從命令列開始解析生成創世塊原始碼
阿新 • • 發佈:2018-11-28
建立創世塊的程式碼解析
在cmd的geth目錄下的main.go中
init函式先於main函式執行,做命令的初始化,其中比較重要的有三個地方,app.Action=geth,app.Commands中consoleCommand,以及App.Before指向的匿名函式
func init() { // Initialize the CLI app and start Geth app.Action = geth app.HideVersion = true // we have a command to print the version app.Copyright = "Copyright 2013-2018 The go-ethereum Authors" app.Commands = []cli.Command{ // See chaincmd.go: initCommand, importCommand, exportCommand, importPreimagesCommand, exportPreimagesCommand, copydbCommand, removedbCommand, dumpCommand, // See monitorcmd.go: monitorCommand, // See accountcmd.go: accountCommand, walletCommand, // See consolecmd.go: consoleCommand, attachCommand, javascriptCommand, // See misccmd.go: makecacheCommand, makedagCommand, versionCommand, bugCommand, licenseCommand, // See config.go dumpConfigCommand, } sort.Sort(cli.CommandsByName(app.Commands)) app.Flags = append(app.Flags, nodeFlags...) app.Flags = append(app.Flags, rpcFlags...) app.Flags = append(app.Flags, consoleFlags...) app.Flags = append(app.Flags, debug.Flags...) app.Flags = append(app.Flags, whisperFlags...) app.Before = func(ctx *cli.Context) error { runtime.GOMAXPROCS(runtime.NumCPU()) if err := debug.Setup(ctx); err != nil { return err } // Start system runtime metrics collection go metrics.CollectProcessMetrics(3 * time.Second) utils.SetupNetwork(ctx) return nil } app.After = func(ctx *cli.Context) error { debug.Exit() console.Stdin.Close() // Resets terminal mode. return nil } }
main函式中的內容比較簡單,這裡不多做任何解釋。
func main() {
if err := app.Run(os.Args); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
通過gopkg.in/urfave/cli.v1包中的程式碼來銜接到cmd/geth/chaincmd包中的程式碼,APP包中中HandleAction函式action的型別是「func(*Context) error」,此時將執行a(context)方法,那麼此時呼叫那個Action呢,就是我們前面提到的App.init()初始化命令時的initCommand,接下來我們來看看cmd/geth/chaincmd中的initCommand:
var ( initCommand = cli.Command{ Action: utils.MigrateFlags(initGenesis), Name: "init", Usage: "Bootstrap and initialize a new genesis block", ArgsUsage: "<genesisPath>", Flags: []cli.Flag{ utils.DataDirFlag, utils.LightModeFlag, }, 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 be participating. It expects the genesis file as argument.`, }
這允許使用現有的配置功能。當所有標誌被遷移時,該功能可以被刪除,並且必須改變現有的配置功能,即使用本地標誌
func MigrateFlags(action func(ctx *cli.Context) error) func(*cli.Context) error {
return func(ctx *cli.Context) error {
for _, name := range ctx.FlagNames() {
if ctx.IsSet(name) {
ctx.GlobalSet(name, ctx.String(name))
}
}
return action(ctx)
}
}
根據給定的JSon格式檔案初始化創世塊
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 an initialise both full and light databases
stack := makeFullNode(ctx)
for _, name := range []string{"chaindata", "lightchaindata"} {
chaindb, err := stack.OpenDatabase(name, 0, 0)
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)
}
log.Info("Successfully wrote genesis state", "database", name, "hash", hash)
}
return nil
}
將初始創世塊儲存
chaindb, err := stack.OpenDatabase(name, 0, 0)
if err != nil {
utils.Fatalf("Failed to open database: %v", err)
}
涉及到的Core層次的程式碼
genesis := new(core.Genesis)
_, hash, err := core.SetupGenesisBlock(chaindb, genesis)
if err != nil {
utils.Fatalf("Failed to write genesis block: %v", err)
}
創世塊的資料結構
type Genesis struct {
Config *params.ChainConfig `json:"config"`
Nonce uint64 `json:"nonce"`
Timestamp uint64 `json:"timestamp"`
ExtraData []byte `json:"extraData"`
GasLimit uint64 `json:"gasLimit" gencodec:"required"`
Difficulty *big.Int `json:"difficulty" gencodec:"required"`
Mixhash common.Hash `json:"mixHash"`
Coinbase common.Address `json:"coinbase"`
Alloc GenesisAlloc `json:"alloc" gencodec:"required"`
// These fields are used for consensus tests. Please don't use them
// in actual genesis blocks.
