core, eth, rpc: split out block validator and state processor

This removes the burden on a single object to take care of all
validation and state processing. Now instead the validation is done by
the `core.BlockValidator` (`types.Validator`) that takes care of both
header and uncle validation through the `ValidateBlock` method and state
validation through the `ValidateState` method. The state processing is
done by a new object `core.StateProcessor` (`types.Processor`) and
accepts a new state as input and uses that to process the given block's
transactions (and uncles for rewords) to calculate the state root for
the next block (P_n + 1).

core/state_processor.go

@@ -0,0 +1,107 @@
+package core
+
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/core/state"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+)
+
+var (
+	big8  = big.NewInt(8)
+	big32 = big.NewInt(32)
+)
+
+type StateProcessor struct {
+	bc *BlockChain
+}
+
+func NewStateProcessor(bc *BlockChain) *StateProcessor {
+	return &StateProcessor{bc}
+}
+
+// Process processes the state changes according to the Ethereum rules by running
+// the transaction messages using the statedb and applying any rewards to both
+// the processor (coinbase) and any included uncles.
+//
+// Process returns the receipts and logs accumulated during the process and
+// returns the amount of gas that was used in the process. If any of the
+// transactions failed to execute due to insufficient gas it will return an error.
+func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB) (types.Receipts, vm.Logs, *big.Int, error) {
+	var (
+		receipts     types.Receipts
+		totalUsedGas = big.NewInt(0)
+		err          error
+		header       = block.Header()
+		allLogs      vm.Logs
+		gp           = new(GasPool).AddGas(block.GasLimit())
+	)
+
+	for i, tx := range block.Transactions() {
+		statedb.StartRecord(tx.Hash(), block.Hash(), i)
+
+		receipt, logs, _, err := ApplyTransaction(p.bc, gp, statedb, header, tx, totalUsedGas)
+		if err != nil {
+			return nil, nil, totalUsedGas, err
+		}
+		receipts = append(receipts, receipt)
+		allLogs = append(allLogs, logs...)
+	}
+	AccumulateRewards(statedb, header, block.Uncles())
+
+	return receipts, allLogs, totalUsedGas, err
+}
+
+// ApplyTransaction attemps to apply a transaction to the given state database
+// and uses the input parameters for its environment.
+//
+// ApplyTransactions returns the generated receipts and vm logs during the
+// execution of the state transition phase.
+func ApplyTransaction(bc *BlockChain, gp *GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *big.Int) (*types.Receipt, vm.Logs, *big.Int, error) {
+	_, gas, err := ApplyMessage(NewEnv(statedb, bc, tx, header), tx, gp)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	// Update the state with pending changes
+	usedGas.Add(usedGas, gas)
+	receipt := types.NewReceipt(statedb.IntermediateRoot().Bytes(), usedGas)
+	receipt.TxHash = tx.Hash()
+	receipt.GasUsed = new(big.Int).Set(gas)
+	if MessageCreatesContract(tx) {
+		from, _ := tx.From()
+		receipt.ContractAddress = crypto.CreateAddress(from, tx.Nonce())
+	}
+
+	logs := statedb.GetLogs(tx.Hash())
+	receipt.Logs = logs
+	receipt.Bloom = types.CreateBloom(types.Receipts{receipt})
+
+	glog.V(logger.Debug).Infoln(receipt)
+
+	return receipt, logs, gas, err
+}
+
+// AccumulateRewards credits the coinbase of the given block with the
+// mining reward. The total reward consists of the static block reward
+// and rewards for included uncles. The coinbase of each uncle block is
+// also rewarded.
+func AccumulateRewards(statedb *state.StateDB, header *types.Header, uncles []*types.Header) {
+	reward := new(big.Int).Set(BlockReward)
+	r := new(big.Int)
+	for _, uncle := range uncles {
+		r.Add(uncle.Number, big8)
+		r.Sub(r, header.Number)
+		r.Mul(r, BlockReward)
+		r.Div(r, big8)
+		statedb.AddBalance(uncle.Coinbase, r)
+
+		r.Div(BlockReward, big32)
+		reward.Add(reward, r)
+	}
+	statedb.AddBalance(header.Coinbase, reward)
+}