path: root/core/chain_makers.go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package core

import (
    "fmt"
    "math/big"
    "math/rand"
    "time"

    "github.com/dexon-foundation/dexon/common"
    "github.com/dexon-foundation/dexon/consensus"
    "github.com/dexon-foundation/dexon/consensus/misc"
    "github.com/dexon-foundation/dexon/core/state"
    "github.com/dexon-foundation/dexon/core/types"
    "github.com/dexon-foundation/dexon/core/vm"
    "github.com/dexon-foundation/dexon/ethdb"
    "github.com/dexon-foundation/dexon/params"
)

func init() {
    rand.Seed(time.Now().UTC().UnixNano())
}

// BlockGen creates blocks for testing.
// See GenerateChain for a detailed explanation.
type BlockGen struct {
    i       int
    parent  *types.Block
    chain   []*types.Block
    header  *types.Header
    statedb *state.StateDB

    gasPool  *GasPool
    txs      []*types.Transaction
    receipts []*types.Receipt
    uncles   []*types.Header

    config *params.ChainConfig
    engine consensus.Engine
}

// SetCoinbase sets the coinbase of the generated block.
// It can be called at most once.
func (b *BlockGen) SetCoinbase(addr common.Address) {
    if b.gasPool != nil {
        if len(b.txs) > 0 {
            panic("coinbase must be set before adding transactions")
        }
        panic("coinbase can only be set once")
    }
    b.header.Coinbase = addr
    b.gasPool = new(GasPool).AddGas(b.header.GasLimit)
}

// SetExtra sets the extra data field of the generated block.
func (b *BlockGen) SetExtra(data []byte) {
    b.header.Extra = data
}

// SetNonce sets the nonce field of the generated block.
func (b *BlockGen) SetNonce(nonce types.BlockNonce) {
    b.header.Nonce = nonce
}

// AddTx adds a transaction to the generated block. If no coinbase has
// been set, the block's coinbase is set to the zero address.
//
// AddTx panics if the transaction cannot be executed. In addition to
// the protocol-imposed limitations (gas limit, etc.), there are some
// further limitations on the content of transactions that can be
// added. Notably, contract code relying on the BLOCKHASH instruction
// will panic during execution.
func (b *BlockGen) AddTx(tx *types.Transaction) {
    b.AddTxWithChain(nil, tx)
}

// AddTxWithChain adds a transaction to the generated block. If no coinbase has
// been set, the block's coinbase is set to the zero address.
//
// AddTxWithChain panics if the transaction cannot be executed. In addition to
// the protocol-imposed limitations (gas limit, etc.), there are some
// further limitations on the content of transactions that can be
// added. If contract code relies on the BLOCKHASH instruction,
// the block in chain will be returned.
func (b *BlockGen) AddTxWithChain(bc *BlockChain, tx *types.Transaction) {
    if b.gasPool == nil {
        b.SetCoinbase(common.Address{})
    }
    b.statedb.Prepare(tx.Hash(), common.Hash{}, len(b.txs))
    receipt, _, err := ApplyTransaction(b.config, bc, &b.header.Coinbase, b.gasPool, b.statedb, b.header, tx, &b.header.GasUsed, vm.Config{})
    if err != nil {
        panic(err)
    }
    b.txs = append(b.txs, tx)
    b.receipts = append(b.receipts, receipt)
}

// Number returns the block number of the block being generated.
func (b *BlockGen) Number() *big.Int {
    return new(big.Int).Set(b.header.Number)
}

// AddUncheckedReceipt forcefully adds a receipts to the block without a
// backing transaction.
//
// AddUncheckedReceipt will cause consensus failures when used during real
// chain processing. This is best used in conjunction with raw block insertion.
func (b *BlockGen) AddUncheckedReceipt(receipt *types.Receipt) {
    b.receipts = append(b.receipts, receipt)
}

// TxNonce returns the next valid transaction nonce for the
// account at addr. It panics if the account does not exist.
func (b *BlockGen) TxNonce(addr common.Address) uint64 {
    if !b.statedb.Exist(addr) {
        panic("account does not exist")
    }
    return b.statedb.GetNonce(addr)
}

// AddUncle adds an uncle header to the generated block.
func (b *BlockGen) AddUncle(h *types.Header) {
    b.uncles = append(b.uncles, h)
}

// PrevBlock returns a previously generated block by number. It panics if
// num is greater or equal to the number of the block being generated.
// For index -1, PrevBlock returns the parent block given to GenerateChain.
func (b *BlockGen) PrevBlock(index int) *types.Block {
    if index >= b.i {
        panic(fmt.Errorf("block index %d out of range (%d,%d)", index, -1, b.i))
    }
    if index == -1 {
        return b.parent
    }
    return b.chain[index]
}

// OffsetTime modifies the time instance of a block, implicitly changing its
// associated difficulty. It's useful to test scenarios where forking is not
// tied to chain length directly.
func (b *BlockGen) OffsetTime(seconds int64) {
    b.header.Time.Add(b.header.Time, big.NewInt(seconds))
    if b.header.Time.Cmp(b.parent.Header().Time) <= 0 {
        panic("block time out of range")
    }
    chainreader := &fakeChainReader{config: b.config}
    b.header.Difficulty = b.engine.CalcDifficulty(chainreader, b.header.Time.Uint64(), b.parent.Header())
}