Number uint64 `json:"number"`
GasUsed uint64 `json:"gasUsed"`
ParentHash common.Hash `json:"parentHash"`
}
檢查創世塊的相關處理邏輯,符合邏輯寫創世塊,或者反饋控制檯相應的問題
func SetupGenesisBlock(db ethdb.Database, genesis *Genesis) (*params.ChainConfig, common.Hash, error) {
if genesis != nil && genesis.Config == nil {
return params.AllProtocolChanges, common.Hash{}, errGenesisNoConfig
}
// Just commit the new block if there is no stored genesis block.
stored := GetCanonicalHash(db, 0) //獲取genesis對應的區塊
if (stored == common.Hash{}) { //如果沒有區塊 最開始啟動geth會進入這裡。
if genesis == nil {
//如果genesis是nil 而且stored也是nil 那麼使用主網路
// 如果是test dev rinkeby 那麼genesis不為空 會設定為各自的genesis
log.Info("Writing default main-net genesis block")
genesis = DefaultGenesisBlock()
} else { // 否則使用配置的區塊
log.Info("Writing custom genesis block")
}
// 寫入資料庫
block, err := genesis.Commit(db)
return genesis.Config, block.Hash(), err
}
// Check whether the genesis block is already written.
if genesis != nil { //如果genesis存在而且區塊也存在 那麼對比這兩個區塊是否相同
block, _ := genesis.ToBlock()
hash := block.Hash()
if hash != stored {
return genesis.Config, block.Hash(), &GenesisMismatchError{stored, hash}
}
}
// Get the existing chain configuration.
// 獲取當前存在的區塊鏈的genesis配置
newcfg := genesis.configOrDefault(stored)
// 獲取當前的區塊鏈的配置
storedcfg, err := GetChainConfig(db, stored)
if err != nil {
if err == ErrChainConfigNotFound {
// This case happens if a genesis write was interrupted.
log.Warn("Found genesis block without chain config")
err = WriteChainConfig(db, stored, newcfg)
}
return newcfg, stored, err
}
// 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.
// 特殊情況:如果沒有提供新的配置,請不要更改非主網鏈的現有配置。
// 如果我們繼續這裡,這些鏈會得到AllProtocolChanges(和compat錯誤)。
if genesis == nil && stored != params.MainnetGenesisHash {
return storedcfg, stored, nil // 如果是私有連結會從這裡退出。
}
// Check config compatibility and write the config. Compatibility errors
// are returned to the caller unless we're already at block zero.
// 檢查配置的相容性,除非我們在區塊0,否則返回相容性錯誤.
height := GetBlockNumber(db, GetHeadHeaderHash(db))
if height == missingNumber {
return newcfg, stored, fmt.Errorf("missing block number for head header hash")
}
compatErr := storedcfg.CheckCompatible(newcfg, height)
// 如果區塊已經寫入資料了,那麼就不能更改genesis配置了
if compatErr != nil && height != 0 && compatErr.RewindTo != 0 {
return newcfg, stored, compatErr
}
// 如果是主網路會從這裡退出。
return newcfg, stored, WriteChainConfig(db, stored, newcfg)
}
ToBlock, 這個方法使用genesis的資料,使用基於記憶體的資料庫,然後建立了一個block並返回。
// ToBlock creates the block and state of a genesis specification.
