Making posv as a separate package

cmd/puppeth/module_node.go

@@ -184,7 +184,7 @@ func (info *nodeInfos) Report() map[string]string {
 			report["Miner account"] = info.etherbase
 		}
 		if info.keyJSON != "" {
-			// Clique proof-of-authority signer
+			// Posv proof-of-stake-voting signer
 			var key struct {
 				Address string `json:"address"`
 			}

cmd/puppeth/wizard_genesis.go

@@ -58,10 +58,10 @@ func (w *wizard) makeGenesis() {
 	}
 	// Figure out which consensus engine to choose
 	fmt.Println()
-	fmt.Println("Which consensus engine to use? (default = clique)")
+	fmt.Println("Which consensus engine to use? (default = posv)")
 	fmt.Println(" 1. Ethash - proof-of-work")
-	fmt.Println(" 2. Clique - proof-of-authority")
+	fmt.Println(" 2. Posv - proof-of-authority")
-	fmt.Println(" 3. Tomo - proof-of-stake-voting")
+	fmt.Println(" 3. Posv - proof-of-stake-voting")
 
 	choice := w.read()
 	switch {
@@ -70,22 +70,17 @@ func (w *wizard) makeGenesis() {
 		genesis.Config.Ethash = new(params.EthashConfig)
 		genesis.ExtraData = make([]byte, 32)
 
-	case choice == "" || choice == "2":
+	case  choice == "2":
 		// In the case of clique, configure the consensus parameters
 		genesis.Difficulty = big.NewInt(1)
 		genesis.Config.Clique = &params.CliqueConfig{
 			Period: 15,
 			Epoch:  30000,
-			Reward: 0,
 		}
 		fmt.Println()
 		fmt.Println("How many seconds should blocks take? (default = 15)")
 		genesis.Config.Clique.Period = uint64(w.readDefaultInt(15))
 
-		fmt.Println()
-		fmt.Println("How many Ethers should be rewarded to signer? (default = 0)")
-		genesis.Config.Clique.Reward = uint64(w.readDefaultInt(0))
-
 		// We also need the initial list of signers
 		fmt.Println()
 		fmt.Println("Which accounts are allowed to seal? (mandatory at least one)")
@@ -113,29 +108,20 @@ func (w *wizard) makeGenesis() {
 			copy(genesis.ExtraData[32+i*common.AddressLength:], signer[:])
 		}
 
-		fmt.Println()
+	case choice == "" || choice == "3":
-		fmt.Println("How many blocks per checkpoint? (default = 990)")
-		genesis.Config.Clique.Epoch = uint64(w.readDefaultInt(990))
-		genesis.Config.Clique.RewardCheckpoint = genesis.Config.Clique.Epoch
-
-		fmt.Println()
-		fmt.Println("How many blocks before checkpoint need to prepare new set of masternodes? (default = 50)")
-		genesis.Config.Clique.Gap = uint64(w.readDefaultInt(50))
-
-	case choice == "3":
 		genesis.Difficulty = big.NewInt(1)
-		genesis.Config.Clique = &params.CliqueConfig{
+		genesis.Config.Posv = &params.PosvConfig{
 			Period: 15,
 			Epoch:  30000,
 			Reward: 0,
 		}
 		fmt.Println()
 		fmt.Println("How many seconds should blocks take? (default = 2)")
-		genesis.Config.Clique.Period = uint64(w.readDefaultInt(2))
+		genesis.Config.Posv.Period = uint64(w.readDefaultInt(2))
 
 		fmt.Println()
 		fmt.Println("How many Ethers should be rewarded to masternode? (default = 10)")
-		genesis.Config.Clique.Reward = uint64(w.readDefaultInt(10))
+		genesis.Config.Posv.Reward = uint64(w.readDefaultInt(10))
 
 		fmt.Println()
 		fmt.Println("Who own the first masternodes? (mandatory)")
@@ -175,11 +161,11 @@ func (w *wizard) makeGenesis() {
 		fmt.Println()
 		fmt.Println("How many blocks per epoch? (default = 990)")
 		epochNumber := w.readDefaultInt(990)
-		genesis.Config.Clique.RewardCheckpoint = uint64(epochNumber)
+		genesis.Config.Posv.RewardCheckpoint = uint64(epochNumber)
 
 		fmt.Println()
 		fmt.Println("How many blocks before checkpoint need to prepare new set of masternodes? (default = 50)")
-		genesis.Config.Clique.Gap = uint64(w.readDefaultInt(50))
+		genesis.Config.Posv.Gap = uint64(w.readDefaultInt(50))
 
 		// Validator Smart Contract Code
 		pKey, _ := crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")

cmd/puppeth/wizard_node.go

@@ -118,7 +118,7 @@ func (w *wizard) deployNode(boot bool) {
 				fmt.Printf("What address should the miner user? (default = %s)\n", infos.etherbase)
 				infos.etherbase = w.readDefaultAddress(common.HexToAddress(infos.etherbase)).Hex()
 			}
-		} else if w.conf.Genesis.Config.Clique != nil {
+		} else if w.conf.Genesis.Config.Posv != nil {
 			// If a previous signer was already set, offer to reuse it
 			if infos.keyJSON != "" {
 				if key, err := keystore.DecryptKey([]byte(infos.keyJSON), infos.keyPass); err != nil {
@@ -131,7 +131,7 @@ func (w *wizard) deployNode(boot bool) {
 					}
 				}
 			}
-			// Clique based signers need a keyfile and unlock password, ask if unavailable
+			// Posv based signers need a keyfile and unlock password, ask if unavailable
 			if infos.keyJSON == "" {
 				fmt.Println()
 				fmt.Println("Please paste the signer's key JSON:")

cmd/tomo/main.go

@@ -29,7 +29,7 @@ import (
 	"github.com/ethereum/go-ethereum/accounts/keystore"
 	"github.com/ethereum/go-ethereum/cmd/utils"
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/consensus/clique"
+	"github.com/ethereum/go-ethereum/consensus/posv"
 	"github.com/ethereum/go-ethereum/console"
 	validatorContract "github.com/ethereum/go-ethereum/contracts/validator/contract"
 	"github.com/ethereum/go-ethereum/core"
@@ -370,7 +370,7 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 						utils.Fatalf("Can't get list of masternode candidates: %v", err)
 					}
 
-					var ms []clique.Masternode
+					var ms []posv.Masternode
 					for _, candidate := range candidates {
 						v, err := validator.GetCandidateCap(opts, candidate)
 						if err != nil {
@@ -378,7 +378,7 @@ func startNode(ctx *cli.Context, stack *node.Node) {
 						}
 						//TODO: smart contract shouldn't return "0x0000000000000000000000000000000000000000"
 						if candidate.String() != "0x0000000000000000000000000000000000000000" {
-							ms = append(ms, clique.Masternode{Address: candidate, Stake: v.String()})
+							ms = append(ms, posv.Masternode{Address: candidate, Stake: v.String()})
 						}
 					}
 					//// order by cap

cmd/utils/flags.go

@@ -33,7 +33,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/fdlimit"
 	"github.com/ethereum/go-ethereum/consensus"
-	"github.com/ethereum/go-ethereum/consensus/clique"
+	"github.com/ethereum/go-ethereum/consensus/posv"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/core"
 	"github.com/ethereum/go-ethereum/core/state"
@@ -1221,8 +1221,8 @@ func MakeChain(ctx *cli.Context, stack *node.Node) (chain *core.BlockChain, chai
 		Fatalf("%v", err)
 	}
 	var engine consensus.Engine
-	if config.Clique != nil {
+	if config.Posv != nil {
-		engine = clique.New(config.Clique, chainDb)
+		engine = posv.New(config.Posv, chainDb)
 	} else {
 		engine = ethash.NewFaker()
 		if !ctx.GlobalBool(FakePoWFlag.Name) {

consensus/clique/clique.go

@@ -25,7 +25,6 @@ import (
 	"sync"
 	"time"
 
-	"fmt"
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
@@ -40,19 +39,16 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/rpc"
-	"github.com/hashicorp/golang-lru"
+	lru "github.com/hashicorp/golang-lru"
 )
 
 const (
-	inmemorySnapshots  = 128                    // Number of recent vote snapshots to keep in memory
+	checkpointInterval = 1024 // Number of blocks after which to save the vote snapshot to the database
-	inmemorySignatures = 4096                   // Number of recent block signatures to keep in memory
+	inmemorySnapshots  = 128  // Number of recent vote snapshots to keep in memory
-	wiggleTime         = 500 * time.Millisecond // Random delay (per signer) to allow concurrent signers
+	inmemorySignatures = 4096 // Number of recent block signatures to keep in memory
-)
 
-type Masternode struct {
+	wiggleTime = 500 * time.Millisecond // Random delay (per signer) to allow concurrent signers
-	Address common.Address
+)
-	Stake   string
-}
 
 // Clique proof-of-authority protocol constants.
 var (
@@ -210,8 +206,6 @@ type Clique struct {
 	signer common.Address // Ethereum address of the signing key
 	signFn SignerFn       // Signer function to authorize hashes with
 	lock   sync.RWMutex   // Protects the signer fields
-
-	HookReward func(chain consensus.ChainReader, state *state.StateDB, header *types.Header) error
 }
 
 // New creates a Clique proof-of-authority consensus engine with the initial
@@ -283,6 +277,9 @@ func (c *Clique) verifyHeader(chain consensus.ChainReader, header *types.Header,
 	}
 	// Checkpoint blocks need to enforce zero beneficiary
 	checkpoint := (number % c.config.Epoch) == 0
+	if checkpoint && header.Coinbase != (common.Address{}) {
+		return errInvalidCheckpointBeneficiary
+	}
 	// Nonces must be 0x00..0 or 0xff..f, zeroes enforced on checkpoints
 	if !bytes.Equal(header.Nonce[:], nonceAuthVote) && !bytes.Equal(header.Nonce[:], nonceDropVote) {
 		return errInvalidVote
@@ -350,75 +347,26 @@ func (c *Clique) verifyCascadingFields(chain consensus.ChainReader, header *type
 	if parent.Time.Uint64()+c.config.Period > header.Time.Uint64() {
 		return ErrInvalidTimestamp
 	}
+	// Retrieve the snapshot needed to verify this header and cache it
+	snap, err := c.snapshot(chain, number-1, header.ParentHash, parents)
+	if err != nil {
+		return err
+	}
+	// If the block is a checkpoint block, verify the signer list
+	if number%c.config.Epoch == 0 {
+		signers := make([]byte, len(snap.Signers)*common.AddressLength)
+		for i, signer := range snap.signers() {
+			copy(signers[i*common.AddressLength:], signer[:])
+		}
+		extraSuffix := len(header.Extra) - extraSeal
+		if !bytes.Equal(header.Extra[extraVanity:extraSuffix], signers) {
+			return errInvalidCheckpointSigners
+		}
+	}
 	// All basic checks passed, verify the seal and return
 	return c.verifySeal(chain, header, parents)
 }
 
-func (c *Clique) GetSnapshot(chain consensus.ChainReader, header *types.Header) (*Snapshot, error) {
-	number := header.Number.Uint64()
-	log.Trace("take snapshot", "number", number, "hash", header.Hash())
-	snap, err := c.snapshot(chain, number, header.Hash(), nil)
-	if err != nil {
-		return nil, err
-	}
-	return snap, nil
-}
-
-func (c *Clique) StoreSnapshot(snap *Snapshot) error {
-	return snap.store(c.db)
-}
-
-func position(list []common.Address, x common.Address) int {
-	for i, item := range list {
-		if item == x {
-			return i
-		}
-	}
-	return -1
-}
-
-func (c *Clique) GetMasternodes(chain consensus.ChainReader, header *types.Header) []common.Address {
-	n := header.Number.Uint64()
-	e := c.config.Epoch
-	switch {
-	case n%e == 0:
-		return c.GetMasternodesFromCheckpointHeader(header, n, e)
-	case n%e != 0:
-		h := chain.GetHeaderByNumber(n - (n % e))
-		return c.GetMasternodesFromCheckpointHeader(h, n, e)
-	default:
-		return []common.Address{}
-	}
-}
-
-func (c *Clique) GetPeriod() uint64 { return c.config.Period }
-
-func YourTurn(masternodes []common.Address, snap *Snapshot, header *types.Header, cur common.Address) (int, int, bool, error) {
-	if len(masternodes) == 0 {
-		return -1, -1, true, nil
-	}
-	pre := common.Address{}
-	// masternode[0] has chance to create block 1
-	var err error
-	preIndex := -1
-	if header.Number.Uint64() != 0 {
-		pre, err = ecrecover(header, snap.sigcache)
-		if err != nil {
-			return 0, 0, false, err
-		}
-		preIndex = position(masternodes, pre)
-	}
-	curIndex := position(masternodes, cur)
-	log.Info("Masternodes cycle info", "number of masternodes", len(masternodes), "previous", pre, "position", preIndex, "current", cur, "position", curIndex)
-	for i, s := range masternodes {
-		fmt.Printf("%d - %s\n", i, s.String())
-	}
-	if (preIndex+1)%len(masternodes) == curIndex {
-		return preIndex, curIndex, true, nil
-	}
-	return preIndex, curIndex, false, nil
-}
-
 // snapshot retrieves the authorization snapshot at a given point in time.
 func (c *Clique) snapshot(chain consensus.ChainReader, number uint64, hash common.Hash, parents []*types.Header) (*Snapshot, error) {
 	// Search for a snapshot in memory or on disk for checkpoints
@@ -433,8 +381,7 @@ func (c *Clique) snapshot(chain consensus.ChainReader, number uint64, hash commo
 			break
 		}
 		// If an on-disk checkpoint snapshot can be found, use that
-		// checkpoint snapshot = checkpoint - gap
+		if number%checkpointInterval == 0 {
-		if (number+c.config.Gap)%c.config.Epoch == 0 {
 			if s, err := loadSnapshot(c.config, c.signatures, c.db, hash); err == nil {
 				log.Trace("Loaded voting snapshot form disk", "number", number, "hash", hash)
 				snap = s
@@ -488,7 +435,7 @@ func (c *Clique) snapshot(chain consensus.ChainReader, number uint64, hash commo
 	c.recents.Add(snap.Hash, snap)
 
