path: root/core/chain_makers.go

package core

import (
    "fmt"
    "math/big"

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/state"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/event"
    "github.com/ethereum/go-ethereum/pow"
)

// So we can generate blocks easily
type FakePow struct{}

func (f FakePow) Search(block pow.Block, stop <-chan struct{}) (uint64, []byte) {
    return 0, nil
}
func (f FakePow) Verify(block pow.Block) bool { return true }
func (f FakePow) GetHashrate() int64          { return 0 }
func (f FakePow) Turbo(bool)                  {}

// So we can deterministically seed different blockchains
var (
    CanonicalSeed = 1
    ForkSeed      = 2
)

// Utility functions for making chains on the fly
// Exposed for sake of testing from other packages (eg. go-ethash)
func NewBlockFromParent(addr common.Address, parent *types.Block) *types.Block {
    return newBlockFromParent(addr, parent)
}

func MakeBlock(bman *BlockProcessor, parent *types.Block, i int, db common.Database, seed int) *types.Block {
    return makeBlock(bman, parent, i, db, seed)
}

func MakeChain(bman *BlockProcessor, parent *types.Block, max int, db common.Database, seed int) types.Blocks {
    return makeChain(bman, parent, max, db, seed)
}

func NewChainMan(block *types.Block, eventMux *event.TypeMux, db common.Database) *ChainManager {
    return newChainManager(block, eventMux, db)
}

func NewBlockProc(db common.Database, cman *ChainManager, eventMux *event.TypeMux) *BlockProcessor {
    return newBlockProcessor(db, cman, eventMux)
}

func NewCanonical(n int, db common.Database) (*BlockProcessor, error) {
    return newCanonical(n, db)
}

// block time is fixed at 10 seconds
func newBlockFromParent(addr common.Address, parent *types.Block) *types.Block {
    block := types.NewBlock(parent.Hash(), addr, parent.Root(), common.BigPow(2, 32), 0, nil)
    block.SetUncles(nil)
    block.SetTransactions(nil)
    block.SetReceipts(nil)

    header := block.Header()
    header.Difficulty = CalcDifficulty(block.Header(), parent.Header())
    header.Number = new(big.Int).Add(parent.Header().Number, common.Big1)
    header.Time = parent.Header().Time + 10
    header.GasLimit = CalcGasLimit(parent)

    block.Td = parent.Td

    return block
}

// Actually make a block by simulating what miner would do
// we seed chains by the first byte of the coinbase
func makeBlock(bman *BlockProcessor, parent *types.Block, i int, db common.Database, seed int) *types.Block {
    var addr common.Address
    addr[0], addr[19] = byte(seed), byte(i)
    block := newBlockFromParent(addr, parent)
    state := state.New(block.Root(), db)
    cbase := state.GetOrNewStateObject(addr)
    cbase.SetGasLimit(CalcGasLimit(parent))
    cbase.AddBalance(BlockReward)
    state.Update()
    block.SetRoot(state.Root())
    return block
}

// Make a chain with real blocks
// Runs ProcessWithParent to get proper state roots
func makeChain(bman *BlockProcessor, parent *types.Block, max int, db common.Database, seed int) types.Blocks {
    bman.bc.currentBlock = parent
    blocks := make(types.Blocks, max)
    for i := 0; i < max; i++ {
        block := makeBlock(bman, parent, i, db, seed)
        _, err := bman.processWithParent(block, parent)
        if err != nil {
            fmt.Println("process with parent failed", err)
            panic(err)
        }
        block.Td = CalcTD(block, parent)
        blocks[i] = block
        parent = block
    }
    return blocks
}

// Create a new chain manager starting from given block
// Effectively a fork factory
func newChainManager(block *types.Block, eventMux *event.TypeMux, db common.Database) *ChainManager {
    genesis := GenesisBlock(0, db)
    bc := &ChainManager{blockDb: db, stateDb: db, genesisBlock: genesis, eventMux: eventMux, pow: FakePow{}}
    bc.txState = state.ManageState(state.New(genesis.Root(), db))
    bc.futureBlocks = NewBlockCache(1000)
    if block == nil {
        bc.Reset()
    } else {
        bc.currentBlock = block
        bc.td = block.Td
    }
    return bc
}

// block processor with fake pow
func newBlockProcessor(db common.Database, cman *ChainManager, eventMux *event.TypeMux) *BlockProcessor {
    chainMan := newChainManager(nil, eventMux, db)
    bman := NewBlockProcessor(db, db, FakePow{}, chainMan, eventMux)
    return bman
}

// Make a new, deterministic canonical chain by running InsertChain
// on result of makeChain
func newCanonical(n int, db common.Database) (*BlockProcessor, error) {
    eventMux := &event.TypeMux{}

    bman := newBlockProcessor(db, newChainManager(nil, eventMux, db), eventMux)
    bman.bc.SetProcessor(bman)
    parent := bman.bc.CurrentBlock()
    if n == 0 {
        return bman, nil
    }
    lchain := makeChain(bman, parent, n, db, CanonicalSeed)
    _, err := bman.bc.InsertChain(lchain)
    return bman, err
}