// GenerateChain creates a chain of n blocks. The first block's
// parent will be the provided parent. db is used to store
// intermediate states and should contain the parent's state trie.
//
// The generator function is called with a new block generator for
// every block. Any transactions and uncles added to the generator
// become part of the block. If gen is nil, the blocks will be empty
// and their coinbase will be the zero address.
//
// Blocks created by GenerateChain do not contain valid proof of work
// values. Inserting them into BlockChain requires use of FakePow or
// a similar non-validating proof of work implementation.
func GenerateChain(config *params.ChainConfig, parent *types.Block, engine consensus.Engine, db ethdb.Database, n int, gen func(int, *BlockGen)) ([]*types.Block, []types.Receipts) {
    if config == nil {
        config = params.TestChainConfig
    }
    blocks, receipts := make(types.Blocks, n), make([]types.Receipts, n)
    chainreader := &fakeChainReader{config: config}
    genblock := func(i int, parent *types.Block, statedb *state.StateDB) (*types.Block, types.Receipts) {
        b := &BlockGen{i: i, chain: blocks, parent: parent, statedb: statedb, config: config, engine: engine}
        b.header = makeHeader(chainreader, parent, statedb, b.engine)

        // Mutate the state and block according to any hard-fork specs
        if daoBlock := config.DAOForkBlock; daoBlock != nil {
            limit := new(big.Int).Add(daoBlock, params.DAOForkExtraRange)
            if b.header.Number.Cmp(daoBlock) >= 0 && b.header.Number.Cmp(limit) < 0 {
                if config.DAOForkSupport {
                    b.header.Extra = common.CopyBytes(params.DAOForkBlockExtra)
                }
            }
        }
        if config.DAOForkSupport && config.DAOForkBlock != nil && config.DAOForkBlock.Cmp(b.header.Number) == 0 {
            misc.ApplyDAOHardFork(statedb)
        }
        // Execute any user modifications to the block
        if gen != nil {
            gen(i, b)
        }
        if b.engine != nil {
            // Finalize and seal the block
            block, _ := b.engine.Finalize(chainreader, b.header, statedb, b.txs, b.uncles, b.receipts)

            // Write state changes to db
            root, err := statedb.Commit(config.IsEIP158(b.header.Number))
            if err != nil {
                panic(fmt.Sprintf("state write error: %v", err))
            }
            if err := statedb.Database().TrieDB().Commit(root, false); err != nil {
                panic(fmt.Sprintf("trie write error: %v", err))
            }
            return block, b.receipts
        }
        return nil, nil
    }
    for i := 0; i < n; i++ {
        statedb, err := state.New(parent.Root(), state.NewDatabase(db))
        if err != nil {
            panic(err)
        }
        block, receipt := genblock(i, parent, statedb)
        blocks[i] = block
        receipts[i] = receipt
        parent = block
    }
    return blocks, receipts
}

func makeHeader(chain consensus.ChainReader, parent *types.Block, state *state.StateDB, engine consensus.Engine) *types.Header {
    var time *big.Int
    if parent.Time() == nil {
        time = big.NewInt(10)
    } else {
        time = new(big.Int).Add(parent.Time(), big.NewInt(10)) // block time is fixed at 10 seconds
    }

    return &types.Header{
        Root:       state.IntermediateRoot(chain.Config().IsEIP158(parent.Number())),
        ParentHash: parent.Hash(),
        Coinbase:   parent.Coinbase(),
        Difficulty: engine.CalcDifficulty(chain, time.Uint64(), &types.Header{
            Number:     parent.Number(),
            Time:       new(big.Int).Sub(time, big.NewInt(10)),
            Difficulty: parent.Difficulty(),
            UncleHash:  parent.UncleHash(),
        }),
        GasLimit: CalcGasLimit(parent, parent.GasLimit(), parent.GasLimit()),
        Number:   new(big.Int).Add(parent.Number(), common.Big1),
        Time:     time,
    }
}

// makeHeaderChain creates a deterministic chain of headers rooted at parent.
func makeHeaderChain(parent *types.Header, n int, engine consensus.Engine, db ethdb.Database, seed int) []*types.Header {
    blocks := makeBlockChain(types.NewBlockWithHeader(parent), n, engine, db, seed)
    headers := make([]*types.Header, len(blocks))
    for i, block := range blocks {
        headers[i] = block.Header()
    }
    return headers
}

// makeBlockChain creates a deterministic chain of blocks rooted at parent.
func makeBlockChain(parent *types.Block, n int, engine consensus.Engine, db ethdb.Database, seed int) []*types.Block {
    blocks, _ := GenerateChain(params.TestChainConfig, parent, engine, db, n, func(i int, b *BlockGen) {
        b.SetCoinbase(common.Address{0: byte(seed), 19: byte(i)})
    })
    return blocks
}

type fakeChainReader struct {
    config  *params.ChainConfig
    genesis *types.Block
}

// Config returns the chain configuration.
func (cr *fakeChainReader) Config() *params.ChainConfig {
    return cr.config
}

func (cr *fakeChainReader) CurrentHeader() *types.Header                            { return nil }
func (cr *fakeChainReader) GetHeaderByNumber(number uint64) *types.Header           { return nil }
func (cr *fakeChainReader) GetHeaderByHash(hash common.Hash) *types.Header          { return nil }
func (cr *fakeChainReader) GetHeader(hash common.Hash, number uint64) *types.Header { return nil }
func (cr *fakeChainReader) GetBlock(hash common.Hash, number uint64) *types.Block   { return nil }