 	// If we've generated a new checkpoint snapshot, save to disk
-	if (snap.Number+c.config.Gap)%c.config.Epoch == 0 {
+	if snap.Number%checkpointInterval == 0 && len(headers) > 0 {
 		if err = snap.store(c.db); err != nil {
 			return nil, err
 		}
@@ -533,39 +480,25 @@ func (c *Clique) verifySeal(chain consensus.ChainReader, header *types.Header, p
 	if err != nil {
 		return err
 	}
-	masternodes := c.GetMasternodes(chain, header)
-	mstring := []string{}
-	for _, m := range masternodes {
-		mstring = append(mstring, m.String())
-	}
-	nstring := []string{}
-	for _, n := range snap.signers() {
-		nstring = append(nstring, n.String())
-	}
 	if _, ok := snap.Signers[signer]; !ok {
-		valid := false
+		return errUnauthorized
-		for _, m := range masternodes {
-			if m == signer {
-				valid = true
-				break
-			}
-		}
-		if !valid {
-			log.Debug("Unauthorized signer found", "block number", number, "signer", signer.String(), "masternodes", mstring, "snapshot from parent block", nstring)
-			return errUnauthorized
-		}
 	}
 	for seen, recent := range snap.Recents {
 		if recent == signer {
 			// Signer is among recents, only fail if the current block doesn't shift it out
-			if limit := uint64(len(masternodes)/2 + 1); seen > number-limit {
+			if limit := uint64(len(snap.Signers)/2 + 1); seen > number-limit {
-				// Only take into account the non-epoch blocks
+				return errUnauthorized
-				if number%c.config.Epoch != 0 {
-					return errUnauthorized
-				}
 			}
 		}
 	}
+	// Ensure that the difficulty corresponds to the turn-ness of the signer
+	inturn := snap.inturn(header.Number.Uint64(), signer)
+	if inturn && header.Difficulty.Cmp(diffInTurn) != 0 {
+		return errInvalidDifficulty
+	}
+	if !inturn && header.Difficulty.Cmp(diffNoTurn) != 0 {
+		return errInvalidDifficulty
+	}
 	return nil
 }
 
@@ -634,51 +567,9 @@ func (c *Clique) Prepare(chain consensus.ChainReader, header *types.Header) erro
 	return nil
 }
 
-func (c *Clique) UpdateMasternodes(chain consensus.ChainReader, header *types.Header, ms []Masternode) error {
-	number := header.Number.Uint64()
-	log.Trace("take snapshot", "number", number, "hash", header.Hash())
-	// get snapshot
-	snap, err := c.snapshot(chain, number, header.Hash(), nil)
-	if err != nil {
-		return err
-	}
-	currentSigners := snap.signers()
-	proposedSigners := make(map[common.Address]struct{})
-	// count all addresses in ms to be masternode
-	for _, m := range ms {
-		proposedSigners[m.Address] = struct{}{}
-		snap.Signers[m.Address] = struct{}{}
-	}
-	// deactivate current masternodes which aren't in ms
-	for _, s := range currentSigners {
-		if _, ok := proposedSigners[s]; !ok {
-			delete(snap.Signers, s)
-		}
-	}
-	nm := []string{}
-	newSigners := snap.signers()
-	for _, n := range newSigners {
-		nm = append(nm, n.String())
-	}
-	c.recents.Add(snap.Hash, snap)
-	log.Info("New set of masternodes has been updated to snapshot", "number", snap.Number, "hash", snap.Hash, "new masternodes", nm)
-	return nil
-}
-
 // Finalize implements consensus.Engine, ensuring no uncles are set, nor block
 // rewards given, and returns the final block.
 func (c *Clique) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
-	// set block reward
-	// FIXME: unit Ether could be too plump
-	number := header.Number.Uint64()
-	rCheckpoint := chain.Config().Clique.RewardCheckpoint
-
-	if c.HookReward != nil && number%rCheckpoint == 0 {
-		if err := c.HookReward(chain, state, header); err != nil {
-			return nil, err
-		}
-	}
-
 	// No block rewards in PoA, so the state remains as is and uncles are dropped
 	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
 	header.UncleHash = types.CalcUncleHash(nil)
@@ -721,31 +612,18 @@ func (c *Clique) Seal(chain consensus.ChainReader, block *types.Block, stop <-ch
 	if err != nil {
 		return nil, err
 	}
-	masternodes := c.GetMasternodes(chain, header)
+	masternodes := []common.Address{}
 	if _, authorized := snap.Signers[signer]; !authorized {
-		valid := false
+		return nil, errUnauthorized
-		for _, m := range masternodes {
-			if m == signer {
-				valid = true
-				break
-			}
-		}
-		if !valid {
-			return nil, errUnauthorized
-		}
 	}
 	// If we're amongst the recent signers, wait for the next block
 	for seen, recent := range snap.Recents {
 		if recent == signer {
 			// Signer is among recents, only wait if the current block doesn't shift it out
 			if limit := uint64(len(masternodes)/2 + 1); number < limit || seen > number-limit {
-				// Only take into account the non-epoch blocks
+				log.Info("Signed recently, must wait for others")
-				if number%c.config.Epoch != 0 {
+				<-stop
-					log.Info("Debugging", "len(masternodes)", len(masternodes), "number", number, "limit", limit, "seen", seen, "recent", recent.String(), "snap.Recents", snap.Recents)
+				return nil, nil
-					log.Info("Signed recently, must wait for others")
-					<-stop
-					return nil, nil
-				}
 			}
 		}
 	}
@@ -753,7 +631,7 @@ func (c *Clique) Seal(chain consensus.ChainReader, block *types.Block, stop <-ch
 	delay := time.Unix(header.Time.Int64(), 0).Sub(time.Now()) // nolint: gosimple
 	if header.Difficulty.Cmp(diffNoTurn) == 0 {
 		// It's not our turn explicitly to sign, delay it a bit
-		wiggle := time.Duration(len(masternodes)/2+1) * wiggleTime
+		wiggle := time.Duration(len(snap.Signers)/2+1) * wiggleTime
 		delay += time.Duration(rand.Int63n(int64(wiggle)))
 
 		log.Trace("Out-of-turn signing requested", "wiggle", common.PrettyDuration(wiggle))
@@ -806,20 +684,3 @@ func (c *Clique) APIs(chain consensus.ChainReader) []rpc.API {
 		Public:    false,
 	}}
 }
-
-func (c *Clique) RecoverSigner(header *types.Header) (common.Address, error) {
-	return ecrecover(header, c.signatures)
-}
-
-// Get master nodes over extra data of previous checkpoint block.
-func (c *Clique) GetMasternodesFromCheckpointHeader(preCheckpointHeader *types.Header, n, e uint64) []common.Address {
-	if preCheckpointHeader == nil {
-		log.Info("Previous checkpoint's header is empty", "block number", n, "epoch", e)
-		return []common.Address{}
-	}
-	masternodes := make([]common.Address, (len(preCheckpointHeader.Extra)-extraVanity-extraSeal)/common.AddressLength)
-	for i := 0; i < len(masternodes); i++ {
-		copy(masternodes[i][:], preCheckpointHeader.Extra[extraVanity+i*common.AddressLength:])
-	}
-	return masternodes
-}

consensus/clique/snapshot.go

@@ -45,8 +45,8 @@ type Tally struct {
 
 // Snapshot is the state of the authorization voting at a given point in time.
 type Snapshot struct {
-	config   *params.CliqueConfig // Consensus engine parameters to fine tune behavior
+	config   *params.PosvConfig // Consensus engine parameters to fine tune behavior
-	sigcache *lru.ARCCache        // Cache of recent block signatures to speed up ecrecover
+	sigcache *lru.ARCCache      // Cache of recent block signatures to speed up ecrecover
 
 	Number  uint64                      `json:"number"`  // Block number where the snapshot was created
 	Hash    common.Hash                 `json:"hash"`    // Block hash where the snapshot was created
@@ -59,7 +59,7 @@ type Snapshot struct {
 // newSnapshot creates a new snapshot with the specified startup parameters. This
 // method does not initialize the set of recent signers, so only ever use if for
 // the genesis block.
-func newSnapshot(config *params.CliqueConfig, sigcache *lru.ARCCache, number uint64, hash common.Hash, signers []common.Address) *Snapshot {
+func newSnapshot(config *params.PosvConfig, sigcache *lru.ARCCache, number uint64, hash common.Hash, signers []common.Address) *Snapshot {
 	snap := &Snapshot{
 		config:   config,
 		sigcache: sigcache,
@@ -76,7 +76,7 @@ func newSnapshot(config *params.CliqueConfig, sigcache *lru.ARCCache, number uin
 }
 
 // loadSnapshot loads an existing snapshot from the database.
-func loadSnapshot(config *params.CliqueConfig, sigcache *lru.ARCCache, db ethdb.Database, hash common.Hash) (*Snapshot, error) {
+func loadSnapshot(config *params.PosvConfig, sigcache *lru.ARCCache, db ethdb.Database, hash common.Hash) (*Snapshot, error) {
 	blob, err := db.Get(append([]byte("clique-"), hash[:]...))
 	if err != nil {
 		return nil, err
@@ -205,15 +205,14 @@ func (s *Snapshot) apply(headers []*types.Header) (*Snapshot, error) {
 		if err != nil {
 			return nil, err
 		}
-		//FIXME: skip signer checking at this step until a good solution found
+		if _, ok := snap.Signers[signer]; !ok {
-		//if _, ok := snap.Signers[signer]; !ok {
+			return nil, errUnauthorized
-		//	return nil, errUnauthorized
+		}
-		//}
+		for _, recent := range snap.Recents {
-		//for _, recent := range snap.Recents {
+			if recent == signer {
-		//	if recent == signer {
+				return nil, errUnauthorized
-		//		return nil, errUnauthorized
+			}
-		//	}
+		}
-		//}
 		snap.Recents[number] = signer
 
 		// Header authorized, discard any previous votes from the signer

consensus/clique/snapshot_test.go

@@ -74,7 +74,7 @@ type testerChainReader struct {
 	db ethdb.Database
 }
 
-func (r *testerChainReader) Config() *params.ChainConfig                 { return params.AllCliqueProtocolChanges }
+func (r *testerChainReader) Config() *params.ChainConfig                 { return params.AllPosvProtocolChanges }
 func (r *testerChainReader) CurrentHeader() *types.Header                { panic("not supported") }
 func (r *testerChainReader) GetHeader(common.Hash, uint64) *types.Header { panic("not supported") }
 func (r *testerChainReader) GetBlock(common.Hash, uint64) *types.Block   { panic("not supported") }
@@ -374,7 +374,7 @@ func TestVoting(t *testing.T) {
 		// Pass all the headers through clique and ensure tallying succeeds
 		head := headers[len(headers)-1]
 
