accounts, consensus, core, eth: make chain maker consensus agnostic (#15497)

* accounts, consensus, core, eth: make chain maker consensus agnostic

* consensus, core: move CalcDifficulty to Engine interface

* consensus: add docs for calcDifficulty function

* consensus, core: minor comment fixups

1 files changed, 44 insertions, 32 deletions

diff --git a/core/chain_makers.go b/core/chain_makers.go
index 59af633df..0e5e3791e 100644
--- a/core/chain_makers.go
+++ b/core/chain_makers.go
@@ -21,7 +21,7 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/consensus/ethash"
+	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/consensus/misc"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -39,11 +39,12 @@ var (
 // 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
+	i           int
+	parent      *types.Block
+	chain       []*types.Block
+	chainReader consensus.ChainReader
+	header      *types.Header
+	statedb     *state.StateDB
 
 	gasPool  *GasPool
 	txs      []*types.Transaction
@@ -51,6 +52,7 @@ type BlockGen struct {
 	uncles   []*types.Header
 
 	config *params.ChainConfig
+	engine consensus.Engine
 }
 
 // SetCoinbase sets the coinbase of the generated block.
@@ -141,7 +143,7 @@ func (b *BlockGen) OffsetTime(seconds int64) {
 	if b.header.Time.Cmp(b.parent.Header().Time) <= 0 {
 		panic("block time out of range")
 	}
-	b.header.Difficulty = ethash.CalcDifficulty(b.config, b.header.Time.Uint64(), b.parent.Header())
+	b.header.Difficulty = b.engine.CalcDifficulty(b.chainReader, b.header.Time.Uint64(), b.parent.Header())
 }
 
 // GenerateChain creates a chain of n blocks. The first block's
@@ -156,44 +158,54 @@ func (b *BlockGen) OffsetTime(seconds int64) {
 // 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, db ethdb.Database, n int, gen func(int, *BlockGen)) ([]*types.Block, []types.Receipts) {
+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)
-	genblock := func(i int, h *types.Header, statedb *state.StateDB) (*types.Block, types.Receipts) {
-		b := &BlockGen{parent: parent, i: i, chain: blocks, header: h, statedb: statedb, config: config}
+	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(db, 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 = makeHeader(b.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 h.Number.Cmp(daoBlock) >= 0 && h.Number.Cmp(limit) < 0 {
+			if b.header.Number.Cmp(daoBlock) >= 0 && b.header.Number.Cmp(limit) < 0 {
 				if config.DAOForkSupport {
-					h.Extra = common.CopyBytes(params.DAOForkBlockExtra)
+					b.header.Extra = common.CopyBytes(params.DAOForkBlockExtra)
 				}
 			}
 		}
-		if config.DAOForkSupport && config.DAOForkBlock != nil && config.DAOForkBlock.Cmp(h.Number) == 0 {
+		if config.DAOForkSupport && config.DAOForkBlock != nil && config.DAOForkBlock.Cmp(b.header.Number) == 0 {
 			misc.ApplyDAOHardFork(statedb)
 		}
 		// Execute any user modifications to the block and finalize it
 		if gen != nil {
 			gen(i, b)
 		}
-		ethash.AccumulateRewards(config, statedb, h, b.uncles)
-		root, err := statedb.CommitTo(db, config.IsEIP158(h.Number))
-		if err != nil {
-			panic(fmt.Sprintf("state write error: %v", err))
+
+		if b.engine != nil {
+			block, _ := b.engine.Finalize(b.chainReader, b.header, statedb, b.txs, b.uncles, b.receipts)
+			// Write state changes to db
+			_, err := statedb.CommitTo(db, config.IsEIP158(b.header.Number))
+			if err != nil {
+				panic(fmt.Sprintf("state write error: %v", err))
+			}
+			return block, b.receipts
 		}
-		h.Root = root
-		return types.NewBlock(h, b.txs, b.uncles, b.receipts), 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)
 		}
-		header := makeHeader(config, parent, statedb)
-		block, receipt := genblock(i, header, statedb)
+		block, receipt := genblock(i, parent, statedb)
 		blocks[i] = block
 		receipts[i] = receipt
 		parent = block
@@ -201,7 +213,7 @@ func GenerateChain(config *params.ChainConfig, parent *types.Block, db ethdb.Dat
 	return blocks, receipts
 }
 
-func makeHeader(config *params.ChainConfig, parent *types.Block, state *state.StateDB) *types.Header {
+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)
@@ -210,10 +222,10 @@ func makeHeader(config *params.ChainConfig, parent *types.Block, state *state.St
 	}
 
 	return &types.Header{
-		Root:       state.IntermediateRoot(config.IsEIP158(parent.Number())),
+		Root:       state.IntermediateRoot(chain.Config().IsEIP158(parent.Number())),
 		ParentHash: parent.Hash(),
 		Coinbase:   parent.Coinbase(),
-		Difficulty: ethash.CalcDifficulty(config, time.Uint64(), &types.Header{
+		Difficulty: engine.CalcDifficulty(chain, time.Uint64(), &types.Header{
 			Number:     parent.Number(),
 			Time:       new(big.Int).Sub(time, big.NewInt(10)),
 			Difficulty: parent.Difficulty(),
@@ -229,32 +241,32 @@ func makeHeader(config *params.ChainConfig, parent *types.Block, state *state.St
 // newCanonical creates a chain database, and injects a deterministic canonical
 // chain. Depending on the full flag, if creates either a full block chain or a
 // header only chain.
-func newCanonical(n int, full bool) (ethdb.Database, *BlockChain, error) {
+func newCanonical(engine consensus.Engine, n int, full bool) (ethdb.Database, *BlockChain, error) {
 	// Initialize a fresh chain with only a genesis block
 	gspec := new(Genesis)
 	db, _ := ethdb.NewMemDatabase()
 	genesis := gspec.MustCommit(db)
 
-	blockchain, _ := NewBlockChain(db, params.AllEthashProtocolChanges, ethash.NewFaker(), vm.Config{})
+	blockchain, _ := NewBlockChain(db, params.AllEthashProtocolChanges, engine, vm.Config{})
 	// Create and inject the requested chain
 	if n == 0 {
 		return db, blockchain, nil
 	}
 	if full {
 		// Full block-chain requested
-		blocks := makeBlockChain(genesis, n, db, canonicalSeed)
+		blocks := makeBlockChain(genesis, n, engine, db, canonicalSeed)
 		_, err := blockchain.InsertChain(blocks)
 		return db, blockchain, err
 	}
 	// Header-only chain requested
-	headers := makeHeaderChain(genesis.Header(), n, db, canonicalSeed)
+	headers := makeHeaderChain(genesis.Header(), n, engine, db, canonicalSeed)
 	_, err := blockchain.InsertHeaderChain(headers, 1)
 	return db, blockchain, err
 }
 
 // makeHeaderChain creates a deterministic chain of headers rooted at parent.
-func makeHeaderChain(parent *types.Header, n int, db ethdb.Database, seed int) []*types.Header {
-	blocks := makeBlockChain(types.NewBlockWithHeader(parent), n, db, seed)
+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()
@@ -263,8 +275,8 @@ func makeHeaderChain(parent *types.Header, n int, db ethdb.Database, seed int) [
 }
 
 // makeBlockChain creates a deterministic chain of blocks rooted at parent.
-func makeBlockChain(parent *types.Block, n int, db ethdb.Database, seed int) []*types.Block {
-	blocks, _ := GenerateChain(params.TestChainConfig, parent, db, n, func(i int, b *BlockGen) {
+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