedb.SnapshotAccountReads + statedb.AccountReads + statedb.AccountUpdates    trieproc += statedb.SnapshotStorageReads + statedb.StorageReads + statedb.StorageUpdates
    blockExecutionTimer.Update(time.Since(substart) - trieproc - triehash)
    // Validate the state using the default validator    substart = time.Now()    if err := bc.validator.ValidateState(block, statedb, receipts, usedGas); err != nil {      bc.reportBlock(block, receipts, err)      atomic.StoreUint32(&followupInterrupt, 1)      return it.index, err    }    proctime := time.Since(start)

// filedir:go-ethereum-1.10.2corestate_processor.go  L50
// Process processes the state changes according to the Ethereum rules by running// the transaction messages using the statedb and applying any rewards to both// the processor (coinbase) and any included uncles.//// Process returns the receipts and logs accumulated during the process and// returns the amount of gas that was used in the process. If any of the// transactions failed to execute due to insufficient gas it will return an error.func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB, cfg vm.Config) (types.Receipts, []*types.Log, uint64, error) {  var (    receipts types.Receipts    usedGas  = new(uint64)    header   = block.Header()    allLogs  []*types.Log    gp       = new(GasPool).AddGas(block.GasLimit())  )  // Mutate the block and state according to any hard-fork specs  if p.config.DAOForkSupport && p.config.DAOForkBlock != nil && p.config.DAOForkBlock.Cmp(block.Number()) == 0 {    misc.ApplyDAOHardFork(statedb)  }  blockContext := NewEVMBlockContext(header, p.bc, nil)  vmenv := vm.NewEVM(blockContext, vm.TxContext{}, statedb, p.config, cfg)  // Iterate over and process the individual transactions  for i, tx := range block.Transactions() {    msg, err := tx.AsMessage(types.MakeSigner(p.config, header.Number))    if err != nil {      return nil, nil, 0, err    }    statedb.Prepare(tx.Hash(), block.Hash(), i)    receipt, err := applyTransaction(msg, p.config, p.bc, nil, gp, statedb, header, tx, usedGas, vmenv)    if err != nil {      return nil, nil, 0, fmt.Errorf("could not apply tx %d [%v]: %w", i, tx.Hash().Hex(), err)    }    receipts = append(receipts, receipt)    allLogs = append(allLogs, receipt.Logs...)  }  // Finalize the block, applying any consensus engine specific extras (e.g. block rewards)  p.engine.Finalize(p.bc, header, statedb, block.Transactions(), block.Uncles())
  return receipts, allLogs, *usedGas, nil}

    // Update the metrics touched during block validation    accountHashTimer.Update(statedb.AccountHashes) // Account hashes are complete, we can mark them    storageHashTimer.Update(statedb.StorageHashes) // Storage hashes are complete, we can mark them
    blockValidationTimer.Update(time.Since(substart) - (statedb.AccountHashes + statedb.StorageHashes - triehash))
    // Write the block to the chain and get the status.    substart = time.Now()    status, err := bc.writeBlockWithState(block, receipts, logs, statedb, false)    atomic.StoreUint32(&followupInterrupt, 1)    if err != nil {      return it.index, err    }    // Update the metrics touched during block commit    accountCommitTimer.Update(statedb.AccountCommits)   // Account commits are complete, we can mark them    storageCommitTimer.Update(statedb.StorageCommits)   // Storage commits are complete, we can mark them    snapshotCommitTimer.Update(statedb.SnapshotCommits) // Snapshot commits are complete, we can mark them
    blockWriteTimer.Update(time.Since(substart) - statedb.AccountCommits - statedb.StorageCommits - statedb.SnapshotCommits)    blockInsertTimer.UpdateSince(start)    switch status {    case CanonStatTy:      log.Debug("Inserted new block", "number", block.Number(), "hash", block.Hash(),        "uncles", len(block.Uncles()), "txs", len(block.Transactions()), "gas", block.GasUsed(),        "elapsed", common.PrettyDuration(time.Since(start)),        "root", block.Root())
      lastCanon = block
      // Only count canonical blocks for GC processing time      bc.gcproc += proctime
    case SideStatTy:      log.Debug("Inserted forked block", "number", block.Number(), "hash", block.Hash(),        "diff", block.Difficulty(), "elapsed", common.PrettyDuration(time.Since(start)),        "txs", len(block.Transactions()), "gas", block.GasUsed(), "uncles", len(block.Uncles()),        "root", block.Root())
    default:      // This in theory is impossible, but lets be nice to our future selves and leave      // a log, instead of trying to track down blocks imports that don't emit logs.      log.Warn("Inserted block with unknown status", "number", block.Number(), "hash", block.Hash(),        "diff", block.Difficulty(), "elapsed", common.PrettyDuration(time.Since(start)),        "txs", len(block.Transactions()), "gas", block.GasUsed(), "uncles", len(block.Uncles()),        "root", block.Root())    }    stats.processed++    stats.usedGas += usedGas
    dirty, _ := bc.stateCache.TrieDB().Size()    stats.report(chain, it.index, dirty)  }  ......