-		snap, err := New(&params.CliqueConfig{Epoch: tt.epoch}, db).snapshot(&testerChainReader{db: db}, head.Number.Uint64(), head.Hash(), headers)
+		snap, err := New(&params.PosvConfig{Epoch: tt.epoch}, db).snapshot(&testerChainReader{db: db}, head.Number.Uint64(), head.Hash(), headers)
 		if err != nil {
 			t.Errorf("test %d: failed to create voting snapshot: %v", i, err)
 			continue

consensus/posv/api.go

@@ -0,0 +1,100 @@
+// Copyright (c) 2018 Tomochain
+//
+// This program 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.
+//
+// This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
+
+package posv
+
+import (
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+// API is a user facing RPC API to allow controlling the signer and voting
+// mechanisms of the proof-of-authority scheme.
+type API struct {
+	chain consensus.ChainReader
+	posv  *Posv
+}
+
+// GetSnapshot retrieves the state snapshot at a given block.
+func (api *API) GetSnapshot(number *rpc.BlockNumber) (*Snapshot, error) {
+	// Retrieve the requested block number (or current if none requested)
+	var header *types.Header
+	if number == nil || *number == rpc.LatestBlockNumber {
+		header = api.chain.CurrentHeader()
+	} else {
+		header = api.chain.GetHeaderByNumber(uint64(number.Int64()))
+	}
+	// Ensure we have an actually valid block and return its snapshot
+	if header == nil {
+		return nil, errUnknownBlock
+	}
+	return api.posv.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
+}
+
+// GetSnapshotAtHash retrieves the state snapshot at a given block.
+func (api *API) GetSnapshotAtHash(hash common.Hash) (*Snapshot, error) {
+	header := api.chain.GetHeaderByHash(hash)
+	if header == nil {
+		return nil, errUnknownBlock
+	}
+	return api.posv.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
+}
+
+// GetSigners retrieves the list of authorized signers at the specified block.
+func (api *API) GetSigners(number *rpc.BlockNumber) ([]common.Address, error) {
+	// Retrieve the requested block number (or current if none requested)
+	var header *types.Header
+	if number == nil || *number == rpc.LatestBlockNumber {
+		header = api.chain.CurrentHeader()
+	} else {
+		header = api.chain.GetHeaderByNumber(uint64(number.Int64()))
+	}
+	// Ensure we have an actually valid block and return the signers from its snapshot
+	if header == nil {
+		return nil, errUnknownBlock
+	}
+	snap, err := api.posv.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
+	if err != nil {
+		return nil, err
+	}
+	return snap.signers(), nil
+}
+
+// GetSignersAtHash retrieves the state snapshot at a given block.
+func (api *API) GetSignersAtHash(hash common.Hash) ([]common.Address, error) {
+	header := api.chain.GetHeaderByHash(hash)
+	if header == nil {
+		return nil, errUnknownBlock
+	}
+	snap, err := api.posv.snapshot(api.chain, header.Number.Uint64(), header.Hash(), nil)
+	if err != nil {
+		return nil, err
+	}
+	return snap.signers(), nil
+}
+
+// Proposals returns the current proposals the node tries to uphold and vote on.
+func (api *API) Proposals() map[common.Address]bool {
+	api.posv.lock.RLock()
+	defer api.posv.lock.RUnlock()
+
+	proposals := make(map[common.Address]bool)
+	for address, auth := range api.posv.proposals {
+		proposals[address] = auth
+	}
+	return proposals
+}

