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 (
	"context"
	"fmt"
	"math/big"

	"github.com/gochain-io/gochain/common"
	"github.com/gochain-io/gochain/consensus"
	"github.com/gochain-io/gochain/core/state"
	"github.com/gochain-io/gochain/core/types"
	"github.com/gochain-io/gochain/core/vm"
	"github.com/gochain-io/gochain/params"
)

// BlockGen creates blocks for testing.
// See GenerateChain for a detailed explanation.
type BlockGen struct {
	i           int
	parent      *types.Block
	chain       []*types.Block
	chainReader consensus.ChainReader
	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
}

// 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(ctx context.Context, tx *types.Transaction) {
	if b.gasPool == nil {
		b.SetCoinbase(common.Address{})
	}
	b.statedb.Prepare(tx.Hash(), common.Hash{}, len(b.txs))
	signer := types.MakeSigner(b.config, b.header.Number)
	// Create a new emv context and environment.
	evmContext := NewEVMContextLite(b.header, nil, &b.header.Coinbase)
	vmenv := vm.NewEVM(evmContext, b.statedb, b.config, vm.Config{})
	receipt, _, err := ApplyTransaction(ctx, vmenv, b.config, b.gasPool, b.statedb, b.header, tx, &b.header.GasUsed, signer)
	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)
}

// 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("block index out of range")
	}
	if index == -1 {
		return b.parent
	}
	return b.chain[index]
}

func (b *BlockGen) SetDifficulty(amt uint64) {
	b.header.Difficulty = new(big.Int).SetUint64(amt)
}

// 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(ctx context.Context, config *params.ChainConfig, first *types.Block, engine consensus.Engine, db common.Database, n int, gen func(context.Context, int, *BlockGen)) ([]*types.Block, []types.Receipts) {
	if config == nil {
		config = params.TestChainConfig
	}
	blocks, receipts := make(types.Blocks, n), make([]types.Receipts, n)

	genblock := func(i int, parent *types.Block, statedb *state.StateDB) (*types.Block, types.Receipts) {
		// TODO(karalabe): This is needed for clique, which depends on multiple blocks.
		// It's nonetheless ugly to spin up a blockchain here. Get rid of this somehow.
		blockchain, _ := NewBlockChain(ctx, db, nil, config, engine, vm.Config{})
		defer blockchain.Stop()
		b := &BlockGen{i: i, parent: parent, chain: blocks, chainReader: blockchain, statedb: statedb, config: config, engine: engine}

		b.header = &types.Header{
			Root:       statedb.IntermediateRoot(b.config.IsEIP158(parent.Number())),
			ParentHash: parent.Hash(),
			GasLimit:   CalcGasLimit(parent, parent.GasLimit(), parent.GasLimit()),
			Number:     new(big.Int).Add(parent.Number(), common.Big1),
			Signers:    parent.Signers(),
			Voters:     parent.Voters(),
			Time:       new(big.Int).Add(parent.Time(), new(big.Int).SetUint64(config.Clique.Period)),
		}

		// Execute any user modifications to the block and finalize it
		if gen != nil {
			gen(ctx, i, b)
		}

		if b.engine != nil {
			if err := b.engine.Prepare(ctx, b.chainReader, b.header); err != nil {
				panic(fmt.Sprintf("failed to prepare %d: %v", b.header.Number.Uint64(), err))
			}
			block := b.engine.Finalize(ctx, b.chainReader, b.header, statedb, b.txs, b.receipts, true)

			stop := make(chan struct{})
			block, _, err := b.engine.Seal(ctx, b.chainReader, block, stop)
			close(stop)
			if err != nil {
				panic(fmt.Sprintf("block seal error: %v", err))
			}
			// 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
	}
	parent := first
	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
}

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