func (g *Genesis) ToBlock() (*types.Block, *state.StateDB) {
db, _ := ethdb.NewMemDatabase()
statedb, _ := state.New(common.Hash{}, state.NewDatabase(db))
for addr, account := range g.Alloc {
statedb.AddBalance(addr, account.Balance)
statedb.SetCode(addr, account.Code)
statedb.SetNonce(addr, account.Nonce)
for key, value := range account.Storage {
statedb.SetState(addr, key, value)
}
}
root := statedb.IntermediateRoot(false)
head := &types.Header{
Number: new(big.Int).SetUint64(g.Number),
Nonce: types.EncodeNonce(g.Nonce),
Time: new(big.Int).SetUint64(g.Timestamp),
ParentHash: g.ParentHash,
Extra: g.ExtraData,
GasLimit: new(big.Int).SetUint64(g.GasLimit),
GasUsed: new(big.Int).SetUint64(g.GasUsed),
Difficulty: g.Difficulty,
MixDigest: g.Mixhash,
Coinbase: g.Coinbase,
Root: root,
}
if g.GasLimit == 0 {
head.GasLimit = params.GenesisGasLimit
}
if g.Difficulty == nil {
head.Difficulty = params.GenesisDifficulty
}
return types.NewBlock(head, nil, nil, nil), statedb
}
Commit方法和MustCommit方法, Commit方法把給定的genesis的block和state寫入資料庫, 這個block被認為是規範的區塊鏈頭。
// Commit writes the block and state of a genesis specification to the database.
// The block is committed as the canonical head block.
func (g *Genesis) Commit(db ethdb.Database) (*types.Block, error) {
block, statedb := g.ToBlock()
if block.Number().Sign() != 0 {
return nil, fmt.Errorf("can't commit genesis block with number > 0")
}
if _, err := statedb.CommitTo(db, false); err != nil {
return nil, fmt.Errorf("cannot write state: %v", err)
}
// 寫入總難度
if err := WriteTd(db, block.Hash(), block.NumberU64(), g.Difficulty); err != nil {
return nil, err
}
// 寫入區塊
if err := WriteBlock(db, block); err != nil {
return nil, err
}
// 寫入區塊收據
if err := WriteBlockReceipts(db, block.Hash(), block.NumberU64(), nil); err != nil {
return nil, err
}
// 寫入 headerPrefix + num (uint64 big endian) + numSuffix -> hash
if err := WriteCanonicalHash(db, block.Hash(), block.NumberU64()); err != nil {
return nil, err
}
// 寫入 "LastBlock" -> hash
if err := WriteHeadBlockHash(db, block.Hash()); err != nil {
return nil, err
}
// 寫入 "LastHeader" -> hash
if err := WriteHeadHeaderHash(db, block.Hash()); err != nil {
return nil, err
}
config := g.Config
if config == nil {
config = params.AllProtocolChanges
}
// 寫入 ethereum-config-hash -> config
return block, WriteChainConfig(db, block.Hash(), config)
}
// MustCommit writes the genesis block and state to db, panicking on error.
// The block is committed as the canonical head block.
func (g *Genesis) MustCommit(db ethdb.Database) *types.Block {
block, err := g.Commit(db)
if err != nil {
panic(err)
}
return block
}
返回各種模式的預設Genesis
// 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),
}
}
// DefaultTestnetGenesisBlock returns the Ropsten network genesis block.
func DefaultTestnetGenesisBlock() *Genesis {
return &Genesis{
Config: params.TestnetChainConfig,
Nonce: 66,
ExtraData: hexutil.MustDecode("0x3535353535353535353535353535353535353535353535353535353535353535"),
GasLimit: 16777216,
Difficulty: big.NewInt(1048576),
Alloc: decodePrealloc(testnetAllocData),
}
}
// DefaultRinkebyGenesisBlock returns the Rinkeby network genesis block.
func DefaultRinkebyGenesisBlock() *Genesis {
return &Genesis{
Config: params.RinkebyChainConfig,
Timestamp: 1492009146,
ExtraData: hexutil.MustDecode("0x52657370656374206d7920617574686f7269746168207e452e436172746d616e42eb768f2244c8811c63729a21a3569731535f067ffc57839b00206d1ad20c69a1981b489f772031b279182d99e65703f0076e4812653aab85fca0f00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"),
GasLimit: 4700000,
Difficulty: big.NewInt(1),
Alloc: decodePrealloc(rinkebyAllocData),
}
}
// DevGenesisBlock returns the 'geth --dev' genesis block.
func DevGenesisBlock() *Genesis {
return &Genesis{
Config: params.AllProtocolChanges,
Nonce: 42,
GasLimit: 4712388,
Difficulty: big.NewInt(131072),
Alloc: decodePrealloc(devAllocData),
}
}