consensus/posv/posv.go

@@ -0,0 +1,845 @@
+// Copyright (c) 2018 Tomochain
+//
+// This program 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.
+//
+// This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
+
+// Package posv implements the proof-of-stake-voting consensus engine.
+package posv
+
+import (
+	"bytes"
+	"errors"
+	"math/big"
+	"math/rand"
+	"sync"
+	"time"
+
+	"fmt"
+	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+	"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"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/rpc"
+	"github.com/hashicorp/golang-lru"
+	"github.com/ethereum/go-ethereum/consensus/clique"
+)
+
+const (
+	inmemorySnapshots  = 128                    // Number of recent vote snapshots to keep in memory
+	inmemorySignatures = 4096                   // Number of recent block signatures to keep in memory
+	wiggleTime         = 500 * time.Millisecond // Random delay (per signer) to allow concurrent signers
+)
+
+type Masternode struct {
+	Address common.Address
+	Stake   string
+}
+
+// Posv proof-of-stake-voting protocol constants.
+var (
+	epochLength = uint64(30000) // Default number of blocks after which to checkpoint and reset the pending votes
+	blockPeriod = uint64(15)    // Default minimum difference between two consecutive block's timestamps
+
+	extraVanity = 32 // Fixed number of extra-data prefix bytes reserved for signer vanity
+	extraSeal   = 65 // Fixed number of extra-data suffix bytes reserved for signer seal
+
+	nonceAuthVote = hexutil.MustDecode("0xffffffffffffffff") // Magic nonce number to vote on adding a new signer
+	nonceDropVote = hexutil.MustDecode("0x0000000000000000") // Magic nonce number to vote on removing a signer.
+
+	uncleHash = types.CalcUncleHash(nil) // Always Keccak256(RLP([])) as uncles are meaningless outside of PoW.
+
+	diffInTurn = big.NewInt(2) // Block difficulty for in-turn signatures
+	diffNoTurn = big.NewInt(1) // Block difficulty for out-of-turn signatures
+)
+
+// Various error messages to mark blocks invalid. These should be private to
+// prevent engine specific errors from being referenced in the remainder of the
+// codebase, inherently breaking if the engine is swapped out. Please put common
+// error types into the consensus package.
+var (
+	// errUnknownBlock is returned when the list of signers is requested for a block
+	// that is not part of the local blockchain.
+	errUnknownBlock = errors.New("unknown block")
+
+	// errInvalidCheckpointBeneficiary is returned if a checkpoint/epoch transition
+	// block has a beneficiary set to non-zeroes.
+	errInvalidCheckpointBeneficiary = errors.New("beneficiary in checkpoint block non-zero")
+
+	// errInvalidVote is returned if a nonce value is something else that the two
+	// allowed constants of 0x00..0 or 0xff..f.
+	errInvalidVote = errors.New("vote nonce not 0x00..0 or 0xff..f")
+
+	// errInvalidCheckpointVote is returned if a checkpoint/epoch transition block
+	// has a vote nonce set to non-zeroes.
+	errInvalidCheckpointVote = errors.New("vote nonce in checkpoint block non-zero")
+
+	// errMissingVanity is returned if a block's extra-data section is shorter than
+	// 32 bytes, which is required to store the signer vanity.
+	errMissingVanity = errors.New("extra-data 32 byte vanity prefix missing")
+
+	// errMissingSignature is returned if a block's extra-data section doesn't seem
+	// to contain a 65 byte secp256k1 signature.
+	errMissingSignature = errors.New("extra-data 65 byte suffix signature missing")
+
+	// errExtraSigners is returned if non-checkpoint block contain signer data in
+	// their extra-data fields.
+	errExtraSigners = errors.New("non-checkpoint block contains extra signer list")
+
+	// errInvalidCheckpointSigners is returned if a checkpoint block contains an
+	// invalid list of signers (i.e. non divisible by 20 bytes, or not the correct
+	// ones).
+	errInvalidCheckpointSigners = errors.New("invalid signer list on checkpoint block")
+
+	// errInvalidMixDigest is returned if a block's mix digest is non-zero.
+	errInvalidMixDigest = errors.New("non-zero mix digest")
+
+	// errInvalidUncleHash is returned if a block contains an non-empty uncle list.
+	errInvalidUncleHash = errors.New("non empty uncle hash")
+
+	// errInvalidDifficulty is returned if the difficulty of a block is not either
+	// of 1 or 2, or if the value does not match the turn of the signer.
+	errInvalidDifficulty = errors.New("invalid difficulty")
+
+	// ErrInvalidTimestamp is returned if the timestamp of a block is lower than
+	// the previous block's timestamp + the minimum block period.
+	ErrInvalidTimestamp = errors.New("invalid timestamp")
+
+	// errInvalidVotingChain is returned if an authorization list is attempted to
+	// be modified via out-of-range or non-contiguous headers.
+	errInvalidVotingChain = errors.New("invalid voting chain")
+
+	// errUnauthorized is returned if a header is signed by a non-authorized entity.
+	errUnauthorized = errors.New("unauthorized")
+
+	// errWaitTransactions is returned if an empty block is attempted to be sealed
+	// on an instant chain (0 second period). It's important to refuse these as the
+	// block reward is zero, so an empty block just bloats the chain... fast.
+	errWaitTransactions = errors.New("waiting for transactions")
+)
+
+// SignerFn is a signer callback function to request a hash to be signed by a
+// backing account.
+//type SignerFn func(accounts.Account, []byte) ([]byte, error)
+
+// sigHash returns the hash which is used as input for the proof-of-stake-voting
+// signing. It is the hash of the entire header apart from the 65 byte signature
+// contained at the end of the extra data.
+//
+// Note, the method requires the extra data to be at least 65 bytes, otherwise it
+// panics. This is done to avoid accidentally using both forms (signature present
+// or not), which could be abused to produce different hashes for the same header.
+func sigHash(header *types.Header) (hash common.Hash) {
+	hasher := sha3.NewKeccak256()
+
+	rlp.Encode(hasher, []interface{}{
+		header.ParentHash,
+		header.UncleHash,
+		header.Coinbase,
+		header.Root,
+		header.TxHash,
+		header.ReceiptHash,
+		header.Bloom,
+		header.Difficulty,
+		header.Number,
+		header.GasLimit,
+		header.GasUsed,
+		header.Time,
+		header.Extra[:len(header.Extra)-65], // Yes, this will panic if extra is too short
+		header.MixDigest,
+		header.Nonce,
+	})
+	hasher.Sum(hash[:0])
+	return hash
+}
+
+// ecrecover extracts the Ethereum account address from a signed header.
+func ecrecover(header *types.Header, sigcache *lru.ARCCache) (common.Address, error) {
+	// If the signature's already cached, return that
+	hash := header.Hash()
+	if address, known := sigcache.Get(hash); known {
+		return address.(common.Address), nil
+	}
+	// Retrieve the signature from the header extra-data
+	if len(header.Extra) < extraSeal {
+		return common.Address{}, errMissingSignature
+	}
+	signature := header.Extra[len(header.Extra)-extraSeal:]
+
+	// Recover the public key and the Ethereum address
+	pubkey, err := crypto.Ecrecover(sigHash(header).Bytes(), signature)
+	if err != nil {
+		return common.Address{}, err
+	}
+	var signer common.Address
+	copy(signer[:], crypto.Keccak256(pubkey[1:])[12:])
+
+	sigcache.Add(hash, signer)
+	return signer, nil
+}
+
+// Posv is the proof-of-stake-voting consensus engine proposed to support the
+// Ethereum testnet following the Ropsten attacks.
+type Posv struct {
+	config *params.PosvConfig // Consensus engine configuration parameters
+	db     ethdb.Database     // Database to store and retrieve snapshot checkpoints
+
+	recents    *lru.ARCCache // Snapshots for recent block to speed up reorgs
+	signatures *lru.ARCCache // Signatures of recent blocks to speed up mining
+
+	proposals map[common.Address]bool // Current list of proposals we are pushing
+
+	signer common.Address // Ethereum address of the signing key
+	signFn clique.SignerFn       // Signer function to authorize hashes with
+	lock   sync.RWMutex   // Protects the signer fields
+
+	HookReward func(chain consensus.ChainReader, state *state.StateDB, header *types.Header) error
+}
+
+// New creates a Posv proof-of-stake-voting consensus engine with the initial
+// signers set to the ones provided by the user.
+func New(config *params.PosvConfig, db ethdb.Database) *Posv {
+	// Set any missing consensus parameters to their defaults
+	conf := *config
+	if conf.Epoch == 0 {
+		conf.Epoch = epochLength
+	}
+	// Allocate the snapshot caches and create the engine
+	recents, _ := lru.NewARC(inmemorySnapshots)
+	signatures, _ := lru.NewARC(inmemorySignatures)
+
+	return &Posv{
+		config:     &conf,
+		db:         db,
+		recents:    recents,
+		signatures: signatures,
+		proposals:  make(map[common.Address]bool),
+	}
+}
+
+// Author implements consensus.Engine, returning the Ethereum address recovered
+// from the signature in the header's extra-data section.
+func (c *Posv) Author(header *types.Header) (common.Address, error) {
+	return ecrecover(header, c.signatures)
+}
+
+// VerifyHeader checks whether a header conforms to the consensus rules.
+func (c *Posv) VerifyHeader(chain consensus.ChainReader, header *types.Header, seal bool) error {
+	return c.verifyHeader(chain, header, nil)
+}
+
+// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers. The
+// method returns a quit channel to abort the operations and a results channel to
+// retrieve the async verifications (the order is that of the input slice).
+func (c *Posv) VerifyHeaders(chain consensus.ChainReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error) {
+	abort := make(chan struct{})
+	results := make(chan error, len(headers))
+
+	go func() {
+		for i, header := range headers {
+			err := c.verifyHeader(chain, header, headers[:i])
+
+			select {
+			case <-abort:
+				return
+			case results <- err:
+			}
+		}
+	}()
+	return abort, results
+}
+
+// verifyHeader checks whether a header conforms to the consensus rules.The
+// caller may optionally pass in a batch of parents (ascending order) to avoid
+// looking those up from the database. This is useful for concurrently verifying
+// a batch of new headers.
+func (c *Posv) verifyHeader(chain consensus.ChainReader, header *types.Header, parents []*types.Header) error {
+	if header.Number == nil {
+		return errUnknownBlock
+	}
+	number := header.Number.Uint64()
+
+	// Don't waste time checking blocks from the future
+	if header.Time.Cmp(big.NewInt(time.Now().Unix())) > 0 {
+		return consensus.ErrFutureBlock
+	}
+	// Checkpoint blocks need to enforce zero beneficiary
+	checkpoint := (number % c.config.Epoch) == 0
+	if checkpoint && header.Coinbase != (common.Address{}) {
+		return errInvalidCheckpointBeneficiary
+	}
+
+	// Nonces must be 0x00..0 or 0xff..f, zeroes enforced on checkpoints
+	if !bytes.Equal(header.Nonce[:], nonceAuthVote) && !bytes.Equal(header.Nonce[:], nonceDropVote) {
+		return errInvalidVote
+	}
+	if checkpoint && !bytes.Equal(header.Nonce[:], nonceDropVote) {
+		return errInvalidCheckpointVote
+	}
+	// Check that the extra-data contains both the vanity and signature
+	if len(header.Extra) < extraVanity {
+		return errMissingVanity
+	}
+	if len(header.Extra) < extraVanity+extraSeal {
+		return errMissingSignature
+	}
+	// Ensure that the extra-data contains a signer list on checkpoint, but none otherwise
+	signersBytes := len(header.Extra) - extraVanity - extraSeal
+	if !checkpoint && signersBytes != 0 {
+		return errExtraSigners
+	}
+	if checkpoint && signersBytes%common.AddressLength != 0 {
+		return errInvalidCheckpointSigners
+	}
+	// Ensure that the mix digest is zero as we don't have fork protection currently
+	if header.MixDigest != (common.Hash{}) {
+		return errInvalidMixDigest
+	}
+	// Ensure that the block doesn't contain any uncles which are meaningless in PoA
+	if header.UncleHash != uncleHash {
+		return errInvalidUncleHash
+	}
+	// Ensure that the block's difficulty is meaningful (may not be correct at this point)
+	if number > 0 {
+		if header.Difficulty == nil || (header.Difficulty.Cmp(diffInTurn) != 0 && header.Difficulty.Cmp(diffNoTurn) != 0) {
+			return errInvalidDifficulty
+		}
+	}
+	// If all checks passed, validate any special fields for hard forks
+	if err := misc.VerifyForkHashes(chain.Config(), header, false); err != nil {
+		return err
+	}
+	// All basic checks passed, verify cascading fields
+	return c.verifyCascadingFields(chain, header, parents)
+}
+
+// verifyCascadingFields verifies all the header fields that are not standalone,
+// rather depend on a batch of previous headers. The caller may optionally pass
+// in a batch of parents (ascending order) to avoid looking those up from the
+// database. This is useful for concurrently verifying a batch of new headers.
+func (c *Posv) verifyCascadingFields(chain consensus.ChainReader, header *types.Header, parents []*types.Header) error {
+	// The genesis block is the always valid dead-end
+	number := header.Number.Uint64()
+	if number == 0 {
+		return nil
+	}
+	// Ensure that the block's timestamp isn't too close to it's parent
+	var parent *types.Header
+	if len(parents) > 0 {
+		parent = parents[len(parents)-1]
+	} else {
+		parent = chain.GetHeader(header.ParentHash, number-1)
+	}
+	if parent == nil || parent.Number.Uint64() != number-1 || parent.Hash() != header.ParentHash {
+		return consensus.ErrUnknownAncestor
+	}
+	if parent.Time.Uint64()+c.config.Period > header.Time.Uint64() {
+		return ErrInvalidTimestamp
+	}
+	// Retrieve the snapshot needed to verify this header and cache it
+	snap, err := c.snapshot(chain, number-1, header.ParentHash, parents)
+	if err != nil {
+		return err
+	}
+	// If the block is a checkpoint block, verify the signer list
+	if number%c.config.Epoch == 0 {
+		signers := make([]byte, len(snap.Signers)*common.AddressLength)
+		for i, signer := range snap.signers() {
+			copy(signers[i*common.AddressLength:], signer[:])
+		}
+		extraSuffix := len(header.Extra) - extraSeal
+		if !bytes.Equal(header.Extra[extraVanity:extraSuffix], signers) {
+			return errInvalidCheckpointSigners
+		}
+	}
+	// All basic checks passed, verify the seal and return
+	return c.verifySeal(chain, header, parents)
+}
+
+func (c *Posv) GetSnapshot(chain consensus.ChainReader, header *types.Header) (*Snapshot, error) {
+	number := header.Number.Uint64()
+	log.Trace("take snapshot", "number", number, "hash", header.Hash())
+	snap, err := c.snapshot(chain, number, header.Hash(), nil)
+	if err != nil {
+		return nil, err
+	}
+	return snap, nil
+}
+
+func (c *Posv) StoreSnapshot(snap *Snapshot) error {
+	return snap.store(c.db)
+}
+
+func position(list []common.Address, x common.Address) int {
+	for i, item := range list {
+		if item == x {
+			return i
+		}
+	}
+	return -1
+}
+
+func (c *Posv) GetMasternodes(chain consensus.ChainReader, header *types.Header) []common.Address {
+	n := header.Number.Uint64()
+	e := c.config.Epoch
+	switch {
+	case n%e == 0:
+		return c.GetMasternodesFromCheckpointHeader(header, n, e)
+	case n%e != 0:
+		h := chain.GetHeaderByNumber(n - (n % e))