// filedir:go-ethereum-1.10.2coreblockchain.go L1500// writeBlockWithState writes the block and all associated state to the database,// but is expects the chain mutex to be held.func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.Receipt, logs []*types.Log, state *state.StateDB, emitHeadEvent bool) (status WriteStatus, err error) {  bc.wg.Add(1)  defer bc.wg.Done()
  // Calculate the total difficulty of the block  ptd := bc.GetTd(block.ParentHash(), block.NumberU64()-1)  if ptd == nil {    return NonStatTy, consensus.ErrUnknownAncestor  }  // Make sure no inconsistent state is leaked during insertion  currentBlock := bc.CurrentBlock()  localTd := bc.GetTd(currentBlock.Hash(), currentBlock.NumberU64())  externTd := new(big.Int).Add(block.Difficulty(), ptd)
  // Irrelevant of the canonical status, write the block itself to the database.  //  // Note all the components of block(td, hash->number map, header, body, receipts)  // should be written atomically. BlockBatch is used for containing all components.  blockBatch := bc.db.NewBatch()  rawdb.WriteTd(blockBatch, block.Hash(), block.NumberU64(), externTd)  rawdb.WriteBlock(blockBatch, block)  rawdb.WriteReceipts(blockBatch, block.Hash(), block.NumberU64(), receipts)  rawdb.WritePreimages(blockBatch, state.Preimages())  if err := blockBatch.Write(); err != nil {    log.Crit("Failed to write block into disk", "err", err)  }  // Commit all cached state changes into underlying memory database.  root, err := state.Commit(bc.chainConfig.IsEIP158(block.Number()))  if err != nil {    return NonStatTy, err  }  triedb := bc.stateCache.TrieDB()
  // If we're running an archive node, always flush  if bc.cacheConfig.TrieDirtyDisabled {    if err := triedb.Commit(root, false, nil); err != nil {      return NonStatTy, err    }  } else {    // Full but not archive node, do proper garbage collection    triedb.Reference(root, common.Hash{}) // metadata reference to keep trie alive    bc.triegc.Push(root, -int64(block.NumberU64()))
    if current := block.NumberU64(); current > TriesInMemory {      // If we exceeded our memory allowance, flush matured singleton nodes to disk      var (        nodes, imgs = triedb.Size()        limit       = common.StorageSize(bc.cacheConfig.TrieDirtyLimit) * 1024 * 1024      )      if nodes > limit || imgs > 4*1024*1024 {        triedb.Cap(limit - ethdb.IdealBatchSize)      }      // Find the next state trie we need to commit      chosen := current - TriesInMemory
      // If we exceeded out time allowance, flush an entire trie to disk      if bc.gcproc > bc.cacheConfig.TrieTimeLimit {        // If the header is missing (canonical chain behind), we're reorging a low        // diff sidechain. Suspend committing until this operation is completed.        header := bc.GetHeaderByNumber(chosen)        if header == nil {          log.Warn("Reorg in progress, trie commit postponed", "number", chosen)        } else {          // If we're exceeding limits but haven't reached a large enough memory gap,          // warn the user that the system is becoming unstable.          if chosen < lastWrite+TriesInMemory && bc.gcproc >= 2*bc.cacheConfig.TrieTimeLimit {            log.Info("State in memory for too long, committing", "time", bc.gcproc, "allowance", bc.cacheConfig.TrieTimeLimit, "optimum", float64(chosen-lastWrite)/TriesInMemory)          }          // Flush an entire trie and restart the counters          triedb.Commit(header.Root, true, nil)          lastWrite = chosen          bc.gcproc = 0        }      }      // Garbage collect anything below our required write retention      for !bc.triegc.Empty() {        root, number := bc.triegc.Pop()        if uint64(-number) > chosen {          bc.triegc.Push(root, number)          break        }        triedb.Dereference(root.(common.Hash))      }    }  }  // 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 := externTd.Cmp(localTd) > 0  currentBlock = bc.CurrentBlock()  if !reorg && externTd.Cmp(localTd) == 0 {    // Split same-difficulty blocks by number, then preferentially select    // the block generated by the local miner as the canonical block.    