+		return c.GetMasternodesFromCheckpointHeader(h, n, e)
+	default:
+		return []common.Address{}
+	}
+}
+
+func (c *Posv) GetPeriod() uint64 { return c.config.Period }
+
+func YourTurn(masternodes []common.Address, snap *Snapshot, header *types.Header, cur common.Address) (int, int, bool, error) {
+	if len(masternodes) == 0 {
+		return -1, -1, true, nil
+	}
+	pre := common.Address{}
+	// masternode[0] has chance to create block 1
+	var err error
+	preIndex := -1
+	if header.Number.Uint64() != 0 {
+		pre, err = ecrecover(header, snap.sigcache)
+		if err != nil {
+			return 0, 0, false, err
+		}
+		preIndex = position(masternodes, pre)
+	}
+	curIndex := position(masternodes, cur)
+	log.Info("Masternodes cycle info", "number of masternodes", len(masternodes), "previous", pre, "position", preIndex, "current", cur, "position", curIndex)
+	for i, s := range masternodes {
+		fmt.Printf("%d - %s\n", i, s.String())
+	}
+	if (preIndex+1)%len(masternodes) == curIndex {
+		return preIndex, curIndex, true, nil
+	}
+	return preIndex, curIndex, false, nil
+}
+
+// snapshot retrieves the authorization snapshot at a given point in time.
+func (c *Posv) snapshot(chain consensus.ChainReader, number uint64, hash common.Hash, parents []*types.Header) (*Snapshot, error) {
+	// Search for a snapshot in memory or on disk for checkpoints
+	var (
+		headers []*types.Header
+		snap    *Snapshot
+	)
+	for snap == nil {
+		// If an in-memory snapshot was found, use that
+		if s, ok := c.recents.Get(hash); ok {
+			snap = s.(*Snapshot)
+			break
+		}
+		// If an on-disk checkpoint snapshot can be found, use that
+		// checkpoint snapshot = checkpoint - gap
+		if (number+c.config.Gap)%c.config.Epoch == 0 {
+			if s, err := loadSnapshot(c.config, c.signatures, c.db, hash); err == nil {
+				log.Trace("Loaded voting snapshot form disk", "number", number, "hash", hash)
+				snap = s
+				break
+			}
+		}
+		// If we're at block zero, make a snapshot
+		if number == 0 {
+			genesis := chain.GetHeaderByNumber(0)
+			if err := c.VerifyHeader(chain, genesis, false); err != nil {
+				return nil, err
+			}
+			signers := make([]common.Address, (len(genesis.Extra)-extraVanity-extraSeal)/common.AddressLength)
+			for i := 0; i < len(signers); i++ {
+				copy(signers[i][:], genesis.Extra[extraVanity+i*common.AddressLength:])
+			}
+			snap = newSnapshot(c.config, c.signatures, 0, genesis.Hash(), signers)
+			if err := snap.store(c.db); err != nil {
+				return nil, err
+			}
+			log.Trace("Stored genesis voting snapshot to disk")
+			break
+		}
+		// No snapshot for this header, gather the header and move backward
+		var header *types.Header
+		if len(parents) > 0 {
+			// If we have explicit parents, pick from there (enforced)
+			header = parents[len(parents)-1]
+			if header.Hash() != hash || header.Number.Uint64() != number {
+				return nil, consensus.ErrUnknownAncestor
+			}
+			parents = parents[:len(parents)-1]
+		} else {
+			// No explicit parents (or no more left), reach out to the database
+			header = chain.GetHeader(hash, number)
+			if header == nil {
+				return nil, consensus.ErrUnknownAncestor
+			}
+		}
+		headers = append(headers, header)
+		number, hash = number-1, header.ParentHash
+	}
+	// Previous snapshot found, apply any pending headers on top of it
+	for i := 0; i < len(headers)/2; i++ {
+		headers[i], headers[len(headers)-1-i] = headers[len(headers)-1-i], headers[i]
+	}
+	snap, err := snap.apply(headers)
+	if err != nil {
+		return nil, err
+	}
+	c.recents.Add(snap.Hash, snap)
+
+	// If we've generated a new checkpoint snapshot, save to disk
+	if (snap.Number+c.config.Gap)%c.config.Epoch == 0 {
+		if err = snap.store(c.db); err != nil {
+			return nil, err
+		}
+		log.Trace("Stored voting snapshot to disk", "number", snap.Number, "hash", snap.Hash)
+	}
+	return snap, err
+}
+
+// VerifyUncles implements consensus.Engine, always returning an error for any
+// uncles as this consensus mechanism doesn't permit uncles.
+func (c *Posv) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
+	if len(block.Uncles()) > 0 {
+		return errors.New("uncles not allowed")
+	}
+	return nil
+}
+
+// VerifySeal implements consensus.Engine, checking whether the signature contained
+// in the header satisfies the consensus protocol requirements.
+func (c *Posv) VerifySeal(chain consensus.ChainReader, header *types.Header) error {
+	return c.verifySeal(chain, header, nil)
+}
+
+// verifySeal checks whether the signature contained in the header satisfies the
+// consensus protocol requirements. The method accepts an optional list of parent
+// headers that aren't yet part of the local blockchain to generate the snapshots
+// from.
+func (c *Posv) verifySeal(chain consensus.ChainReader, header *types.Header, parents []*types.Header) error {
+	// Verifying the genesis block is not supported
+	number := header.Number.Uint64()
+	if number == 0 {
+		return errUnknownBlock
+	}
+	// Retrieve the snapshot needed to verify this header and cache it
+	snap, err := c.snapshot(chain, number-1, header.ParentHash, parents)
+	if err != nil {
+		return err
+	}
+
+	// Resolve the authorization key and check against signers
+	signer, err := ecrecover(header, c.signatures)
+	if err != nil {
+		return err
+	}
+	masternodes := c.GetMasternodes(chain, header)
+	mstring := []string{}
+	for _, m := range masternodes {
+		mstring = append(mstring, m.String())
+	}
+	nstring := []string{}
+	for _, n := range snap.signers() {
+		nstring = append(nstring, n.String())
+	}
+	if _, ok := snap.Signers[signer]; !ok {
+		valid := false
+		for _, m := range masternodes {
+			if m == signer {
+				valid = true
+				break
+			}
+		}
+		if !valid {
+			log.Debug("Unauthorized signer found", "block number", number, "signer", signer.String(), "masternodes", mstring, "snapshot from parent block", nstring)
+			return errUnauthorized
+		}
+	}
+	for seen, recent := range snap.Recents {
+		if recent == signer {
+			// Signer is among recents, only fail if the current block doesn't shift it out
+			if limit := uint64(len(masternodes)/2 + 1); seen > number-limit {
+				// Only take into account the non-epoch blocks
+				if number%c.config.Epoch != 0 {
+					return errUnauthorized
+				}
+			}
+		}
+	}
+	return nil
+}
+
+// Prepare implements consensus.Engine, preparing all the consensus fields of the
+// header for running the transactions on top.
+func (c *Posv) Prepare(chain consensus.ChainReader, header *types.Header) error {
+	// If the block isn't a checkpoint, cast a random vote (good enough for now)
+	header.Coinbase = common.Address{}
+	header.Nonce = types.BlockNonce{}
+
+	number := header.Number.Uint64()
+	// Assemble the voting snapshot to check which votes make sense
+	snap, err := c.snapshot(chain, number-1, header.ParentHash, nil)
+	if err != nil {
+		return err
+	}
+	if number%c.config.Epoch != 0 {
+		c.lock.RLock()
+
+		// Gather all the proposals that make sense voting on
+		addresses := make([]common.Address, 0, len(c.proposals))
+		for address, authorize := range c.proposals {
+			if snap.validVote(address, authorize) {
+				addresses = append(addresses, address)
+			}
+		}
+		// If there's pending proposals, cast a vote on them
+		if len(addresses) > 0 {
+			header.Coinbase = addresses[rand.Intn(len(addresses))]
+			if c.proposals[header.Coinbase] {
+				copy(header.Nonce[:], nonceAuthVote)
+			} else {
+				copy(header.Nonce[:], nonceDropVote)
+			}
+		}
+		c.lock.RUnlock()
+	}
+	// Set the correct difficulty
+	header.Difficulty = CalcDifficulty(snap, c.signer)
+
+	// Ensure the extra data has all it's components
+	if len(header.Extra) < extraVanity {
+		header.Extra = append(header.Extra, bytes.Repeat([]byte{0x00}, extraVanity-len(header.Extra))...)
+	}
+	header.Extra = header.Extra[:extraVanity]
+
+	if number%c.config.Epoch == 0 {
+		for _, signer := range snap.signers() {
+			header.Extra = append(header.Extra, signer[:]...)
+		}
+	}
+	header.Extra = append(header.Extra, make([]byte, extraSeal)...)
+
+	// Mix digest is reserved for now, set to empty
+	header.MixDigest = common.Hash{}
+
+	// Ensure the timestamp has the correct delay
+	parent := chain.GetHeader(header.ParentHash, number-1)
+	if parent == nil {
+		return consensus.ErrUnknownAncestor
+	}
+	header.Time = new(big.Int).Add(parent.Time, new(big.Int).SetUint64(c.config.Period))
+	if header.Time.Int64() < time.Now().Unix() {
+		header.Time = big.NewInt(time.Now().Unix())
+	}
+	return nil
+}
+
+func (c *Posv) UpdateMasternodes(chain consensus.ChainReader, header *types.Header, ms []Masternode) error {
+	number := header.Number.Uint64()
+	log.Trace("take snapshot", "number", number, "hash", header.Hash())
+	// get snapshot
+	snap, err := c.snapshot(chain, number, header.Hash(), nil)
+	if err != nil {
+		return err
+	}
+	currentSigners := snap.signers()
+	proposedSigners := make(map[common.Address]struct{})
+	// count all addresses in ms to be masternode
+	for _, m := range ms {
+		proposedSigners[m.Address] = struct{}{}
+		snap.Signers[m.Address] = struct{}{}
+	}
+	// deactivate current masternodes which aren't in ms
+	for _, s := range currentSigners {
+		if _, ok := proposedSigners[s]; !ok {
+			delete(snap.Signers, s)
+		}
+	}
+	nm := []string{}
+	newSigners := snap.signers()
+	for _, n := range newSigners {
+		nm = append(nm, n.String())
+	}
+	c.recents.Add(snap.Hash, snap)
+	log.Info("New set of masternodes has been updated to snapshot", "number", snap.Number, "hash", snap.Hash, "new masternodes", nm)
+	return nil
+}
+
+// Finalize implements consensus.Engine, ensuring no uncles are set, nor block
+// rewards given, and returns the final block.
+func (c *Posv) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
+	// set block reward
+	// FIXME: unit Ether could be too plump
+	number := header.Number.Uint64()
+	rCheckpoint := chain.Config().Posv.RewardCheckpoint
+
+	if c.HookReward != nil && number%rCheckpoint == 0 {
+		if err := c.HookReward(chain, state, header); err != nil {
+			return nil, err
+		}
+	}
+
+	// No block rewards in PoA, so the state remains as is and uncles are dropped
+	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
+	header.UncleHash = types.CalcUncleHash(nil)
+
+	// Assemble and return the final block for sealing
+	return types.NewBlock(header, txs, nil, receipts), nil
+}
+
+// Authorize injects a private key into the consensus engine to mint new blocks
+// with.
+func (c *Posv) Authorize(signer common.Address, signFn clique.SignerFn) {
+	c.lock.Lock()
+	defer c.lock.Unlock()
+
+	c.signer = signer
+	c.signFn = signFn
+}
+
+// Seal implements consensus.Engine, attempting to create a sealed block using
+// the local signing credentials.
+func (c *Posv) Seal(chain consensus.ChainReader, block *types.Block, stop <-chan struct{}) (*types.Block, error) {
+	header := block.Header()
+
+	// Sealing the genesis block is not supported
+	number := header.Number.Uint64()
+	if number == 0 {
+		return nil, errUnknownBlock
+	}
+	// For 0-period chains, refuse to seal empty blocks (no reward but would spin sealing)
+	if c.config.Period == 0 && len(block.Transactions()) == 0 {
+		return nil, errWaitTransactions
+	}
+	// Don't hold the signer fields for the entire sealing procedure
+	c.lock.RLock()
+	signer, signFn := c.signer, c.signFn
+	c.lock.RUnlock()
+
+	// Bail out if we're unauthorized to sign a block
+	snap, err := c.snapshot(chain, number-1, header.ParentHash, nil)
+	if err != nil {
+		return nil, err
+	}
+	masternodes := c.GetMasternodes(chain, header)
+	if _, authorized := snap.Signers[signer]; !authorized {
+		valid := false
+		for _, m := range masternodes {
+			if m == signer {
+				valid = true
+				break
+			}
+		}
+		if !valid {
+			return nil, errUnauthorized
+		}
+	}
+	// If we're amongst the recent signers, wait for the next block
+	for seen, recent := range snap.Recents {
+		if recent == signer {
+			// Signer is among recents, only wait if the current block doesn't shift it out
+			if limit := uint64(len(masternodes)/2 + 1); number < limit || seen > number-limit {
+				// Only take into account the non-epoch blocks
+				if number%c.config.Epoch != 0 {
+					log.Info("Debugging", "len(masternodes)", len(masternodes), "number", number, "limit", limit, "seen", seen, "recent", recent.String(), "snap.Recents", snap.Recents)
+					log.Info("Signed recently, must wait for others")
+					<-stop
+					return nil, nil
+				}
+			}
+		}
+	}
+	// Sweet, the protocol permits us to sign the block, wait for our time
+	delay := time.Unix(header.Time.Int64(), 0).Sub(time.Now()) // nolint: gosimple
+	if header.Difficulty.Cmp(diffNoTurn) == 0 {
+		// It's not our turn explicitly to sign, delay it a bit
+		wiggle := time.Duration(len(masternodes)/2+1) * wiggleTime
+		delay += time.Duration(rand.Int63n(int64(wiggle)))
+
+		log.Trace("Out-of-turn signing requested", "wiggle", common.PrettyDuration(wiggle))
+	}
+	log.Trace("Waiting for slot to sign and propagate", "delay", common.PrettyDuration(delay))
+
+	select {
+	case <-stop:
+		return nil, nil
+	case <-time.After(delay):
+	}
+	// Sign all the things!
+	sighash, err := signFn(accounts.Account{Address: signer}, sigHash(header).Bytes())
+	if err != nil {
+		return nil, err
+	}
+	copy(header.Extra[len(header.Extra)-extraSeal:], sighash)
+
+	return block.WithSeal(header), nil
+}
+
+// CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
+// that a new block should have based on the previous blocks in the chain and the
+// current signer.
+func (c *Posv) CalcDifficulty(chain consensus.ChainReader, time uint64, parent *types.Header) *big.Int {
+	snap, err := c.snapshot(chain, parent.Number.Uint64(), parent.Hash(), nil)
+	if err != nil {
+		return nil
+	}
+	return CalcDifficulty(snap, c.signer)
+}
+
+// CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
+// that a new block should have based on the previous blocks in the chain and the
+// current signer.
+func CalcDifficulty(snap *Snapshot, signer common.Address) *big.Int {
+	if snap.inturn(snap.Number+1, signer) {
+		return new(big.Int).Set(diffInTurn)
+	}
+	return new(big.Int).Set(diffNoTurn)
+}
+
+// APIs implements consensus.Engine, returning the user facing RPC API to allow
+// controlling the signer voting.
+func (c *Posv) APIs(chain consensus.ChainReader) []rpc.API {
+	return []rpc.API{{
+		Namespace: "posv",
+		Version:   "1.0",
+		Service:   &API{chain: chain, posv: c},
+		Public:    false,
+	}}
+}
+
+func (c *Posv) RecoverSigner(header *types.Header) (common.Address, error) {
+	return ecrecover(header, c.signatures)
+}
+
+// Get master nodes over extra data of previous checkpoint block.
+func (c *Posv) GetMasternodesFromCheckpointHeader(preCheckpointHeader *types.Header, n, e uint64) []common.Address {
+	if preCheckpointHeader == nil {
+		log.Info("Previous checkpoint's header is empty", "block number", n, "epoch", e)
+		return []common.Address{}
+	}
+	masternodes := make([]common.Address, (len(preCheckpointHeader.Extra)-extraVanity-extraSeal)/common.AddressLength)
+	for i := 0; i < len(masternodes); i++ {
+		copy(masternodes[i][:], preCheckpointHeader.Extra[extraVanity+i*common.AddressLength:])
+	}
+	return masternodes
+}

consensus/posv/snapshot.go

@@ -0,0 +1,311 @@
+// Copyright (c) 2018 Tomochain
+//
+// This program 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.
+//
+// This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
+
+package posv
+
+import (
+	"bytes"
+	"encoding/json"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/params"
+	lru "github.com/hashicorp/golang-lru"
+	"github.com/ethereum/go-ethereum/consensus/clique"
+)
+
+// Vote represents a single vote that an authorized signer made to modify the
+// list of authorizations.
+//type Vote struct {
+//	Signer    common.Address `json:"signer"`    // Authorized signer that cast this vote
+//	Block     uint64         `json:"block"`     // Block number the vote was cast in (expire old votes)
+//	Address   common.Address `json:"address"`   // Account being voted on to change its authorization
+//	Authorize bool           `json:"authorize"` // Whether to authorize or deauthorize the voted account
+//}
+
+// Tally is a simple vote tally to keep the current score of votes. Votes that
+// go against the proposal aren't counted since it's equivalent to not voting.
+//type Tally struct {
+//	Authorize bool `json:"authorize"` // Whether the vote is about authorizing or kicking someone
+//	Votes     int  `json:"votes"`     // Number of votes until now wanting to pass the proposal
+//}
+
+// Snapshot is the state of the authorization voting at a given point in time.
+type Snapshot struct {
+	config   *params.PosvConfig // Consensus engine parameters to fine tune behavior
+	sigcache *lru.ARCCache      // Cache of recent block signatures to speed up ecrecover
+
+	Number  uint64                      `json:"number"`  // Block number where the snapshot was created
+	Hash    common.Hash                 `json:"hash"`    // Block hash where the snapshot was created
+	Signers map[common.Address]struct{} `json:"signers"` // Set of authorized signers at this moment
+	Recents map[uint64]common.Address   `json:"recents"` // Set of recent signers for spam protections
+	Votes   []*clique.Vote                     `json:"votes"`   // List of votes cast in chronological order
+	Tally   map[common.Address]clique.Tally    `json:"tally"`   // Current vote tally to avoid recalculating
+}
+
+// newSnapshot creates a new snapshot with the specified startup parameters. This
+// method does not initialize the set of recent signers, so only ever use if for
+// the genesis block.
+func newSnapshot(config *params.PosvConfig, sigcache *lru.ARCCache, number uint64, hash common.Hash, signers []common.Address) *Snapshot {
+	snap := &Snapshot{
+		config:   config,
+		sigcache: sigcache,
+		Number:   number,
+		Hash:     hash,
+		Signers:  make(map[common.Address]struct{}),
+		Recents:  make(map[uint64]common.Address),
+		Tally:    make(map[common.Address]clique.Tally),
+	}
+	for _, signer := range signers {
+		snap.Signers[signer] = struct{}{}
+	}
+	return snap
+}
+
+// loadSnapshot loads an existing snapshot from the database.
+func loadSnapshot(config *params.PosvConfig, sigcache *lru.ARCCache, db ethdb.Database, hash common.Hash) (*Snapshot, error) {
+	blob, err := db.Get(append([]byte("posv-"), hash[:]...))
+	if err != nil {
+		return nil, err
+	}
+	snap := new(Snapshot)
+	if err := json.Unmarshal(blob, snap); err != nil {
+		return nil, err
+	}
+	snap.config = config
+	snap.sigcache = sigcache
+
+	return snap, nil
+}
+
+// store inserts the snapshot into the database.
+func (s *Snapshot) store(db ethdb.Database) error {
+	blob, err := json.Marshal(s)
+	if err != nil {
+		return err
+	}
+	return db.Put(append([]byte("posv-"), s.Hash[:]...), blob)
+}
+
+// copy creates a deep copy of the snapshot, though not the individual votes.
+func (s *Snapshot) copy() *Snapshot {
+	cpy := &Snapshot{
+		config:   s.config,
+		sigcache: s.sigcache,
+		Number:   s.Number,
+		Hash:     s.Hash,
+		Signers:  make(map[common.Address]struct{}),
+		Recents:  make(map[uint64]common.Address),
+		Votes:    make([]*clique.Vote, len(s.Votes)),
+		Tally:    make(map[common.Address]clique.Tally),
+	}
+	for signer := range s.Signers {
+		cpy.Signers[signer] = struct{}{}
+	}
+	for block, signer := range s.Recents {
+		cpy.Recents[block] = signer
+	}
+	for address, tally := range s.Tally {
+		cpy.Tally[address] = tally
+	}
+	copy(cpy.Votes, s.Votes)
+
+	return cpy
+}
+
+// validVote returns whether it makes sense to cast the specified vote in the
+// given snapshot context (e.g. don't try to add an already authorized signer).
+func (s *Snapshot) validVote(address common.Address, authorize bool) bool {
+	_, signer := s.Signers[address]
+	return (signer && !authorize) || (!signer && authorize)
+}
+
+// cast adds a new vote into the tally.
+func (s *Snapshot) cast(address common.Address, authorize bool) bool {
+	// Ensure the vote is meaningful
+	if !s.validVote(address, authorize) {
+		return false
+	}
+	// Cast the vote into an existing or new tally
+	if old, ok := s.Tally[address]; ok {
+		old.Votes++
+		s.Tally[address] = old
+	} else {
+		s.Tally[address] = clique.Tally{Authorize: authorize, Votes: 1}
+	}
+	return true
+}
+
+// uncast removes a previously cast vote from the tally.
+func (s *Snapshot) uncast(address common.Address, authorize bool) bool {
+	// If there's no tally, it's a dangling vote, just drop
+	tally, ok := s.Tally[address]
+	if !ok {
+		return false
+	}
+	// Ensure we only revert counted votes
+	if tally.Authorize != authorize {
+		return false
+	}
+	// Otherwise revert the vote
+	if tally.Votes > 1 {
+		tally.Votes--
+		s.Tally[address] = tally
+	} else {
+		delete(s.Tally, address)
+	}
+	return true
+}
+
+// apply creates a new authorization snapshot by applying the given headers to
+// the original one.
+func (s *Snapshot) apply(headers []*types.Header) (*Snapshot, error) {
+	// Allow passing in no headers for cleaner code
+	if len(headers) == 0 {
+		return s, nil
+	}
+	// Sanity check that the headers can be applied
+	for i := 0; i < len(headers)-1; i++ {
+		if headers[i+1].Number.Uint64() != headers[i].Number.Uint64()+1 {
+			return nil, errInvalidVotingChain
+		}
+	}
+	if headers[0].Number.Uint64() != s.Number+1 {
+		return nil, errInvalidVotingChain
+	}
+	// Iterate through the headers and create a new snapshot
+	snap := s.copy()
+
+	for _, header := range headers {
+		// Remove any votes on checkpoint blocks
+		number := header.Number.Uint64()
+		if number%s.config.Epoch == 0 {
+			snap.Votes = nil
+			snap.Tally = make(map[common.Address]clique.Tally)
+		}
+		// Delete the oldest signer from the recent list to allow it signing again
+		if limit := uint64(len(snap.Signers)/2 + 1); number >= limit {
+			delete(snap.Recents, number-limit)
+		}
+		// Resolve the authorization key and check against signers
+		signer, err := ecrecover(header, s.sigcache)
+		if err != nil {
+			return nil, err
+		}
+		//FIXME: skip signer checking at this step until a good solution found
+		//if _, ok := snap.Signers[signer]; !ok {
+		//	return nil, errUnauthorized
+		//}
+		//for _, recent := range snap.Recents {
+		//	if recent == signer {
+		//		return nil, errUnauthorized
+		//	}
+		//}
+		snap.Recents[number] = signer
+
+		// Header authorized, discard any previous votes from the signer
+		for i, vote := range snap.Votes {
+			if vote.Signer == signer && vote.Address == header.Coinbase {
+				// Uncast the vote from the cached tally
+				snap.uncast(vote.Address, vote.Authorize)
+
+				// Uncast the vote from the chronological list
+				snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...)
+				break // only one vote allowed
+			}
+		}
+		// Tally up the new vote from the signer
+		var authorize bool
+		switch {
+		case bytes.Equal(header.Nonce[:], nonceAuthVote):
+			authorize = true
+		case bytes.Equal(header.Nonce[:], nonceDropVote):
+			authorize = false
+		default:
+			return nil, errInvalidVote
+		}
+		if snap.cast(header.Coinbase, authorize) {
+			snap.Votes = append(snap.Votes, &clique.Vote{
+				Signer:    signer,
+				Block:     number,
+				Address:   header.Coinbase,
+				Authorize: authorize,
+			})
+		}
+		// If the vote passed, update the list of signers
+		if tally := snap.Tally[header.Coinbase]; tally.Votes > len(snap.Signers)/2 {
+			if tally.Authorize {
+				snap.Signers[header.Coinbase] = struct{}{}
+			} else {
+				delete(snap.Signers, header.Coinbase)
+
+				// Signer list shrunk, delete any leftover recent caches
+				if limit := uint64(len(snap.Signers)/2 + 1); number >= limit {
+					delete(snap.Recents, number-limit)
+				}
+				// Discard any previous votes the deauthorized signer cast
+				for i := 0; i < len(snap.Votes); i++ {
+					if snap.Votes[i].Signer == header.Coinbase {
+						// Uncast the vote from the cached tally
+						snap.uncast(snap.Votes[i].Address, snap.Votes[i].Authorize)
+
+						// Uncast the vote from the chronological list
+						snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...)
+
+						i--
+					}
+				}
+			}
+			// Discard any previous votes around the just changed account
+			for i := 0; i < len(snap.Votes); i++ {
+				if snap.Votes[i].Address == header.Coinbase {
+					snap.Votes = append(snap.Votes[:i], snap.Votes[i+1:]...)
+					i--
+				}
+			}
+			delete(snap.Tally, header.Coinbase)
+		}
+	}
+	snap.Number += uint64(len(headers))
+	snap.Hash = headers[len(headers)-1].Hash()
+
+	return snap, nil
+}
+
+// signers retrieves the list of authorized signers in ascending order.
+func (s *Snapshot) signers() []common.Address {
+	signers := make([]common.Address, 0, len(s.Signers))
+	for signer := range s.Signers {
+		signers = append(signers, signer)
+	}
+	for i := 0; i < len(signers); i++ {
+		for j := i + 1; j < len(signers); j++ {
+			if bytes.Compare(signers[i][:], signers[j][:]) > 0 {
+				signers[i], signers[j] = signers[j], signers[i]
+			}
+		}
+	}
+	return signers
+}
+
+// inturn returns if a signer at a given block height is in-turn or not.
+func (s *Snapshot) inturn(number uint64, signer common.Address) bool {
+	signers, offset := s.signers(), 0
+	for offset < len(signers) && signers[offset] != signer {
+		offset++
+	}
+	return (number % uint64(len(signers))) == uint64(offset)
+}