if block.NumberU64() < currentBlock.NumberU64() {      reorg = true    } else if block.NumberU64() == currentBlock.NumberU64() {      var currentPreserve, blockPreserve bool      if bc.shouldPreserve != nil {        currentPreserve, blockPreserve = bc.shouldPreserve(currentBlock), bc.shouldPreserve(block)      }      reorg = !currentPreserve && (blockPreserve || mrand.Float64() < 0.5)    }  }  if reorg {    // Reorganise the chain if the parent is not the head block    if block.ParentHash() != currentBlock.Hash() {      if err := bc.reorg(currentBlock, block); err != nil {        return NonStatTy, err      }    }    status = CanonStatTy  } else {    status = SideStatTy  }  // Set new head.  if status == CanonStatTy {    bc.writeHeadBlock(block)  }  bc.futureBlocks.Remove(block.Hash())
  if status == CanonStatTy {    bc.chainFeed.Send(ChainEvent{Block: block, Hash: block.Hash(), Logs: logs})    if len(logs) > 0 {      bc.logsFeed.Send(logs)    }    // In theory we should fire a ChainHeadEvent when we inject    // a canonical block, but sometimes we can insert a batch of    // canonicial blocks. Avoid firing too much ChainHeadEvents,    // we will fire an accumulated ChainHeadEvent and disable fire    // event here.    if emitHeadEvent {      bc.chainHeadFeed.Send(ChainHeadEvent{Block: block})    }  } else {    bc.chainSideFeed.Send(ChainSideEvent{Block: block})  }  return status, nil}

  // Any blocks remaining here? The only ones we care about are the future ones  if block != nil && errors.Is(err, consensus.ErrFutureBlock) {    if err := bc.addFutureBlock(block); err != nil {      return it.index, err    }    block, err = it.next()
    for ; block != nil && errors.Is(err, consensus.ErrUnknownAncestor); block, err = it.next() {      if err := bc.addFutureBlock(block); err != nil {        return it.index, err      }      stats.queued++    }  }  stats.ignored += it.remaining()
  return it.index, err}

// filedir:go-ethereum-1.10.2coreblockchain.go L2124// reorg takes two blocks, an old chain and a new chain and will reconstruct the// blocks and inserts them to be part of the new canonical chain and accumulates// potential missing transactions and post an event about them.func (bc *BlockChain) reorg(oldBlock, newBlock *types.Block) error {  var (    newChain    types.Blocks    oldChain    types.Blocks    commonBlock *types.Block
    deletedTxs types.Transactions    addedTxs   types.Transactions
    deletedLogs [][]*types.Log    rebirthLogs [][]*types.Log
    // collectLogs collects the logs that were generated or removed during    // the processing of the block that corresponds with the given hash.    // These logs are later announced as deleted or reborn    collectLogs = func(hash common.Hash, removed bool) {      number := bc.hc.GetBlockNumber(hash)      if number == nil {        return      }      receipts := rawdb.ReadReceipts(bc.db, hash, *number, bc.chainConfig)
      var logs []*types.Log      for _, receipt := range receipts {        for _, log := range receipt.Logs {          l := *log          if removed {            l.Removed = true          } else {          }          logs = append(logs, &l)        }      }      if len(logs) > 0 {        if removed {          deletedLogs = append(deletedLogs, logs)        } else {          rebirthLogs = append(rebirthLogs, logs)        }      }    }    // mergeLogs returns a merged log slice with specified sort order.    mergeLogs = func(logs [][]*types.Log, reverse bool) []*types.Log {      var ret []*types.Log      if reverse {        for i := len(logs) - 1; i >= 0; i-- {          ret = append(ret, logs[i]...)        }      } else {        for i := 0; i < len(logs); i++ {          ret = append(ret, logs[i]...)        }      }      return ret    }  )  // Reduce the longer chain to the same number as the shorter one  if oldBlock.NumberU64() > newBlock.NumberU64() {    // Old chain is longer, gather all transactions and logs as deleted ones    for ; oldBlock != nil && oldBlock.NumberU64() != newBlock.NumberU64(); oldBlock = bc.GetBlock(oldBlock.ParentHash(), oldBlock.NumberU64()-1) {      oldChain = append(oldChain, oldBlock)      deletedTxs = append(deletedTxs, oldBlock.Transactions()...)      collectLogs(oldBlock.Hash(), true)    }  } else {    // New chain is longer, stash all blocks away for subsequent insertion    for ; newBlock != nil && newBlock.NumberU64() != oldBlock.NumberU64(); newBlock = bc.GetBlock(newBlock.ParentHash(), newBlock.NumberU64()-1) {      newChain = append(newChain, newBlock)    }  }  if oldBlock == nil {    return fmt.Errorf("invalid old chain")  }  if newBlock == nil {    return fmt.Errorf("invalid new chain")  }  // Both sides of the reorg are at the same number, reduce both until the common  // ancestor is found  for {    // If the common ancestor was found, bail out    if oldBlock.Hash() == newBlock.Hash() {      commonBlock = oldBlock      break    }    // Remove an old block as well as stash away a new block    oldChain = append(oldChain, oldBlock)    deletedTxs = append(deletedTxs, oldBlock.Transactions()...)    collectLogs(oldBlock.Hash(), true)
    newChain = append(newChain, newBlock)
    // Step back with both chains    oldBlock = bc.GetBlock(oldBlock.ParentHash(), oldBlock.NumberU64()-1)    if oldBlock == nil {      return fmt.Errorf("invalid old chain")    }    newBlock = bc.GetBlock(newBlock.ParentHash(), newBlock.NumberU64()-1)    if newBlock == nil {      return fmt.Errorf("invalid new chain")    }  }  // Ensure the user sees large reorgs  if len(oldChain) > 0 && len(newChain) > 0 {    logFn := log.Info    msg := "Chain reorg detected"    if len(oldChain) > 63 {      msg = "Large chain reorg detected"      logFn = log.Warn    }    logFn(msg, "number", commonBlock.Number(), "hash", commonBlock.Hash(),      "drop", len(oldChain), "dropfrom", oldChain[0].Hash(), "add", len(newChain), "addfrom", newChain[0].Hash())    blockReorgAddMeter.Mark(int64(len(newChain)))    blockReorgDropMeter.Mark(int64(len(oldChain)))    blockReorgMeter.Mark(1)  } else {    log.Error("Impossible reorg, please file an issue", "oldnum", oldBlock.Number(), "oldhash", oldBlock.Hash(), "newnum", newBlock.Number(), "newhash", newBlock.Hash())  }  // Insert the new chain(except the head block(reverse order)),  // taking care of the proper incremental order.  for i := len(newChain) - 1; i >= 1; i-- {    // Insert the block in the canonical way, re-writing history    bc.writeHeadBlock(newChain[i])
    // Collect reborn logs due to chain reorg    collectLogs(newChain[i].Hash(), false)
    // Collect the new added transactions.    addedTxs = append(addedTxs, newChain[i].Transactions()...)  }  // Delete useless indexes right now which includes the non-canonical  // transaction indexes, canonical chain indexes which above the head.  indexesBatch := bc.db.NewBatch()  for _, tx := range types.TxDifference(deletedTxs, addedTxs) {    rawdb.DeleteTxLookupEntry(indexesBatch, tx.Hash())  }  // Delete any canonical number assignments above the new head  number := bc.CurrentBlock().NumberU64()  for i := number + 1; ; i++ {    hash := rawdb.ReadCanonicalHash(bc.db, i)    if hash == (common.Hash{}) {      break    }    rawdb.DeleteCanonicalHash(indexesBatch, i)  }  if err := indexesBatch.Write(); err != nil {    log.Crit("Failed to delete useless indexes", "err", err)  }  // If any logs need to be fired, do it now. In theory we could avoid creating  // this goroutine if there are no events to fire, but realistcally that only  // ever happens if we're reorging empty blocks, which will only happen on idle  // networks where performance is not an issue either way.  if len(deletedLogs) > 0 {    bc.rmLogsFeed.Send(RemovedLogsEvent{mergeLogs(deletedLogs, true)})  }  if len(rebirthLogs) > 0 {    bc.logsFeed.Send(mergeLogs(rebirthLogs, false))  }  if len(oldChain) > 0 {    for i := len(oldChain) - 1; i >= 0; i-- {      bc.chainSideFeed.Send(ChainSideEvent{Block: oldChain[i]})    }  }  return nil}