consensus/posv/snapshot_test.go

@@ -0,0 +1,404 @@
+// Copyright (c) 2018 Tomochain
+//
+// This program 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.
+//
+// This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
+
+package posv
+
+import (
+	"bytes"
+	"crypto/ecdsa"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+type testerVote struct {
+	signer string
+	voted  string
+	auth   bool
+}
+
+// testerAccountPool is a pool to maintain currently active tester accounts,
+// mapped from textual names used in the tests below to actual Ethereum private
+// keys capable of signing transactions.
+type testerAccountPool struct {
+	accounts map[string]*ecdsa.PrivateKey
+}
+
+func newTesterAccountPool() *testerAccountPool {
+	return &testerAccountPool{
+		accounts: make(map[string]*ecdsa.PrivateKey),
+	}
+}
+
+func (ap *testerAccountPool) sign(header *types.Header, signer string) {
+	// Ensure we have a persistent key for the signer
+	if ap.accounts[signer] == nil {
+		ap.accounts[signer], _ = crypto.GenerateKey()
+	}
+	// Sign the header and embed the signature in extra data
+	sig, _ := crypto.Sign(sigHash(header).Bytes(), ap.accounts[signer])
+	copy(header.Extra[len(header.Extra)-65:], sig)
+}
+
+func (ap *testerAccountPool) address(account string) common.Address {
+	// Ensure we have a persistent key for the account
+	if ap.accounts[account] == nil {
+		ap.accounts[account], _ = crypto.GenerateKey()
+	}
+	// Resolve and return the Ethereum address
+	return crypto.PubkeyToAddress(ap.accounts[account].PublicKey)
+}
+
+// testerChainReader implements consensus.ChainReader to access the genesis
+// block. All other methods and requests will panic.
+type testerChainReader struct {
+	db ethdb.Database
+}
+
+func (r *testerChainReader) Config() *params.ChainConfig                 { return params.AllPosvProtocolChanges }
+func (r *testerChainReader) CurrentHeader() *types.Header                { panic("not supported") }
+func (r *testerChainReader) GetHeader(common.Hash, uint64) *types.Header { panic("not supported") }
+func (r *testerChainReader) GetBlock(common.Hash, uint64) *types.Block   { panic("not supported") }
+func (r *testerChainReader) GetHeaderByHash(common.Hash) *types.Header   { panic("not supported") }
+func (r *testerChainReader) GetHeaderByNumber(number uint64) *types.Header {
+	if number == 0 {
+		return core.GetHeader(r.db, core.GetCanonicalHash(r.db, 0), 0)
+	}
+	panic("not supported")
+}
+
+// Tests that voting is evaluated correctly for various simple and complex scenarios.
+func TestVoting(t *testing.T) {
+	// Define the various voting scenarios to test
+	tests := []struct {
+		epoch   uint64
+		signers []string
+		votes   []testerVote
+		results []string
+	}{
+		{
+			// Single signer, no votes cast
+			signers: []string{"A"},
+			votes:   []testerVote{{signer: "A"}},
+			results: []string{"A"},
+		}, {
+			// Single signer, voting to add two others (only accept first, second needs 2 votes)
+			signers: []string{"A"},
+			votes: []testerVote{
+				{signer: "A", voted: "B", auth: true},
+				{signer: "B"},
+				{signer: "A", voted: "C", auth: true},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Two signers, voting to add three others (only accept first two, third needs 3 votes already)
+			signers: []string{"A", "B"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: true},
+				{signer: "B", voted: "C", auth: true},
+				{signer: "A", voted: "D", auth: true},
+				{signer: "B", voted: "D", auth: true},
+				{signer: "C"},
+				{signer: "A", voted: "E", auth: true},
+				{signer: "B", voted: "E", auth: true},
+			},
+			results: []string{"A", "B", "C", "D"},
+		}, {
+			// Single signer, dropping itself (weird, but one less cornercase by explicitly allowing this)
+			signers: []string{"A"},
+			votes: []testerVote{
+				{signer: "A", voted: "A", auth: false},
+			},
+			results: []string{},
+		}, {
+			// Two signers, actually needing mutual consent to drop either of them (not fulfilled)
+			signers: []string{"A", "B"},
+			votes: []testerVote{
+				{signer: "A", voted: "B", auth: false},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Two signers, actually needing mutual consent to drop either of them (fulfilled)
+			signers: []string{"A", "B"},
+			votes: []testerVote{
+				{signer: "A", voted: "B", auth: false},
+				{signer: "B", voted: "B", auth: false},
+			},
+			results: []string{"A"},
+		}, {
+			// Three signers, two of them deciding to drop the third
+			signers: []string{"A", "B", "C"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: false},
+				{signer: "B", voted: "C", auth: false},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Four signers, consensus of two not being enough to drop anyone
+			signers: []string{"A", "B", "C", "D"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: false},
+				{signer: "B", voted: "C", auth: false},
+			},
+			results: []string{"A", "B", "C", "D"},
+		}, {
+			// Four signers, consensus of three already being enough to drop someone
+			signers: []string{"A", "B", "C", "D"},
+			votes: []testerVote{
+				{signer: "A", voted: "D", auth: false},
+				{signer: "B", voted: "D", auth: false},
+				{signer: "C", voted: "D", auth: false},
+			},
+			results: []string{"A", "B", "C"},
+		}, {
+			// Authorizations are counted once per signer per target
+			signers: []string{"A", "B"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: true},
+				{signer: "B"},
+				{signer: "A", voted: "C", auth: true},
+				{signer: "B"},
+				{signer: "A", voted: "C", auth: true},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Authorizing multiple accounts concurrently is permitted
+			signers: []string{"A", "B"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: true},
+				{signer: "B"},
+				{signer: "A", voted: "D", auth: true},
+				{signer: "B"},
+				{signer: "A"},
+				{signer: "B", voted: "D", auth: true},
+				{signer: "A"},
+				{signer: "B", voted: "C", auth: true},
+			},
+			results: []string{"A", "B", "C", "D"},
+		}, {
+			// Deauthorizations are counted once per signer per target
+			signers: []string{"A", "B"},
+			votes: []testerVote{
+				{signer: "A", voted: "B", auth: false},
+				{signer: "B"},
+				{signer: "A", voted: "B", auth: false},
+				{signer: "B"},
+				{signer: "A", voted: "B", auth: false},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Deauthorizing multiple accounts concurrently is permitted
+			signers: []string{"A", "B", "C", "D"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: false},
+				{signer: "B"},
+				{signer: "C"},
+				{signer: "A", voted: "D", auth: false},
+				{signer: "B"},
+				{signer: "C"},
+				{signer: "A"},
+				{signer: "B", voted: "D", auth: false},
+				{signer: "C", voted: "D", auth: false},
+				{signer: "A"},
+				{signer: "B", voted: "C", auth: false},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Votes from deauthorized signers are discarded immediately (deauth votes)
+			signers: []string{"A", "B", "C"},
+			votes: []testerVote{
+				{signer: "C", voted: "B", auth: false},
+				{signer: "A", voted: "C", auth: false},
+				{signer: "B", voted: "C", auth: false},
+				{signer: "A", voted: "B", auth: false},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Votes from deauthorized signers are discarded immediately (auth votes)
+			signers: []string{"A", "B", "C"},
+			votes: []testerVote{
+				{signer: "C", voted: "B", auth: false},
+				{signer: "A", voted: "C", auth: false},
+				{signer: "B", voted: "C", auth: false},
+				{signer: "A", voted: "B", auth: false},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Cascading changes are not allowed, only the account being voted on may change
+			signers: []string{"A", "B", "C", "D"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: false},
+				{signer: "B"},
+				{signer: "C"},
+				{signer: "A", voted: "D", auth: false},
+				{signer: "B", voted: "C", auth: false},
+				{signer: "C"},
+				{signer: "A"},
+				{signer: "B", voted: "D", auth: false},
+				{signer: "C", voted: "D", auth: false},
+			},
+			results: []string{"A", "B", "C"},
+		}, {
+			// Changes reaching consensus out of bounds (via a deauth) execute on touch
+			signers: []string{"A", "B", "C", "D"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: false},
+				{signer: "B"},
+				{signer: "C"},
+				{signer: "A", voted: "D", auth: false},
+				{signer: "B", voted: "C", auth: false},
+				{signer: "C"},
+				{signer: "A"},
+				{signer: "B", voted: "D", auth: false},
+				{signer: "C", voted: "D", auth: false},
+				{signer: "A"},
+				{signer: "C", voted: "C", auth: true},
+			},
+			results: []string{"A", "B"},
+		}, {
+			// Changes reaching consensus out of bounds (via a deauth) may go out of consensus on first touch
+			signers: []string{"A", "B", "C", "D"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: false},
+				{signer: "B"},
+				{signer: "C"},
+				{signer: "A", voted: "D", auth: false},
+				{signer: "B", voted: "C", auth: false},
+				{signer: "C"},
+				{signer: "A"},
+				{signer: "B", voted: "D", auth: false},
+				{signer: "C", voted: "D", auth: false},
+				{signer: "A"},
+				{signer: "B", voted: "C", auth: true},
+			},
+			results: []string{"A", "B", "C"},
+		}, {
+			// Ensure that pending votes don't survive authorization status changes. This
+			// corner case can only appear if a signer is quickly added, removed and then
+			// readded (or the inverse), while one of the original voters dropped. If a
+			// past vote is left cached in the system somewhere, this will interfere with
+			// the final signer outcome.
+			signers: []string{"A", "B", "C", "D", "E"},
+			votes: []testerVote{
+				{signer: "A", voted: "F", auth: true}, // Authorize F, 3 votes needed
+				{signer: "B", voted: "F", auth: true},
+				{signer: "C", voted: "F", auth: true},
+				{signer: "D", voted: "F", auth: false}, // Deauthorize F, 4 votes needed (leave A's previous vote "unchanged")
+				{signer: "E", voted: "F", auth: false},
+				{signer: "B", voted: "F", auth: false},
+				{signer: "C", voted: "F", auth: false},
+				{signer: "D", voted: "F", auth: true}, // Almost authorize F, 2/3 votes needed
+				{signer: "E", voted: "F", auth: true},
+				{signer: "B", voted: "A", auth: false}, // Deauthorize A, 3 votes needed
+				{signer: "C", voted: "A", auth: false},
+				{signer: "D", voted: "A", auth: false},
+				{signer: "B", voted: "F", auth: true}, // Finish authorizing F, 3/3 votes needed
+			},
+			results: []string{"B", "C", "D", "E", "F"},
+		}, {
+			// Epoch transitions reset all votes to allow chain checkpointing
+			epoch:   3,
+			signers: []string{"A", "B"},
+			votes: []testerVote{
+				{signer: "A", voted: "C", auth: true},
+				{signer: "B"},
+				{signer: "A"}, // Checkpoint block, (don't vote here, it's validated outside of snapshots)
+				{signer: "B", voted: "C", auth: true},
+			},
+			results: []string{"A", "B"},
+		},
+	}
+	// Run through the scenarios and test them
+	for i, tt := range tests {
+		// Create the account pool and generate the initial set of signers
+		accounts := newTesterAccountPool()
+
+		signers := make([]common.Address, len(tt.signers))
+		for j, signer := range tt.signers {
+			signers[j] = accounts.address(signer)
+		}
+		for j := 0; j < len(signers); j++ {
+			for k := j + 1; k < len(signers); k++ {
+				if bytes.Compare(signers[j][:], signers[k][:]) > 0 {
+					signers[j], signers[k] = signers[k], signers[j]
+				}
+			}
+		}
+		// Create the genesis block with the initial set of signers
+		genesis := &core.Genesis{
+			ExtraData: make([]byte, extraVanity+common.AddressLength*len(signers)+extraSeal),
+		}
+		for j, signer := range signers {
+			copy(genesis.ExtraData[extraVanity+j*common.AddressLength:], signer[:])
+		}
+		// Create a pristine blockchain with the genesis injected
+		db, _ := ethdb.NewMemDatabase()
+		genesis.Commit(db)
+
+		// Assemble a chain of headers from the cast votes
+		headers := make([]*types.Header, len(tt.votes))
+		for j, vote := range tt.votes {
+			headers[j] = &types.Header{
+				Number:   big.NewInt(int64(j) + 1),
+				Time:     big.NewInt(int64(j) * int64(blockPeriod)),
+				Coinbase: accounts.address(vote.voted),
+				Extra:    make([]byte, extraVanity+extraSeal),
+			}
+			if j > 0 {
+				headers[j].ParentHash = headers[j-1].Hash()
+			}
+			if vote.auth {
+				copy(headers[j].Nonce[:], nonceAuthVote)
+			}
+			accounts.sign(headers[j], vote.signer)
+		}
+		// Pass all the headers through posv and ensure tallying succeeds
+		head := headers[len(headers)-1]
+
+		snap, err := New(&params.PosvConfig{Epoch: tt.epoch}, db).snapshot(&testerChainReader{db: db}, head.Number.Uint64(), head.Hash(), headers)
+		if err != nil {
+			t.Errorf("test %d: failed to create voting snapshot: %v", i, err)
+			continue
+		}
+		// Verify the final list of signers against the expected ones
+		signers = make([]common.Address, len(tt.results))
+		for j, signer := range tt.results {
+			signers[j] = accounts.address(signer)
+		}
+		for j := 0; j < len(signers); j++ {
+			for k := j + 1; k < len(signers); k++ {
+				if bytes.Compare(signers[j][:], signers[k][:]) > 0 {
+					signers[j], signers[k] = signers[k], signers[j]
+				}
+			}
+		}
+		result := snap.signers()
+		if len(result) != len(signers) {
+			t.Errorf("test %d: signers mismatch: have %x, want %x", i, result, signers)
+			continue
+		}
+		for j := 0; j < len(result); j++ {
+			if !bytes.Equal(result[j][:], signers[j][:]) {
+				t.Errorf("test %d, signer %d: signer mismatch: have %x, want %x", i, j, result[j], signers[j])
+			}
+		}
+	}
+}

contracts/utils.go

@@ -46,7 +46,7 @@ type rewardLog struct {
 
 // Send tx sign for block number to smart contract blockSigner.
 func CreateTransactionSign(chainConfig *params.ChainConfig, pool *core.TxPool, manager *accounts.Manager, block *types.Block) error {
-	if chainConfig.Clique != nil {
+	if chainConfig.Posv != nil {
 		// Find active account.
 		account := accounts.Account{}
 		var wallet accounts.Wallet

core/blockchain.go

@@ -1189,13 +1189,13 @@ func (bc *BlockChain) insertChain(chain types.Blocks) (int, []interface{}, []*ty
 		stats.processed++
 		stats.usedGas += usedGas
 		stats.report(chain, i, bc.stateCache.TrieDB().Size())
-		if i == len(chain)-1 && bc.chainConfig.Clique != nil {
+		if i == len(chain)-1 && bc.chainConfig.Posv != nil {
 			// epoch block
-			if (chain[i].NumberU64() % bc.chainConfig.Clique.Epoch) == 0 {
+			if (chain[i].NumberU64() % bc.chainConfig.Posv.Epoch) == 0 {
 				CheckpointCh <- 1
 			}
 			// prepare set of masternodes for the next epoch
-			if (chain[i].NumberU64() % bc.chainConfig.Clique.Epoch) == (bc.chainConfig.Clique.Epoch - bc.chainConfig.Clique.Gap) {
+			if (chain[i].NumberU64() % bc.chainConfig.Posv.Epoch) == (bc.chainConfig.Posv.Epoch - bc.chainConfig.Posv.Gap) {
 				M1Ch <- 1
 			}
 		}

core/chain_makers.go

@@ -176,7 +176,7 @@ func GenerateChain(config *params.ChainConfig, parent *types.Block, engine conse
 	}
 	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.
+		// TODO(karalabe): This is needed for posv, which depends on multiple blocks.
 		// It's nonetheless ugly to spin up a blockchain here. Get rid of this somehow.
 		blockchain, _ := NewBlockChain(db, nil, config, engine, vm.Config{})
 		defer blockchain.Stop()

core/genesis.go

@@ -348,8 +348,8 @@ func DefaultRinkebyGenesisBlock() *Genesis {
 // be seeded with the
 func DeveloperGenesisBlock(period uint64, faucet common.Address) *Genesis {
 	// Override the default period to the user requested one
-	config := *params.AllCliqueProtocolChanges
+	config := *params.AllPosvProtocolChanges
-	config.Clique.Period = period
+	config.Posv.Period = period
 
 	// Assemble and return the genesis with the precompiles and faucet pre-funded
 	return &Genesis{

eth/backend.go

@@ -29,7 +29,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/consensus"
-	"github.com/ethereum/go-ethereum/consensus/clique"
+	"github.com/ethereum/go-ethereum/consensus/posv"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/contracts"
 	"github.com/ethereum/go-ethereum/contracts/validator/contract"
@@ -186,8 +186,8 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 	// Set global ipc endpoint.
 	eth.blockchain.IPCEndpoint = ctx.GetConfig().IPCEndpoint()
 
-	if eth.chainConfig.Clique != nil {
+	if eth.chainConfig.Posv != nil {
-		c := eth.engine.(*clique.Clique)
+		c := eth.engine.(*posv.Posv)
 
 		// Inject hook for send tx sign to smartcontract after insert block into chain.
 		importedHook := func(block *types.Block) {
@@ -209,18 +209,18 @@ func New(ctx *node.ServiceContext, config *Config) (*Ethereum, error) {
 		}
 		eth.protocolManager.fetcher.SetImportedHook(importedHook)
 
-		// Hook reward for clique validator.
+		// Hook reward for posv validator.
 		c.HookReward = func(chain consensus.ChainReader, state *state.StateDB, header *types.Header) error {
 			client, err := eth.blockchain.GetClient()
 			if err != nil {
 				log.Error("Fail to connect IPC client for blockSigner", "error", err)
 			}
 			number := header.Number.Uint64()
-			rCheckpoint := chain.Config().Clique.RewardCheckpoint
+			rCheckpoint := chain.Config().Posv.RewardCheckpoint
 			if number > 0 && number-rCheckpoint > 0 {
 				// Get signers in blockSigner smartcontract.
 				addr := common.HexToAddress(common.BlockSigners)
-				chainReward := new(big.Int).Mul(new(big.Int).SetUint64(chain.Config().Clique.Reward), new(big.Int).SetUint64(params.Ether))
+				chainReward := new(big.Int).Mul(new(big.Int).SetUint64(chain.Config().Posv.Reward), new(big.Int).SetUint64(params.Ether))
 				totalSigner := new(uint64)
 				signers, err := contracts.GetRewardForCheckpoint(chain, addr, number, rCheckpoint, client, totalSigner)
 				if err != nil {
@@ -285,9 +285,9 @@ func CreateDB(ctx *node.ServiceContext, config *Config, name string) (ethdb.Data
 
 // CreateConsensusEngine creates the required type of consensus engine instance for an Ethereum service
 func CreateConsensusEngine(ctx *node.ServiceContext, config *ethash.Config, chainConfig *params.ChainConfig, db ethdb.Database) consensus.Engine {
-	// If proof-of-authority is requested, set it up
+	// If proof-of-stake-voting is requested, set it up
-	if chainConfig.Clique != nil {
+	if chainConfig.Posv != nil {
-		return clique.New(chainConfig.Clique, db)
+		return posv.New(chainConfig.Posv, db)
 	}
 	// Otherwise assume proof-of-work
 	switch {
@@ -413,9 +413,9 @@ func (s *Ethereum) ValidateStaker() (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	if s.chainConfig.Clique != nil {
+	if s.chainConfig.Posv != nil {
 		//check if miner's wallet is in set of validators
-		c := s.engine.(*clique.Clique)
+		c := s.engine.(*posv.Posv)
 		snap, err := c.GetSnapshot(s.blockchain, s.blockchain.CurrentHeader())
 		if err != nil {
 			return false, fmt.Errorf("Can't verify miner: %v", err)
@@ -425,18 +425,18 @@ func (s *Ethereum) ValidateStaker() (bool, error) {
 			return false, nil
 		}
 	} else {
-		return false, fmt.Errorf("Only verify miners in Clique protocol")
+		return false, fmt.Errorf("Only verify miners in Posv protocol")
 	}
 	return true, nil
 }
 
 // Store new set of masternodes into local db
-func (s *Ethereum) UpdateMasternodes(ms []clique.Masternode) error {
+func (s *Ethereum) UpdateMasternodes(ms []posv.Masternode) error {
 	// get snapshot from local db
-	if s.chainConfig.Clique == nil {
+	if s.chainConfig.Posv == nil {
-		return errors.New("not clique")
+		return errors.New("not posv")
 	}
-	c := s.engine.(*clique.Clique)
+	c := s.engine.(*posv.Posv)
 	return c.UpdateMasternodes(s.blockchain, s.blockchain.CurrentHeader(), ms)
 }
 
@@ -446,13 +446,13 @@ func (s *Ethereum) StartStaking(local bool) error {
 		log.Error("Cannot start mining without etherbase", "err", err)
 		return fmt.Errorf("etherbase missing: %v", err)
 	}
-	if clique, ok := s.engine.(*clique.Clique); ok {
+	if posv, ok := s.engine.(*posv.Posv); ok {
 		wallet, err := s.accountManager.Find(accounts.Account{Address: eb})
 		if wallet == nil || err != nil {
 			log.Error("Etherbase account unavailable locally", "err", err)
 			return fmt.Errorf("signer missing: %v", err)
 		}
-		clique.Authorize(eb, wallet.SignHash)
+		posv.Authorize(eb, wallet.SignHash)
 	}
 	if local {
 		// If local (CPU) mining is started, we can disable the transaction rejection

internal/ethapi/api.go

@@ -30,7 +30,7 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/common/math"
-	"github.com/ethereum/go-ethereum/consensus/clique"
+	"github.com/ethereum/go-ethereum/consensus/posv"
 	"github.com/ethereum/go-ethereum/consensus/ethash"
 	"github.com/ethereum/go-ethereum/contracts"
 	"github.com/ethereum/go-ethereum/core"
@@ -44,6 +44,7 @@ import (
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/syndtr/goleveldb/leveldb"
 	"github.com/syndtr/goleveldb/leveldb/util"
+	"github.com/ethereum/go-ethereum/consensus/posv"
 )
 
 const (
@@ -862,12 +863,12 @@ func (s *PublicBlockChainAPI) rpcOutputBlock(b *types.Block, inclTx bool, fullTx
 			log.Error("Fail to get signers from block signer SC.", "error", err)
 		}
 		// Get block epoc latest.
-		if s.b.ChainConfig().Clique != nil {
+		if s.b.ChainConfig().Posv != nil {
 			engine := s.b.GetEngine()
-			lastCheckpointNumber := rpc.BlockNumber(b.Number().Uint64() - (b.Number().Uint64() % s.b.ChainConfig().Clique.Epoch))
+			lastCheckpointNumber := rpc.BlockNumber(b.Number().Uint64() - (b.Number().Uint64() % s.b.ChainConfig().Posv.Epoch))
 			prevCheckpointBlock, _ := s.b.BlockByNumber(ctx, lastCheckpointNumber)
 			if prevCheckpointBlock != nil {
-				masternodes := engine.(*clique.Clique).GetMasternodesFromCheckpointHeader(prevCheckpointBlock.Header(), b.Number().Uint64(), s.b.ChainConfig().Clique.Epoch)
+				masternodes := engine.(*posv.Posv).GetMasternodesFromCheckpointHeader(prevCheckpointBlock.Header(), b.Number().Uint64(), s.b.ChainConfig().Clique.Epoch)
 				countFinality := 0
 				for _, masternode := range masternodes {
 					for _, signer := range signers {

internal/web3ext/web3ext.go

@@ -20,7 +20,7 @@ package web3ext
 var Modules = map[string]string{
 	"admin":      Admin_JS,
 	"chequebook": Chequebook_JS,
-	"clique":     Clique_JS,
+	"posv":       Posv_JS,
 	"debug":      Debug_JS,
 	"eth":        Eth_JS,
 	"miner":      Miner_JS,
@@ -63,47 +63,47 @@ web3._extend({
 });
 `
 
-const Clique_JS = `
+const Posv_JS = `
 web3._extend({
-	property: 'clique',
+	property: 'posv',
 	methods: [
 		new web3._extend.Method({
 			name: 'getSnapshot',
-			call: 'clique_getSnapshot',
+			call: 'posv_getSnapshot',
 			params: 1,
 			inputFormatter: [null]
 		}),
 		new web3._extend.Method({
 			name: 'getSnapshotAtHash',
-			call: 'clique_getSnapshotAtHash',
+			call: 'posv_getSnapshotAtHash',
 			params: 1
 		}),
 		new web3._extend.Method({
 			name: 'getSigners',
-			call: 'clique_getSigners',
+			call: 'posv_getSigners',
 			params: 1,
 			inputFormatter: [null]
 		}),
 		new web3._extend.Method({
 			name: 'getSignersAtHash',
-			call: 'clique_getSignersAtHash',
+			call: 'posv_getSignersAtHash',
 			params: 1
 		}),
 		new web3._extend.Method({
 			name: 'propose',
-			call: 'clique_propose',
+			call: 'posv_propose',
 			params: 2
 		}),
 		new web3._extend.Method({
 			name: 'discard',
-			call: 'clique_discard',
+			call: 'posv_discard',
 			params: 1
 		}),
 	],
 	properties: [
 		new web3._extend.Property({
 			name: 'proposals',
-			getter: 'clique_proposals'
+			getter: 'posv_proposals'
 		}),
 	]
 });

miner/worker.go

@@ -26,7 +26,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/consensus"
-	"github.com/ethereum/go-ethereum/consensus/clique"
+	"github.com/ethereum/go-ethereum/consensus/posv"
 	"github.com/ethereum/go-ethereum/consensus/misc"
 	"github.com/ethereum/go-ethereum/contracts"
 	"github.com/ethereum/go-ethereum/core"
@@ -275,7 +275,7 @@ func (self *worker) update() {
 				self.currentMu.Unlock()
 			} else {
 				// If we're mining, but nothing is being processed, wake on new transactions
-				if self.config.Clique != nil && self.config.Clique.Period == 0 {
+				if self.config.Posv != nil && self.config.Posv.Period == 0 {
 					self.commitNewWork()
 				}
 			}
@@ -342,8 +342,8 @@ func (self *worker) wait() {
 				self.commitNewWork()
 			}
 
-			if self.config.Clique != nil {
+			if self.config.Posv != nil {
-				c := self.engine.(*clique.Clique)
+				c := self.engine.(*posv.Posv)
 				snap, err := c.GetSnapshot(self.chain, block.Header())
 				if err != nil {
 					log.Error("Fail to get snapshot for sign tx signer.")
@@ -449,17 +449,17 @@ func (self *worker) commitNewWork() {
 	// Only try to commit new work if we are mining
 	if atomic.LoadInt32(&self.mining) == 1 {
 		// check if we are right after parent's coinbase in the list
-		// only go with Clique
+		// only go with Posv
-		if self.config.Clique != nil {
+		if self.config.Posv != nil {
 			// get masternodes set from latest checkpoint
-			c := self.engine.(*clique.Clique)
+			c := self.engine.(*posv.Posv)
 			masternodes := c.GetMasternodes(self.chain, parent.Header())
 			snap, err := c.GetSnapshot(self.chain, parent.Header())
 			if err != nil {
 				log.Error("Failed when trying to commit new work", "err", err)
 				return
 			}
-			preIndex, curIndex, ok, err := clique.YourTurn(masternodes, snap, parent.Header(), self.coinbase)
+			preIndex, curIndex, ok, err := posv.YourTurn(masternodes, snap, parent.Header(), self.coinbase)
 			if err != nil {
 				log.Error("Failed when trying to commit new work", "err", err)
 				return
@@ -586,13 +586,13 @@ func (self *worker) commitNewWork() {
 		log.Info("Commit new mining work", "number", work.Block.Number(), "txs", work.tcount, "uncles", len(uncles), "elapsed", common.PrettyDuration(time.Since(tstart)))
 		self.unconfirmed.Shift(work.Block.NumberU64() - 1)
 	}
-	if work.config.Clique != nil {
+	if work.config.Posv != nil {
 		// epoch block
-		if (work.Block.NumberU64() % work.config.Clique.Epoch) == 0 {
+		if (work.Block.NumberU64() % work.config.Posv.Epoch) == 0 {
 			core.CheckpointCh <- 1
 		}
 		// prepare set of masternodes for the next epoch
-		if (work.Block.NumberU64() % work.config.Clique.Epoch) == (work.config.Clique.Epoch - work.config.Clique.Gap) {
+		if (work.Block.NumberU64() % work.config.Posv.Epoch) == (work.config.Posv.Epoch - work.config.Posv.Gap) {
 			core.M1Ch <- 1
 		}
 	}

params/config.go

@@ -71,7 +71,7 @@ var (
 		EIP158Block:         big.NewInt(3),
 		ByzantiumBlock:      big.NewInt(1035301),
 		ConstantinopleBlock: nil,
-		Clique: &CliqueConfig{
+		Posv: &PosvConfig{
 			Period: 15,
 			Epoch:  30000,
 		},
@@ -82,16 +82,16 @@ var (
 	//
 	// This configuration is intentionally not using keyed fields to force anyone
 	// adding flags to the config to also have to set these fields.
-	AllEthashProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil}
+	AllEthashProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil,nil}
 
-	// AllCliqueProtocolChanges contains every protocol change (EIPs) introduced
+	// AllPosvProtocolChanges contains every protocol change (EIPs) introduced
-	// and accepted by the Ethereum core developers into the Clique consensus.
+	// and accepted by the Ethereum core developers into the Posv consensus.
 	//
 	// This configuration is intentionally not using keyed fields to force anyone
 	// adding flags to the config to also have to set these fields.
-	AllCliqueProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil, &CliqueConfig{Period: 0, Epoch: 30000}}
+	AllPosvProtocolChanges = &ChainConfig{big.NewInt(1337), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, nil,nil, &PosvConfig{Period: 0, Epoch: 30000}}
 
-	TestChainConfig = &ChainConfig{big.NewInt(1), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil}
+	TestChainConfig = &ChainConfig{big.NewInt(1), big.NewInt(0), nil, false, big.NewInt(0), common.Hash{}, big.NewInt(0), big.NewInt(0), big.NewInt(0), nil, new(EthashConfig), nil,nil}
 	TestRules       = TestChainConfig.Rules(new(big.Int))
 )
 
@@ -121,6 +121,7 @@ type ChainConfig struct {
 	// Various consensus engines
 	Ethash *EthashConfig `json:"ethash,omitempty"`
 	Clique *CliqueConfig `json:"clique,omitempty"`
+	Posv   *PosvConfig   `json:"posv,omitempty"`
 }
 
 // EthashConfig is the consensus engine configs for proof-of-work based sealing.
@@ -133,6 +134,18 @@ func (c *EthashConfig) String() string {
 
 // CliqueConfig is the consensus engine configs for proof-of-authority based sealing.
 type CliqueConfig struct {
+	Period uint64 `json:"period"` // Number of seconds between blocks to enforce
+	Epoch  uint64 `json:"epoch"`  // Epoch length to reset votes and checkpoint
+}
+
+// String implements the stringer interface, returning the consensus engine details.
+func (c *CliqueConfig) String() string {
+	return "clique"
+}
+
+
+// PosvConfig is the consensus engine configs for proof-of-stake-voting based sealing.
+type PosvConfig struct {
 	Period           uint64 `json:"period"`           // Number of seconds between blocks to enforce
 	Epoch            uint64 `json:"epoch"`            // Epoch length to reset votes and checkpoint
 	Reward           uint64 `json:"reward"`           // Block reward - unit Ether
@@ -141,8 +154,8 @@ type CliqueConfig struct {
 }
 
 // String implements the stringer interface, returning the consensus engine details.
-func (c *CliqueConfig) String() string {
+func (c *PosvConfig) String() string {
-	return "clique"
+	return "posv"
 }
 
 // String implements the fmt.Stringer interface.
@@ -151,8 +164,8 @@ func (c *ChainConfig) String() string {
 	switch {
 	case c.Ethash != nil:
 		engine = c.Ethash
-	case c.Clique != nil:
+	case c.Posv != nil:
-		engine = c.Clique
+		engine = c.Posv
 	default:
 		engine = "unknown"
 	}